This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada
The inherent strain method is an effective scheme in terms of calculation time and accuracy for metallic additive manufacturing (AM) process simulation aiming deformation prediction, support structure failure, re-coater device contact prediction and so on. In addition to these functionalities, we recently developed the distortion compensation functionality that seek for the optimum AM geometry from target CAD geometry considering deformation induced by AM processes such as build, un-clamping base plate, cutting from base plate, support removal, heat treatment and so on.
The CAD geometry to be formed by AM is named as the target geometry, and the geometry for defining laser scan strategy is named as the AM geometry. In the conventional AM process, the target geometry and the AM geometry are same, the laser scan strategy is defined based on CAD data that is also target geometry. However, thermal deformation is not small in case of selective laser melting (SLM) type metal AM, and it is difficult to form the target shape with the conventional workflow. For this reason, users build a larger size and obtain a target shape by post-processing such as grinding. The cost of post processing is not negligible and the merit of the AM that allows to form arbitrary shapes is halved.
In the developed distortion compensation functionality, deformation is predicted by numerical analysis, and the target geometry is corrected to obtain optimum AM geometry with predicted deformation. It is necessary to repeat this correction process multiple times until deviation become small enough since AM geometry and deformation are in a nonlinear relationship.
Numerical experiments using this functionality were carried out and it was confirmed that the difference between the target geometry and build geometry can be reduced by numerical analysis with a few iterations. And this distortion compensation functionality is effective for seeking for the near net shape AM condition for metal parts forming.
|Date||18th June 2019|
|Organisation||MSC Japan, Ltd|