Warping in SLM additive manufacturing processes: estimation through thermo-mechanical analysis

In additive manufacturing (AM), uneven cooling and thermal deformations deteriorate the quality of manufactured parts. However, the complexity of the non-linear systems, which are required for the modelling of the plasticity phenomena that take place, requires long simulations, a fact that renders them impractical, especially for machine control. In this study, a proof of concept for a numerical-empirical modelling approach of the thermo-mechanical phenomena of the AM process of selective laser melting (SLM) is presented. The dynamic elastic equation is solved in a two-dimensional (2D) space utilizing finite differences (FD); the solution of the coupled dynamic thermal equation is used as input. Movement of the laser heating and melting phase change are also considered. The effects of plasticity in the x-axis of the part are taken into account, utilizing a re-meshing strategy while an empirical bottom boundary condition is used for the encapsulation of the plasticity effects of the z-axis of the part. In this way, the effects of plasticity are taken into account in the proposed thermo-mechanical model, without the need to solve complex non-linear systems. The results of this study have been experimentally validated.