Electromechanical impedance instrumented circular piezoelectric-metal transducer for corrosion monitoring: Modeling and validation

Corrosion induced thickness loss of metallic structures is one of the most common issues across multiple industries. In our previous work, a new type of corrosion sensor based on lead zirconate titanate (PZT) using electromechanical impedance (EMI) technique was proposed. The sensor is fabricated by bonding a PZT patch onto a metal plate. The previous work has demonstrated that the peak frequencies in the conductance signatures decrease linearly with the increase of the corrosion induced thickness loss. However, a theoretical model that fully describe the coupled vibration between piezoelectric element and the metal plate, and the EMI characteristics has not been established. This paper presents the theoretical modeling of the EMI instrumented circular piezoelectric-metal transducer for corrosion monitoring purpose. Based on electro-elastic and Kirchhoff plate theory, the EMI responses of the transducer operated in transverse bending modes with free boundary conditions were modeled. Finite element modeling calculations and experimental measurement were conducted to validate the theoretical results with good agreement.