SURFACE DAMAGE ACCUMULATION IN LOW-CYCLE FATIGUE - PHYSICAL ANALYSIS AND NUMERICAL MODELING

The physical low-cycle fatigue damage of smooth 316 L stainless steel specimens is described at a mesoscopic scale (i.e. the grain size). More than 80% of the low-cycle fatigue lifetime consists of the development of multiple surface short cracks, the surface lengths of which are less than ten grain sizes. High densities of surface cracks lower than a grain size favour statistical aspects of their mutual interactions and their developments. This gives rise to an approach of low-cycle fatigue damage based on statistical physics. The fatigue damage description consists of accumulation of elementary independent damage events: the cracking of one grain. The statistical aspect of fatigue damage accumulation led to the development of numerical Monte Carlo type modelling. Principles of the modelling are presented. Low-cycle fatigue lifetime predictions concern in-air experiments and corrosion-fatigue experiments on 316 L stainless steel.