Category: Stress

While anxiety symptoms vary wide, odds are sensible that at some purpose you’ve knowledgeable occasional physical and emotional distress signals like panic-struck respiration, your heart pounding in your chest, hassle sleeping, feelings of dread, or perhaps loops of worry. That’s traditional. By itself, anxiety isn’t a controversy. It anchors the protecting biological response to danger that reinforces heartbeat and respiration, pumping aerated blood to your muscles as your body prepares to fight or take flight. A small indefinite quantity of healthy anxiety will persuade you to urge to figure on time, push you to review arduous for associate degree test, or discourage you from wandering dark streets alone.

“Experiencing anxiety is traditional,” says Dr. Cistron Beresin, executive of the Clay Center for Healthy Young Minds at Massachusetts General Hospital. “A specific amount of hysteria will even be useful. the matter is that generally the systems underlying our anxiety responses get dysregulated, so we tend to react or react to the incorrect things.”

Constant anxiety levies a toll on health. for instance, anxiety will increase levels of the strain internal secretion Cortef, raising force per unit area, that contributes over time to heart issues, stroke, aeropathy, and sexual pathology. And a 2017 Lancet study exploitation brain scans measured activity in a locality known as the corpus amygdaloideum, that mounts split-second responses to danger and encodes recollections of horrifying events. bigger activity within the corpus amygdaloideum related with higher risk for cardiovascular disease and stroke, possibly, the researchers speculated, by triggering system production of additional white cells to fight perceived threats. In individuals fighting emotional stress, this would possibly drive inflammation and plaque formation that ends up in heart attacks and strokes. Quality of life suffers, too. Intrusive thoughts, dread of panic attacks, intense self-consciousness and worry of rejection, and different hallmarks of hysteria disorders compel individuals to avoid anxiety-provoking things. This interferes with relationships, work, school, and activities as individuals isolate themselves, flip down opportunities, and forgo doable joys in life.

Max Psychiatry, www.maxpsychiatry, we are purposefully here to support ,create awareness and fully focused on providing complete behavioral healthcare at large. We have expertise in treating variety of mental/behavioral health disorders in adults and adolescents. Ideally, at Max Psychiatry with vast and in-depth research and surveys were able to analyze key signs and symptoms that we are going to discuss to help create awareness and ultimately allow individuals to be able to curb anxiety related problems.

Sign and symptoms of anxiety

• Difficulty Concentrating-Some studies show that anxiety will interrupt remembering, a kind of memory accountable for holding short info. this might facilitate make a case for the dramatic decrease in performance individuals usually expertise in periods of high anxiety.
• Irritability-According to one our recent study as well as over half-dozen,5000 adults, over ninetieth of these with generalized mental disorder reportable feeling extremely irritable in periods once their anxiety disorder was at its worst
• Fatigue-For some, fatigue will follow an attack, whereas for others, the fatigue will be chronic. It’s unclear whether or not this fatigue is because of different common symptoms of hysteria, like sleep disorder or muscle tension, or whether or not it’s going to be associated with the secretion effects of chronic anxiety

However, it’s vital to notice that fatigue may be an indication of depression or different medical conditions, thus fatigue alone isn’t enough to diagnose AN mental disturbance.

• Trouble Falling or Staying Asleep-Waking up within the middle of the night and having hassle falling asleep are the 2 most ordinarily according issues. Sleep disturbances are strongly associated with anxiety disorders
• Panic Attack-Panic attacks turn out associate degree intense, overwhelming sensation of worry which will be draining. This extreme worry is often in the middle of speedy heartbeat, sweating, shaking, shortness of breath, chest tightness, nausea and worry of dying or losing management.

Having listed some of the key signs and symptoms, our organization come up with almost possible solutions to help individuals navigate through these difficulties. Below are some activities we researched on to help one distract and possibly curb anxiety.

• Get your heart pumping, lungs respiratory deeply, muscles operating, and positive hormones flowing, walk, jog, run stairs, Jump rope, swim, move your body any manner you’re ready and you get pleasure from. think about it as sweating the anxiety out of you.
• Learn something new-browse a shop and gather some books on a subject that sounds fascinating to you. you’ll be able to do that at a library, too. you’ll be able to explore on your own with no pressure to perform. If you relish categories and getting ready work for a grade, that’s an excellent distraction, too (as long as you actually relish this and also the else pressure of analysis won’t increase anxiety).
• Lifestyle Changes-Things like obtaining exercise, avoiding alcohol and different recreational medication, limiting caffeine, maintaining a healthy diet, and obtaining enough sleep will usually facilitate to calm anxiety.
• Medications-Medical prescriptions to treat anxiety. Commonly used are antidepressant-anxiety medications such as buspironea, benzodiazepine for relief of panic attacks.

MENTAL HEALTH AWERENESS-STRESS MANAGEMENT

Stress management starts with characteristic the sources of stress in your life. This isn’t as easy because it sounds. whereas it’s simple to spot major stressors like dynamical jobs, moving, or a longing a divorce, pinpointing the sources of chronic stress are often a lot of sophisticated. It’s only too simple to overlook however your own thoughts, feelings, and behaviors contribute to your everyday stress levels. Sure, you will recognize that you’re perpetually disquieted regarding work deadlines, however perhaps it’s your procrastination, instead of the particular job demands, that’s inflicting the strain.

To identify your true sources of stress, look closely at your habits, attitude, and excuses:

• Do you make a case for away stress as temporary (“I simply have 1,000,000 things occurring right now”) although you can’t keep in mind the last time you took a breather?
• Do you outline stress as Associate in Nursing integral a part of your work or home life (“Things are invariably crazy around here”) or as a component of your temperament (“I have lots of nervous energy, that’s all”)?
• Do you blame your stress on people or outside events, or read it as entirely traditional and unexceptional?
• Until you settle for responsibility for the role you play in making or maintaining it, your stress level can stay outside your management.

While stress is Associate in Nursing automatic response from your system, some stressors arise at sure times: your commute to figure, a gathering together with your boss, or family gatherings, as an example. once handling such sure stressors, you’ll be able to either amendment matters or change your reaction. once deciding that choice to opt for in any given state of affairs, it’s useful to consider the four A’s: avoid, alter, adapt, or accept. Avoid unnecessary stress, Alter the situation, adapt to the situation, or Accept the things you cannot change.

Stress will be effectively managed in many alternative ways that. the most effective stress management plans sometimes embrace a mixture of stress relievers that address stress physically and psychologically and facilitate to develop resilience and cope skills.

Use fast stress relievers. Some stress relief techniques will add simply some minutes to calm the body’s stress response. These techniques provide a ‘quick fix’ that helps you are feeling calmer at the instant, and this may facilitate in many ways that. once your stress response isn’t triggered, you will approach issues additional thoughtfully and proactively. you will be less probably to knock at others out of frustration, which might keep your relationships healthier. Nipping your stress response within the bud can even keep you from experiencing chronic stress.

Quick stress relievers like respiration exercises, as an example, might not build your resilience to future stress or minimize the stressors that you just face, however they’ll facilitate calm the body’s physiology once the strain response is triggered. Develop stress-relieving habits. Some techniques are less convenient to use once you are within the middle of a nerve-racking state of affairs. however, if you apply them often, they’ll facilitate you manage stress generally by being less reactive thereto and additional able to reverse your stress response quickly and simply.

Long-term healthy habits, like exercise or regular meditation, will facilitate to market resilience toward stressors if you create them an everyday a part of your life. Communication skills and different modus vivendi skills will be useful in managing stressors and ever-changing however we tend to feel from ‘overwhelmed’ to ‘challenged’ or perhaps ‘stimulated.’

Eliminate stressors once you will. you will not be able to fully eliminate stress from your life or perhaps the most important stressors, however there are areas wherever you’ll be able to minimize it and acquire it to a manageable level. Any stress that you just will cut out can minimize your overall stress load. as an example, ending even one virulent relationship will facilitate your additional effectively cater to different stress your expertise as a result of you will feel less engulfed.

Abstract

The capacity of stainless steel to withstand fire conditions can be determined from the stress-strain relationships. This report analyses the mechanical properties of EN 1.4301 and EN 1.4462 stainless steel types in order to explain how these properties affect the stress-strain relationships. It also reviews past studies into the material properties of steel under fire conditions and examines the various models proposed for steel fire designs. The analysis bases on two tests, the steady state and transient-state tests, which can explain the behavior of steel at elevated temperatures. Stress-strain relationships provide an accurate prediction of the properties of stainless steel under fire conditions. Engineers and studies have conducted many studies involving both transient-state and steady state tests to determine the material properties of steel under fire conditions.

This work explores the mechanical attributes data of stainless steel at sublime temperatures. Accurate predictions of the material properties including yield strength, elastic modulus and ultimate strength at elevated temperatures, of between 20◦C to 900◦C, proposed by different studies compare with the European, American, and British standards. Furthermore, other studies propose a strain-stress model of stainless steel at elevated temperatures. The stress-strain relationship is important in evaluating the capacity of stainless steel to withstand fire conditions.

Introduction

In fire design models of various materials, factors such as yield strength of the material, the shape and dimensions of cross-section and reduction factors for yield strength and elastic modulus provide relevant data for designing fire resistant material. Buchanen, Moss, Seputro, and Welsh (2004) posit that, the stress-strain relationship of a material “at elevated temperatures is important in assessing the load-bearing level of the structure when in fire condition” (p.1505). For a steel structure to exhibit mechanical resistance to fire, its load-bearing function should be high in exposure to relevant fire conditions. In addition, in order to study the deformation processes during high rate strain deformation, the analyst should apply deformation modes of the load bearing structure, micro-twins, and micro-bands, for both carbon and stainless steels.

In most structural applications, Engineers use austenitic and duplex steels. Austenitic steels have a combination of good qualities including a high design strength of 220N/mm², corrosion resistance and fabrication properties. The commonly used austenitic stainless steel grades include 304/304L and 316/316L while the most commonly used duplex stainless steel is grade 1.4462. Steady-state tensile tests and transient states determine the stress-strain relationships at high temperature conditions for stainless steel (Drysdale 1999, p. 87).The stress-strain relationship for carbon steel is different from that of stainless steel (figures 1 and 2).

From a stress-strain curve, structural engineers determine the mechanical properties of stainless steel such as elastic modulus, yield strength, ultimate strength, and strain. The non-linear stress-strain relationship of stainless steel is an indication that its behavior is sensitive to elevated temperature and yield stress. As a result, to establish a non-numerical model for steel structures, the stress-strain relationship is important. The stress-strain relationship and the mechanical properties of stainless steel at elevated temperatures are important in fire design models for steel.

Literature Review

The Steady-State test

To study the behavior of stainless steel at elevated temperatures, the material data of the steel obtained through testing is important. ca Steady-state tensile tests and transient-state procedures determine the stress-strain relationships of stainless steel at high temperature conditions. Steady-state tests are of two types; strain controlled tests, whereby strain is maintained as a constant while the load is varied or load-controlled tests, where the load rate is maintained at a constant level. To generate data for fire design guidance of stainless steel, the steady state tests are therefore important. Outinen, Kaitila, and Makelainen (2000) conducted isothermal material tests (steady-state tests) for cold worked materials at elevated temperature (p. 6). They used three types of austenitic stainless steel: the Polarit 761, Polarit, 731 and Polarit, 711 in these tests. In steady-state tests, they heated the test material to a specified temperature before applying the tensile load. In their experiment, they maintained constant temperature as they varied the loads. The temperature in steady-state tests is maintained at a specified level while the load is continually changed. This means that only the load rate has an effect on the results, as the temperature is a constant. The stress at a particular strain normally decreases with the load rate (Sakumoto, Nakazato, & Matsuzaki 1996, p.399).

In contrast to carbon steels, stainless steel stress-strain relationship is non-linear with no clear yield point (Figures 1 and 2). As a result, engineers define the yield stress/strain (point) for stainless steel in reference to a 0.2% proof strain (Eurocode 2001, p. 3). Outinen, Kaitila and Makelainen obtained stress values in relation to different proof strains including 0.1%, 0.2% and 2%, measured the values of modulus of elasticity and tensile strength of the material before comparing these values with pr EN 1993-1-2 [1] values (2000, p. 11). The three test materials behaved differently with regard to stress-strain relationships. Outinen and Makelainen carried out steady state tests on stainless steel grade EN 1.4301 using a tensile testing machine (2001, p. 3). The stress-strain values for cold formed material compared to those of the base material. In both tests, they obtained the modulus of elasticity values, which is the stress-strain ratio at a single point, from the stress-strain curves and compared with standard values.

The Transient State Tests

Transient state tests involve subjecting the test material to constant tensile stress and increasing temperature. The gradual increase in temperature is due to two reasons; firstly, in load-controlled tests, there is a rapid loss of tensile strength, which the loading machine cannot measure when the temperature rapidly increases. Secondly, for each specified temperature, the analyst needs the strain data for the conversion of the transient test results into stress-strain curves (Rhodes 1991, p. 231). This test involves temperature and strain measurement to generate temperature-strain curves. Such curves provide important strain properties of the material at elevated temperatures. The analyst deducts thermal elongation, the expansion due to heating, from the total strain. The analyst then converts the resultant results to stress-strain curves before establishing the mechanical attributes of the stainless steel. The transient-state method, in comparison to the steady-state method, gives a more realistic technique for determining the behavior of stainless steel under fire situations.

Chen and Young, in carrying out transient tests for stainless steel, placed the specimen under a constant tensile stress levels while increasing the temperature systematically from 100 ⁰C to 900⁰C at equal intervals of 100^oC (2005, p. 229). They used these transient test results to construct stress-strain curves, which give the elastic modulus values at different temperatures for any given specimen. To determine the expansion level of the specimen after exposure to conditions of fire, Chen and Young measured the thermal elongation of the material at 2MPa tensile stress level and then compared these values with the BS 5950-8 and EC3-1.2 thermal elongation values for EN 1.4462 stainless steel. In comparison to European Code 3 and the British Standard 5950-8, their thermal elongation values were lower than the predicted values. They used the reduction factors, which represent the ratio involving the yield strengths of the stainless steel to normal room temperature of 22 ⁰ C for stainless steel types EN 1.4301 and EN 1.4462 at proof strains of 0.2%, 0.5%, 1.5 % and 2 %. Plotting the reduction factors against different temperatures indicated that, for the two types of stainless steel tested by Chen and Young, the steady state values were equivalent to transient state values at 0.2% yield strengths (2005, p. 232).

Outinen and Makelainen conducted the transient tests for stainless steel EN 1.4301 different stress levels with the temperature rate maintained at 20⁰C, 10⁰C and 30⁰C (2001, p. 2). In addition, they subjected some test material, base material and cold-formed material to high temperature rates in order to determine the behavior of the material at high temperatures. The cold-formed material had higher yield strength in this experiment (almost twice) compared to the base material. The mechanical properties other than “yield strength such as modulus of elasticity, yield stress, and thermal elongation were also higher in cold-formed material compared to the base material” (Outinen & Makelainen 2001, p.4). Again, the stress-strain curves for transient state tests and steady-state tests were almost similar in this experiment, showing a clear uniformity of the results obtained from different tests.

