Piezoelectric Impedance Methods for Damage Detection and Sensor Validation

Abstract

This article presents an overview and recent applications in impedance‐based structural health monitoring (SHM). The basic principle behind this technique is to apply high‐frequency structural excitations (typically greater than 30 kHz) through surface‐bonded piezoelectric transducers, and measure the local mechanical impedance by monitoring the current and voltage applied to the piezoelectric transducers. Changes in impedance indicate changes in the structure, which in turn can indicate that damage has occurred. Previous experimental studies are summarized to demonstrate how this technique can be efficiently used to detect structural damage in real time. The impedance method also has applications in the field of sensor self‐diagnostics and validation in determining the operational status of piezoelectric active sensors used in SHM. The feasibility of this sensor validation procedure is demonstrated by analytical studies and experimental examples, where the functionality of surface‐mounted piezoelectric sensors was continuously deteriorated.

An integrated algorithm for structural health monitoring of composite plate using electromechanical impedance

“…The simulation results show that remarkable up shifting in the base line of imaginary admittance spectrum occurs and slope angle of the spectrum increases with the increase of the area desponding percentage, as shown in Figure (9). This result matches with experimental results obtained by Park et al [7] regarding the same issue. Accordingly, this step is crucial in the proposed algorithm as the base-line of the imaginary admittance spectrum is acquired for the healthy case and used as a reference for self-diagnose check.…”

“…The electromechanical impedance (EMI) technique is one of the techniques that benefits from PWAS advantages [7] . Electric (impedance/admittance) measured on the PWAS terminals can be considered as Frequency Response Function (FRF) for the host structure which is very similar to VBDI techniques.…”

Method for removing temperature effect in impedance-based structural health monitoring systems using polynomial regression

“…The higher the values of RMSD and CCDM, the more differences exist between the baseline and monitoring signatures, 22 whereas, for identical signatures, RMSD and CCDM values would be close to zero. To detect damage using the metric indices, threshold values which ensure that the structure is healthy must be set.…”

“…Damage affects the mass, damping, and stiffness characteristics of a structure; consequently, the structure's mechanical impedance is also affected when damage occurs. 8,22 The mechanical impedance is not straightforward to be measured, but Liang et al 5 discovered that the changes in the mechanical impedance of a structure are reflected in the electrical impedance of a PZT transducer attached to the surface of this structure by an adhesive layer, since these both quantities are related through the following equation 5,7 Z…”

“…The degree of dependence, although, is influenced by the type of the piezoceramic, such as 5H or 5A. 22,23 This dependence has been studied and measured experimentally by Sabat et al 24 for two different PZT patches.…”