Role of intermolecular potential in adhesive wear behaviors for elastic-plastic spherical microcontacts

Abstract

This paper aims to investigate the effects of intermolecular potential on adhesive wear behaviors of microcontacts between a rigid flat and an elastic-plastic sphere, using a Finite Element (FE) model. In this model, a separation-dependent adhesive pressure, governed by the Lennard-Jones (LJ) potential, is applied to the surfaces of both the rigid flat and the sphere under combined normal loading and tangential displacement. To assess material damage, the Johnson–Cook (JC) failure and fracture energy criteria are utilized, allowing for element deletion upon reaching the damage threshold. The role of intermolecular potential in the adhesive wear behaviors of spherical microcontacts is evaluated, focusing on wear volume, wear rate, wear morphology and fracture propagation mode under various dimensionless normal loads and adhesive energies. Two fracture propagation modes, namely bidirectional-like and unidirectional-like modes, dependent on normal load and adhesive energy, have been identified. The transition from mild to severe wear regime is found to be closely related to the fracture propagation mode. Additionally, an interesting observation is that relatively high adhesive energy could result in decreased wear volume and wear rate under certain normal loads, which can be attributed to the change in fracture propagation mode caused by the adhesive pressure.