Snap-Through of Unsymmetric Cross-Ply Laminates Using Piezoceramic Actuators

The paper discusses the concept of using a piezoceramic actuator bonded to one side of a two-layer unsymmetric cross ply [0/90] _T laminate to provide the moments necessary to snap the laminate from one stable equilibrium shape to another. The results presented are considered an alternative to existing morphing concepts wherein actuators are used to elastically warp structures into a shape other than their natural and unique equilibrium shape. These existing concepts require the continuous application of power to maintain the warped shape. With the concept discussed here, the actuators are used only to change from one equilibrium shape to another, so continuous power is not needed. The paper discusses several phases of modeling, including bonding the actuator to the laminate and applying voltage to the actuator to effect the shape change, and experimental work. Two models are developed, a simple model and a more refined one. Both are based on the Rayleigh-Ritz technique and the use of energy and variational methods. The experimental phase of the study is discussed, particularly the measurement of the voltage level needed to snap the laminate. The voltage measurements are compared with predictions and the agreement between measurements and the predictions of the refined model are reasonable, both qualitatively and quantitatively. Suggestions for future activities are presented.