Experimental and numerical study of a piezoelectric diaphragm, a smart sensor for electromechanical impedance-based structural health monitoring

One of the promising techniques for online damage monitoring of structures is the electromechanical impedance (EMI) based method. This method uses the electrical admittance of a piezoelectric transducer to detect damage. A piezoelectric diaphragm consisting of a circular piezoelectric material laid on a brass circular thin electrode is a favorable transducer. Although the brass electrode makes the installation of the transducer easy, it affects the measured electrical admittance. This effect is important when the electrical admittance of a free piezoelectric transducer is measured to calibrate its material properties. In this paper, the effect of such an electrode on the electrical admittance is investigated. Results show that the electrical admittance is drastically affected by the Young’s modulus of brass. From a calibration point of view, the Young’s modulus of the piezoelectric material and the piezoelectric strain coefficient have the most significant effect on the real and imaginary parts of the electrical admittance respectively