Two-dimensional modeling of the effects of external vibration on the PZT impedance signature

The electromechanical impedance (EMI) technique using piezoelectric ceramic lead zirconate titanate (PZT) transducers has been increasingly applied to structural health monitoring (SHM) of aerospace, civil and mechanical structures. The PZT transducers are usually surface bonded to or embedded in a structure and subjected to actuation so as to interrogate the structure at the desired frequency range. The interrogation results in electromechanical admittance (inverse of EMI) signatures which can be used to estimate the structural health or integrity according to the changes of the signatures. In the existing EMI method, the vibration of the structure caused by the external excitations has been considered only for the one-dimensional scenario. This paper develops a two-dimensional EMI model to account for the effect of external excitation on the PZT admittance signature. An application is illustrated with modeling of a cantilevered Kirchhoff plate interrogated by a single surface-bonded PZT transducer. Experiments and numerical simulations are also carried out to verify the theoretical model. Finally, the effects of external excitation on PZT impedance signatures are discussed.