Finite-element analysis of effects of the laser-processed bimaterial component size on stresses and distortion

Processing of bimaterial parts via a moving laser beam has been investigated using three-dimensional (3D) finite-element modeling. Effects of the size of parts on the temperature distribution, thermal transient stresses, residual stresses, and distortion have been evaluated. The result indicates that the size of the part to be processed has strong influence on the transient temperature, transient stresses, residual stresses, and distortion of the part. Distortion is small when the size of the part is small and can be predicted from the thermal-expansion mismatch between the two materials. However, when the size of the part becomes large, both distortion and residual stresses increase. Furthermore, both distortion and residual stresses, in this case, cannot be predicted based on the thermal-expansion mismatch alone. The distortion, in this case, is mainly determined by the asymmetrical plastic deformation driven by transient thermal stresses, while residual stresses are dictated by the thermal-expansion mismatch and the temperature gradient of the part before and during cooling.