Piston is affected by gas explosion pressure and the reciprocating inertia force and their common feature is that they effect along the axis direction of the piston, so the axis direction of piston bears the bigger load. From the Fig4, we can see that the maximum stress appears the center of piston pin
top, which is accordance to engine design manual. Piston pin top is the easiest fracture parts. When piston operating, the maximum equivalent stress value of piston pin is about 8 M Pa and equivalent stress value of the other parts is under6 M Pa. From the analysis of strain, the maximum strain appears in the piston top, the maximum strain is about 0. 06%. The results of these simulations analysis provides a strong theory basis for failure problems of the piston.