A thermomechanical finite element model and its comparison to inherent strain method for powder-bed fusion process

Abstract

In this study, a thermomechanical model is developed to predict the melt-pool dimensions and residual stresses for laser powder bed fusion process. Inherent strain method is also used to predict residual stresses by using only the thermal solution that is free the complexities involved with the mechanical solution. A unique approach is developed to define the surface heat losses as volumetric heat losses in order to avoid the definition of traction-free surfaces and their re-definition after layer deposition. The thermal process simulations predict melt-pool dimensions of experimental cross-sections of single tracks within approximately 10% agreement. The thermomechanical process model is used to forecast the effect of process parameters on the melt-pool dimensions and residual stresses. The inherent strain method reproduces the residual stresses within 15% accuracy, approximately six times faster in comparison to the thermomechanical model, and free of any convergence issues related with the displacement field solution.