Thermo-Mechanical Fatigue Life Assessment of a Diesel Engine Piston

In this study, a precise finite element analysis has been carried out on a diesel engine piston, in order to attain its high cycle fatigue (HCF) safety factor and low cycle fatigue (LCF) life. In order to calculate the HCF safety factor, a macro has been developed using ANSYS Parametric Design Language (APDL). The relative stress gradient parameter is used in order to perceive stress concentration and notch effect. In high cycle fatigue assessment, the effect of mean stress is considered using Haigh diagram. Different LCF life assessment methods have been used to investigate LCF life of piston and their results are compared to each other. The diesel engine piston is subjected to non-proportional multiaxial loading. The non-proportional loading leads to an additional cyclic hardening in the material. Critical plane LCF theories are appropriate for consideration of the additional cyclic hardening effect on the LCF life reduction of the piston.