Multiphysics modeling and optimization of an innovative shape memory alloy-polymer active composite

Abstract

Shape memory alloys (SMAs) are a unique class of smart materials capable of recovering significant deformations through temperature variations, making them attractive for adaptive structures and morphing applications. However, integrating SMAs into polymer composites poses significant challenges, such as interfacial delamination and matrix overheating during thermal activation, in addition predicting the stress acting on the SMA during the actuation is pivotal. Addressing these issues is crucial for realizing the full potential of SMA-based active composites in aerospace, automotive, and renewable energy sectors. This study presents a novel multi-material design strategy for SMA-polymer active composites, featuring a rigid PC/ABS layer for mechanical integrity, a soft high-temperature silicone coating for encapsulating SMA wires, and aluminum terminals for wire crimping. A comprehensive multiphysics FEM model was developed to accurately capture the coupled thermo-mechanical response. Extensive experimental characterization and validation were conducted, followed by systematic parametric studies to investigate the effects of critical design parameters on key performance metrics. The developed prototype exhibited remarkable shape morphing capabilities, with a maximum tip deflection of 68 mm (deflection-to-length ratio of 0.4). Excellent agreement between experiments and simulations was achieved, with a maximum error of 1.7 % in tip deflection, validating the accuracy of the multiphysics model. Parametric analyses quantified the trade-offs between geometric parameters, revealing their influence on activation temperature, deflection, SMA wire stress, and fatigue life. Optimal configurations enabling low activation temperatures (<150 °C), low stress levels (<400 MPa), and high predicted fatigue life (>50,000 cycles) were identified. The multi-material design approach effectively addressed common issues in SMA-polymer composites, enabling reliable actuation cycles without damage accumulation. The validated multiphysics model and parametric insights provide a comprehensive framework for optimizing the design and performance of SMA-polymer active composites, paving the way for their widespread adoption in shape morphing applications. Potential implications include the development of adaptive aerodynamic surfaces, deployable structures, and energy-efficient systems across various industries.