Piezoelectric PZT/epoxy composites for sensing and actuating torsional motion

A pure PZT piezoceramic is unable to generate or sense twisting motion for applications including beams, plates, or shell panels because of its transverse isotropy (mm 6 symmetry), which permits only a bending motion. The design of a piezoceramic/polymer composite element which is orthotropic in the plane is the key to producing twisting motion, since this composite is stiff enough to provide actuation. The composite element can also sense twisting. With the requirement of orthotropy in mind, composites have been made by cutting rods from a PZT plate and placing them in an epoxy matrix. A plate theory analysis provides information on the optimum orientation angle of the PZT/epoxy composite to provide twisting actuation and sensing.