At elevated temperatures, the stress-strain curve of the stainless steel is important in the design of stainless steel for fire. Most of the stress-strain models bases on hot rolled stainless steel. Chen and Young proposed a stress-strain curve model for cold formed stainless steel at elevated temperatures (2005, p. 235). The model bases on steady-state results for EN 1.4462 and EN 1.4301 types of stainless steel.

The Mechanical Properties of Stainless Steel at Elevated Temperatures

Different stainless steel types exhibit different mechanical properties at elevated temperatures. To understand the behavior and the stress-strain relationship of stainless steel in fire conditions, the mechanical properties such as elastic modulus, yield strength and proportional limit are important (Rasmussen 2003, p. 47). The European standard for the structural design of steel structures provides a reference for examining these properties. The stress-strain curves converted from both steady and transient test results present these stainless steels’ mechanical properties: elastic modulus, ultimate stress, and yield strength (Ramberg, & Osgood 1973, p. 47).

Elastic Modulus

The modulus of elasticity (E) is the modulus tangent at a point in the linear curve relative to the initial section of the curve, where the curve is linear. For steel, “the elastic modulus is a constant over a range of strains” (Myllymaki 2001, p. 8). In Chen and Young tests, they first converted the transient-test results into stress-strain curves from which they obtained the elastic modulus. The data obtained for each stainless steel specimen is normalized by comparing it with the initial elastic modulus in order to eliminate the minor variations in elastic modulus (2005, p. 236). Chen and Young’s repeated the transient tests to minimize the variations in the elastic modulus.

In determining the modulus of elasticity of EN 1.4301 stainless steel, Outinen and Makelainen used both the transient state and the steady state results and compared each specimen to the values obtained at the initial part of the stress-strain curves (2001, p. 5). The results from the different tests varied greatly hence the need to compare the results from various tests. After comparing the different tests, Outlinen and Makelainen found that the modulus of elasticity for stainless steel EN 1.4301 dropped with increase in temperature (2001, p. 5).

To determine the reduction factor for elastic modulus, Outinen and Makelein in their tests, used the transient-test results obtained from base material and strain-hardened material to construct stress-strain curves. It is also possible to determine the reduction factors for elastic modulus from steady-state tensile tests (Ala-Outinen, & Oksanen 1997, p. 21). Since the proportional limit of austenitic stainless is not clear, it is difficult to determine the reduction factor and the elastic modulus from their stress-strain curves. Therefore, a linear regression analysis of the transient-test results enhances the determination of the reduction factor for the elastic modulus. Outinen, Kaitila and Makelainen carried out an extensive experiment aimed at determining the mechanical properties of structural steels S355 and S460 with yield strength (fy) =355 N/mm2 and fy =460N/mm2 respectively (2000, p. 13)

The Yield Strength

To determine the yield strength of stainless steel, analysts usually use the 0.2% non-proportional strain. The yield strength refers to the level of stress that can cause permanent deformation. It is the point beyond which permanent deformation occurs. It is normally determined from the early portions of stress-strain curves. In Eurocode 3, the yield strength bases on 2% strain (EC3, 2007, p.2). Outinen and Makelainen determined the yield strength from stress-strain curves derived from the transient-test results (2001, p. 7). They compared the base material of EN 1.4301 and cold formed material of the same stainless steel at 0.2% strain. The yield strength of EN 1.4301 base material was lower than that of the cold-formed material at moderate temperature (22^oC). Using stainless steel types EN 1.4301 and EN 1.4462, Chen and Young on the other hand, involved four strain levels; the 0.2%, 0.5%, 1.55, and 2.0% at different temperatures. They obtained reduction factors for yield strength in the tests, which was expressed as a ratio between various yield strengths relative to room temperature.

The Australian Standard (AS 4100) provides the standard for predicting the yield strength for steel types EN 1.4301 and EN 1.4571 within 400^oC and 900^oC range of temperatures. On comparing the yield strengths obtained, Chen and Young found out that the ASI 4100(4) prediction was only conservative between 600^oC and 900^oC and did not predict well the yield strength for temperatures below 400^oC. However, the yield strengths results obtained by Chen and Young were close to Ala-Outinen and Oksanen results for both transient and steady test results.

Therefore, they found AS 4100 prediction inapplicable for temperatures less than 400^oC. Chen and Young proposed a new equation for predicting the yield strength for cold-formed stainless steel at elevated temperatures. Using the new equation, the values of the reduction factor for yield strength correspond to the stainless steel test results. The reduction factors of 0.5%, 1.5%, and 2%, for both hot-formed and cold-formed stainless steel types EN 1.4462 and EN 1.4301, the yield strength predicted by the British standard applies within the temperature range of 550^oC to 960^oC. In other words, the reduction factor for yield strength of cold-formed stainless steel is much higher than the values provided in the ASI 4100. Chen and Young found that the yield strength values for cold-formed material were higher, on average, to the nominal values provided in the Eurocode 3 at a temperature beyond 600^oC.

One of the most important factors in modeling of stainless steel mechanical properties at elevated temperatures is the yield strength. According to Eurocode 3, the achievement of yield limit for hot rolled steels is possible at 2% total strain at room temperature conditions (EC3, 2001, p. 2). However, Ala-Outinen proposed the use of 0.2% proof stress for those structural members (columns) affected by buckling modes and 1.5% proof stress for those may fail due to bending (beams) (1996, p. 12).

Ultimate Strength/strain

Ultimate strength is the maximum stress that the stainless steel can withstand (Cheaitani, & Burdekin 1993, p. 21). Chen and Young using the steady-state results for the ultimate strength for stainless steel type EN 1.44262 and type EN 1.4301, found out that the reduction values for type EN 1.44462 were higher than that of EN 1.4301 for all test temperatures. Chen and Young propose an equation that can predict the ultimate strength of stainless steel. The unified equation predictions correspond with the test values obtained for stainless steel type 1.4462 and EN 1.4301. The ultimate strength of stainless steel measures the maximum capacity of temperature that the steel structure can bear, beyond which it can withstand no additional temperature.

Caldwell (1965) attempted to evaluate the ultimate strength of a steel ship structure by using a rigid plastic mechanism analysis (p. 411). To evaluate the ultimate strength of stainless steel and structural members, structural analysis is important. When performing the structural analysis, the engineer must consider the buckling effect and yielding of the steel. Experts refer this technique to as electro-plastic large deflection analysis.

Fire Resistance Design

Fire design for stainless steel forms an essential component of the design procedure of steel structural members. The methods used for fire design of stainless steel ensure that the structure designed to operate in the normal room temperature (22^oC) can further withstand the additional increase in temperature. The engineer subjects the material to fire, for a certain duration set for a specific structural steel component. There are three ways to perform an effective design for fire: computationally, use of tabulated data or by use of both methods. The steel design should incorporate fire protection materials to protect the structures from fire and enhance their stability in case of fire. The fire resistance time is a common criterion used to test for fire resistance of a steel structure. The fire resistance time refers to the time from the start of a fire to the time when the load bearing capacity of the steel decreases to the level of the loads (Iso-Mustajärvi, & Inha 1999, p. 59). The fire design criterion is important in determining the resistance of the steel structure with regard to the highest temperature attained and the loads the fire subjects to the structure. Steel structures fall into four different groups based on the required fire resistance time: the R15-, R30-, R60- and R90-classes, with R15 representing the ‘resistance’ of the material followed by the fire resistance time in minutes.

The Eurocode 3 part 1.2 provides simple calculation models for fire design of stainless steel structures. The calculation applies c to Class 1 and 2 cross-sections.

However, under certain restrictions the rules can also apply to Class 3 and 4 cross-sections. The buckling effect is more significant in thin-walled cross-sections, particularly in class 4 cross-sections (Hautala, & Schmidt 1998, p. 71). Since the fire design methods are limited, standards recommend that the engineers should not subject the cold-formed stainless steel to a temperature exceeding 350^oC at any given time, otherwise, they should use a thick layer of an insulator with steel, which is often uneconomical and a difficult fire design. Eurocode 3 specifications allow a partial safety factor of 1.0 for all load combinations in fire conditions (EC3, 2001, p.3).

Among the important studies carried out to determine the behavior of cold formed stainless steel under fire conditions was that by Ala-Outinen. The study involved experimental and numerical analysis of buckling effect of rectangular hollow sections (RHS). Engineers commonly use the RHS materials as building and roofing materials. In his study, Ala-Outinen subjected columns of RHS, 90mmm long, to transient state tests at an elevated temperature of 300^oC for duration of three minutes (Ala-Outinen 1996, p.16). Subsequently, he increased the temperature at the rate of 10^oC per minute. The study found out that local buckling led to the columns losing their load bearing capacity at mid-length for concentrically loaded columns and near the top of the column for eccentrically loaded columns.

Based on the equations of the Eurocode 3 part 1.3, Ala-Outinen proposed a calculation method for a room temperature design. To determine the width of the columns, he recommended that the values of the modulus of elasticity and yield strength be reduced in line with the Eurocode 3, part 1.2 (1996, p. 21). In this particular study, the set stress values were equal to the yield strength at 0.2% strain. The Eurocode 1, part 2.2 provides guidelines for determining the load reduction factor, which usually lies in the range of 0.6-0.7. The load reduction factor helps to construct a load bearing capacity curve. The curve provides for calculation of the critical temperature of the material. Ala-Outinen found that the critical temperature for the columns tested at load reduction factor, 0.7, to be around 400^oC using this procedure (Ala-Outinen 1996, p. 24). The critical temperature, thus obtained, is significantly higher than the 350^oC contained in the Eurocode 3, part 1.2.

Structural Fire Design Models for Stainless Steel

There exist many models for predicting the failure temperature of steel wall studs. Gernlich proposed a method for determination of the level of resistance of steel wall studs (Ranby 1999, p. 31). This model employs equations for reduction of the modulus of elasticity and the yield strength as recommended in the AISI standard. The method involves first determining the stresses at the cross-section due to eternal loads before the calculation of the critical temperature. The critical temperature in this case is the temperature at which yield strength of steel is equivalent to the stress applied (Guedes, Gordo, & Teixeira 1998, p.179). The next step involves calculation time of failure as a function of temperature rise. This model considers the deflection that arises due to bending. However, the model neglects the buckling effects.

Alfawakhiri and Sultan (2000) model involved use of load bearing lightweight steel framed (LSF) walls exposed to fire on a single side (p. 73). The authors tested six different configurations of the LSF walls each containing cold-formed steel wall studs sandwiched with two layers fire-resistant gypsum board each12.7 mm thick. Materials used as insulators included wool, glass, and cellulose. They suggested a fire resistance model for load-bearing LSF walls based on steady state and transient-state tests. The major limitation of this model is its assumption that fire prevents buckling.

Another fire design model is the one proposed by Feng, Wang and Davies (2001, p. 65). The authors conducted preliminary tests and compared their results to the European, British and American design models. They subjected the test material to steady-state tests, where they first exposed the test material to elevated temperature before subjecting it to a load. Using reduced modulus of elasticity values at 0.2% proof stress- as suggested in the Eurocode 3 part 1.2, engineers can make analytical predictions. The authors concluded that the critical temperature of thin-walled steel walls at load ratio of 0.7 is significantly higher than the 350^oC as suggested by Eurocode 3. In addition, the study concluded that the reduced material properties extend the temperature beyond the 350^oC. However, the study failed to include the temperature gradients and buckling modes in the analytical predictions.

In contrast to Feng et al. study, Lee, Mahendran, and Makelainen (2001, p. 17) involved the buckling behavior of thin walled test material. Lee et al. used 400mm sections of test material just as Feng et al study revealed. Lee et al then subjected these materials to steady state tests. Lee at al. then used the test results obtained and finite element analysis results to calculate the buckling coefficient, kT, at elevated temperatures. This study found out that finite element analysis could model the behavior of steel in fire conditions. However, the use of small lengths of the test specimens limited the buckling modes in this study.

During a fire situation, the inner and the exposed sides of the steel wall studs normally experience different temperatures causing a steep temperature gradient within the cold-formed steel studs. Typically, the exposed side can have an average of 300°C higher than the external side (Young, & Rasmussen 1998, p. 140). This means that the mechanical properties of steel subjected to fire are highly affected at the side exposed to fire compared to the external side. At the same time, thermal elongation is much higher on the fireside than on the external side, which makes the steel studs to deflect towards the fire source (Buchanan and Klippstein 1978, p. 89). As a result, the axial compression forces acting on the steel studs produce bending that leads to flexural buckling directed towards the fire. In practice, therefore, the flexural buckling is the relevant buckling mode. However, the use of insulation material such as gypsum board prevents flexural, torsional, and flexural-torsional buckling (Chen, & Young 2004, p139).

Flexural-Torsional Buckling

Eurocode 3 provides equations for evaluating the ultimate strength, the flexural, and the torsion-flexural buckling strength. When stainless steel undergoes compression, it experiences lateral bending and deflection occurs (Uy, & Bradford 1995, p. 53). The material then buckles. When the axial load increases, lateral deflections also increase causing the material to collapse. Steel under compression may buckle in three different ways: torsional buckling, flexural buckling, or a combination of both flexural and torsional buckling (Nylander 1956, p. 7).

Flexural buckling occurs when the material buckles in a cross-section by bending in the plane of symmetry whereas torsional-flexural buckling occurs in cruciform sections whereby torsional buckling (twisting) occurs before flexural buckling (bending) at symmetrical or unsymmetrical cross sections. Ranby (1999, p. 34) presents a method of evaluating the yield and the buckling strengths. Both torsion and flexure can occur at a single symmetric section leading to buckling at the line of symmetry. For steel, “the flexural buckling is more in symmetrical sections than in non-symmetrical sections…Torsion-buckling mode is common in non-symmetrical sections regardless of the dimensions or shape of the section” (Thonton 1993, p.485). However, steel beams exhibit torsion resistance to compression at elevated temperatures.

Uy and Bradford (1994, p. 259) used a geometrically non-linear finite element analysis to evaluate the torsion resistance of steel beams at elevated temperatures based on the mechanical properties of steel provided in Eurocode 3, part 1.2 (EC3 2001, p. 3). In their study, the fact that stress-strain relationship is different at elevated temperatures compared to room temperatures affected the lateral-torsion buckling curve of steel at elevated temperatures. In addition, the elastic modulus decreases faster compared to the yield strength at elevated temperatures. The study found out that residual stresses at elevated temperatures do not highly affect the buckling resistance of steel beams. This arose due to smaller difference between residual and yield stresses at elevated temperatures (Mirambell, & Real 2000, p. 109).

Based on the design procedures contained in Eurocode 3, part 1.3, Ranby (1999, p. 35) developed a method for determining the buckling resistance in steel fire designs. In this method, the designer applies the equations of Eurocode 3 for the calculation of buckling resistance in fire designs after considering the reduction of mechanical properties of the material and the buckling performance of the material in the finite element analysis (Young, &Yan 2000, p. 11). Ranby’s study involved steel wall studs.

