Multi-objective topology optimization of energy absorbing structures incorporating shape memory polymers: Design, behavior, and recoverability

This study focuses on the design and evaluation of topology-optimized structures to enhance energy absorption performance. A novel curved unit cell (CurvoTopoCell) was designed using a multi-objective topology optimization framework based on a weighted-sum scalarization approach, enabling the simultaneous improvement of stiffness, specific energy absorption, and crush force efficiency. Four distinct configurations (M1–M4) were fabricated via 3D printing with PLA + filament. Key parameters, including specific energy absorption, mean crushing force, crush force efficiency, equivalent elastic modulus, and energy absorption efficiency coefficient were analyzed across three quasi-static compressive loading cycles and thermal recovery phases. Results demonstrated that the optimized unit cell achieved a 23% improvement in SEA compared to the other unit cells, attributed to reduced mass and enhanced strength. Experimental tests revealed that configuration M1 exhibited the highest initial SEA and Pmean. However, M3 showed superior cyclic stability, with only a 31% decrease in SEA, 25% decline in CFE, and 94.3% height recovery. Key innovations include integrating multi-objective topology optimization with shape-memory material (PLA+) for structural recovery, and introducing four novel configurations with distinct mechanical responses. These findings provide strategies for developing lightweight, reusable energy absorbers in automotive and aerospace applications.