1. Context

Parts and structures subjected to cyclic mechanical or thermo-mechanical stresses can fail at stress levels far lower than those observed under creep or monotonic loading. Fatigue failure is often insidious, consisting of a slow process of crack propagation that can extend over several hundred or thousands of load cycles, without any detectable change in the physical-mechanical properties of the material at the scale of the part or structure in question. This has been a major scientific, technological and industrial issue since the beginning of the industrial revolution in the naval and railway industries.