Towards the optimal design of support structures for laser powder bed fusion-based metal additive manufacturing via thermal equivalent static loads

Abstract

In laser powder bed fusion (LPBF)-based metal additive manufacturing, support structures play a crucial role in ensuring part-printability. However, support structures often consume significant amount of material, print-time and post-processing time. Furthermore, the optimal design of these support structures is challenging due to the transient nature of the LPBF process. Consequently, support structures are often sub-optimal, and are designed based on experience. Here, we propose the concept of an aggregate equivalent static load (ESL) for the design of support structures. Starting with a simple transient simulation of the layer-wise LPBF build process, we extract the ESL at the end of each time step. An aggregate ESL is then computed for minimizing the thermal compliance of support structures, subjected to a volume constraint. The ESL concept is demonstrated here using truss-type support structures; however, it is equally applicable for other types of supports. Truss-type supports are generated using a novel greedy algorithm, and then the aggregate ESL strategy is applied to optimize the size of truss members. Numerical experiments are conducted to ascertain the self-consistency of the proposed method. The optimized cross-section areas of truss members are then converted to manufacturable designs, and sample parts are fabricated for validation.