Influence of engineered residual stresses on the fatigue properties of aluminium alloys: experimental and numerical investigations

The present work adds to the state of the art by tackling the problem of fatigue with a double approach. First, an experimental approach with the aim of determining if an innovative technology, called laser shock peening, is more effective than the currently employed techniques --- shot peening and cold expansion --- in reducing the sensitivity of aluminium alloys to fatigue. Second, a numerical approach, based on linear elastic fracture mechanics and plasticity-induced crack closure, which exploits finite element simulations to study growth rate and shape evolution of corner cracks in three different scenarios of increasing complexity: open hole, pin-loaded hole, and cold-expanded pin-loaded hole. Regarding the numerical studies on fatigue propagation, simulation results are compared with experimental data and reveal that the adopted numerical strategy can simulate quite well both crack growth rate and front shape evolution in absence of residual stresses. On the other hand, with the introduction of residual stresses induced by cold expansion, the model yields extremely non-conservative fatigue crack propagation results.