Numerical simulation of cyclic plasticity in mechanical components under low cycle fatigue loading: accelerated material models

Abstract

Numerical simulations of components subjected to low-cycle fatigue loading require an accurate modeling of the material cyclic plasticity behavior until complete stabilization. In some circumstances, especially in case of small plastic strains, it may happen that the material model needs a huge number of cycles to reach complete stabilization, which results into an unfeasible simulation time. An acceleration technique, based on a fictitious increase of the parameter that controls the speed of stabilization in the combined (kinematic and isotropic) model, may be used. To check the efficiency and the correctness of the acceleration technique, the case of a welded cruciform joint under low cycle fatigue, taken from the literature, is here considered. The joint can be analyzed with a two-dimensional finite element model, which permits a relatively fast simulation to be completed until stabilization even with a combined kinematic-isotropic plasticity model (reference case). A comparison of this reference case with accelerated models is performed. Results in term of equivalent total strain range show that the acceleration procedure does not alter the welded joint cyclic behavior at stabilization, whereas it drastically reduces the computational time.