Jiazhao Huang, Pengyu Chen, Chu Long Tham, Muthu Vignesh Vellayappan, Guo Dong Goh, Jingyi Yang, Xiaoying Qi, David W. Rosen, Mui Ling Sharon Nai
• Optimized PLA hinge achieved 99.53 % recovery after first folding cycle. • Recovery ratio dropped to ∼25 % after 50 cycles at 65 °C. • Training temperature governs trade-off between actuation speed and lifespan. • Origami-inspired structure with optimized hinge design fully deployed within 8 s. 4D additive manufacturing (4D-AM) enables printed structures to undergo programmable deformations in response to external stimuli. However, the optimization of geometric and process parameters remains a key challenge in enhancing performance and reliability. This study investigates the shape memory behavior of foldable hinges made from polylactic acid (PLA) using fused deposition modeling (FDM), which are critical elements in deployable 4D structures. A Taguchi design of experiments was applied to examine the effects of hinge thickness, length, printing speed, and training temperature on the shape recovery ratio and durability. The optimal hinge configuration, with a thickness of 0.8 mm, length of 0.6 mm, printing speed of 50 mm/s, and training temperature of 65 °C, achieved an initial recovery ratio of 99.53 %. Hinges trained at higher temperatures between 75 and 85 °C exhibited faster recovery but reduced lifespan, indicating a trade-off between actuation speed and durability. An over-recovery exceeding 100 % was also observed, likely attributed to geometric nonlinearity and thermal effects near glass transition region. The optimized hinge design was successfully implemented in an origami-inspired deployable structure, achieving deployment within 8 s. These findings were expected to provide quantitative guidelines for balancing speed, fidelity, and lifespan in 4D-AM components for reconfigurable systems.