Topology Optimization Design and Performance Comparison of a Land–Air UAV Rotary Arm Integrating Additive Manufacturing Constraints

This study achieves a 30.8% mass reduction in amphibious UAV rotary arms via additive manufacturing-constrained topology optimization (AM-constrained TO), establishing lightweight design as the primary objective. To evaluate structural efficiency, we systematically compare three strategies: AM-constrained TO, Hexagonal Honeycomb infill (HC), and central lightening holes (ES). All configurations target comparable mass reduction. Using the SIMP method with manufacturing constraints, TO designs were generated. FEA and tensile tests evaluated stiffness, strength, failure modes, and Specific Energy Absorption (SEA). The key innovation lies in the TO approach: It achieves the primary objective of 30.8% mass reduction while simultaneously enhancing structural integrity and outperforming HC, ES, and Solid Baseline (SB) configurations in stiffness (2234 ± 76 MPa), Specific Energy Absorption (742 ± 29 J/m3), and stress distribution uniformity. The HC configuration shows progressive collapse but has the lowest stiffness (886 ± 17 MPa) and SEA (432 ± 5 J/m3) due to FDM inter-layer bonding limits. The ES configuration has the second-highest tensile strength (19.489 ± 0.19 MPa), but stress concentration around the hole reduces energy absorption, resulting in lower SEA (620 ± 15 J/m3) than TO.