A Numerical Elastoplastic Model for Rough Contact

Abstract

Pressure distributions due to surface roughness in contact induce high stresses just beneath the surface. These stresses can bring on crack initiation and micro-pitting. A purely elastic contact model to account for these effects is restrictive because stress fields often exceed the yield strength of the material. Plastic flow occurs and modifies the surface shape and material properties (work hardening). This paper presents a numerical model for elastoplastic rough contact. It allows the determination of real pressures and permanent surface displacements (flattening of asperities) as well as residual stress and plastic strains useful in fatigue analysis). The material is assumed to obey the Von-Mises yield criterion with linear kinematic hardening. Real surface profiles obtained from a measurement can be considered. In addition, simplified methods have been used to treat cyclic loading. Thus the ability of a rough surface to reach an elastic shakedown state can be investigated, even for a three-dimensional contact found, for instance, in roller bearings.