Modeling the high cycle fatigue behavior of T-joint fillet welds considering weld-induced residual stresses based on continuum damage mechanics

A nonlinear continuum damage mechanics (CDM) model for multiaxial high cycle fatigue which incorporates the cyclic plasticity constitutive equation is developed in the finite element (FE) framework. FE simulation of T-joint fillet welding is first performed to identify welding residual stresses employing sequentially coupled three-dimensional (3-D) thermo-mechanical FE formulation. The high cycle fatigue damage model is then applied to the T-joint fillet welds subjected to cyclic fatigue loading to compute the fatigue life considering the residual stresses. The calculated total fatigue life which includes the fatigue crack initiation and the propagation is compared with the test result. The FE results demonstrate that the high cycle fatigue damage model proposed in this work gives a correct prediction of the fatigue life of the welds, and welding residual stresses cannot be disregarded in an estimation of the fatigue life of the welds.