ABSTRACT
Abstract Surface-mounted piezoelectric materials poled in the same direction as the applied electric field are known to induce membrane strains only. This could be seen as their conven tional extension actuation mechanism. However, when piezoelectric materials are constrained and poled perpendicularly to the applied electric field, they act through their shear modes. This is the newly defined shear actuation mechanism. It is the objective of the present paper to compare both mechanisms with the help of an adaptive sandwich beam finite element, with either active surface layers (for extension mechanism) or active core (for shear mechanism). Segmented configurations are studied for cantilever beams. Deflection, stress and vibration characteristics are compared for various parameters (structure/actuator stiffness ratio, actuator’s position and length,...). The shear actuation mechanism is found to present several promising features for brittle piezoceramics use. 12
1. Introduction
Piezoelectric materials used to control noise and vibration, either surface-mounted or embedded in host struc tures, are commonly poled in parallel to the applied electric field. Hence, they act through their conventional extension mechanism. This was extensively used and studied in the literature either in purely active [3] or hybrid passive/active systems [8]. However, constrained piezoelectric materials, poled in perpendicular to the imposed electric field, use their thickness shear mode, leading to the less known shear actuators. Although mentioned by [6], the first preliminary study was presented by [7] using a commercial finite element code. A theoretical model was later presented by the same authors [9].
