Topology optimisation of self-supporting structures based on the multi-directional additive manufacturing technique
Jun Ye, Qichen Guo, Hongjia Lu, Pinelopi Kyvelou, Yang Zhao, Leroy Gardner, Yi Min Xie
Abstract
Although additive manufacturing (AM) continues to gain widespread adoption, the overhang problem remains a critical issue affecting printing quality. The design of self-supporting structures via topology optimisation approaches has been extensively studied. However, current optimisation research predominantly focuses on 3-axis AM machines, overlooking the more recently developed multi-axis machines. Moreover, the performance sacrifice due to overhang constraints in 3-axis AM can be significant, especially in structures with small volume fractions. To address this, we propose a two-step approach considering overhang constraints for multi-axis AM. This approach begins with a structure optimised using traditional topology optimisation. In the first step, a new optimisation problem determines printing surfaces for the given structure. If the proportion of unprintable elements isn't satisfactory, a second re-optimisation step is carried out to further reduce the unprintable proportion. Several examples demonstrate the effectiveness of the proposed approach. Notably, the significant performance sacrifice associated with the 3-axis AM approach becomes negligible when applying our multi-axis AM-based method.