Topology optimization for additive manufacturing: Accounting for overhang limitations using a virtual skeleton

This article proposes a new method for reducing the amount of support material required for 3-D printing of complex designs generated by topology optimization. This procedure relies on solving sequentially two structural optimization problems – the first on a discrete truss-based model and the second on a continuum-based model. In the optimization of the discrete model, the maximum overhang limitation is imposed based on geometrical parameters. The optimized discrete pattern is then projected on to the continuum so that it influences the material distribution in the continuum optimization. The method is explained and investigated on a set of test cases in 2-D and subsequently demonstrated on examples in 3-D. Numerical results indicate that the designs obtained by this approach exhibit improved printability as they have fewer overhanging features. In some cases, practically no supporting material will be required for printing the optimized design.