Conclusion

Unlike carbon steel, the stress-strain relationship of stainless steel is non-linear with no clear yield point. To establish the stress-strain relationship of stainless steel, engineers use the steady state and transient-state tests. These tests evaluate the mechanical properties of steel such as the elastic modulus, the yield strength, and the ultimate tensile strength. The properties enable the structural designers to understand the behavior and the stress-strain relationship of steel under fire conditions.

Different studies have proposed various models for predicting the failure temperature and the buckling modes of steel at elevated temperatures. Using the stress-strain curves, the analysts can model the behavior of steel under fire conditions to determine the mechanical properties of steel at such elevated temperatures in order to predict whether it can withstand additional increase in temperature. Engineers usually use insulation materials to protect Steel structures from fire. The stress-strain relationship provides for determination of the steel’s ability to withstand elevated temperatures, which is important in designing fire design models of stainless steel.

Reference List

Ala-Outinen, T., 1996. Fire resistance of austenitic stainless steels Polarit 725 (EN 1.4301) and Polarit 761 (EN 1.4571). VTT research notes. pp. 14-25

Ala-Outinen, T., & Oksanen, T., 1997. Stainless steel compression members exposed To Fire. VTT research notes, pp. 21.

Alfawakhiri, F., & Sultan, M., 2000. Fire resistance of load-bearing LSF assemblies. Fifteenth International Specialty Conference on Cold-Formed Steel Structures, pp. 73

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Cheaitani, M., & Burdekin, F., 1993. Ultimate strength of cracked tubular joints. Proc. 5th International Symposium on Tubular Structures, pp. 21-23.

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Chen, J., & Young, B., 2005. Stress–strain curves for stainless steel at elevated Temperatures. Engineering Structures, 28 (5), pp. 229-239

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Feng, M., Wang, Y., & Davies, J., 2001. Behavior of cold-formed thin-walled steel short Columns under uniform high temperatures, Proceedings of the International Seminar on Steel Structures in Fire, pp. 65.

Guedes, C., Gordo, J., & Teixeira, A., 1998. Elasto-plastic behavior of plates subjected To heat loads. Journal of Constructional Steel Research, 45(2) pp. 179-83.

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Literature Review

A good number of transportation vehicles incorporate structural components with thin walled designs. Such structures have numerous advantages that warrant their use in the industry. This design is important because it accommodates stringent requirements during crush events. The main function of this design is to sustain abnormal loads. Other components are also important in dissipating impact energy in a controllable manner, which may have a limiting effect on the deceleration effect of a vehicle and therefore ensuring a general safety. From initial stages of growth in transportation industry, several regulations and recommendations laid down were to help engineers design structural components air, land, and sea with thin walls. “In terms of structural analysis this means that the corresponding computational models are restricted to the elastic analysis typically limited to infinitesimal deformation” (Abramowicz 2003, p.92). Although this design is still under use, the initial regulation did not provide the best alternative that warrants its continual use this is the main reason there is little literature work on this design.

Thin walled structures are not only a basic requirement in the industry but also help in sustenance of abnormal loading that occurs during accidents and other major events. Most crush worthy vehicles must incorporate the impacts of energy management requirement and the expected level of integrity. A typical example in a plane case, a train accident, or a car involves using structures that can sustain crash load without excess deformation likely to compromise passenger’s safety (Abramowicz 1966). This consideration takes the priority of the passengers’ safety to ensure they do not experience the effects of either deformation or heat dissipated by the parts involved in the impact. “At the same time other structural components must dissipate the kinetic energy of a vehicle while keeping the deceleration level below the tolerable limit” (Abramowicz 2003, p.92). It turns out that some parts of either a car or a plane must meet the two requirements in equal measures for instance the structural assemble of side panel in a car passenger must meet the two requirement to offer guaranteed safety to the passengers.

Incorporation of these conditions is not only important to fast moving cars but also to cases of reduced speed accidents like ships that may ground on narrow rocks. However, in this scenario dissipation of energy is not a main factor like what happened to the previous case because the amount and capacity of energy absorbed in a ship hull is far lower than what a fast moving plane or car experiences. In this case, the engineers would put their focus on the integrity issues at the expense of energy dissipation. The integrity consideration must ensure an effective method that minimize damages to the hull structure as well as related damages that may result from this impact. Initial studies suggest that crashworthiness were probably the most important designs with experimental recommendations (Mamalis et al. 2003; Tarigopula et al. 2006). These designs were trusted because they played a significant role in the industry, however, some numerical tools using a non-linear finite element was missing hence making the industry to lag behind. When later on 1980 the industry made some progress by the inclusion of this non-linear finite element into the design model. Crush structures with thin walled tubes incorporated yet another important design simulation called the macro element approach or the kinematic design. Alexander was the main brain behind this innovation.

There are features that characterize a deformed pattern in a thin walled structural design, for instance a crushing process that involves a plastic crushing component occurs when elasticity process or elastic plastic buckling happens. The main feature that characterizes this process is the localization of deformations plastics in some parts of the structural component. The deposition occurs in some relatively small parts. The localization of plastic deformation takes place in narrow hinged zones or lines (Johnson & Mamalis, 1978; Ohkami et al. 1990), an area that experiences a number of plastic deformations because it is very vulnerable to this problem. Diagrammatic representation presented below shows examples of these deformations and how their impact looks like.

These figures represent a typical example of plastic deformations; diagram (A) represents a folding pattern similar to that of a crushing shell structural component with identical patterns along the zones of impact. The second figure labeled (B) represents a model of superfolding element; a combination of four of this will create a layer of folding within a crushing square column. Figure labeled (C) represents a rare folding phenomenon because of its complex mode of patterns similar to a car crushed roof or a bowed ship. The last representation labeled (d) is a composition of multiple superfolding elements (Mamalis et al. 2003; Tarigopula, et al. 2006).

Geometrical similitude is an interesting crushing phenomenon, some engineers observes that a good number of actual folding patterns occurs through assembling of single representative element of the fold. This makes it easy to describe the deformation element from a concept of special macro element known as the superfolding element as shown in the diagrams above (Drazetic et al. 1993; Liu & Day 2006; Nia & Hamedani 2010). This concept helps in describing the geometry as well as its cross sectional dimension.

Equation one

Let one arm of the superfolding element be a and b

Total lenght (C) = a + t

The central angular pattern = ∅

Wall thickness ta of arm of the lenght a

Wall thickness tb of the lenght b

This deformation, which is plastic in orientation, creates five deformation mechanisms. These includes the rolling of deformations, creation of a bend along the stationery hinge line, creation of a deformed floating toroidal surface, deformations bending along hinge lines, along inclination, and locking of traveled hinge lines, and finally conical surfaces opens widely.

Folding mechanism happens through either asymmetrical or symmetrical orientations as shown in the diagrams below. These are typical examples of single superfolding models under the control of switching parameters.

Deformation process is under the control of singular process both in asymmetrical and symmetrical mode. The time like parameter that determines this process must obey the equation below.

Deformation (equation two)

0 ≤ a ≤ af

This equation defines rotational aspects of face sides in the elements, which takes place from the upright posture in the initial stages. In this case, a = 0, a = af = π/2 during the initial folding processes and terminates when this equation comes complete.

Symmetrical deformation will result in folding as shown below.

Internal energy dissipation rate and the capacity of energy dissipated

Equation three

Internal energy dissipation rate and the capacity of energy dissipated.

Where

S represents shell mid surface

n represents quantity of lines in plastic hinge

Li represents length of hinge

Ø represents rotational rate of jump movement across the hinge line in motion

Kab represents components of curvature rate

Eab represents rates of tensor extension

Mabb and Nab represents components of conjugate stress in a generalized scenario

Taking an example of SE deformation, the above equation makes assumption on a file composed of shells arranged in either toroid or cylinder (axisymmetric) (Toksoy, Guden, 2011; Noels, Stainier & Ponthot 2004). Besides, the equation assumes inextensibility within the hooped direction to give an expansion of a different rate of dissipated internal energy as follows

Equation (4) on different rate of dissipated internal energy

This equation (i) changes to (ii) below

If we integrate equation (ii) with 0≤a≤a1 interval the expansion changes to a single Se energy dissipated as shown below

Equation five

Figures on right side of the above equation defines switching of a, this corresponds to both symmetrical and asymmetrical models when combined.

Equation six

To report on damaged momentum analysis, the first step should involve computation of equivalent barrier speed (EBS). This variable describes the barrier equivalent velocity; the formula below describes its computation process that incorporates determination of energy a vehicle dissipates when a crush occurs (Alexander 1960; Wierzbicki & Abramowicz 1987).

Speed determination

The term equivalent describes the possibility that the speed used may not be ‘actual’; this means that EBS relies on approximation and assumption of speed employed (Toksoy &Guden 2011; Noels, Stainier & Ponthot, 2004). Any effect from post impact velocity gives EBS that is different from the actual speed as shown below.

Choice of Model

Choice of models depends on the type of material required for the thin walled structures, which can either be a solid or plastic FE. Models are the basis for structural analysis. Appropriate models determine structural features and the functions of the structure in design. The main rationale to this innovativeness is the desire to solve problems related to progressive collapse in axial compressed cylindrical tubes. The process involved assumption of kinematic admissive deformation. The main challenge to this method is the assumption on expected observation rather than inclusion of theoretical assumption to the model. With this method it is possible to determine elementary aspects of a crushing process simply by application of relevant formulas. These formulas help in determination of significant properties of crushes as well as deepening the insight of the folding process (Schneider & Jones 2004). This process is however, very important in development of designs that determines a given simulation tool. To effectively elucidate how these processes relates to the entire thin walled structures it is important to use a kinematic approach in determining how crushing mechanism impacts its effects on various design. The application of these calculations in designing a thin walled component is necessary to optimize dissipation of impact energy (Mamalis et al. 2003; Tarigopula et al. 2006).

Geometrical Model

Structural engineering devotes most their time in designing and finding effective methods of creating suitable methods and fail to accord enough time on to actual analysis of the model. The current thin walled models use reduced elements like plate shells, which are however not very effective raising the demand for simulations that use solid elements. Solid types are more adequate than the conventional types. Application of nonlinear to the shell elements is not possible; secondly conventional models are prone to severe modeling errors. A good simulation technique should have a combination of embedded domain and low order elements (Duster et al. 2008; Rank et al. 2011). This technique reduces the need to engage the engineers in preparing model analysis while also presenting accurate and efficient models. These advantages are the basis for recommending a combined model in thin walled structures.

There are three models of thin walled structures with hexahedral mesh. These include single surfaced mesh, the multiple surfaces meshing, and a complex type of meshing. According to Sorger et al. (2012) single surfaced meshing sweeps along the surface referred to as reference surface. A multiple type consists of sets of intersecting solid shells.

Strain-rate Sensitivity

Strain rate influences the crushing behavior in thin walled structures like the columns and beams. Many structural materials of very low-carbon steel, mild like aluminum alloys have stronger strain rate influence than conventional materials. Effective width methodology helps in determination of thin-walled strength. Evaluation of this parameter depends on reduced or effective cross-sectional dimension and the elastic limits of the optimal stress. To solve the problem finite element method combined with analytical designs that employs plastic mechanical approach is appropriate.

Cowper-Symonds formula stated below is effective for determination of strain rate

This equation presents a relationship that exists between strain rate and the initial dynamic stress load, however the main shortening arise from its inability to account for the effects from strain hardening phenomenon.

Perzyna et al. (1971) application model is the best method for determining strain rate sensitivity, this model aligns with the Cowper-Symonds method describes previously. However, this model applies the hardening of isotropic strain as well as integration of constitute relationships of repetitive mapping.

The main advantage of this method is therefore the presence of compatible stiff tangents for every step of matrix integration as follows.

Stress and strain Relationship

Subjecting a thin-walled structure to tensional or compressive forces results in either elongation of shortening of the material, the poison’s ratio will determine changes in cross-sectional area of the material.

Structural model and loading

The material strain rate has a greater influence on thin-walled crushing behaviors. The capacity to carry a load would increase with an increase of strain rate. However, based on the two methods of analyzing (that is plastic mechanism and the FE analysis) the plastic approach is more susceptible to the effects of strain rate than the FE analysis with regard to column subjected to compressive forces.

Stress and Strain Profile

Stress and strain are directly proportional to one another, an increase in strain results in a constant increase in stress until reaching a certain point called the elastic limit. This limit results in permanent deformation. Applying a high magnitude of force that goes beyond the elastic limit will result in permanent change. This leads to permanent deformation as well; this state sets in because eradication of that load does not change the deformed size or the shape. Force applied before the structure breaks is the ultimate stress while yield stress is the type of stress a structure yields when loaded with a material that makes it go beyond elastic limit This profiling is important to thin walled-structures (Koganti & Caliskan 2001).

Occurrence of Fracture and Deformation

Occurrence of deformation and fractures depends on several factors that determine changes in stress and strain as shown in the diagram below. These factors include object geometry, size of the structure, and forces applied. These factors give rise to a number of fractures and deformations. Between the necking region and strain hardening region the ultimate strength is the transformational factor that determines occurrence of fracture.

If withdrawal of force happens in case the structure is elastic, the state of deformation will not be permanent because the object regains its previous state of size/shape. Such materials represent a nonlinear elastic deformation that obeys this principle.

σ = Eε

Where σ represents stress applied, ε represents resulting strain while E represents material’s constant figure called Young’s modulus. In Young’s Modulus formula the slope depends on stress and strain.

Deformation process is under the control of singular process both in asymmetrical and symmetrical mode. The time like parameter that determines this process must obey the equation below.

0 ≤ a ≤ af

This equation defines rotational aspects of face sides in the elements, which takes place from the upright posture in the initial stages. In this case, a = 0 during the initial folding processes and terminates when this equation a = af = π/2¹ comes complete.

Fracture is an irreversible deformation type, once the material reaches elastic limit it breaks as shown in the diagram below. The point of fracture is at a level in which application of more forces beyond the ultimate strength level causes irreversible deformation as shown below.

The diagram above shows two major regions a structure undergoes before it fractures namely the elastic region and the plastic region. An increase in strain results in an increase of stress until the structure gets to a point that any additional strain does not increase the stress resulting in fracture. There are very few structures with permanent inelasticity, most structures are either elastic to a lesser or greater limit.

Activation Energy

The equation below represents activation energy computational formula. From a chemical point of view activation energy is the minimal amount of energy acquired by a substance to enable it transform from one form to another.

When a graph of In(K/T) is plotted against 1/T the result is a linear presentation, which gives activation energy.

This energy is important for any material that experiences strain, because it determines its ability to change from form to another.

Fracture mechanisms

Fracture mechanics helps in elucidation of crack propagation of thin walled materials. Analysis of crack propagation depends on solid mechanics analysis. The analysis helps in characterization of fracture resistance. The tool is necessary to improve mechanical performance of the thin walled structure. There are two types of fracture mechanism; these are linear elastic and elastic plastic. To elucidate crack length, estimation of free energy change is the primary stage. This change comes from the deduction process involving elastic (EE) and surfaces energy (SE) (that is SE-EE), however, failure sets in at the point when free energy begins absorption of critical crack length. These changes obey Griffith relationship represented below.

