Effect of Bonding Layer on Admittances of PWASs Bonded on Thin Slender Substrates: Correlation Between Measurements and Simulation

The effects of the bonding layers on the admittances of piezoelectric wafer active sensors (PWASs) bonded on thin slender substrates are investigated in this paper. Experimental measurements demonstrated that the bonding layer strongly influences the resonant characteristics of the PWAS. Based on the time-of-flight of the wave packets at or near the resonance frequencies, we identified that the some resonances are due to the flexural mode of the substrate while the others are due to the extensional mode. To understand these effects, multi-mode analytical models were developed to simulate the admittances of the PWAS under these two vibration modes. The deformation of the PWAS was coupled to the substrate using a shear lag parameter. The parameters of the bonding were adjusted to match the simulated and measured admittances. A frequency dependent PWAS loss parameter is suggested for improving the match of the resonant amplitudes.