Fatigue Life Assessment for an Aluminum Alloy Piston Using Stress Gradient Approach Described in the FKM Method

Engine piston is one of the most complex components among all automotive. The engine can be called the heart of a car and the piston may be considered the most important part of an engine. In fact, piston has to endure thermo-mechanical cyclic loadings in a wide range of operating conditions. This paper presents high cycle fatigue (HCF) life prediction for an aluminum alloy piston using stress gradient approach described in the Forschungs Kuratorium Maschinenbau (FKM) method. For this purpose, first Solid works software was used to model the piston. Then Ansys Workbench software was used to determine temperature and stress distribution of the piston. Finally, in order to study the fatigue life of the piston based on HCF approach, the results were fed into the nCode Design Life software. The numerical results showed that the temperature maximum occurred at the piston crown center. The results of finite element analysis (FEA) indicated that the stress and number of cycles to failure have the most critical values at the upper portion of piston pin and piston compression grooves. To evaluate properly of results, stress analysis and HCF results is compared with real samples of damaged piston and it has been shown that critical identified areas, match well with areas of failure in the real samples. The lifetime of this part can be determined through FEA instead of experimental tests.