FATIGUE LITE PREDICTION METHODS IN AN ENGINE MATERIAL

Often, machine members are found to have failed due to the action of repeated or
fluctuating stresses; yet the most careful analysis revealed that the actual maximum
stresses were well below the ultimate strength of the material, and quite @uently even
below the yield strength. The most distinguish characteristic of this failures is that ttre
stresses have b€en repeated a very large number of times. Hence, the failtre is called a
fatigue failure. tn this study, crankshaft has been used as a component to analyze and
evaluate its fatigue perfonnance. Fatigue is the primary cause of failurc in int€rnal
combustion engines due to the cyclic loading conditions and the stress concentratiom in
the crank pin fillet. There are a lot of methods used to predict the f*igrre life. However,
for this projecL only the most common method to predict the fatigue life will be focuse{
namely Stress Life Method and Strain Life Method. These two methods will be
compared and one method will be selected to be used in fatigue life estimation of the
crankshaft. Finite Element Analysis (FEA) will be done using ANSYS to obtain
variation of stress magnitude at critical locations. In addition, the effect of diffeleot
manufacturing pnocess and material will be investigatd to determine the fatipe
performance of the crankshaft.