Conventional flapping-wing aircraft are often limited by structural complexity and high energy consumption due to the use of motors and transmission systems. To tackle these challenges, this work presents a self-flapping aircraft powered by electrothermal actuation. By employing a liquid crystal elastomer (LCE) fiber-based engine, a multi-field coupled electrothermal–mechanical model is developed to establish the governing equations of the system, which are numerically solved using a fourth-order Runge–Kutta method. The results show that under steady electrothermal excitation, the flapping-wing aircraft exhibits a supercritical Hopf bifurcation, shifting from a stationary state into a self-oscillatory regime. This sustained oscillation arises from the balance between electrothermally generated strain and damping dissipation. Both the flight speed and the oscillation frequency can be effectively regulated by tuning the system parameters. Featuring a simple structure, adjustable dimensions, and no requirement for complex controllers, this self-flapping wing aircraft has potential applications in biomimetic flight, swarm robotics, and adaptive soft robotics.
Liang et al. (Sun,) studied this question.