Residual stress and distortion model in direct metal laser sintering process

Abstract

Additive layer manufacturing is growing very fast in the aircraft and aerospace industries in order to reduce the cost and time of the manufacturing / assembly process. Transient temperature fields in additive manufacturing such as Direct Metal Laser Sintering (DMLS) are critical due to the fact that transient temperatures directly affect residual stresses and thus undesired deformations of produced parts. Hence, there is a need for developing reliable simulation tools for predicting residual stresses so that preventive actions like support design or changing build direction can be taken. Although there has been research going on over 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 in the industrial problems due to long computation time. This study introduces a multi-physics based finite element modeling approach for the fast prediction of the residual stresses and distortions of the parts in the DMLS. 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.