Fatigue represents a crucial challenge for ageing aircraft fleets, where life extension is of high economic interest. Promising approaches are residual stress modification techniques aiming at introducing compressive residual stresses in regions susceptible to fatigue. Laser shock peening (LSP) represents such a very promising local residual stress modification technique by combining the generation of relatively deep compressive residual stresses of high magnitude, high surface quality, and flexible process application. Since, compressive residual stresses are accompanied by tensile residual stresses that may accelerate fatigue, they have to be placed in non-susceptible regions to achieve overall fatigue life improvement. Additionally, the retarding and accelerating mechanisms of fatigue crack growth (FCG) in residual stress fields are not exactly known. Therefore, the aims of this thesis are the prediction of residual stresses generated by LSP and the investigation of FCG influenced by these residual stresses in aeronautical lightweight alloys to subsequently describe the FCG influencing mechanisms. This thesis closely links experiments with simulation to develop a virtual twin, also referred to as multi-step simulation, including LSP process simulation and FCG calculation. While the LSP process simulation and the FCG prediction are separately validated by experiments, a novel so-called “experimental simulation” proves that external loading and macroscopic residual stresses can be used to explain accelerated and retarded FCG affected by LSP treatment. Crack closure is found to be the main FCG retarding mechanism. Thereupon, recommendations for efficient LSP application in terms of FCG retardation are given. Finally, the virtual twin is applied to other lightweight alloys as well as to a fundamentally different laser system, demonstrating its adaptability and serving as an indication of a cross-material explanation about accelerated and retarded FCG in LSP-induced residual stress fields.weiterlesen