Topology design of continuous fiber-reinforced polymer structures for impact resistance with process constraints

The advancement of additive manufacturing (AM) for continuous fiber-reinforced polymer (CFRP) composites substantially enlarges design freedom, whereas impact-resistant topology optimization for CFRP-AM structures remains challenging due to the separation between design and manufacturing. In this work, an additive manufacturing-driven topology optimization framework is proposed for additively manufactured CFRP structures under low-velocity impact, with size, overhang-angle, and suspended-length constraints explicitly incorporated. Material layout and fiber orientation are defined as design variables and incorporated simultaneously into the manufacturability constraints. Both in-plane and out-of-plane manufacturability are achieved by incorporating size and overhang-angle constraints into a unified skeleton-guided framework, enabling smooth fiber paths adapted to topology boundaries together with manufacturable interlayer overhang angles. Suspended-length constraint is further introduced to restrict unsupported spans and enable support-free integrated fabrication. The proposed framework is applied to sandwich structures composed of a load-bearing stiffener core and topology-optimized face sheets (SCTF), where concurrent optimization of the core and face sheets under coupled manufacturability constraints is validated through numerical design and drop-weight experiments, showing significant improvements in impact resistance and manufacturability.