Abstract: In order to control the thermal stress of forming process, based on “element birth and death” technology of finite element method, a numerical simulation of three-dimensional temperature field and stress field during multi-track and multi-layer laser metal deposition shaping(LMDS) process is developed with ANSYS parametric design language (APDL). The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool- powder and laser-powder. The temperature field, temperature gradient, thermal stress field and distribution of residual stress are obtained. The results indicate that although the nodes on different layers are activated at different time, their temperature variations are similar. The temperature gradients of samples are larger near the molten pool area and mainly along z-direction. The transient thermal stress has concentrated in large temperature gradient area, which is in accordance with thermal stress forming theory. Through analyzing the residual stress of the as-formed samples in different directions, distribution rule of residual stress is achieved from temperature gradient perspective. And formation mechanism of residual stress is verified with an indirect way. Finally, it’s verified that the analysis results are consistent with actual situation by the experiments with same process parameters.

Key words: Residual stress, Laser metal deposition shaping, Numerical simulation, Transient temperature field, Transient thermal street field