Design considerations and applications of shape memory alloy-based actuation in morphing structures: A systematic review

Shape memory alloys (SMAs) enable unique actuation capabilities through reversible phase transformations when heated, making them promising for adaptive structures. Integrating SMAs into composites creates smart systems with controllable shape morphing functionality. This paper reviews recent research on SMA-driven shape morphing composites. SMAs exhibit pseudoelasticity and the shape memory effect due to austenite-martensite phase changes, enabling high recoverable strains and tailored shape recovery. These properties have motivated growing interest in SMA-based active composites for applications like aerospace, automotive, soft robotics, and biomedicine. The paper categorizes SMA integration strategies into fully embedded versus hybrid layouts. Key design trade-offs are analyzed regarding achievable deformation modes, manufacturability, activation uniformity, and interfacing. Proper SMA positioning and insulation are crucial to prevent matrix overheating and enable unconstrained actuation. Enhancing SMA-matrix adhesion and balancing component thermomechanical properties are also critical. The unique capabilities of SMA hybrid composites are highlighted through case studies across diverse fields. Ongoing challenges around actuation speeds, fatigue life, and interfacial durability motivate new material development and manufacturing optimizations. Overall, SMA-enabled active composites present exciting potential for reversible, programmable shape morphing. This review synthesizes recent progress and provides insights to guide future research and innovation.