Tunable thermally bistable multi-material structure

The shape memory effect in polymers and alloys enables programming the response of structures via temperature changes; however, the number of materials exhibiting such memory behavior is limited, their response to thermal load is considerably slow, and programming is required to guide the deformation of shape memory materials. The recently revived structural bistability concept offers a potential to design and program reconfigurable structures. In this study, we introduce a thermally bistable structure that displays an abrupt shape memory effect along with snap-through instability behavior. We demonstrate the effect of the wall stiffness of the structure on the bistability of a mechanically bistable element and its nonlinear response. We utilize the thermal softening behavior of two distinct polymers to design a bistable bimaterial structure that restores its original shape when the environment reaches a specific temperature, referred to as triggering temperature. The results reveal that the triggering temperature can change within a range of 300C by changing the width ratio of the stiff material at the wall from 0 to 0.5 for specific material composition. The proposed concept offers new opportunities to utilize tessellated bistable structures as self-sensing actuators and intelligent deployable structures since they can be designed to reconfigure in response to certain changes in temperature.

Mots clés

mechanical metamaterials; bistable structures; architected thermal actuators; shape memory behavior