Using FEM to study the frictional instability induced by third-body particles confined in frictional interface

Purpose A finite element method (FEM) model of the frictional behavior of two rough surfaces with a group of third-body particles confined by the surface asperities is established. By monitoring the stress distribution, friction force and the displacement of the surfaces, how the frictional instability is induced by these particles is studied. This modeling job aims to explore the relation between the meso-scale behavior and the macro-scale frictional behavior of these particles. Design/methodology/approach By using FEM, a 2D model of two frictional rough surfaces with a group of elastic or elasto-plastic particles confined by surface asperities is established. The Mises stress, macro friction force and displacements of elements are monitored during compressing and shearing steps. Findings The macro friction coefficient is more stable under higher pressure and smaller under higher shearing speed. The dilatancy of the interface is caused by the elevation effect of the particles sheared on the peak of the lower surface, particles collision and third body supporting. The combined effect of particles motion and surface–surface contact will induce high-frequency displacements of surface units in restricted direction. Originality/value Previous studies about third-body tribology are mainly concentrated on the frictional behavior with large number of particles distributed homogeneously across the interface, but this paper focuses on the behavior of third-body particles confined by surface asperities. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0544/