Temperature-regulated boundary constrain multistable structures and designed metamaterials

Traditional bistable curved beams are constrained by fixed boundary conditions, where their steady-state behaviors are passively determined by initial parameters, making them unsuitable for dynamic environments. In the present study, we establish a temperature-regulated curved beam spring model to regulate its steady-state behaviors with different stable states, such as bistability, monostable snapping, monostability, and snap-back phenomena. The numerical simulations for the proposed model reveal that small vertical stiffness can easily result in snap-back phenomena. In contrast, increasing lateral stiffness can facilitate the transition of steady-state behaviors from monostable to monostable snapping, or even to bistable snapping under large vertical stiffness. To validate the theoretical and simulation results of the proposed model, we also conducted an experimental study. In experimental work, a temperature-sensitive polymer of polylactic acid was selected for constructing the boundary support structures of the curved beams. Furthermore, we designed metamaterial structures based on this type of curved beam model as unit cells to achieve stimuli-responsive behavior with temperature and shape memory effect. The shape memory effect can be dynamically regulated by boundary conditions, eliminating high-temperature programming steps in traditional shape memory polymers. This study extends the theoretical model of bistable curved beams by considering general boundary conditions and provides an approach for designing environment-adaptive intelligent metamaterials, expanding their potential applications in soft robotics and biomedicine structures.