Torsional and flexural control of sandwich composite beams with piezoelectric actuators

A mathematically one-dimensional model was developed to predict the static response of composite sandwich beams subjected to loads induced by piezoelectric (PZT) actuators. The model was derived using Reddy's (1984) displacement field for a laminated plate which consists of cubic variation of the in-plane displacement through the thickness.

In this model, beam deformations include extension, bending, transverse shear, St. Venant torsion, and torsion due to warping of the cross section out of its plane. The PZT actuators can be configurated to induce a bimoment, resulting in twist cf the beam through the warping of the cross section. Hence directionally attached PZT (DAP) actuator elements, which cause twist by inducing tensile and compressive strains at 45° to the longitudinal axis of the beams, are not necessary to actuate twist. For an aluminum beam example, it is shown that the PZT bimomet control produced about 2.7 times more twist than the conventional DAP control.