Stress and fatigue analysis of engine pistons using thermo-mechanical model

Abstract

This paper presents a thermo-mechanical finite element analysis model for the stress and fatigue analyses of engine pistons. The model consists of the piston, piston pin, piston ring, bushing, cylinder liner and connecting rod. The oil film and contact pressure are considered in the contact surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. A self-compiled code, which considers the factors of the piston skirt profile and ellipticity, is applied to calculate the initial clearance at the oil film surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. The dynamic loads of the piston and connecting rod under the peak torque and peak power cases are calculated using powertrain commercial software, which are then used to carry out the stress and fatigue analyses. Compared with those published in literature, the present model is able to simulate the actual working conditions of the piston more accurately. The model can be used to evaluate and assess the piston skirt pressure, the stress and fatigue life of the concerned areas of the piston.