Influence of local friction coefficient and strain hardening on the scratch resistance of polymeric surfaces investigated by finite element modeling

Abstract

In this study, we propose the mechanical analysis of contact between a rigid spherical indenter and an amorphous polymeric surface during scratching. Experimental scratch tests, using our specific experimental set-up, allowing in situ observation of the contact area and also of the residual groove, have clearly shown the influence both of the local friction and the strain hardening of the tested surface. A 3D finite element modelling (FEM) of the corresponding scratch tests has been developed by assuming a two segments simplified constitutive law, a linear elastic behaviour followed by a linear strain hardening. The friction at the interface between the indenter and the material was modelled with a Coulomb's friction coefficient varying between 0 and 0.5, and the ratio a/R was fixed at a constant value of 0.3 to simulate elastic-plastic contacts. Evolutions of the apparent friction coefficient and of the contact pressure are presented.