Influence of Plasticity-Induced Residual Stresses on Rolling Contact Fatigue

Abstract

Preloading the rolling elements of a rolling element bearing beyond their yield limit will result in subsurface plastic strains in the deformed material. These plastic strains are manifested in the form of a three-dimensional state of residual stresses. In this analysis, a two-dimensional plane–strain J2-based plasticity model with two different hardening laws—that is, (1) linear kinematic hardening and (2) nonlinear kinematic hardening—is utilized. Using the J2 plasticity model, the effects of hardening laws, material properties, and residual stress on rolling contact fatigue are investigated. Due to the presence of initial residual stresses, the equivalent von Mises stress decreases, which consequently leads to improved rolling contact fatigue life. However, due the presence of the residual stresses, the local yield point of the material also decreases. Due to these competing mechanisms, there is an optimum level up to which beneficial effects of the residual stresses are observed. For each of the hardening models, three different yield limits typical of bearing materials are studied and the effect of residual stress is evaluated. It is observed that the optimum pattern of residual stress is a function of the hardening response of the material, yield limit, and service load of operation. Based on the numerical results, a generalized equation for both of the hardening laws is proposed in order to estimate the optimum preload required to achieve maximum enhancement in rolling contact fatigue life.