Guided wave generation, sensing and damage detection using in-plane shear piezoelectric wafers

This work presents guided wave generation, sensing, and damage detection in metallic plates using in-plane shear (d₃₆ type) piezoelectric wafers as actuators and sensors. The conventional lead zirconate titanate (PZT) based on induced in-plane normal strain (d₃₁ type) has been widely used to excite and receive guided waves in plates, pipes or thin-walled structures. The d₃₆ type of piezoelectric wafer, however, induces in-plane (or called face) shear deformation in the plane normal to its polarization direction. This form of electromechanical coupling generates more significant shear horizontal (SH) waves in certain wave propagation directions, whose amplitudes are much greater than those of Lamb waves. In this paper, an analysis of SH waves generated using in-plane shear electromechanical coupling is firstly presented, followed by a multiphysics finite element analysis for comparison purposes. Voltage responses of both the conventional d₃₁ and the new d ₃₆ sensors are obtained for comparison purposes. Results indicate that this type of wafer has the potential to provide a simple quantitative estimation of damage in structural health monitoring.