Surface separation in elastoplastic contacts

TL;DR

This paper develops a theoretical and numerical framework to analyze how plastic deformation affects surface separation in rough contacts, integrating Persson's theory with boundary element simulations.

Contribution

It introduces a procedure within Persson's multiscale contact mechanics theory to predict surface separation considering plastic smoothing effects.

Findings

Good agreement between theory and boundary element simulations.

Plastic deformation leads to increased surface separation due to smoothing.

The method accounts for plastic stiffening at high deformation levels.

Abstract

Understanding the contact between rough surfaces undergoing plastic deformation is crucial in many applications. We study the effect of plastic deformation on the surface separation between two solids with random roughness. Assuming a constant penetration hardness, we propose a procedure within Persson's multiscale contact mechanics theory to obtain the average surface separation by applying the elastic formulation to an effective power spectrum that accounts for plastic smoothing. Deterministic numerical simulations based on the boundary element method are used to validate the procedure and show good agreement with the theoretical predictions. The treatment also provides a route to incorporate plastic stiffening of the roughness as the stress state becomes increasingly hydrostatic at large plastic deformation.