Topology optimization for hybrid additive-subtractive manufacturing incorporating dynamic process planning

Hybrid additive–subtractive manufacturing (HASM) is a revolutionary technique that, the interplay between additive and subtractive processes within an integrated machine tool allows for the fabrication of traditionally challenging complex geometries with excellent quality. However, part design for hybrid manufacturing has mostly been done by experts with rare support from computational design algorithms. Hence, the primary contribution of this work is to propose a solution for HASM-oriented structural topology optimization that incorporates both dynamic process planning and accessibility constraints. This novel optimization algorithm is developed under a unified SIMP and magic needle framework. Two sets of design variables are proposed: one for the topological description while the other for identifying the printing stage-related subdivisions. Accordingly, a series of additive manufacturing (AM) and subtractive manufacturing (SM) dedicated geometric constraints are developed based on these design variables to enable the cutting tool and laser head accessibility. Supported by the sensitivities, the structural geometry and fabrication fields can be simultaneously optimized. The effectiveness of the algorithm is proved through several numerical and experimental case studies. All the factors of cutting tool directions, HASM stages, and specific tool shapes are thorough investigated.