3D XFEM investigation of the plasticity effect on fatigue propagation under thermo-mechanical loading

The aim of this paper is to propose a computation strategy for fatigue propagation simulation of a crack by taking into account the plasticity. Feulvarch et al. (Comput Methods Appl Mech Eng 361: 112805, 2020) recently proposed a first XFEM formulation capable of overcoming the volumetric locking phenomenon due to plastic incompressibility in 3D. This formulation is here applied to quadratic elements for the mode I propagation of a crack in a valve structure submitted to cyclic thermo-mechanical loading. A simulation strategy is proposed where it is not necessary to compute all the cycles and thus the complete plastic history. This is of great interest because it avoids the treatment of the possible closing of the crack and uses the conventional J-integral. The application reveals the interest of taking plasticity into account for the propagation accuracy.