Numerical simulation of low cycle fatigue damage in multiphase materials

The physical low cycle fatigue damage of smooth 316L stainless steel, ferritic-pearlitic steel and synthetic Al-12%Si specimens is described at a mesoscopic scale. More than 80% of low cycle fatigue lifetime consists in the development of multiple surface short cracks. High densities of surface cracks, the length of which being lower than the average distance between two propagation barriers (grain boundaries or/and interphase boundaries) favour statistical aspects of their mutual interactions and developments. This gives rise to an approach of low cycle fatigue damage based on statistical physics (accumulation of elementary random damage events) through the development of numerical Monte-Carlo type modelling. Principles and results of the modelling are presented.