Modeling and experimental validation of a quantitative bar-type corrosion measuring probe using piezoelectric stack and electromechanical impedance technique

Corrosion coupon method has been widely used to estimate the corrosion rate in multiple industries. However, in this method, the weights of the coupons are measured periodically, which limit the application for on-line monitoring. In this paper, a novel type of quantitative bar-type corrosion measuring probe using piezoelectric stack and electromechanical impedance (EMI) technique was proposed. The probe consists of a piezoelectric stack and a metal bar. The multilayer models were used to derive the solution of the probe in longitudinal vibration mode. Five probe prototypes with designated probe length were fabricated to simulate uniform corrosion induced mass loss and investigate the EMI response with probe length. The relationship between the corrosion induced probe length loss and the first and second resonant and anti-resonant frequencies were analyzed. The measured results agreed well with the theoretical predictions. In addition, the accelerated corrosion tests were also performed to induce corrosion to the probe in a realistic setup and further validate the efficacy of the proposed method. The present study proved the feasibility of using the proposed bar-type corrosion measuring probe to quantitatively assess the corrosion amount by introducing the longitudinal vibration with piezoelectric stack and EMI.