PERFORMANCE AND OPTIMIZATION OF INDUCED STRAIN ACTUATED STRUCTURES UNDER EXTERNAL LOADING

This paper addresses the actuator/substrate thickness ratio that maximizes the static/dynamic response of a beam for a variety of actuator-structure integration configurations, actuator activation levels, and inertia/external loading conditions. The three different actuator-structure integration configurations considered are actuators embedded inside the substrate, actuators bonded to the surface of the substrate, and actuators discretely attached and offset from the surface of the substrate. In the category of embedded actuators, a shallow embedment just beneath the surface usually maximizes the moment/induced curvature, but for stiffer actuators, a deeper embedment results in a greater induced curvature. For surface-bonded actuators, a physical basis for the existence of an optimum thickness ratio is presented. For the discretely attached actuator configuration, the induced curvature can be more than doubled depending on the actuator/substrate stiffness ratio. The optimum thickness ratio besides the local actuator/beam properties is shown to be a function of the external loads, boundary conditions, and actuator activation level. The effect of thickness ratio on the dynamic response is also investigated. Anomalies in beam response using some of the prevalent methods for computing the static and dynamic responses of such systems are discussed.