The Influence of Vibrations on the Electromechanical Impedance Method Applied to Square Thin Plates

Abstract

The paper studies the influence of external vibrations on the electromechanical impedance signature of thin square aluminum plates. The plate has bonded on it two piezoelectric elements: one bonded in the center of the plate used for electromechanical impedance and another, on the corner, for generating small external vibrations. The spectrum frequencies of external vibrations were considered to be in the medium and high frequency range, with different levels of amplitudes. The plate is hung by a hook, and free boundary conditions at the plate’s edge are therefore considered. Comparisons of different bonding adhesives of the piezoelectric elements, permanent and temporary, are experimentally done. Comparisons of experimental electromechanical impedance measurements with and without vibrations at different fixed frequencies are presented to evaluate their effects. Theoretical electromechanical impedance signature calculated by three methods, integration method, correlation method, and Discrete Fourier Transform, was compared with the experimental data, on a simulated signal similar to the ones acquired by impedance analyzers. Comparisons of experimental data and numerical finite-element results for the electromechanical impedance signature are also made.