Spatial Electrostrictive Actuations of Flexible Circular Tubes

This paper is aimed to study dynamic actuation of circular tubular shell structures coupled with distributed electrostrictive actuator segments. A mathematical model of the hybrid elastic/electrostrictive circular tubular shell, including the electrostrictive/elastic/control couplings, is derived. The generalized electrostrictive control actuation induced by an arbitrary electrostrictive actuator segment consists of three contributing components: the circumferential membrane control action, the longitudinal bending control action, and the circumferential bending control action. In particular, spatial modal actuation characteristics of the total actuation and the three contributing components corresponding to various design parameters (e.g., actuator thickness, shell radius, and thickness) are evaluated and compared with respect to actuator patch sizes. Analysis data suggest that the electrostrictive membrane control actuation dominates the overall control action in lower shell modes; however, the control moment becomes important in higher shell modes. Optimal placements of electrostrictive actuator segments on the circular tubular shell are identified. Modal filtering behaviors, due to cancellation of internal attenuation/amplification effects, occur when large-size actuators are used, rendering the actuation less effective.