Flexoelectric Actuation and Vibration Control of Carbon-Nanotube Reinforced Rings

Precision actuation and vibration control are essential in many engineering applications. This study focuses on flexoelectric actuation and active vibration control of carbon nanotube (CNT) reinforced ring shells. Vibration control is implemented in two aspects respectively resulting from 1) actuator selection and 2) structural compositions. Based on the converse flexoelectric effect, flexoelectric materials are used as actuators to precisely control the ring structures. The stiffness of the ring structure is manipulated by designing the CNT distribution types (i.e., uniformly distributed (UD), X, and O) in rings, so as to influence the vibration behaviors. The essential influence of different distribution types on ring’s mechanical properties is expounded. To study the actuation effect, controllable displacements of the CNT reinforced rings are analyzed with respect to design parameters. The response of open-loop control with constant actuation voltage and that of closed-loop control under displacement feedback control are compared. Analytical results demonstrate that using O type and smaller volume fraction can enhance the actuation and control effects. For the open-loop responses, amplified displacements are observed due to overactuation. Displacement feedback control is introduced to avoid overactuation by adjusting the actuation voltages.