An electromechanical impedance model of a piezoceramic transducer-structure in the presence of thick adhesive bonding

In the past few decades, piezoceramic (PZT) transducers have been used extensively in the vibration and noise control of engineering structures. However, in the last decade, PZT transducers have also been used in electromechanical impedance (EMI) based methods of structural health monitoring (SHM). In the EMI methods, the PZT transducers are either surface bonded using adhesive or wrapped with a protective cover and then bonded or embedded inside the host structure. They are then subjected to excitation in the desired frequency ranges to predict the electromechanical (EM) admittance signatures. These EM signatures serve as an indicator of the health/integrity of the structure. The existing PZT-structure interaction methods consider both the PZT transducer and the adhesive layer to be negligible in mass and are thus ignored. However, for wrapped PZT, the presence of thick adhesive significantly reduces the magnitude of the EM signature. This paper presents the formulation of a three-dimensional (3D) interaction model of a PZT-structure which considers the mass of both the PZT transducers and the adhesive. The model is generic in nature compared to the existing interaction models. The model is verified experimentally and is expected to be applicable to the non-destructive evaluation (NDE) of most engineering structures.