An elastic-plastic damage model of rolling contact fatigue considering nonmetallic inclusion

Nonmetallic inclusions are inevitable by-products during the manufacturing process of metal components. In this study, a finite element model of a steel matrix under Hertzian contact loading is established with a sphere nonmetallic inclusion embedded beneath the surface, and an algorithm based on the representative volume element method is developed to investigate the damage mechanism affected by inclusion. The material in the representative volume element follows the non-linear isotropic/kinematic hardening law to consider the strengthening behavior and ratcheting of the steel, and the inclusion is assumed to be relatively rigid without any yield occurring. The stress components in the elastic regime can be conveniently obtained by the finite element tool, while the plastic field can be iteratively determined according to the plastic flow criterion. The damage induced by both the elastic and plastic components in a loading cycle is calculated based on the method of continuum damage mechanics. The Young's moduli of damaged elements are then updated by a subroutine to account for the material weakening effect due to the damage. The model considers the elastic/plastic interactions in the material system, and the conclusions are expected to provide insight into the crack formation at the matrix/inclusion boundary.