Laser beam welding residual stresses of cracked T-joints

A damage tolerance analysis methodology for Laser Beam Welded (LBW) structures is proposed. The Residual Stresses (RSs) of LBW T-joints are initially calculated through the thermo-mechanical simulation of the LBW process. Through cracks of variable length are considered in the vicinity of the weld and the calculated RS field is introduced in the numerical calculation of the Stress Intensity Factors (SIFs). As the Finite Element (FE) models used for the thermo-mechanical simulation cannot be the same to those required for the fracture analysis, a special numerical routine based on interpolation techniques is applied for the transfer of RS field to the fracture mechanics FE model. The computation of SIFs at the crack front is performed for mode-I external loading. The RS effect of various cracked T-joint configurations on the SIF values at different through-the-thickness locations is studied. It is shown that both the RS field, as well as the other studied parameters, have a significant influence on the calculated stress intensity factor values.