Wear debris: a review of properties and constitutive models

Wear appears as gradual removal of a material from contacting and rubbing surfaces of solids during their relative sliding. The mechanism of wear involves formation of debris particles. The particles have small sizes and different shapes. The wear debris can be "rolled over" into cylindrical, spherical and needle-like particles. Particles are detached from rubbing surfaces and they form a more or less continuous interfacial layer.They transmit forces, moments and displacements (translational and rotational)at the contact interface. The presence of wear debris between sliding surfaces affects frictional and wear behaviour signiffcantly. Constitutive relations characterize quasi-solid, quasi-fluid and granular-like behaviour of wear particles. In the paper, two constitutive models of wear debris are discussed: (a)material continuum, (b) granular medium. The continuum models are formulated for a micropolar thermoelastic material, micropolar fluid and thermo-viscous fluid.