Abstract: In order to magnify the output angular displacement of piezoelectric bimorph further, a bimorph actuator with a connecting rod mechanism is proposed based on the method of increasing the output angle and torque of piezoelectric bimorph by post-buckled pre-compression (PBP). A static numerical model with a torsion spring on its end is founded. And the rigid-flexible coupling Lagrange equation dynamic model and FEM model both with small rudder are also established. The results indicate a better coincidence between the numerical and FEM models. Statics results show that connection rod mechanism proposed can produce an output angular displacement which is 4 times bigger than that produced by the original PBP driver, and the biggest output angular reaches 26.3°, reducing the output torque. The dynamics results show the transfer and distribution of the interior energy of actuator mechanism. Taking the small rudder in this paper as a driving object, the average output angular velocity reaches 2 000°/s, and the control bandwidth reaches 30 Hz, which are much better than those of the ordinary servo actuator. Therefore, the design and simulation of the proposed actuator can provide the theoretical basis to the development of micro-flight rudder characterized by large displacement, small output torque and high control bandwidth.

Key words: aircraft structure and design, pre-compression piezoelectric bimorph, actuator, output angular displacement, rigid-flexible coupling, Lagrange equation