Robust optimization for reducing welding-induced angular distortion in fiber laser keyhole welding under process parameter uncertainty

Welding-induced angular distortion is a typical out-of-plane distortion, which brings negative effects on the joints' quality. Therefore, the selection of appropriate process parameters to minimize or control welding-induced distortion under uncertainty has become of critical importance. In this paper, a robust process parameter optimization framework is proposed to reduce welding-induced distortion in fiber laser keyhole welding under parameter uncertainty. Firstly, a three-dimensional thermal-mechanical finite element model (FEM) for simulating the welding-induced distortion is developed and validated by laser welding experiment. Secondly, a Gaussian process (GP) model is constructed to build the relationship between the input process parameters and output responses. Finally, uncertainty quantification of both process parameter uncertainty and GP model uncertainty is derived. The obtained uncertainty quantification formulas are used in the robust optimization problem to minimize welding-induced distortion. The effectiveness and reliability of the obtained robust optimum are verified by the Monte Carlo method.