Novel approach to optimized support structures in laser beam melting by combining process simulation with topology optimization

Additive manufacturing is gaining importance in different industries, being on the verge to broad industrial application. Especially in laser beam melting (LBM) of metals, support structures play a vital role in the successful production of parts, since they are responsible for supporting overhanging features and preventing warpage. Today, these support structures are often massive and lead to high postprocessing effort for removal and surface finishing. Existing structures do not meet the needs of the individual part, adding cost to the production of additive parts without even fulfilling all their respective tasks. To reduce the manufacturing and finishing effort in LBM, new ways of support structure application have to be found. One way to decrease the material consumption, and therefore the overall costs in terms of raw material and manufacturing effort, is to use topology optimization for the generation of support structures. This study presents an extension of the current approaches, which take into account the task of supporting overhanging features, by using a finite element analysis of the manufacturing process of LBM to assess the loads applied to the support structures by residual stresses during the manufacturing process. This is critical especially to the LBM of metals. A case study of a cantilever beam is carried out to investigate the general validity of the proposed procedure. First, a simulation of the manufacturing process of the cantilever as well as the respective support structures is conducted. Second, using the simulation's results as input, topology optimization of the support structures by applying the solid isotropic material with penalization method is executed. The result, resembling tree-like features, demonstrates the capabilities of the procedure and points out the possibility of using variable densities within one structure. Finally, critical needs in research to further develop the approach are pointed out.