E Represents material’s Young modulus

γ represents density of surface energy

C Represents a constant figure

This formula assumes that E = 62 GPa and γ = 1 J/m²

Behaviour of stress/strain through lobe or ribbon formation

Ribbon formation mechanisms depend on the effects of stress and strain. There are features that characterize a lobe or ribbon formation pattern in a thin walled structural design, for instance a crushing process that involves a plastic crushing component occurs when elasticity process or elastic plastic buckling happens. The main feature that characterizes this process is the localization of deformations plastics in some parts of the structural component. The deposition occurs in some relatively small parts. The localization of plastic deformation takes place in narrow hinged zones or lines (Johnson & Mamalis, 1978; Ohkami et al. 1990), an area that experiences a number of plastic deformations because it is very vulnerable to this problem.

Elasticity and Elastic Limit

Elasticity of a structure is its ability to regain the original shape and size upon the withdrawal of deformation size. Different materials have different levels of elasticity; while some are more elastic others are less elastic. Elastic limit is the maximum stress that a given structure would exhibit. Applying a high magnitude of force that goes beyond the elastic limit will result in permanent change. This leads to permanent deformation as well; this state sets in because eradication of that load does not change the deformed size or the shape. Force applied before the structure breaks is the ultimate stress while yield stress is the type of stress a structure yields when loaded with a material that makes it go beyond elastic limit. The diagram below represents various stages of elasticity and deformation before reaching a permanent stage beyond which withdrawal of force would not result in the restoration of the original shape.

How Fracture and Deformation Relates to other Characteristics of Materials

Fracture and deformation relates largely with the inherent characteristics of the material exposed to strain. The ease with which a material undergoes deformation before fracturing depends on the type of material it is made up of; irreversible elastic deformation termination of applied forces causes the material to return to its initial shape.

Some materials have strong resistance to strain and therefore the Young’s Modulus formula would slope at a lower gradient than a material with less resistance. Some material would not undergo fracturing while others would experience irreversible deformation resulting in fracture. Those thin-walled structures with larger strain would not reach elastic limits and if they do the force applied would be greatest. Other factors that determine this relationship includes object geometry, size of the structure, and forces applied. These factors give rise to a number of fractures and deformations. Between the necking region and strain hardening region the ultimate strength is the transformational factor that determines occurrence of fracture

Conclusion

Thin walled structures have gone transformation by using different structural models that improves their strength and durability. This is of importance to the passenger in terms of offering protection, several transportation vehicles incorporate structural components with thin walled designs. Their design is accustomed to offer stringent requirements during crush events and therefore making the structure able to sustain abnormal loads. The type of material must however have certain designs with appropriate model choice. Other features that determines structural important includes the elasticity and its elastic limits, deformation property and fracturing ability, and stress/strain relationship.

References

Abramowicz, W 1966, ‘Extremal paths in progressive plasticity’, Int J Impact Engng, vol. 18, no.7/8, pp.753–64.

Abramowicz, W 2001, ‘Macro element method on crashworthiness of vehicles’, in J Ambrosio (ed.), Crashworthiness—energy management and occupant protection, Springer, Wien, New York, pp. 203-302.

Abramowicz, W 2003, ‘Thin-walled structures as impact energy absorbers’, Thin-Walled Structures, vol. 41, pp. 91–107.

Abramowicz, W & Wierzbicki, T 1989, ‘Axial crushing of multi-corner sheet metal columns’, J App Mech, vol. 56, no.1, pp.113–20.

Alexander, JM 1960, ‘An approximate analysis of the collapse of thin cylindrical shells under axial loading Q’, J Mech Appl Math, vol.13, no.1, pp.10–5.

Drazetic, P, Markiewicz, E & Ravalard, Y 1993, ‘Application of Kinematic Models to Compression and Bending in Simplified Crash Calculation’, International Journal of Mechanical Science, vol. 35, no. ¾, pp. 179 – 191.

Duster, A, Parvizian, J, Yang, Z & Rank, E 2008, ‘The finite cell method for three-dimensional problems of solid mechanics’, Computer Methods in Applied Mechanics and Engineering, vol. 197, pp. 3768–3782.

Johnson, W & Mamalis, AG 1978, Crashworthiness of vehicles, Mechanical Engineering Publications Ltd, London.

Koganti, RP & Caliskan, AG 2001, ‘Stochastic applications in crashworthiness’, Proceedings of 2001 ASME International Mechanical Engineering Congress and Exposition, pp. 89-96.

Liu, YC & Day, ML 2006, ‘Simplified Modelling of Thin-Walled Box Section Beam’, International Journal of Crashworthiness, vol. 11, no.3, pp. 263–272.

Mamalis, A, Manolakos, D, Loannidis, M, Kostazos, P & Dimitriou, C 2003, ‘Finite Element Simulation of the Axial Collapse of Metallic Thin-Walled Tubes with Octagonal Cross-Section’, Thin-Walled Structures, vol. 41, pp. 891–900.

Mamalism, AG, Manolakos, DE, Ioannidis, MB, Kostazos, PK & Chirwa, EC 2003, ‘Static and dynamic axial collapse of fibreglass composite thin-walled tubes: finite element modelling of the crush zone’, Environmental Modelling and Assessment, vol. 8, no. 3, pp. 247-54.

Nia, AA & Hamedani, JH 2010, ‘Comparative analysis of energy absorption and deformations of thin walled tubes with various section geometries’, Thin-Walled Structures, vol. 48, no.12, pp. 946-54.

Noels, L, Stainier, L & Ponthot, JP 2004, ‘Combined implicit/explicit algorithms for crashworthiness analysis’, International Journal of Impact Engineering, vol. 30, pp. 1161-77.

Ohkami, Y, Shimamura, M, Takada, K, Tomizawa, H, Motomura, K & Usuda, M 1990, Collapse of thin-walled curved beam with closed-hat section—Part. 1, Study on Collapse Characteristic, SAE paper 900460.

Perzyna, P et al. 1971, ‘Applications of visco {elasticity – in Polish)’, Os-solineum, Wrocaw, Warszawa.

Rank, E, Kollmannsberger, S, Sorger, C & Duster, A 2011, ‘Shell Finite Cell Method: A High Order Fictitious Domain Approach for Thin-Walled Structures’, Computer Methods in Applied Mechanics and Engineering, vol. 200, pp. 3200-3209.

Schneider, F & Jones, N 2004, ‘Impact of thin-walled high-strength steel structural sections. Proceedings of the Institution of Mechanical Engineers, Part D’, Journal of Automobile Engineering, vol. 218, no. 2, pp. 131-58.

Sorger, C, Frischmann, F, Kollmannsberger, S & Rank, E 2012, ‘TUM.GeoFrame: Automated high order hexahedral mesh generation for shell-like structures, in progress’, Computer Methods in Applied Mechanics and Engineering, vol. 230, pp. 200-221.

Tarigopula, V, Langseth, M, Hopperstad, OS & Clausen, AH 2006, ‘Axial crashing of thin walled high-strength steel sections’, International Journal of Impact Engineering, vol. 32, pp. 847-82.

Toksoy, AK & Guden, M 2011, ‘The optimisation of the energy absorption of partially Al foam-filled commercial 1050H14 and 6061T4 Al crash boxes’, International Journal of Crashworthiness, vol.16, no.1, pp. 97-109.

Wierzbicki, T & Abramowicz W 1987, The manual of crashworthiness engineering, Vols. I–IV, Centre for Transportation Studies, MIT, Cambridge, MA.

Literature Review

Crushability of a structure is the likelihood that the structure will crash, whether it is a vehicle, building, bridge, or antenna masts. In designing structures, which can withstand a crashes, a lot of emphases has to be applied because it is vital in preventing and reducing the rate of recurrence of death and fatality accident (Smith 2001). Many scholars have taken their time investigating the aspect of crushability of some structures, as well as the capacity of absorption of various structures. They have taken intensive studies of the thin-walled structures including tubes, stiffeners, and shells (Smith 2003). Through their studies, they have discovered that these structures are very efficient impact energy absorbers. The studies explain the geometrical shape of a structure of deformation in energy absorbers and give accounts for their various geometrical shapes. The studies further explain the method of crash, the strain hardening and strain rate effect. There exist several approaches for determining the absorption of energy for structures. One of the approaches is by using what is known as the finite element analysis. The second approach is that of experimental analysis. The third approach is the use of theoretical analysis or conceptual analysis (Smith 2002). Using the finite element analysis is highly exorbitant coastwise and consumes a lot of time. The same case applies to Experimental analysis. To that effect, the best choice of an approach is the theoretical or the conceptual analysis of collapse mechanism (Smith 2002).

Choice of Model

The choice of approach is done in the preliminary stages of structural design of shapes. Theoretical method is a simple approach for predicting the crash behavior and energy absorption of a structures and shapes. For example, circular pipes have found wide application in Engineering and construction as structural members. This has provided enough exposure of circular tubes to studies of its collapse behavior, with a special interest on its energy absorption. To do a forecast the crash reactions of structural materials, a scholar needs to use the finite element analysis or the experimental analysis for obtain more perfect outcomes. However, they have to prepare in advance and allocate fun to cover the costs. The most appropriate model in the early design phases is the approximating model of tubes crash mechanism (Arduini and Nanni 1997). This study aims to design a closed-form solution as the optimal design of thin-walled circular tube, which can withstand a lot of energy when subjected to bending forces. It takes into account, the rate of energy absorption of circular structures such as hinges in the circular direction. The three dimensional geometrical crash mechanisms were evaluated by placing an additional slanted hinge lines along the longitudinal cross-section of tube in the length of elastically bending area. The model was developed in the consideration of energy rate conservation. It therefore implies that, the rates of internal energy absorption were computed for each hinge line.

Geometrical Model

To determine the desired structural properties of loads, the first step is the analysis of the requirements related to the strength, displacements, cyclic life and the weight. Apart from the strength, the design shape and size is often determined by maximum displacement. The requirements of service life are essential in determining design. Therefore, they have to be well defined in every step of stress analysis.Take a simply beam supported at both ends from the bottom with a length of 2L. The plate bounded by the beam also has a length of 2l. A longitudinal force N0 pulls the beam at both ends marked of the beam. It also experiences a pair of end moments M₀ and a transverse load marked as T(x).

This analysis assumes that the only existing forces are the cross-sectional shear stress and strain in the beam. It does not take into account the existence of the cross-sectional normal stress in the beam and the plate. It also assumes that each layer in the arrangement is elastic and of uniform strength. Specific energy absorption equations SEA is expressed in the form of SEA= Em (do / Pcm Ge), where Do is the maximum normal stress, Gm is the natural gravitational force (10N). Em is the compacting strain and Pcm is the density of the material used. In this case we construct a cylindrical shape, hence calculations of energy absorption using analytical equations. The relationship between Do and Pcm is very vital in this computation of energy absorption for crushable materials. The main aim of this computation is to determine the density of the material hence the size of bending angles required. In this case Energy absorbed (SEA) = 7500 Joules, length is 375mm. What we want to calculate is the Pcm.

SEA =Em (Do/Pcm*Ge)

7500=40(355/Pcm*10)

Pcm= (40*355)/7500

Pcm= 1.893Kg/mm³

The density of the envelope is 1.893Kg/mm³.

Strain-rate Sensitivity

The index m for measuring strain-rate sensitivity, is usually determined by drawing the elements of stress against the strain. The resultant graph gives a constant known as the strain rates. The curves in normal conditions show an S shapes. The second method of determining strain rate is known as the multi-strain rate jump test (Aprile and Limkatanyu 2001). This procedure involved application of increase and reduction of m by 20 percent for every100 percent rise in the material length. Multi-strain test enables an engineer to examine the strain rate behavior whenever values of strain of material changes. The data are represented on curves, which demonstrate bell-shape curvature that are characteristically super plastic materials. Strain rate is directly proportional to strain.

Stress and strain Relationship

This research first defines stress and strain, and then it provides the relationship between the two in relation to the elastic region. The correlation between stress and strain uses axial stress and strain cases. Normal stress is the stress, which an object encounters when a force is applied along its longitudinal axis. It is also called axial stress. It is represented by the equation P=F/A where F if the axial stress and A is the cross-sectional area.

The standard unit for measuring stress is Newton per Square Metre or Pascal (Pa). Normal strain is calculated as the ratio of displacement to the initial size of the object or the deformed material. Normal strain is represented with the equation E= (L1-L2)/L1.Strain is therefore unit-less, because it is a ratio of lengths. Shear stress is a pair of forces that tends to deform an object at the moving point. It applies in cases where a purely sheer force is exerted on a structure. The formula for obtaining shear stress is similar to the formula for tensile stress. Likewise to the standard units remains the same as those of tensile stress.

The dependence that exists between the two forces of stress and strain is represented in figure 3.

Modeling and loading

The properties of materials, modeling abilities and the loading capabilities are essential tools in calculating structural behavioral characteristics of the object materials, for example, its displacement and stress distribution as related to relevant anticipated forces. It is vital to determine whether a structure is linear or non-linear to predict how it will behave when subjected to external load In the case of a linear structural; its behavior is directly influenced by the external force of the load. In this case, the principle of superposition is applied, which states that the reaction in response to many loads applied is the same as the sum of loads. On the other hand, for a non-linear structure, the behavior is dependent on other physical properties such as the volume, strength and shape. The same experiment and calculation has to be repeated for different amounts of forces (Lu et al 2005). Performing calculation using linear the linear equilibrium equation is a rather complicated process but guarantees accurate results for various geometrical shapes. Examples of physical properties of structures, which play vital roles here, are elasticity, shear stress and pressure vessels. Using static loads in the stress analysis reveals the anticipated impacts of the real forces the structural object is bound to withstand (Rahimi and Hutchinson 2001). The theoretical design phase of stress analysis allows verification of such impacts and in terms of their validity. Here, validity means they fall within the acceptable range of loads.

Stress and Strain Profile

Let α denote elements of stress tensor, which is refers to a set of a three dimensional Cartesian coordinate, with axes Yl, Y2, and Y3. The equations of equilibrium position are represented as :(dαij/dyj)+Fi=P(d²ui/dt²),

Where αij= αji, and Fi is the force per unit volume of the body, ui the displacement of the motion, and p the mass density of the body. The element Ti of the pressure (force per unit area) acting on a plane with normal (ni) is represented as Ti= α_ijn_j

Strain $ij and rotation Rij elements are defined using displacement gradients by the model: $_ij=1/2((du_i/dy_j) + (Du_j/Dy_i)) and Rij= 1/2((du_i/dy_j) – (Du_j/Dy_i))

In the cases of finite deformation, other appropriate measures apply, using a model: ((D²$_ij/D_ykD_yl) + (D²$_kl/D_yiD_yj)) = ((D²$_ik/D_yjD_yl) + (D²$_jl/D_yiD_yk))

These are referred to as compatibility equations and they prove that a strain fields are derived from displacements. However, strain and stress have a different constant of proportionality (Ahmed et al 2001). This report first gives the definition of stress-strain relationship, and then it describes their relationship in terms of elastic region and plastic region. The correlation between stress and strain is reinforced by uni-axial and bi-axial cases. For ductile materials, an equation for the curve is r=F/A_0, which is simplified as r=Gy, where G is a constant called the shear modulus. It creates the relationship between the shear stress and the strain existing in the elastic region. In the cases of linear and isotropic materials, the constants E and G are connected through the formula: G = E/ (2 (1+v).

