Reversible Actuation of Fiber-Reinforced Composites Through Embedded Shape Memory Alloys

Abstract Achieving controlled shape change in fiber reinforced polymer (FRP) composites while maintaining their high strength-to-weight ratios is highly desirable for applications in biomedical fields, aerospace structures, and advanced robotics. Shape memory alloy (SMA) wires, with their unique properties such as the shape memory effect and superelasticity, enable electrothermal actuation, making them a promising candidate for integration into these composites. In this study, pre-strained SMA wires were embedded within random mat glass fiber reinforced polymer composite (GFRP) to induce controlled actuation through thermal activation. The hybrid SMA-GFRP composites were manufactured using a wet lay-up vacuum bagging technique. Upon heating, the embedded SMA wires contracted, generating forces that actuated the composite structure. The SMA wires were arranged asymmetrically within the laminate thickness, alternating between resin-saturated fabric layers (fabric/wires/fabric/fabric). Three composite samples were manufactured to assess the effect of increasing wire volume fraction on actuation performance. The samples were tested in a cantilever beam configuration, with tip deflection ranging from 17.8 mm to 30.7 mm, depending on the wire volume fraction. This work uniquely discusses the influence of wire volume fraction on actuation behavior and interfacial bonding, revealing that as the wire volume fraction increased, the likelihood of debonding between the wire and resin also increased. The results highlighted the potential of hybrid active SMA-GFRP composites for replacing traditional actuation methods in various engineering applications.