Numerical modelling of the effect of fretting wear on fretting fatigue

This thesis reports the development of a method for predicting the fretting fatigue life of a system which takes into consideration the material removed as a result of fretting wear. The first implementation is based on a critical plane, multiaxial fatigue model and a damage accumulation framework. The model is applied to both ‘cylinder on flat’ and ‘rounded edge punch on flat’ geometries, for which experimental data from the literature is used for comparison.. The method is able to predict a number of key experimentally observed phenomena, which existing approaches are unable to do. The dependence of fretting fatigue life on slip amplitude is captured demonstrating a critical range of slip amplitudes, relating to the partial slip regime, for which a minimum in life is predicted. The method is also shown to predict the occurrence of cracking at specific locations in the slip region. The method indicates that these phenomena are dependent on the relative rates of wear and fatigue damage occurring across the contact. The second implementation treats the nucleation and propagation fatigue phases separately. The fatigue model adopted above is reformulated to serve as a nucleation model, whilst the crack propagation phase is based on a fracture mechanics perspective. The method is used to study the effect of wear on both the propagation and nucleation aspects of fatigue. The method is also employed to investigate the role of fretting wear in fretting fatigue crack arrest