Shape Memory Polymer-Based Metamaterial Structures: Comprehensive Performance Assessment of Constrained Recovery Behaviors

Shape memory polymer (SMP)-based metamaterial structures combine the advantages of metamaterial structures and shape memory materials, offering promising applications in intelligent actuation. However, the evolution of the recovery force and its underlying recovery mechanisms in such structures remain insufficiently understood, and a standardized method for comprehensively evaluating shape memory performance has yet to be established. To address these challenges, this study systematically investigated SMP-based metamaterial structures with distinct deformation modes through shape memory experiments. The results show that structural configuration, geometric parameter and precompression strongly influence the recovery behavior. The recovery mechanisms were clarified by analyzing the variations in deformation and recovery across different structures. Moreover, the classical Gibson–Ashby power-law model was extended by introducing the recovery modes to predict recovery behavior. A comprehensive performance index, integrating recovery force and force recovery ratio, was proposed to quantitatively assess recovery capability. Furthermore, an empirical predictive equation was developed to describe the relationship between the recovery force and its influencing factors, including structural geometry, loading conditions and deformation modes, thereby enabling a two-way design of structures and their performances. This work provides a theoretical foundation for evaluating and designing SMP-based metamaterial structures with programmable recovery performance.