Bistable‐Shape Memory Synergy Enables Self‐Triggered Snap‐Through with Ultrahigh Energy Density

Abstract

Abstract Traditional bistable actuators triggered by external mechanical load generally exhibit low energy density, severely restricting their applications in autonomous systems. This study presents a novel integration of thermally induced phase transformation in shape memory alloys (SMAs) with the rapid deformation mechanisms of bistable structures, creating an intelligent bistable actuator. It is self‐triggered via thermal activation, without the need for an external mechanical actuator to initiate snap‐through, exhibiting high energy density. The synergy of thermally induced martensitic reverse transformation and structural constraints allows the actuator to achieve a volumetric energy density of 1.19 × 10⁴ J m − 3 , surpassing the highest reported values for bistable actuators. By controlling local strain distribution and martensite orientation through geometric parameters ( t/l , h/l ), the actuator is able to launch a payload with a mass of 1176 times that of the actuating element, achieving a jumping height of 265 mm (30 times its own height), with a snap‐through response completed in 4 ms. Extended structural designs enable multimodal actuation capabilities, including horizontal catapulting, torque‐driven rotation, and temperature‐programmed multi‐step grab‐and‐jump operations. The proposed material–structure synergistic design paradigm advances the development of programmable thermally triggered actuation systems with high energy density, demonstrating potential for applications in robotics, micro‐automation systems, and smart actuators.