Modeling three-dimensional rough surface and simulation of temperature and flow field in laser transmission welding

The traditional Laser Transmission Welding (LTW) simulation method assumes that the welding contact interface is smooth. However, the actual welding interfaces exhibit a large number of rough surfaces. The mismatch may decrease the accuracy of the traditional finite element model (FEM). Thus, this work aims to establish a three-dimensional (3D) FEM model considering the rough surface. Numerical model for 3D rough surface of welding specimen is established. The distribution of molten pool area, temperature and flow field coupling are discussed. Then, a series of experiments were set up to obtain the weld width to verify the model. The results show that the temperature of the contact surface between the transparent part and the absorbent layer is discontinuous, which is consistent with the incomplete contact of the contact surface under real welding conditions. The error of weld width values between the simulated and experiment is smaller, which also confirm that the established model is more precise.