Shape-shifting smart hooks for adaptive interlocking interfaces

Abstract

Abstract Interlocking systems are integral to modern engineering applications, and shape-shifting smart hooks offer a transformative solution for reconfigurable, adaptive fastening. This study investigates the design, fabrication, and performance of hooks made from epoxy shape memory polymers (ESMPs), leveraging their thermo-responsive behavior for autonomous engagement and disengagement. These hooks enable noise-free operation, energy efficiency, and reusability, making them well-suited for multifunctional applications. Comprehensive mechanical and thermal analyses were conducted to optimize fabrication parameters and evaluate the material’s shape memory behavior, with a focus on the influence of crosslink density and glass transition temperature ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">g</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) on tunable performance. Experimental results demonstrated mechanical robustness, adaptability, and reliable shape recovery across various conditions, including cyclic fatigue testing, thermal activation, and load-bearing scenarios. Finite element simulations provided insights into stress distribution and deformation mechanisms, complementing experimental observations and validating the suitability of ESMP-based hooks for diverse applications. To demonstrate practical potential, several application scenarios were experimentally validated—spanning soft robotics, prosthetics, and adaptive fastening—where ESMP hooks enabled secure, reversible engagement across different object types and surface conditions. These demonstrations are grouped into two categories: active integration with actuation systems (e.g. prosthetic fingers and soft grippers), and passive shape-adaptive interlocking in confined environments (e.g. cable bundles and metallic clusters). The study also introduced scalable fabrication methods, enhanced fatigue resistance, and precise thermal programming for shape recovery. Collectively, these findings establish ESMP-based smart hooks as a promising solution for robotics, aerospace, and modular systems requiring durable, reconfigurable fastening.