A modified electro-mechanical impedance model of piezoelectric actuator-sensors is presented in this study. The presented model treats the bonding layer between a piezoelectric patch and a host structure as a spring-mass-damper system in the coupled electro-mechanical analysis. The effect of bonding layers on the dynamic interaction between piezoelectric actuator-sensors and host structures is thus taken into account. The model is then used for debonding detection of composite patches. A debonding model is accordingly developed. The debonding model uses infinitesimal-length springs to model the joint between a composite patch and its base structure. The spring stiffness varies with the joint rigidity and directly influences the structural mechanical impedance as well as the piezoelectric electric admittance. A numerical example is provided to reveal the effect of bonding layers and demonstrate the feasibility of the proposed detection method.

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