Investigation of self-resetting active multistable laminates

Elastically multistable structures, that is, structures possessing more than one elastically stable equilibrium configuration, are particularly attractive for advanced shape changing (morphing) aircraft applications because no, control effort is required to maintain the structural shape in any specific stable equilibrium. For example, thin, unsymmetric, fiber-reinforced composite laminates (e.g., [0/90](Tau)) can have multiple equilibrium shapes, and such laminates can be changed from one stable shape to another by a simple snap-through action. Furthermore, previous work by the first author with others demonstrated the use of a planar piezocomposite actuator to snap a bistable laminate from one equilibrium shape to another, but not back again. Such a self-resetting capability is desirable in many practical applications. The present paper describes analytical and experimental efforts to model and demonstrate self-resetting, piezoelectrically controlled, multistable laminates., The work is based on a two-ply, [0/90](Tau) graphite-epoxy laminate that is sandwiched between two piezocomposite actuators. A simplified analytical model of the structure was developed to fine-tune the design of an experimental test article and correlate with results from testing. The simplified model captures the global response of the experimental device and predicts self-resetting actuation. Differences between the analytical and experimental results are identified, and possible reasons for these differences are explored.