Electromechanical Impedance Response of a Cracked Timoshenko Beam

Abstract

Typically, the Electromechanical Impedance (EMI) technique does not use an analytical model for basic damage identification. However, an accurate model is necessary for getting more information about any damage. In this paper, an EMI model is presented for predicting the electromechanical impedance of a cracked beam structure quantitatively. A coupled system of a cracked Timoshenko beam with a pair of PZT patches bonded on the top and bottom surfaces has been considered, where the bonding layers are assumed as a Kelvin-Voigt material. The shear lag model is introduced to describe the load transfer between the PZT patches and the beam structure. The beam crack is simulated as a massless torsional spring; the dynamic equations of the coupled system are derived, which include the crack information and the inertial forces of both PZT patches and adhesive layers. According to the boundary conditions and continuity conditions, the analytical expression of the admittance of PZT patch is obtained. In the case study, the influences of crack and the inertial forces of PZT patches are analyzed. The results show that: (1) the inertial forces affects significantly in high frequency band; and (2) the use of appropriate frequency range can improve the accuracy of damage identification.

Structural Damage Recognition Based on the Finite Element Method and Quantum Particle Swarm Optimization Algorithm

“…Considering it, there is always a difference between the theoretical modeling analysis and the actual measurement results, and usually, this difference will affect the accuracy of damage identification. But at the same time, the research in References [27,28] shows that the peak frequency variation of the conductance curve calculated by the model before and after the structural damage is very close to peak frequency variation in experiment. Therefore, in order to reduce the impact of the difference between theoretical modeling and experiment on the accuracy of damage recognition, the objective function is designed as follows:…”

System-on-Chip Integration of a New Electromechanical Impedance Calculation Method for Aircraft Structure Health Monitoring

“…According to the piezoelectricity equations, the 1D piezoelectric patch admittance model (Equation (1)) is directly linked to the stiffness of the host structure where the sensor is pasted [19,20]. Therefore, the electromechanical impedance of the PZT patch could be considered as the indicator of the structure integrity: $\frac{1}{Z_{\mathit{\text{PZT}}}(f)}=\mathit{\text{if}}.C_0\left[1-k_{31}^2(\frac{K_{\mathit{\text{structure}}}(f)}{K_{\mathit{\text{structure}}}(f)+K_{\mathit{\text{PZT}}}(f)})\right]$where k 31 is the electro-mechanical coupling factor of the PZT, C 0 is the capacitance of the sensor; K structure and K PZT are respectively the stiffness of the host structure and the stiffness of the sensor itself.…”

Evaluation of the Influence of Sensor Geometry and Physical Parameters on Impedance-Based Structural Health Monitoring

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