Finite element modeling of residual stress relaxation in steel butt welds under cyclic loading

• The real stress state in steel butt welds subjected to cyclic mechanical loading is evaluated.
• FE thermal simulation of plate butt welding is performed to identify the residual stresses.
• The cyclic plasticity constitutive model is employed to simulate the cyclic relaxation.
• The FE analysis model can effectively predict redistribution of the residual stresses.

This study attempts to develop a numerical method to predict the real stress state in steel butt welds subjected to cyclic mechanical loading. 3-D FE thermal simulation of a butt welding is first performed to obtain the residual stresses. Then, 3-D elastic–plastic FE model which incorporates the cyclic plasticity constitutive equation based on the Chaboche nonlinear kinematic hardening and the isotropic hardening rule is developed to evaluate redistribution of the residual stresses under cyclic external loading. The analytical results have shown that the FE analysis method devised here can effectively predict the cyclic relaxation of the residual stresses.