Analysis of Plastic Strain Varied with Depth on Micro-contact Point under the Thermo-mechanical Coupling

Abstract

A thermo-mechanical coupling model for a rigid flat plane and an elastic-plastic rough surface based on three-dimensional fractal theory is established. The model considers the elasto-plastic deformation of the rough solid, the interaction between asperities,and the heat flux coupling between the sliding surfaces. By using the finite element method, the frictional sliding process of the rough surface and the flat plane is simulated. The plastic deformation varied with depth on the contact asperity of the rough solid are analyzed. The numerical results from the analysis and simulation show that the equivalent plastic strain on the frictional contact surface layer increases obviously when the relative sliding velocity changes suddenly and the instantaneous flash temperature emerges. On this frictional contact surface layer, through the different contact asperity, the distribution of the plastic deformation varied with the depth is different. The maximum equivalent plastic strain may be located on the contact surface or in some depth under the contact surface. These results are validated by experimental observation results available in the literature. The experimental results are obtained by studying the surface layer deformation photograph of the metal after the dry friction. The plastic deformation on the frictional contact surface layer accumulates during the frictional sliding, which will result in the micro-hole and the crack source around the micro-defects on the contact surface layer.