Additively manufactured Shape Memory Alloy Hybrid Composites with a polymer matrix featuring a re-entrant honeycomb structure

Abstract

Stereolithography (SLA) and Tailored Fiber Placement (TFP) were combined to fabricate shape memory alloy hybrid composites (SMAHC) featuring a three-layer structure and exhibiting out of plane bending deformation when activated, in a fully integrated, additive manufacturing process. SMA wires as active elements were attached to a textile reinforcement layer, which then was embedded within a UV-curable polymer matrix and combined with a geometrically tailored toplayer, featuring the re-entrant honeycomb architecture. Exploiting the design freedom of SLA, the overall mechanical response of the SMAHC can be systematically adjusted, enabling controlled out-of-plane bending during thermal activation. Two different SMA integration strategies - manual embedding and automated TFP were investigated to assess their influence on actuation behavior, reproducibility, and deformation behaviour. A total of eight geometric configurations were manufactured and experimentally characterized using synchronized optical measurements. The results demonstrate that the combination of SLA-based fabrication and textile-mediated SMA integration enables precise control over the actuation response, while the use of re-entrant honeycomb structures provides an effective approach to tailor stiffness and deformation characteristics. In particular, the automated TFP integration yields improved reproducibility and more symmetric deformation behavior compared to manual fabrication. The presented approach establishes a fully additive manufacturing route for SMAHCs, enabling the realization of structurally integrated, morphing composite systems with programmable mechanical properties.