In the linear isotropic material, the plane stress state makes assumption that αz=Rxz = Ryx = 0, and Yxz=Yyz=0.

State of plane stress appears in a thin metal plate, which is subjected to various forces acting in the center of the plane of the plate. Plane stress state is evenly distributed, reaching out to the surface of an object or a machine. Essentially, it occurs anywhere on the surface of the object free from external load.

Occurrence of Fracture and Deformation

Deformation and fracture takes place on a material when a force is applied on it beyond its elasticity. The concept of elasticity does not take into consideration the aspect of plastic deformation or fracture. This is because the general assumption is that the reactions of the plate conform to the conditions satisfying the elastic limit. It is therefore vital to determine if the elastic limit of the plate is exceeded through induced stress or deformation. This is done by a laboratory experimental method known as the appropriate verification and validation distribution in the whole structure. Alternatively, appropriate verification and validation can be carried out against finite element simulation and modeling, done through customized software (Hibbeler 2005). In a study of mechanism of fracture and deformation of a super alloy of wrought nickel at high temperature, investigations were done under isothermal cyclic creep and creep condition. The study revealed that the creep-fatigue interaction, which was characterised by the tensile hold duration and introduced to the creep stress, exhibited no significant impact in creep life regardless of the durations of holds used (Teng et al 2002). It also revealed that by introducing the tensile hold duration, it led to decline in the count of cycles to failure and a corresponding increase in the hold duration. The experiment showed a decrease in the strain rate at the isothermal cyclic creep. The more conspicuous decrease in the strain rate is only attributed to the participation of a more active fatigue in the process of fracture and deformation (Chen and Teng 2001).

Activation Energy

Another vital factor involved is the activation energy for the super plastic deformation and fracture, denoted by letter Q. This was determined by assuming that the strain rate sensitivity follows a Type of dependence for absolute temperatures $.exp(Q/R.T)=Aαⁿ where letter A represents the material constant, G represents the gas constant while letter n represents the stress exponent, expressed as n = 1/m. To calculate the activation energy under a constant strain rate $, we use the following formula:

Lnα= (ln$-lnA)/n +1/T*Q/R*n

The activation energy A is obtained by the gradient of the line plotted with lnα against. 1/T is Q/(R * n). In this experiment, the alloy is found to act at an activation energy calculated using the principal strain rate of 7.49*(10–⁴ /s) and a true strain $ = 0.5

Figure 6 shows the plotted curve with an initial strain rate 7.5 * 10^–4/ s for temperatures between 390 °C and 500 °C. The flow curve stresses during true strain 0.5 and at various ranges of temperatures. Taking the strain-rate sensitivity index m to be 0.46 over the range of temperature between 390 and 550°C, the mean activation energy Q for any given test condition is: Q = k * R/m. In this case Q=8420.069*8.3140/0.46. The calculation obtains approximate value of activation energy as 151.87kJmol^-1.

Fracture mechanisms

Investigation of structure along the plane adjacent to the crack initiation reveals that the crack initiation takes place more at the grain boundary intersections with the specimen surface no matter the duration of hold time. Secondary cracks appear to dominate the grains boundaries perpendicular to the applied stress (Rice 1968). All the fractures occurred at either the creep or cyclic-creep having long hold durations with inter-granular fracture initiation and propagation mode. Based on fracture mechanism examination at the destruction process, regardless of the hold time, the leading role of inter-granular breakage was evident. This is a proof that the determinant factor to fracture and deformation is the creep (Nairn 2000). From the study of inter-granular fractures, its analysis revealed that fatigue mechanisms contributed in the destruction process when a shorter hold time of 30 was applied to low cycle fatigue. In these scenarios, there existed the intra-granular fractures and initiation of fatigue. In the higher stages of cracks, the fractures were propagated by inter-granular mechanisms. The impacts of fatigue became more pronounced with the decrease in hold time. After the opening of critical crack, further propagation of the fracture was that of mixed breakage form and inter-granular cleavage.

Behavior of stress/strain through lobe or ribbon formation

Practically, the true stress and true strain usually find application in mechanics. Lateral strains and axial strains are related in ratio known as the Poisson’s ratio that is the ratio of the lateral strain to axial strains (Ascione and Feo 2000). The ratio is expressed in the form V= -$x/$z = $y/$x. In theory, the maximum value of Poisons ratio is 0.5. Most metals have the value between 0.23 and 0.38. Take an example of a uniform ribbon of length l, width w and height h. Its volume V is obtained by V=l*w*h

V=l*w*h

δV = δl wh + δw lh + δh lw

δV /V = (δl / l) + (δw / w) + (δh / h)

This implies that the volumetric strain of a fractured body is the sum of its linear strains in each of three mutually perpendicular directions of the height, length and width.

e_v = (e_x +e_y +e_z)

The strain, which goes with a shearing action, is referred to as shear strain. An object is permanently distorted by applying external forces or share forces at the angle. It is measured in the units of radian. Shear strain is denoted by symbol Ф. Take an example of a cube shape ABRP in figure 7. Two forces Q are applied on it at the bottom and top. These two forces called sharing forces are equal and opposite. The two forces are AB and RP. If the lower surface is made into a fixed base, the cube will experiences distortion through angle Φ to assume the newly acquired shape ABR’P’. Now the shear strain or distortion (deformation) per unit length is calculated as:

Shear strain of the cube = RR’ / RP = RR’ / BR = Φ radian

Elasticity and Elastic Limit

Elasticity of an object is the property of the object, which enables the object to, regains its original shape and size when the force causing deformation is withdrawn (Teng et al 2002). Majority of materials are elastic in nature but their elasticity is of a lesser value. Perfectly elastic materials are rare to find in nature. Elastic limit is defined as the maximum stresses to which a material can obey behave with the property of elasticity. If the elastic limit of an object is exceeded then the object will be permanently deformed by the force. The object will not be able to assume its initial shape and size at the removal of the force, so the result will be a permanent deformation. The object is said to have undergone residual strain. When an object is subjected to weight beyond its elastic limit then the stress increases to a point at which the object begins to yield (Täljsten 1997). This stress is known as yield stress. The study of Physical properties and behavior of various materials are founded on the relationship between strain and stress and on a common law called Hooke’s law, which states that stress is directly proportional to strain for as long as elastic limit is not exceeded. If S is the stress induced in an object and e the strain corresponding to S, then for Hooke’s Law to be satisfied,

S / e = E. E is a constant known as the Young’s modulus or the modulus of elasticity.

How Fracture and Deformation Relates to other Characteristics of Materials

The deformation and fracture models are useful in predetermining relationships that exist between fracture toughness and other physical properties as yield stress, strain hardening exponent and ultimate strength. Other characteristics include uniform elongation and the reduction of area deformation and cracking. As it has already been seen that that a does not change due to changes in the structure of the material, a number of experimental evidences were found to validate the formula which relates the fracture properties to other characteristics (Chaallal et al 1998). The experiments performed on a carbon steel and on a martensitic steel confirmed the relation equation K = Aa. In the following equation KIC = A20y it follows that the analysis of other fracture models indicate the existence of fracture toughness and its relation to other mechanical properties.

In many practical situations, the relationships shown above can be obtained for approximate values of the anticipated fracture toughness of the material from its mechanical properties and for the examination of the assumed fracture toughness of new materials, which are developed without conducting the deforming and expensive fracture toughness tests.

Conclusion

In conclusion, the two ideas of brittle fissure of the engineering materials are based on the fracture mechanisms, the Decohesion mechanism and coalescence mechanism. Decohesion mechanism reflects the heart of fracture toughness for a perfect structure material. On the other hand, the coalescence mechanism reflects the minimum fracture toughness of a material of an actual structure (Rabinvich and Frostig 2000). The coalescence fracture mechanism is observed with in majority of engineering materials. It requires large amounts of fracture energy. Therefore, it is vital to do investigation for both coalescence and Decohesion fracture toughness mechanisms in order to analyze the properties of the deformation process to optimize the structure of the material. The coalescence fracture mechanism is based on model parameters, that is, characteristic distance denoted by X, and micro-cleavage stress O. The two are directly related to the minimum fracture toughness property of the material. Fracture toughness depends on the temperature of materials as well as the loading rate (Bonacci and Maalej 2001). This is especially applicable for both steels and various ceramic objects in the brittle and ductile. The most important methods of improving fracture toughness of the engineering materials are associated with both the plasticization and the creation of structures would increase their minimum fracture toughness quality. To achieve this, it is necessary to increase two fundamental parameters of the material deformation that is the characteristic distance X and amount of cleavage stress.

References

Ahmed, O., Van Gemert, D. and Vandewalle, L. 2001. Improved model for plate-end shear of CFRP strengthened RC beams, Cement and Concrete Composites, 23, 3-19.

Aprile, A., Spacone, E. and Limkatanyu, S. 2001. Role of bond in RC beams strengthened with steel and FRP plates, Journal of Structural Engineering, ASCE, 127(12), 1445-1452.

Arduini, M. and Nanni, A. 1997. Parametric study of beams with externally bonded FRP reinforcement, ACI Structural Journal, 94(5), 493-501.

Ascione, L. and Feo, L. 2000. Modeling of composite/concrete interface of RC beams strengthened with composite laminates, Composites: Part B, 31, 535-540.

Bonacci, J.F. and Maalej, M. 2001. Behavioural trends of RC beams strengthened with externally bonded FRP, Journal of Composites for Construction, ASCE, 5(2), 102-113.

Chaallal, O., Nollet, M.J. and Perraton, D. 1998. Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates: Design guidelines for shear and flexure, Canadian Journal of Civil Engineering, 25(4), 692-704.

Chen, J.F. and Teng, J.G. 2001. Anchorage strength models for FRP and steel plates bonded to concrete, Journal of Structural Engineering, ASCE, 127(7), 784-791.

Hibbeler, R. 2005. Mechanics of Materials, Seventh Edition in SI Units, Singapore: Prentice Hall, Pearson Education Asia Pty Ltd.

Lu, X.Z., Teng, J.G., Ye, L.P and Jiang, J.J. 2005. Bond-slip models for FRP sheets/plates bonded to concrete, Engineering Structures, 27(6), 920-937.

Rabinvich, O. and Frostig, Y. 2000. Closed-form high-order analysis of RC beams strengthened with FRP strips, Journal of Composites for Construction, ASCE, 4, 65-74.

Rahimi, H. and Hutchinson A. 2001. Concrete beams strengthened with externally bonded FRP plates, Journal of Composites for Construction, ASCE, 5(1), 44-56.

Smith, S.T. and Teng, J.G. 2001. Interfacial stresses in plated beams, Engineering Structures, 23, 857-871.

Smith, S.T. and Teng, J.G. 2002. FRP-strengthened RC beams-I: Review of debonding strength models, Engineering Structures, 24(4), 385-395.

Smith, S.T. and Teng, J.G. 2002. FRP-strengthened RC beams-II: Assessment of debonding strength models, Engineering Structures, 24(4), 397-417.

Smith, S.T. and Teng, J.G. 2003. Shear-bending interaction in debonding failures of FRP-plated RC beams, Advances in Structural Engineering, 6(3), 183-199.

Täljsten, B. 1997. Strengthening of beams by plate bonding, Journal of Materials in Civil Engineering, ASCE, 9(4), 206-212.

Teng, J.G., Chen, J.F., Smith, S.T. and Lam, L. 2002. FRP strengthened RC Structures, U.K: Wiley, Chichester

Teng, J.G., Zhang, J.W. and Smith, S.T. 2002. Interfacial stress in RC beams bonded with a soffit plate: a finite element study, Construction and Building Materials, 16(1), 1-14.

Nairn, J. 2000. Analytical Fracture Mechanics Analysis of the Pull-out Test Including the Effects of Friction and Thermal Stresses, Salt Lake City, USA: Material Science & Engineering Department University of Utah.

Rice, J. 1968. Mathematical Analysis in the Mechanics of Fracture, New York: Academic Press.

It is commonly believed that athletes cope with stress better than non-athletes, either as a natural consequence of their training or due to better mental health. It may be reasoned that these stress management skills are particularly helpful in a collegiate environment since students are exposed to various academic, social, and financial stressors. I hypothesize that student-athletes in college have better stress management skills than their non-athletic peers. To test this hypothesis, a quantitative survey will be carried out amongst the athletic and non-athletic populations of my local university.

The questionnaire will consist of three parts: basic information, a stress scale, and a stress-coping inventory. Firstly, students will be asked to provide some background information so they can be labeled as either an athlete or non-athlete. Secondly, they will be asked to assess how often they experienced common symptoms of stress within the last month. It will include questions such as how frequently they experienced headaches and insomnia, as well as how often they were angered because of events outside of their control. Their responses will then be categorized as “low perceived stress,” “moderate perceived stress,” and “high perceived stress.” Thirdly, students will be asked to answer multiple-choice questions related to factors associated with successful stress management. A few examples include the quality of their diet, the frequency of alcohol and tobacco use, and the likelihood of asking friends or family for help. The students will then be qualified as possessing superior, above-average, average, or below-average stress management skills. A quantitative analysis will reveal whether athletes are statistically more likely to have lower perceived stress and engage in better stress-coping mechanisms.

Introduction

One common characteristic of most team sports such as American football, rugby, soccer and ice hockey is that they often involve a high level of physical and sometimes aggressive contact. This in fact is the main difference between these and other non contact sports such as basketball, netball, volley ball, etc. which involve much less contact.

In studies that focus on the motivation and emotion involved in contact sports, it has been reported that much of the pleasure associated with these sports lies in the aggression involved in the physical aspect. Within such sports it is unlikely to see a player receive punitive action for aggressive response such as a hard tackle or a strong body check and aggressive physical plays form a key aspect of these games (Kerr 1999, Page 115).

Research on the motives and emotion in sport indicate most researchers agree that the violence that characterizes most contact sports is not the same as what is typically understood of aggression outside of sport. In the context of sport aggression is mainly aimed at expressing dominance over opponents.

Within the rules of the games there are often means to check unsporting conduct when it occurs during play. However, despite of the existence of such safety measures it goes without saying that the risks inherent in contact sports can not be compared with those of non contact sports. In non contact sports the greatest risk is often losing the match or failing to complete the task where as in the case of contact sports a real risk of injury exists (Kerr 1999, Page 120).

Another major concern and common cause of decline among top sporting personalities can be associated with stress. Taking the case of George Best, the English soccer star of the 70’s, we have a clear case of stress related decline. It is reported that after having a brilliant career with his team Manchester United, Best suffered from depression, alcoholism and had legal issues leading to his eventual exit from the sport.

Among the reasons cited for this behavior included stress of not being able to perform after the club failed to sustain the high performing squad it once had enlisted. In other cases the sports men and women faced with pressure to produce favorable results resort to use of performance enhancing drugs or other recreational drugs to relieve the associated pressure (Kerr 1999, Page 155).

