Numerical and experimental investigation into the evolution and distribution of residual stress in laser transmission welding of PC/Cu/PC

In the process of laser transmission welding of polycarbonate (PC) based on copper film interlayer (PC/Cu/PC), the residual stresses may lead to the formation of cracks, deformation and other defects. The measurement of residual stress has faced problems of insufficient accuracy and complicated operation. In this paper, the three-dimensional (3D) thermo-mechanical coupling model for residual stress distribution was developed by applying COMSOL, in which PC's material performance and thermo-solid coupling were applied. During the simulations, the calculations of temperature distribution and residual stresses were conducted in sequential coupling. The effect of time dependence of thermal parameters on the residual stress distribution was studied. A dynamic and static strain gauge test system was used to evaluate the residual stress. The evaluated residual stress, actual HAZ boundary and the thermal expansion measured by the optical microscope were used to prove the authenticity of the model. The results indicated the maximum deviation between the simulated residual stress and the actual measured residual stress is 1.2 MPa. The present work will promote the research of residual stress of PC laser transmission welding parts with metal absorption layer.