Phase-field modeling of low cyclic fatigue in ductile materials

Abstract

Plastic strains in engineering structures occur if the loading conditions exceed the designed values. The loading above the yield strength of the material leads to fatigue of the structure and fracture. The fracture occurs after a lower number of cycles, in comparison to the high cyclic fatigue when the material operates in the elastic range. However, the fatigue behavior of structures made of ductile materials in the range above the yield strength can be simulated by Phase-Field Damage Modeling (PFDM) approach, which includes a fatigue degradation function. In this paper, the cyclic tensile loading-unloading behavior is simulated by PAK finite element method software with Von Mises plasticity constitutive model and Simo’s hardening function. The material parameters are proposed for generic metal with the phase-field constants set to show the phenomena which can be simulated. The results show that the proposed theory and implementation should be further investigated and applied to simulate the experimental testing of ductile materials under cyclic loading and fatigue conditions.