On the growth of rolling contact fatigue cracks using weight functions

The present paper discusses the estimation of the stress state of Rolling Contact Fatigue (RCF) cracks according to linear elastic fracture mechanics, by making use of the weight function to obtain the Stress Intensity Factors. The weight functions are considered for both the mode I and mode II Stress Intensity Factor and are based on existing formulations for an inclined edge crack in a finite width plate for which Green's functions are derived by means of a numerical methods. The Stress Intensity Factors been predicted for a side crack having an inclination angle typical for RCF defects in a plate of finite width supported by an elastic foundation and subjected to a moving wheel load, modelled as a patch load. The Stress Intensity Factors are obtained by superimposing the bending moment due to the moving load, and local stresses due to normal pressure and tangential tractions resulting from the contact with the wheel. These local stresses are determined using theoretical solutions partially available in the literature. The Stress Intensity Factors obtained are compared with the results of numerical models presented in the literature regarding the RCF crack growth.