In this paper the discussion will provide some information on stress and injury in sport with a view to providing the reader with the sports men and women’s perspective.

Definition of Stress

The term stress is widely used and refers to any factor whether internal or external that makes the adaptation to an environment difficult. In addition to the increased complexity in the environment of an individual this phenomena causes increase in effort to maintain the equilibrium with the external environment (Humphrey, Yow and Bowden 2000, Page 2).

Stress results owing to several contributing factors which in some instances may cause confusion owing to the close relationship between these factors. One of the factors is tension which may be taken to mean unnecessary or exaggerated muscle activity. Tension is a spontaneous reaction resulting from the dominant mental condition that may result in stress. Emotion is factor that may be confused with stress and refers to an individual’s reaction to external stimuli.

Another factor that is often confused with stress is anxiety, which refers to uneasiness of the mind. It may be assumed that anxiety is the source of stress. Another factor that may lead to stress is depression which refers to an intense feeling of sadness in an individual (Humphrey, Yow and Bowden 2000, Page 3-4).

Although individuals react differently to stress there are a few common physiological reactions. For example, an increase in the heart rate, increased perspiration, increase in blood pressure, dilation of pupils, knotting of the stomach, difficulty in swallowing and a tight feeling in the chest.

Professional sports careers are often very demanding on the athletes involved and are a cause of increased stress in the lives of these athletes. It is interesting to note that in some sports such as American Football increased risk of cardiovascular disease that is often associated with stress was reported to have other causes such as large body size and obesity (Selden, Helzberg & Waeckerle 2009, Page 812).

Potential Causes of Injury in Sport

In addition to the possibility of injury that is inherent with sports, stress is also likely to increase the possibility of injury for the athlete. In the recent past there has been a lot of research on the relationship between bone health and exercise.

This research was found to be important owing to the implications of falling victim to a stress fracture on the running career of a young athlete. Data from track athletes indicated that stress related bone injuries comprise between 11% and 21% of all bone injuries in athletics. In addition to this it was also reported that women are especially at a higher risk of experiencing stress related bone injuries.

Among the reasons provided for this include low bone mineral density, menstrual irregularities, dietary factors and prior history of similar injuries. Prevention of such injury can be achieved through maximizing peak bone mass at a young age. In addition to this it is important to maintain adequate calcium based nutrition, proper caloric intake and an optimal balance of hormones and energy (Nattiv 2000, Page 1).

Although the prevalence of stress fractures is high among female athletes’ they also occur among male athletes. It has been reported that among player of Australian Rules football 5% of injuries were stress fractures. This data implies that stress fractures are a more common injury in the sport than groin injuries, dislocation of shoulders and knee injuries. Additional data indicated that the number of games missed as a result of these injuries has been on the rise from 28 in 1995, 66 in 1996 to 83 in 1997.

Furthermore this type of injury was not confined to professional athletes only but also affected amateur athletes’ where 4% of the injuries reported were stress related fractures. It has been suggested that the increase may be attributed to the increases in training load and in particular running training. Most clubs within these leagues have increased pre season cross training to reduce the incidences of the injuries (Brukner & Bennel 1999, Page 1).

The main cause of these injuries is overuse. An injury based on overuse involves certain muscles or bones of the body and develops over a period of time as a result of too much repetitive activity. The nature of the exercises associated with sports has the ability to cause such injuries. The repeated drills and routines that athletes’ are bound to go through on a regular basis are possible triggers. The injury gradually deteriorates over time until corrective therapy is applied (Hodson 1999, Page 1).

This case is evident in young footballers with load, posture, technique and equipment featuring as the main causative factors. It is currently the norm to develop sporting talent at a young age and many adolescents are recruited as potential candidates in sport training facilities.

These adolescents are encouraged to train and play more especially when considered to be gifted in a particular discipline. This induction at an early age without proper training may be the source of such injuries in the future of a player. It has been reported that children experience growth spurts from the ages of 7 to 18 years.

For those children engaged actively in sport at young ages their bodies develop muscle at a faster rate than skeletal development. Factors such as the incomplete development of bone tissue, reduced flexibility attributable to growth spurts are all potential causes for injury. It is reported that fast growing children are at a greater risk than those who grow slowly (Hodson 1999, Page 3).

The data from this report suggests that coaching staff need to be provided with adequate training on the physical aspects related to growth and integrate these into their training regimen. In addition to this the coaching staffs also need training to spot symptoms early and avoid serious injuries occurring within their teams.

Injuries in sport are not entirely isolated to stress and some are the result of contact that characterizes the games. It has been reported that in the game of soccer there is a risk of 13 to 35 injuries per 1000 hours of play. After the thigh, the feet and ankles have the greatest potential for injury in soccer with a potential incidence of 39 injuries per 1000 hours of play. The most common cause of this type of injury (ankle or foot injury) has been reported to be direct contact especially during tackling.

It was also reported that there is a higher incidence of injury during competition than during training which has been attributed to the increased speed of play. Other potential causes of foot and ankle injuries in soccer include hard ground, resumption of training after a break, poor footwear and increased intensity of training and running. This suggests that attention should be paid to these areas to limit the number and prevalence of such injuries among soccer players (Oztekin, Boya, Ozcan, and Zeren & Pinar 2009, Page 22).

Other than bone injuries athletes also suffer from a number of muscle injuries during games. It has been reported that over the past two decades injury trends have changed within the elite soccer circles with hamstring injuries becoming the most prevalent. In the English Premier League these injuries accounted for almost 12% of all reported injuries during a season. In addition to a high prevalence hamstring injuries have a very high rate of recurrence when there is premature return to play or inadequate rehabilitation programs.

It goes without saying that injury to key players can result in reduced performance and eventually have a negative impact of financial well being of the player and team.

As a result of this research has been carried out to identify high risk groups and prepare appropriate remedial actions for these groups. The research indicated that older players were more susceptible to hamstring injuries and as such their training required exercises to allow them adapt e.g. flexibility exercises. In addition to this it was found that screening may be useful within clubs to identify potential targets and adjust the training accordingly (Henderson, Barnes & Portas 2010, Page 397).

References

Brukner, P. & Bennel, K. (1999). Stress Fractures and Football. Journal of Science and Medicine in Sport, 2(1), 33.

Harry, J. H., Yow, D. A. & Bowden, W. W. (2000). Stress In College Athletics: Causes, Consequences and Coping. Binghamton, NY: Harworth Press Inc.

Henderson, G., Barnes, C. A. & Portas, M. D. (2010). Factors Associated with Increased Propensity of Hamstring Injury in English Premier League Soccer Players. Journal of Science and Medicine in Sport, 13, 397-402.

Hodson, A. (1999). Too Much Too Soon? The Risk of Overuse in Young Football Players. Journal of Bodywork & Movement Therapies, 3(2), 85-91.

Kerr, J. H. (1999). Motivation and Emotion in Sport: Reversal Theory. Psychology Press.

Nattiv, A. (2000). Stress Fractures and Bone Health in Track and Field Athletes. Journal of Science and Medicine in Sport, 3(3), 268-279.

Oztekin, H. H., Boya, H., Ozcan, O., Zeren, B. & Pinar, P. (2009). Foot and Ankle Injuries and Time Lost From Play in Professional Soccer Players. The Foot, 19, 22-28.

Selden, M. A.., Helzberg, J. H. & Waeckerle, J. F. (2009). Early Cardiovascular Mortality in Professional Football Players: Fact or Fiction? The American Journal of Medicine, 122(9), 811-814.

Accidents occur unexpectedly and the effects they bring about may be severe depending on their nature. The effects that are brought about by accidents vary in severity, and duration within which they affect individuals either directly or indirectly attached to the incidence. Air crash is one of the most fatal accidents and in most of the reported cases; there have been more casualties than survivors. The effects that are brought about by an air crash may be classified as either physical or psychological. In the physical effects, air crash brings about death, disability and injuries.

The effects from air crash are determined by among other things, the cause of the crash, the altitude and its speed at the time of crash. In addition, whether the aircraft catches fire or not after crash is another issue that determines severity of air accidents. There have been situations when survivors of air crash succumbed to fires erupting upon hitting the ground. Since the crash limits mobility, most of the victims succumb helplessly before the arrival of rescue teams. Among the different categories of persons affected by air crash, there are the survivors, family members and friends, members of the rescue team and the health practitioners handling the victims.

While the survivors may be affected by both physical and psychological aspects, most of the indirect victims suffer from psychological problems. After crashing, there are individuals who manage to remain arrive and in some instances leave the airplane before fire eruption. These persons are mostly partially hurt but get to experience the others burning helplessly inside the aircraft. The experiences by either direct or indirect victims lead to development of Post Traumatic Stress Disorder (Epstein, Fullerton & Ursano 1998). This is a serious condition that affects persons having disturbing pasts, and who might have experienced shocking incidences.

The problem is manifested within an individual after the scenes from past experiences starts top recur, and they disturb the peace and rational aspect in an individual. Such persons may start to hallucinate, experience strange and horrifying dreams and if not monitored in time, the disease can get worse. Physical defects that may be experienced after air crash differ according to the impact and the nature of the crash. While to some it may be worse, there are those who manage to escape with slight injuries.

The survivors of air crash first develop stress and depression, coupled with fear. Since most air crashes are horrifying, survivors carry the horrifying scenes along even after recovering from the physical injuries. Although the stress may not develop immediately, the victims start comparing certain incidences with the specific crash, and its then that stress emerges. Hallucinations may start, with victims hearing cries and calls for help from those who perished in the crash. These experiences make the individuals unable to concentrate in their work and depression slowly sets in. This problem is also related to issues such as age, sex, and health status of the victims. While middle-aged persons perform better than the aged, the young workforce seems to be at a greater risk of developing post traumatic stress disorder (Epstein, Fullerton & Ursano 1998).

The post traumatic stress disorder is therefore one of the key issues that arise among survivors and other victims of air crash. The recurrence of the incidence and exaggerated horrifying images and incidences are some of the main issues after air crash. The other persons that are affected by the air crash are members of the rescue team. Whether rescue comes from professionals or volunteers, the scenes present at the crash site may be too bad to watch. Body parts and trapped individuals are some of the scenes that may haunt the helper. Although it may seem like a normal life-saving task, the images and incidences at the crash site may be too bad for the rescue members. In addition, the healthcare professionals who attend to the victims and survivors are also affected by the conditions of the survivors (Epstein, Fullerton & Ursano 1998). The images that are recorded by the medical professionals and other individuals connected to the crash are the ones that generate stress and depression.

Fear and avoidance of certain places and activities are other effects that are developed after surviving plane crash. Traveling and especially by air starts to bother some individuals and they therefore struggle to defeat the fear, but finally gives up. The withdrawal aspect is very dangerous since it increases the vulnerability of the victims to other psychological problems. According to Epstein, Fullerton and Ursano (1998), the risk factors depend on various other external issues like age of the patient, duration and degree of exposure, social support offered, gender, intelligence and the social class within which the victim belongs.

Severity of the victim’s conditions continues even after being admitted to a health facility. The experiences of the survivor are worsened by the hospital’s atmosphere and the many cries and even deaths that are witnessed. Research by Alexander (1990) associated social class with victims’ susceptibility. The research had findings that associated the conditions of the survivor after the crash with whether their social backgrounds were well-off. Unemployed persons as well as those with unstable backgrounds were found to be more vulnerable than those with stable social and financial backgrounds. The flashbacks and the physical deformities are some of the worst effects that survivors must live with (Chung et al. 2001). Although the physical deformities are confused for the visible regions only, the internal organs are also affected and in most cases, injuries to internal organs lead to lifetime support, or death.

Coping with damaged spleen, kidneys and other important body organs is a factor that may lead to lifetime medication and this may be financially and socially unbearable. The physical injuries are therefore largest influence to psychological problems. The scars that are left serve as reminders to the horrifying effects and coupled by the injury’s strains, post traumatic stress disorder sets in. children of the victims are also known to be affected by the condition even if born after the accident. This is due to the scars present on the parent and the stories existing about the crash. The victims also feel guilty of having survived and the condition gets worse, if the duration for protracted exposure to the horrifying scenes was long.

To reduce the effects, a counseling program should be introduced immediately after the crash. Although the program is expected to start immediately after recovery of the patient, it’s at times integrated with the healing process for severe cases. The focus of counseling should be on inspiring hope to those affected. This is especially to those left with deformities. A normal and healthy person, who later can’t walk perform certain tasks must be given the hope to live and be assured of prosperity through other means (Johnson et al. 2009). In addition, the counseling program is also meant to ease the feelings that haunt victims after recovery. The feelings lead to stress, which lead to depression; helping in identification and coping with the aftermath is very important.

Educating the victims and identifying the problems facing them is another important aspect that counseling should focus on. With the objectives properly laid out, the implementation process should be properly initiated. The implementation process should never worsen the situation; instead, it should be encouraging to the victims and serve as a beacon of hope. The approach of the counselors to the victims may increase the feeling of guilt. It is essential that the victims are notified in advance and in the appropriate way possible. Despite the essence of the counseling program, it can never be forced down an individual.

The counseling sessions should be voluntary, but also inspired by the counselors. Despite the alienation of the survivors and unwillingness to cooperate, counselors should ensure that victims are aware of the consequences and encourage them to participate. It should therefore start in hospitals, where the practitioners should state how normal their conditions were and the various ways of dealing with them. This is meant to give the patient positive feelings and trust. Eventually, the patients are expected to trust the counseling program to join in (Alexander 1990).

The counseling session should help the victims to live comfortably for the rest of their lives and remain available to them, even after showing signs of full recovery. They should inspire hope and assure the victims that they are safe, while encouraging every individual to dispel memories of past and focus on the bright future ahead. The helpers also require psychological counseling. This is due to the exposure to disaster and to some extent guilt of something they feel they should have done. The counseling program should be coupled by a debriefing measure that seeks to ease the feelings’ expressions. In addition, it’s meant to review the roles and responsibilities of the helper through identification of the positive gains available.

The debriefing program should also be a solution-seeking initiative, with focus being on the victims. It should therefore be more focused on making the helpers more vibrant in their work and always work with positive dedication. They should also ensure that the most affected are given the support they require, and that all accept their roles for increased efficiency. Respecting the success or any eventuality of the rescue teams should be encouraged as it gives the helpers assurance and removes the feeling of guilt. The practice is therefore very important in ensuring that the survivors lead a normal life, while the helpers carry on with their responsibilities without being affected by scenes from the past.

While the survivors are the most affected especially those that sustained physical deformities, the helpers are equally affected and it’s only through proper medication and counseling that the individuals can cope (Johnson et al. 2009). Social and family support is also important as it encourages openness and builds trust from the victim. With assurance of a better future, survivors tend to slowly forget the past and attain full recovery and experience speedy adaptation.

References

Alexander, DA 1990, ‘Psychological intervention for victims and helpers after disasters’, British Journal of General Practice, vol. 40, pp. 345-348.

