Strength-enhanced volume decomposition for multi-directional additive manufacturing

Multi-axis additive manufacturing exploits additional degrees of freedom to enhance printability and flexibility compared to conventional 3D printing. Among various multi-axis additive manufacturing approaches, multi-directional printing decomposes the printing volume into sub-volumes and assigns individual printing directions to each sub-volume. Multi-directional printing enables support-free fabrication of complex and freeform geometry with minimum setup changes, which though requires elaborate process planning and printing trajectory generation. Current process planning approaches for multi-directional printing focus on support-free fabrication but do not consider the mechanical strength in its volume decomposition planning. Therefore, this paper proposes an integrated strength-support volume decomposition optimization method that simultaneously achieves support-free printing and strength enhancement. The proposed method establishes an optimization problem to enhance the mechanical strength and the support-free index, with the partition planes as the optimization variables. The mechanical strength model is established by finite element analysis, capturing the inter-layer and intra-layer strength differences in printing. The final optimization problem is solved via a heuristic beam search algorithm, and confirmative simulation results are verified through multi-axis printing and bending tests on representative 3D models (L-shaped beam, Stanford Bunny, etc.).