The interaction between the piezoelectric (PZT) patch and the beam being monitored are influenced by the properties and behaviour of the interface layer. Due to the mechanical or electrical loading, the distribution of the deformation is not uniform within the sensor, since the strain along the structure and the PZT are nonlinear. In this paper, analytical studies carried out to study the influence of bonding layer on the electrical and mechanical signatures of the PZT affixed to a structure are presented. PZT attached to a beam made of different materials such as steel, aluminium and concrete are considered for the study. Effect of imperfection in bonding, thickness of adhesive on the response signatures are presented. It is observed that the electrical and mechanical signatures depend on the properties of the interface layer between PZT and surface of the attached structure. The thickness and length of adhesive is found to have significant effect on the response of PZT which can be used for detecting the debonding of the sensors.

Keywords: Piezoelectric sensor, Impedance, Interface layer, Debonding.