Chung, MC, Easthope, Y, Chung, C & Clark-Carter, D 2001, ‘Traumatic stress and coping strategies of sesternary victims following an aircraft disaster in Coventry’ Stress and Health vol. 17, no. 2, pp. 67–75.

Epstein, R, Fullerton, CS & Ursano, RJ 1998, ‘Posttraumatic stress disorder following an air disaster: A prospective study’, The American Journal of Psychiatry, vol. 155, no. 1, pp. 934-938.

Johnson, M, Ken, L, Harris, L, Gillespie, M, Pusateri, A & Holcomb, C 2009, ‘Mortality associated with injuries sustained by aircraft accident burn survivors’, Internet Journal of Rescue and Disaster, vol. 8, no. 2, pp. 1-10.

Introduction

College student athletes engage in various kinds of sports based on their talents, interests or other personal reasons. Sporting is characterized with elements of stress as seen from research mainly from the competition, uncertainty of the outcome, isolation, identity crisis and other effects from lack of enough time to engage with other activities as well as the perceptions of their peers, family and society to them with their individual expectations.

While much research is based on addressing these stress factors the college student athletes are faced with (Donohue, Miller, Crammer, Cross and Covassin, 2007), it is worth realizing that they are also students and hence not exempted from academics.

It is therefore necessary to focus on how college athletes deal with stress from sports, social life involvement and academics. This project recognizes the need to address these issues as being very crucial. We thus seek to provide recommendations for enabling college student athletes to deal with stress from sports, social life and academics as well as adequately create a balance in these areas through effective time management.

Description of Intervention

Research asserts that engaging in leisure activities acts as a way of coping with stress and related problems due to the directing of tension, anger and other emotions to some physical activity such as sporting activity (Chalip, Thomas & Voyle, 1992).

However, further research has found that engaging in a sporting activity can also be a source of stress in itself especially due to the aspects of competitions, injuries, high expectations of relevant people on the athletes and balancing in life (Donohue et al., 2007). The college student athletes are faced with specific problems that stem from the sports, academics, social life and other significant relationships in their lives.

Donohue et al. (2007) suggest that the lack of a standardized instrument to measure the specific problems experienced by college student athletes makes it difficult to address their problems. They however argue that the college student athlete is faced with specific problems that are mostly stress-related.

This project seeks to evaluate and address the aspects of stress, social life and academics that college student athletes face and the various ways of enabling them deal with such stress issues and establish a balance between their sports, academics and social life. In particular, the intervention will put emphasis on improving the relationship of the athletes with their coaches.

Elements of Intervention

College student athletes, as Donohue et al. (2007) assert, have specific problems that are not adequately addressed through standard research instruments. In this project, the elements are based on the sources of stress for the college student athletes. The main focus is on the relationships the athletes have which determine their negative or positive reactions and attitudes.

These relevant relationships are with their families, peers, teammates and coaches. In addressing these relations, more emphasis has been laid on the coaches since research shows that college student athletes have positive relationships with their families, peers and teammates but negative relations with their coaches due to their use of punitive measures (Donohue et al., 2007).

Further, as Kimball and Freysinger (2003) suggest, the elements of gender and race are of concern in this project. The research provides that there are significant differences in the perceptions of college student athletes in reference to gender.

While females are more affected in terms of the desire for close social relations due to their relational attributes, males are less affected by social isolation although both genders are affected to some degree. Additionally, the element of race comes up with the fact that race plays a crucial role in the stress issues of college student athletes (Kimball & Freysinger, 2003).

The students from a minority race are more affected socially from their involvement in social activity since the level of isolation increases from the effects of racial minority and involvement in sports. Additionally, others are less affected from stress issues since participation in the sporting activities helps them have teammates as friends thus reducing their levels of isolation.

The element of academics – particularly the graduation rates of college student athletes – is raised by Rishe (2003). While the study recognizes that there is no significant difference in the graduation rates between college athletes and non-athletes, it recognizes that this is from the support mechanisms that enable the college athletes manage time effectively. This means that the community, especially the school administration, has to develop programs that enable the college athletes to balance their academics and sports.

In this regard, academics are significant in the lives of the college student athletes since it is not guaranteed for them to engage in professional sports. This project is thus evidence based coaching practice and training to enable coaches become influential in helping the college student athletes deal with stress in their sports and advice them on balancing their sports, academics and social life.

Further, the project involves the production of a manual for the use by the stakeholders and college student athletes based on time management and dealing with stress. The basic question of the research study for this project is whether the democratic style of leadership for coaches can positively influence student college athletes in terms of motivation and help them deal with stress issues they face.

Contribution and Implementation of the Intervention

The contributions of this project are bound to be vast. This is relevant not just for the athletes but also the administrators, analysts, coaches, teachers, peers, families and their friends.

This intervention has the ability to increase the awareness of the specific problems facing the college athletes and provide opportunity to be used as a survey instrument in addressing these problems. This project also contributes to the field of sports and leisure by addressing leisure as a cause of stress so that it can maintain its objective of enabling the college athletes cope with stress.

The contributions of the elements raised increases the realization of the policy makers to address them such as racial discrimination in schools and the aspects of gender issues in sports. This research study can also be useful as a foundation of future research since the field of college athletes issues of stress is very wide and thus this project focuses on one section of this field.

The implementation of the intervention requires the training of coaches through the evidence-based research. Since the focus of the research study is on whether the democratic style of leadership for coaches can help college athletes deal with stress issues, the coaches are the main focus.

The sample is made up of ten coaches of different schools and in randomly selected sporting activities. The success of their leadership will be determined through a pre test questionnaire as well as post test analysis of such leadership. The success of democratic leadership will also require the evaluation of the athletes who are 100, ten from each school.

The manuals on stress and time management for college student athletes can be adequately applied by the stakeholders such as school administrators, policy makers, parents, students, the government and the athletes themselves together with their peers to enable them become aware of the specific problems the college students athletes face and the ways of helping them deal with them.

The implementation can be based in training programs, encouraging support for the athletes especially for the relationships they have with their families, teammates, coaches and peers as well as teammates and strict adherence to academic requirements by the administrators to enable the student athletes adequately participate in academics increasing their success. Further implementation is through counseling programs and the encouragement of positive behaviors for the athletes.

Evaluation of the Intervention

The intervention in this project recognizes that there is limited standardized instrument for research in specific problems facing college student athletes (Donohue et al., 2007). The evaluation of the success of this research study is based on the objectives of the study and makes use of evaluation measures applied in other past relevant research.

The use of the evidence based coaching practice would require training of the coaches and the use of manuals for counseling of students athletes while encouraging their training and that of the relevant people in their lives. The aim of the project is to foster positive coaching style for the coaches specifically the democratic style which increases the level of motivation of the athletes thus enabling them deal with the problems facing them objectively (Donohue et al., 2007).

Further, it seeks to increase the awareness of the relevant people in the lives of the athletes on the specific problems the athletes face. These relevant relationships are their families, peers and teammates with the objective of enabling them increase their support for the college student athletes in the areas of social life mostly for the peers and teammates, encouraging balance between sports and academics mostly by the families while the teammates are able to encourage positive behaviors among themselves.

Further, the intervention hopes to increase the skills of the college student athletes in their management of stress related issues from sports, social life and academics and the increasing their ability to balance the areas. The evaluation of the support of the peers would involve the SARI instrument based on 10 statements from Donohue et al. (2007) and also other support in terms of general interactions, cheering and support during sporting events and inclusion of college athletes in their academic discussions.

The evaluation of the objectives of the project is based on the target group of the coaches as well as the subjects of study who are the college athletes. In the case of the coaches, the evaluation is based on the expectations upon them which are the adopting of the democratic style of leadership. This will be measured through the level of support, praise and social support they offer to the college student athletes.

The evaluation of this is based on the Student Athlete Relationship Instrument developed by Donohue et al. (2007). This instrument utilizes 25 statements for the relationships the athletes have with the coaches based on a 7-point Likert scale with the scale items ranging from “extremely disagree” to “extremely agree”. This measures the level of motivation the athletes have to the sport due to their coaches as well as their perceptions of his/her coaching style.

Further evaluation of the effectiveness of the coaches’ practice would be based on observation means assessing the use of positive feedback and the reinforcements’ strategies used in the course of the sports training and interactions with the college student athletes (Donohue et al., 2007). The non-democratic style shall be seen from the diversions from the positive results expected, the SARI reports of the athletes and the observation of the communication and support the coach gives to the athletes.

The evaluation of the changes in the relevant people in the lives of the athletes would also make use of the Student Athlete Relationship Instrument (SARI) by Donohue et al. (2007) based on each group. For example, in evaluating the success impact of the manuals on the families, the instrument would make use of 24 statements on family support for the athletes to answer.

The aspect of graduation rates among college athletes would be measured using the measures adapted in Rishe (2003) which would reveal the effect of training programs and the ability of the college student athletes to balance between sports, social life and their academic requirements. All these measures are based on the objective of the study based on democratic leadership in terms of how this can increase the motivation and confidence of the athletes to have their peers also believe in them and cheer them.

Further, the measures on alcohol related problems and gambling are based on evaluating how the democratic style of leadership by coaches can help athletes deal with stress issues more objectively thus avoiding such behaviors. This style is also evaluated in interactions between teammates in the influence of democratic style in fostering teamwork.

The ability to gauge unexpected outcomes would be based on the diversion of the results from the expectations, while the results would also reveal the personal influence on the project. The measures used for evaluation as the SARI measures, Daily Drinking questionnaire, Rutgers Alcohol Problems Index, measures adapted in Rishe (2003) can be applied in other studies and contexts involving college students especially on alcohol and other behavioral studies (Leichliter, Meilman, Presley & Cashin, 1998).

The effects of changes affecting the whole system such as the administration of the school and the family unit through the changes of the student would be identified through feedback mechanisms both the feedback received as well as the failure to receive any feedback (Sherburne & Ruth, 2010).

This is also to be established through observational studies and evaluation for changes. The procedure to conduct this project would involve communication with the schools and relevant administration and mostly the coaches. This would then facilitate the issuing of questionnaires to the coaches regarding their style of leadership and their perceptions of how affects the college athletes.

The college student athletes will also be given questionnaires to fill and return at their own convenience. Emphasis would be on the practice training of the coaches with regards the styles of leadership as well as the motivations and support of athletes. This would involve delegations with them on the need to come up with strategies for identifying and solving specific problems of the student athletes and then initiating practice for the application of the democratic style.

The findings from the research would be mailed to the families and communicated face to face with the coaches, school administrators and the athletes themselves and mailed for other users such as sport psychologists.

The other factors to be considered in the project would be differentiating the support of families from pressure-related stress on the athletes, the season for carrying out the project since past research has established that research done on athletes need to be in the season of sporting activity to increase the levels of feedback and reliability of information received (Kimball & Freysinger, 2003), the differences in sports in terms of stress levels and support accorded (Martens, Dams-O’Connor, Duffy & Gibson, 2006)

The college athletes are not the main study sample, but they are part of the subjects involved in gauging the success of the selected sample which is ten coaches. The main focus is no the effects of their use of democratic style of leadership on the athletes mainly in dealing with their stress related issues.

Conclusion

College student athletes are affected by specific problems most of which are associated with stress factors. This project intervention will evaluate the specific problems college student athletes face in terms of stress from their sporting activities, social life and academics.

It will provide the mechanisms for addressing ways of establishing balance through increased support by focusing on the effectiveness of the use of democratic style of leadership for coaches. The project is evidence based coach practice and training, and evaluation. The project has established the implementation and contributions to sports study and the modes of evaluation. The factors of concern however are the effects of democratic style of leadership, differences in sports and the season of carrying out the research.

Reference List

Chalip, L., Thomas, D. R., & Voyle, J. (1992). Sport, recreation, and well-being. Palmerston North, NZ: Dunmore Press.

Donohue, B., Miller, A., Crammer, L., Cross, C., & Covassin, T. (2007). A standardized method of assessing sport specific problems in the relationships of athletes with their coaches, teammates, family and peers. Journal of Sport Behavior, 30(4), 375-397.

Kimball, A., & Freysinger, V. (2003). Leisure, stress, and coping: The sport participation of collegiate student-athletes. Leisure Sciences, 25, 115-141.

Leichliter, S., Meilman, W., Presley, A., & Cashin, J. (1998). Alcohol use and related consequences among students with varying levels of involvement in college athletics. Journal of American College Health, 46, 257–262.

Martens, M., Dams-O’Connor, K., Duffy, C., & Gibson, J. (2006). Perceived alcohol use among friends and alcohol consumption among college athletes. Journal of the Society of Psychologists in Addictive Behavior, 20(2), 178-184.

Rishe, P. (2003). A reexamination of how athletic success impacts graduation rates: Comparing student athletes to all other undergraduates. American Journal of Economics, 62(2), 407-427.

Sherburne, C., & Ruth, S. (2010). College athletes’ perceptions about relational development, communication and interpersonal competence. Journal of Humanities and Social Sciences, 70(9), 419-429.

Introduction

College student athletes engage in sports for various personal reasons and interests. Participation in college sports is based on personal choices and leaves the athletes with stress issues involving competition in the sports, maintenance of good grades and social life as well as time management for all these activities (Kimball & Freysinger, 2003).

The involvement of college athletes in sports exposes them to stress which applies to different generations over the years. The stress affecting not only affects their sporting, but also other disciplines such as health, psychology, leisure, social life and academics all of which form a crucial part of the athletes’ life.

In addition, the athletes are faced with pressure and high expectations in the fields, confusion about their identity as well as the increased peer pressure (Donohue, Miller, Crammer, Cross & Covassin, 2007). As a result, there are many opportunities for counseling and other support programs for the college athletes due to the increase in health issues, involvement in crime, self esteem problems, drug abuse and related vices, and peer and parental pressure.

It is worth noting that field-based research helps these students by giving them recommendations on handling the problems especially in the career and vocational concerns, fear of success, academic problems, conflicts in terms of identity, poor sporting performance and isolation problems (Sherburne & Ruth, 2010).

Additionally, college athletes can either venture into professional sport or academics and other sport-related entrepreneurial activities and this creates the need for guidance in identifying themselves and in decision making especially regarding career development. The relevant journal articles regarding college athletes and stress issues will be reviewed in this paper.

The review helps to provide information regarding how college athletes deal with stress, balance between studies and sports and how they manage their time. The articles that provide a historical insight to the topic include studies conducted by: Rishe (2003), Kimball and Freysinger (2003) and Martens, Dams-O’Connor, Duffy and Gibson (2006).

Donohue, Miller, Crammer, Cross and Covassin (2007) provide the best practice in the subject area while Sherburne and Ruth (2010) and Huang, Durand, Derevensky, Gupta and Paskus (2007) provide a theoretical background for the subject of college student athletes and stress influences.

Literature Review

Kimball and Freysinger (2003) conducted a research study entitled “Leisure, stress, and coping: The sport participation of collegiate student-athletes” which explores the stress experiences of college student athletes that are influenced by their participation in sporting activity.

They provide a strong historical background and approach for the relationship between college student athletes’ participation in sport, stress issues and coping mechanisms by evaluating historical researches conducted on sport psychology. Historical research suggests the existence of a relationship between participating in leisure activities such as sports in that leisure itself could provide sources of stress for college student athletes (Iwasaki & Smale, 1998).

