Dynamic Behavior of Structure-mounted Disk-shape Piezoelectric Sensors Including the Adhesive Layer

Piezoelectric (PZT) transducers are commonly used for numerous diagnostic techniques for nondestructive evaluation (NDE) of structures. Researchers in the past have shown that the presence of an adhesive layer between the PZT patch and the structure could have a significant impact both on the amplitude of the wave propagated into the structure and on its Electromechanical impedance (EMI) signature. To account for losses, models have been developed to describe the effects of the adhesive layer. Nonetheless, the models found in the literature are strictly valid for either 1D or rectangular PZT patches only. The aim of this article is to develop a dynamic model for a disk, PZT patch connected to a structure by means of a thin adhesive layer. Unlike previous works, it was found that for disk-shape sensors the effect of the adhesive layer is frequency dependent and that the losses due to the shear deformation of the adhesive layer for the case near the first radial resonant mode were considerably lower than for the quasi-static case. In order to validate the model developed in this article, experimental data are compared to the predicted EMI signatures of disk-shape sensors mounted on a structure for various configurations.