IMPEDANCE-BASED MODELING OF INDUCED STRAIN ACTUATORS BONDED ON RING STRUCTURES

An impedance-based model to describe the in-phase, out-of-phase and un symmetric actuation of induced strain actuators bonded to the surface of a circular ring has been developed. The essence of the impedance ap proach is to match the actuator impedance with the structural impedanc e at the ends of the actuators, which includes the dynamic effects of the system. In the model derivation, the dynamics of the ring are base d on the Rayleigh-Ritz method. The appropriate representation of the l oading due to induced strain actuation is discussed. The in-phase and out-of-phase actuation authority is compared. It is shown that out-of- phase actuation has higher authority in exciting the lower order bendi ng modes, while in-phase actuation has higher authority in exciting th e higher order circumferential modes. In-phase actuation does excite t he lower order bending modes through the in-plane and out-of-plane dis placement coupling, but with an order of magnitude lower than out-of-p hase actuation. A good correlation between the dynamic finite element analysis using piezoelectric elements available in ANSYS 5.0 is found. Experimental results of a circular ring actuated in-phase and out-of- phase are also presented. Different methods of bonding straight actuat ors on curved surfaces are investigated. Experimental verification of the impedance-based models is conclusive, particularly for the out-of- phase actuation. (C) 1997 Academic Press Limited.