The inherent strain method for simulation of additive manufacturing–A critical assessment based on a new variant of the method

Abstract

AbstractTo reduce computational time of thermo‐mechanical simulation of additive manufacturing processes, the inherent strain (IS) method is quite efficient, but suffers from a lack of predictivity, preventing concurrent quantitative prediction of distortion and stress. In order to investigate the predictive ability of the IS method, a new variant of the method is proposed in which the determination of the IS tensor is based on simulation results from a standard thermo‐elastic‐viscoplastic simulation applied to a few learning layers of the studied part. More precisely, the inherent strains are determined by a direct resolution performed in each finite element, with a negligible computation cost. Because of these specific features, the predictive ability of this IS method is formulated as its ability to replicate the distortion and stress predicted by the reference standard thermo‐elastic‐viscoplastic simulation. The proposed IS method provides perfect results in a validation test where full‐field inherent strains are used in each added layer: the distortion and stress predicted by the thermo‐elastic‐viscoplastic simulation are exactly replicated by the IS method. However, when applying the IS method to the simulation of an entire part, here a turbine blade mock‐up, the results are degraded with respect to the reference solution obtained by the thermo‐elastic‐viscoplastic simulation. Results are then discussed to evaluate the limitations of the proposed method, and of the IS method in general.