Modeling of residual stress and distortion in direct metal laser sintering process: a fast prediction approach

Abstract

Additive manufacturing (AM) is growing rapidly in the advanced industrial applications to reduce the cost and time of the manufacturing and assembly processes. The evolution of temperature during AM processes such as direct metal laser sintering (DMLS) has a considerable effect on residual stresses and thus undesired distortions in the parts. Therefore, the development of a fast and reliable simulation tool is essential to predict residual stresses and resulting distortions so that preventive actions including effective support design or building in a different direction can be taken. Although researchers have been studying for more than a decade to understand and model the complex physical phenomena involved in the DMLS process, the solutions provided in the literature are not fully applicable to the industrial problems due to long computational time. This study introduces an analytical approach and a multi-physics based finite element modeling (FEM) approach for rapid estimation of the residual stresses and distortions of the parts encountered in the DMLS process. The modeling approach incorporates the features of plasticity and hardening mechanism into the FEM environment. FEM simulation results on residual stress and distortions are validated by experimental measurements on Inconel 625 and presented in the article. The simulation results are in good agreement with the experimental measurement within a range of 0.2-9% error. In addition, four different freeform geometries are selected to investigate the prediction and computational performance of the developed model. The simulation results are in line with the experimental measurements for the freeform geometries within a range of 12-24% error.