A new approach for thermomechanical modeling of residual stresses in selective laser melting

Abstract

Residual stresses generated during selective laser melting (SLM) can severely affect the component’s performance. Correctly estimating such a defect prior to fabrication is therefore crucial. Our objective is to develop a finite element model with a new approach for simulating the laser-material interactions to accurately predict these stresses while keeping a reasonable computational time. To do so, we introduce the track discretization technique, which consists in defining the various tracks of the laser beam path and discretizing them to reproduce the scanning strategy. The existing layer-by-layer and track-by-track heating are also implemented. All three versions of the model employ a constant and uniform body heat flux. Their results are compared to those of the detailed simulation using the Goldak heat source. SLM of an AlSi10Mg square plate is studied for testing purposes. von Mises and normal stresses, \({\sigma }_{11}\) and \({\sigma }_{22}\), are probed along specific paths to assess the efficiency of each approach. Heating entire layers was the fastest but the worst for predicting stress anisotropy. A more realistic representation of the scanning pattern by adding the various tracks and subdividing them enhances precision of the estimations. The trade-off between accuracy and rapidity of execution was obtained with three track subdivisions. In this case, the estimates were consistent with the detailed simulation results, and the errors were, on average, 20–30% lower than those of the more simplified versions. The duration of the simulation was 335 min vs 1297 min with the detailed procedure, which corresponds to a significant gain of 74.2%.