Multiflexoelectric Actuation and Control of Beams

摘要

Flexoelectric materials subject to inhomogeneous electric field can actuate and control flexible structures based on the converse flexoelectric effect. An atomic force microscope (AFM) probe placed on top of a flexoelectric patch can generate a nonuniform electric field with an excitation control voltage, and consequently, an internal actuation stress is generated in the flexoelectric material. The induced flexoelectric membrane force and bending moment, in turn, influence the vibration of the structure. Because of high stress concentration of the flexoelectric actuation, multiple AFM probes/patches are necessary to alleviate potential fracture. In this study, the vibration control effectiveness of an elastic cantilever beam with multiple AFM probes/patches placed at optimal locations is evaluated. The beam is excited initially with an external mechanical force. In case studies, both open-loop and closed-loop control methods are imposed, and optimal combinations of three actuator positions are chosen to minimize the tip displacement. For the open-loop responses, amplified tip displacements are also observed due to overactuation. Displacement feedback control is proposed. Free vibration, and open-loop and closed loop vibration control are compared for the first three beam modes. The results prove that multiple flexoelectric actuators can effectively accelerate the beam damp process with closed-loop control.