Snapping-enabled self-sustained rotation in liquid crystal elastomers under continuous light irradiation

Liquid crystal elastomers can convert steady photothermal energy into autonomous mechanical motion, providing promising opportunities for soft robotics, energy harvesting, and sensing. However, conventional light-power Liquid crystal elastomer rotors generally rely on continuous deformation, which limits the mechanical output associated with each actuation cycle. Here, we propose a snapping-enabled self-rotation system that temporally separates energy accumulation from mechanical release. Under steady illumination, an Liquid crystal elastomer fiber gradually contracts and stores elastic energy until its tensile force exceeds a locking threshold, triggering the instantaneous snapping of a mass ball towards the radially outward direction. The resulting unbalanced torque drives the rotation of a disc. During rotation, individual tubes sequentially enter and leave the illuminated region, enabling a continuous cycle of energy accumulation, snapping, and resetting under steady illumination. A nonlinear dynamical model coupling continuous photothermal evolution with discrete snapping events is established to describe the resulting hybrid dynamical system. Numerical results reveal a supercritical Hopf bifurcation from a static state to sustained self-rotation, demonstrating the emergence of autonomous periodic motion through the balance between photothermal energy input and mechanical dissipation. The self-rotation frequency exhibits non-monotonic dependence on key system parameters, with distinct optimal regimes arising from the competition between thermal, mechanical, and snapping dynamics. These results elucidate how discrete energy-release events can reorganize the dynamics of photothermally driven Liquid crystal elastomer systems and provide a new mechanism for generating sustained mechanical motion under steady energy input.