High-frequency emi signatures for damaged plates using finite element method

Based on the finite element method, an electromechanical impedance (EMI) model for a damaged plate with imperfectly bonded piezoelectric patches is established in the paper. The property of bonding layer between the PZT sensor/actuators and the host plate is taken into account based on the peel stress model as well as the shear lag model. The damage appearing in the plate is modeled by a change in Young´s modulus in the damaged area. Then, the three-dimensional (3D) model of piezoelectric patch-adhesive-damaged plate coupled system is developed. Both the peel stress and the shear stress along the piezoelectric patches are simulated under various excitation frequencies. The numerical results show that excitation frequency affect remarkably the shear stress as well as the peel stress distribution between PZT wafers and host plate and thus some assumptions adopted in the conventional EMI models should be revised accordingly. Finally, the effects of damage severity and expansion on high-frequency EMI signatures are investigated. The simulation indicates that the present EMI model can be used to detect the damages in the structures.