Quasi-Static Behavior of Individual C-Block Piezoelectric Actuators

Most piezoelectric actuators used in smart structure applications are either stiff stacks which produce high forces and small deflections, or compliant benders which produce large deflections and small forces. This leaves a mid-range gap in actuator performance in which many applications operate. A new class of solid state actuators, known as C-blocks, has been developed as a mid-range actuator. A C-block is a semicircular composite bender actuated with piezoelectric layers. It can be combined in series and/or parallel to increase actuator deflection and/or force. A simple, linear analytical model for the quasi-static force-deflection behavior of a generic individual C-block is presented in this paper. This model can be used to determine the relationship between force and deflection, as well as the free deflection, blocking force, actuator stiffness, and maximum energy transferable to the actuated system. This model was experimentally verified with three case studies: PZT-8 and PZT-5H ceramic unimorphs; PVdF polymeric bimorphs; and four-layer PVdF polymeric multimorphs. The results from these case studies confirm that C-blocks are over six times stiffer, and generate over two-and-a-half times more force than a comparable straight bender.