Lois de frottement

Friction laws and plastic deformation

CEMEF, Ecole des Mines de Paris, Sophia-Antipolis

Abstract

A number of friction laws are proposed to users such as developers of numerical codes, who may have to face a difficult choice. We try to show how friction laws - surface behaviour - are related to rheological plastic laws - bulk behaviour. The theory of plasticity has prompted a considerable amount of works, so that the present approach can help better understand and more rigorously formulate friction laws, but also enrich them with phenomena well known in plasticity, yet too much overlooked in tribology. We also discuss the necessity of regularizing, or rubbing out discontinuities of these laws, and the effect of such mathematical and numerical treatments. Finally, the choice of a law must escape usual schemes - simplicity of use or traditions - and should derive from the physics of microscopic contact interactions; a few examples are given.