Elastoplastic Fretting Contact Analysis of Piston Crown-Skirt Joint Surface base on BEM-FEM coupling Method

An entire engine cycle is simulated to elucidate the evolution of contact states under realistic loads. At the top dead center (0°crank angle), the maximum axial load results in elevated contact pressure and minimal slip. In contrast, at a crank angle of 315°, lateral forces become predominant, leading to increased shear stress and the slip regions.

During the downward stroke, as combustion pressure diminishes and inertia forces prevail, contact pressure decreases, thereby reducing the overall contact area. This phase is particularly susceptible to fretting damage due to the diminished normal force, which facilitates micro-slips between the contact surfaces. The increased variability in shear stress during this phase suggests a potential for slip and the initiation of fretting damage.

These findings underscore the necessity of optimizing preload force and taper angle to enhance stability and mitigate wear.The study also incorporates varying preload forces and taper angles to assess their impacts on contact pressure, tangential shear stress, and stick-slip behavior. The results indicate that reducing the taper angle from 0.25° to 0° improves the distribution of contact pressure, minimizes slip zones, and increases stable contact areas.

Additionally, an increase in preload force correlates with a reduction in slip, with near-complete elimination observed at a preload of 2000 N. These findings suggest that optimizing taper angle and preload force can significantly enhance the performance of the piston crown-skirt joint, thereby reducing fretting wear and prolonging component lifespan.