A refined shear lag model for adhesively bonded piezo-impedance transducers

Abstract

The performance (sensing/actuating) of a piezotransducer highly depends upon the ability of the bond layer to transfer the stress and strain (through shear lag mechanism) between the transducer and the structure. Therefore, the coupled electromechanical response of the piezotransducer should consider the effect of dynamic behaviour, geometry and composition of the adhesive layer used to bond the transducer patch on the structure. This article presents a new refined analytical model for inclusion of the shear lag effect in modelling of adhesively bonded piezoelectric ceramic (lead zirconate titanate) patches for consideration in the electromechanical impedance technique. The previous models neglected the inertial term in shear lag formulations for simplicity. The present refined model, on the other hand, considers the inertial and the shear lag effects simultaneously, and is therefore more rigorous and complete. In this article, the formulations are first derived for one-dimensional case, and then extended to two-dimensional lead zirconate titanate–structure interaction. The overall results are found to be in better proximity to experimental observations. The refined formulations are employed for a detailed stress analysis of the bond layer. The article concludes with a parametric study on the influence of various sensor parameters on the electromechanical impedance signatures.

Sensor Fault Diagnosis for Impedance Monitoring Using a Piezoelectric-Based Smart Interface Technique

“…The bonding layer plays an important role in the EM impedance formulation to obtain accurate results [29,33,34,38]. The previous impedance models of the piezoelectric interface only consider the effect of the structural damage on the EM impedance and ignored the role of the bonding layer [20,35].…”

“…where K o is the dynamic stiffness of the system without the bonding layer. It is assumed that the mass m b makes an only ignorable contribution to the dynamic stiffness of the bonding layer K 11 [32,33]. By substituting Equation 7into Equation (5b) and neglecting the inertial force of the bonding layer, the relationship between the mechanical impedance with and without considering the bonding layer can be obtained, as follows:…”

“…The shear-lag effect is the phenomenon of the difference in the PZT's strain relative to the host structure's strain [33]. The shear-lag occurs when the bonding layer is too thick or the shear modulus is too small.…”

“…Bhalla and Soh [23] formulated a shear-lag model to analyze the mechanism of force transfer through the bonding layer between the PZT and the host structure. The shear-lag model was then upgraded by including the shear stress and the inertial in the EM impedance derivation [33]. Park et al [34] extended the impedance model of Xu and Liu [32] to take into account the degradations in the sensor quality and the bonding layer.…”

Mechanical impedance measurement and damage detection using noncontact laser ultrasound

“…First, because piezoelectric transducers are directly attached to a target structure, they are vulnerable to harsh environments, such as high temperature, corrosive or radioactive conditions, and are not conformable to curved surfaces [6]. For example, the variability of the bonding condition between the piezoelectric transducer and the host structure can deteriorate the robustness and repeatability of EMI measurement [7]. Furthermore, the EMI waveform can be distorted by the cross talk between the excitation and sensing transducers or temperatureinduced variations of transducer capacitance [8].…”