Numerical Modeling of Non-linear Thermal Stress in Direct Metal Laser Sintering Process of Titanium Alloy Products
The heat transfer and residual stress evolution in direct metal laser sintering process of titanium alloy are studied. A numerical model is developed in COMSOL Multiphysics environment, with temperature-dependent material properties of TiAl6V4 considered. The existing theoretical models for both elastic and plastic problems are reviewed, and comparisons with the simulation results are made. The thermo-mechanical coupled simulation is performed. 3-D simulation is used to study single-layer laser sintering and the interaction between lateral lines. 2-D model is used to study the multi-layer effects. The results reveal the change of residual stresses and strains among the multiple layers with the change of local base temperature, laser power, support plate thickness, etc. Also, compared to elastic case, plastic results show lower residual stresses but higher strains, as well as plastic strain accumulation. The result of local laser sintering simulation provides a better understanding of the complex thermal mechanical mechanisms of laser sintering additive manufacturing processes.