Abstract:

    A coupling thermal stress finite element model is proposed to investigate the physical phenomenon that the surface pits can improve the thermal performance of pistonliner. First, nonlinear analysis is carried out on the contact problem, and the contact force and the friction work are obtained. This friction work is then converted into thermal energy as a surface heat flux, which is taken as the boundary condition of the governing equations of temperature field, thus, the coupling between stress field and temperature field is achieved. Simulation was conducted and results show that the maximum temperature on the piston surface with pits is locally higher than that of smooth piston surface, but the overall temperature distribution is uniform. One of the main reasons for local wear of smooth piston skirt is due to the temperature focus which can induce poor heat conduction. The pits can disperse the heat of the piston skirt that avoids the wear and hightemperature adhesion. Therefore, the surface pits can enhance the wear resistance of the piston skirt and prolong the service life of pistons.

Key words: solid state mechanics, pistoncylinder, frictional heat, contact finite element, thermal stress coupling