However, Kimball and Freysinger (2003) narrow their research to focus on college sport, the stress process and the influences of gender and race in shaping the stress experience for college student athletes to provide more explanations for leisure, coping with stress and health relationships.

The study relied on a gender balanced sample but of different races and academic levels. The study involved interviews to identify stressors both within and outside the sporting activity, stressors from other previous research and other structural factors. The study provides the historical background of the sources of stress for the college student athletes providing information as to how college athletes perceive stress, influences such as race and gender as well as the benefits of sports in reducing stress for the college athletes.

For example Dale (2000) provides the meaning of stress to the student athletes. In addition, the researchers found that though leisure can be a source of stress, it also has significant positive effects on health and acts as a means of coping with stress. The study also revealed that there are differences in gender perceptions towards college sport and stress and that race is a causal factor of stress among college student athletes especially for those of a minority race since it affects their social life and increases isolation.

The study revealed that concepts of self determination, social support and control affect the students with indications that the college sports both generate and buffer stress.

The study however was limited by not examining the relationship between leisure and health for the college student athletes and the racial disparities used were not conclusive. Another limitation is the assumption that participating in sport for the college student athletes would be a stressful experience which may have limited analysis due to the subjective nature of stress and individual differences (Kimball & Freysinger, 2003).

Donohue et al. (2007) conducted a study whose main objective was to develop an instrument that would assess the specific sport problems in the relationships between athletes and their coaches, peers, family and teammates. The researchers provide a best practice approach for the negative and positive role these relationships play in the stress influences of college athletes as well as their role in coping and support mechanisms for the athletes.

The researchers shed light on the great influence of motivation on the athletes, the determinant role of parents in sport motivation for athletes; the role of peers in companionship, esteem, support and recognition for accomplishments, and the negative influence of coaches on the athletes. The relationships presented in the study form the foundation for the role they play in influencing the college athletes in competing in sports, managing their social and academic life as well as time management.

Donohue et al. (2007) present the best practices for the relationship between college student athletes and how they deal with stressors in sport competition, maintenance of good grades and social life as well as time management. They highlight the positive and negative influence these relationships have on the college athletes both as creating stress and providing coping mechanisms.

For example, coaches influence the stress levels of the athletes during competition, peers and teammates provide the athletes with a social life by providing friendship and social support while parents determine the balance they have with their academics.

Donohue et al. (2007) use the ratings on happiness from the relationships and their influence on the sporting performance of the athletes whose results are used to form the Student Athlete Relationship Instrument (SARI). The results support the assertion that family members have greater influence on the involvement and achievement of college athletes in sports than their coaches.

Huang et al. (2007) conducted a study which analyzes gambling among college student athletes. The researchers base their study on the concern that the prevalence rates of gambling among the youth, gender differences, the influence of sporting and the concern for public health require more attention despite claims that the issues of gambling among youths is limited (Derevensky & Gupta, 2000).

This study provides theoretical background on the relationship between college student athletes and how they deal with stressors in sport competition, how they balance academic and social life as well as their time management strategies. This is demonstrated by the significant differences between gambling by athletes and non-athletes.

The athletes in the study were more involved in gambling than non-athletes with the involvement varying with the type of sport and gender thus presenting the differences in stress levels and management in different sports and gender.

Huang et al. (2007) show that out of the interviews and surveys conducted the college student athletes were motivated to engage in gambling for the sake of money. Further, the athletes had a highflyer level of engagement in sport wagering such as taking money for playing poorly and influencing the outcome of games with a certain percentage of them being pathological gamblers.

These behaviors can be highly associated with the stress factors that result from participating in sporting activities but the degree of stress varies with the sport. The study is limited by its reliance on the survey and lack of diverse sources of evidence. In addition, the responses were anonymous and not based on schools hence measurement of responses was not highly objective (Huang et al., 2007).

Martens et al. (2006) conducted a study titled, “Perceived alcohol use among friends and alcohol consumption among college athletes,” whose purpose was to determine whether alcohol-related problems and individual consumption of alcohol for college student athletes was more influenced by their close teammates or those in other different sports with similar behaviors than their non-athletic friends.

Further, the researchers sought to establish gender influences on individual consumption of alcohol and related behavior. The study established its findings that the college athletes were influenced more by their teammates and close athletes in other sports than by their non- athletic friends, with male students more involved in alcohol consumption than females.

This comprehensive study relates to the relationship between college student athletes and how they deal with stressors in sport competition, balancing of academic and social life as well as time management. The alcohol related problems affected the ability of the college athletes to concentrate on academics while much time was spent in sports and social life with the teammates. This study presents a rich theoretical background for the subject.

Past research shows that college student athletes who are considered to be at risk are more likely to engage in heavy alcohol consumption than non-athletes due to the high pressure and stress they face (Leichliter, Meilman, Cashin & Presley, 1998). The study makes use of a sample of 170 college student athletes who filled in the questionnaires administered by researchers.

The research revealed that the athletes perceived and estimated that their friends had higher alcohol consumption levels than themselves, with men having higher rates of alcohol consumption and alcohol-related behavior than women. Further, the research suggests that the involvement in sporting activities caused isolation and segregation which played a key role in their behaviors.

Conflicts in identity for the athletes were more pronounced in women while the influence of alcohol consumption is higher in team sports than individual sports. The research however is limited by the use of a cross-sectional study design which made it difficult to form conclusions that link causes and effects of the variables under investigation. Moreover, the method of data collection used relies on only one institution and the season on which the study was based did not coincide with sport competition events.

Rishe (2003) conducted a study titled “A reexamination of how athletic success impacts graduation rates: Comparing student athletes to all other undergraduates.” The study serves as a way of improving on past research on the subject through narrowed focus on the graduation rate of student athletes thus presenting a rich historical background on the subject.

This study is relevant to the relationships of how college student athletes deal with stressors from competing in sports, maintaining good grades and social life as well as time management. The academic performance of such athletes is revealed by their graduation rates or the venture of some athletes into sporting careers.

Past research shows that success in sports leads to poor academic performance (William, Tollison & Goff, 1986) while an inverse relationship exists between graduation rates and some sporting activities such as football (Tucker, 1992). In his study, Rishe (2003) makes use of empirical analysis with four cohorts from 308 division-1 schools.

The study shows that the degree of success of athletics influences the disparity in graduation between non-athletes and athletes and argues that college athletes are not affected negatively by the success of the athletic programs in their school. Rishe suggests that the difference in graduation rates between non-athletes and athletes is due to the pressures to succeed athletically which sometimes causes the athletes to focus more on sports.

This is relevant to the theoretical subject because of the fact that the pressure to succeed acts as a stressor to athletes and influences how they balance their academics, sports and social life. Rishe (2003) shows that female college athletes have higher graduation rates than their male counterparts, a fact that is explained by the gender differences in dealing with stress.

Additionally, the influences of the athletic program in place together with resources available as well as the control programs available are crucial in analyzing the graduation rates for athletes.

This is related to the issues of how college athletes deal with stressors of competition in the sport which is made efficient through effective athletic programs; maintenance of good grades which is influenced by availability of learning resources and institutional controls which also influence their social life; and time management skills needed to provide the right balance between sports, academics and social life.

The objective of the study by Sherburne and Ruth (2010) is to evaluate how participation in sports for college students influences their social skills and development, an area that has limited research. The study provides a review of past research that asserted that college athletes spend less time in socialization and communication with other people other than those in their sport or team as compared to non-athletes (Sherburne & Ruth, 2010).

The past research assumed that college athletes do not have much time to socialize because of the pressure of sports and academic work. In relation to the topic, Sherburne and Ruth (2010) highlight the stressors of social life that college student athletes contend with since the other peers assume that they do not have any time for socializing due to their tight sports and academic schedules. They further do not understand them and fail to recognize that the expectations that come with sports can be stressful for the athletes.

The study analyzed differences between non-athletes and athletes in the aspects of interpersonal competences and communication using questionnaires and communication competence scale. However, the survey did not find significant differences between non-athletes and athletes.

This means that once there are established support mechanisms, administrative control and balanced athletic programs, the difference in the social, academic and general differences between athletes and non-athletes are likely to be minimized. This is due to the relevance of coping mechanisms and other counseling services that keep athletes in balance (Sherburne & Ruth, 2010).

Further evaluation of interviews and focus group discussions revealed that college student athletes faced social isolation because of lack of time which narrows down to time management and conflict of identity. This is because there is confusion on whether they first identify as athletes then students or vice versa. Isolation is also due to the uncertainties that the college students face regarding the competitive nature of sports with the probabilities of winning or losing which create tension for them.

Uncertainty is also experienced by the students in academics some of whom are prone to poor performance. The study found a correlation between the personal life (socialization) of college athletes and their performance in. The research provides suggestions for future research and the development of support mechanisms through administration, coaching, mentoring and counseling to help the athletes acquire good socialization and communication skills for improved performance in sports and life (Sherburne & Ruth, 2010).

Discussion

The research on the college student athletes and how they deal with stress in sport competition, maintenance of good grades and social life as well as time management is still relevant and of crucial importance in the face of increased stress issues on the verge of competition. The results of the studies reviewed in this paper have provided the platform upon which the study will be undertaken since they provided the historical insights and theoretical approach for the topic and offered best practices for the issue under investigation.

Reference List

Dale, G. (2000). Distractions and coping strategies of elite decathletes during their most memorable performances. The Sport Psychologist, 14 (1), 17–41.

Donohue, B., Miller, A., Crammer, L., Cross, C., & Covassin, T. (2007). A standardized method of assessing sport specific problems in the relationships of athletes with their coaches, teammates, family and peers. Journal of Sport Behavior, 30(4), 375-397.

Huang, J., Durand, J., Derevensky, J., Gupta, R., & Paskus, T. (2007). A national study on gambling among US college student athletes. Journal of American College Health, 56(2), 93-99.

Iwasaki, Y., & Smale, B. (1998). Longitudinal analyses of the relationships among life transitions, chronic health problems, leisure, and psychological well-being. Leisure Sciences, 20, 25–52.

Kimball, A., & Freysinger, V. (2003). Leisure, stress, and coping: The sport participation of collegiate student-athletes. Leisure Sciences, 25, 115-141.

Leichliter, J. S., Meilman, P. W., Presley, C. A., & Cashin, J. R. (1998). Alcohol use and related consequences among students with varying levels of involvement in college athletics. Journal of American College Health, 46, 257–262.

Martens, M., Dams-O’Connor, K., Duffy, C., & Gibson, J. (2006). Perceived alcohol use among friends and alcohol consumption among college athletes. Journal of the Society of Psychologists in Addictive Behavior, 20(2), 178-184.

Rishe, P. (2003). A reexamination of how athletic success impacts graduation rates: Comparing student athletes to all other undergraduates. American Journal of Economics, 62(2), 407-427.

Sherburne, C., & Ruth, S. (2010). College athletes’ perceptions about relational development, communication and interpersonal competence. Journal of Humanities and Social Sciences, 70(9), 419-429.

Tucker, B. (1992). The Impact of Big-Time Athletics on Graduation Rates. Atlantic Economic Journal, 20, 65–73.

William, F., Tollison, D., & Goff, B. (1986). Pigskins and Publications. Atlantic Economic Journal, 14, 46–50.

Introduction

The demands of an athlete both professional and family life causes stress and anxiety. Therefore, we can not talk of the effects of demands without stress and it is effect. Mental health can also be another issue to be looked at while defining the cause’s demands. we can define stress in many ways. Stress is a harmful physical and emotional response that occur to and individual when the requirements of an activity exceed the capabilities and needs of the individual. ( www.ilo.org).As a matter of fact every individual is affected by anxiety, which is the reaction of an individual when he encounters stress. A great amount of stress can affect the performance of an athlete because he lacks concentration in what he is doing. Pre-competition anxiety has been the great important focus when researching about athletics.

It can also be defined as “the emotional, cognitive, behavioral and physiological reaction to aversive and noxious aspects of work, work environments and work organizations. It is a state characterized by high levels of arousal and distress and often by feelings of not coping.” (www.tcd.ie). from this definition demands can be related with

In relation to sports and specifically athletics it can be defined as a physiological reaction to aversive and noxious aspects of athletics and environments i.e. excessive pressures or the demands placed on them.

It is clear to everyone that you have to be mentally fit for you to be an athletic performer, you must be stress free, you must be a positive thinker, you must be aiming high at all times and even setup goals that you must achieve in life. All this attribute to mental health that one must bear. Therefore, when you see this, alongside other factors then you should be to point out that one could be optimistic athletic performer because this is the major requirements.

A good performing athlete has higher mental resistance and his performance is not affected by his mind. He is resistant to any change, when his mind is disturbed, he continues with his activities well up to the end. He is frank and does not hide anything, even if he realizes any point of weakness; he points it out and tries to improve it.

The athlete must be in good health, he should be free from diseases all the time, he should have a good physical composition and be physically fit because the activities he is involved in are demanding and requires someone to be strong enough to be able to succeed.

Causes of Stress for Athletes

There are different types of stress that affect different athletes from different lifestyles. This can be subdivided into two that is personal and situational.

1. Here are some of the personal causes of stress
   1. Cognitive anxiety, which includes worry, and uncertainty,
   2. Somatic anxiety this includes movement changes in the perceived physiological stimulation
   3. Behavioral anxiety this involves peoples behaviors.
2. Situational is related to the events and uncertainty. An athlete may feel burdened when entering into real action

Effects of Demands (stress) to an athlete

The physiological reaction athletes to threats or pressure prepare them for intense physical activity of athletic. This can be observed through changes of the heartbeat and inhalation pace. In the body, there will be diversion of more blood to the muscles than to other organs. The result is the release of adrenaline raising levels of glucose and free fatty acids in the blood stream to provide greater energy (www.personal.psu.edu )

Importance of stress management

Stress can be positive or negative. Under normal circumstances, athletes should be able to find new balances and responses in their reactions to events. Such a stress cannot be said to be negative, as it will act as a motivational factor. “A moderate level of stress can be an important motivational factor and can be instrumental in achieving a dynamic adaptation to new situations. If health is considered as a dynamic equilibrium, stress is part of it. There is no health without interaction with other people and with the environment. Only excesses of stress are pathological.” (International labor organization)

In athletics, therefore stress normal and necessary. What should be avoided is intense, continuous or repeated which a person is unable to cope with, or if support is lacking, stress then becomes a negative phenomenon, which can lead to physical illness and psychological disorders. In a work context, it often results in inadequate adaptation to situations, people, and failure to perform at an optimal level. (International labor organization)

References

Dik B. (2004); measures of career interest; John Willey.

Doraten B. (1999); cross country runners and track and field athletes.

International labor organization (2007). Web.

Pendergrass L. (1999); Examination of the concurrent validity of scores from the CISS for student-athlete college major selection; counseling and development.

Penn state, stress management. Web.

Summers J. (2004); sports psychology: theory application and issues; Chichester.

Weinberg R.S (2003/2007); foundations of sports and exercise psychology.