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.

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This article deals with the analysis of the power consumption in the piezoelectric ceramic patch of lead zirconate titanate and the losses arising from the adhesive bonding with the host structure. When a lead zirconate titanate patch is utilized as an impedance transducer in the electromechanical impedance technique, it acts both as a sensor and as an actuator (dual effect) for the range of frequency. Power consumption occurs in two forms. First part of the energy is used to actuate the lead zirconate titanate patch and produce deformations. The other part of the energy is dissipated within the piezo-mechanical system due to the internal mechanical loss and the associated heat generation. The determination of the power consumption characteristics for an active piezo-system is very important for designing an efficient intelligent structure with optimized mass and energy combination. Adhesive bond itself acts as an added stiffness, mass and damper and plays an important role in mechanical and electrical energy conversion. Hence, a detailed investigation is needed to characterize the power consumption and energy issues associated with bond layer driven by lead zirconate titanate patch, which is the main aim of this article.

Hydration of concrete is a very complicated and multiphase process, where the cement gel transforms into a hardened state from plastic/semiplastic phase. Proper progression of the hydration process ensures the development of targeted mechanical properties such as the elastic modulus, the coefficient of thermal expansion, the Poisson’s ratio, and finally, the characteristic strength of concrete. Concrete experiences large thermal variations during the early phase of hydration due to the heat generated during the formation of cement hydration compounds, which contributes to shrinkage and cracking, somewhat making ground for the ultimate failure in the long run. Therefore, it is utmost important to monitor the progression of hydration for enhancing performance during the curing and the early service life. This article presents a new reusable external configuration of piezo-impedance transducers to monitor the hydration process in concrete structures using the electro-mechanical impedance technique. The proposed configuration consists of a thin metal foil instrumented with piezoelectric ceramic patch at the free end with the other end of the foil embedded inside the concrete. This configuration is compared against a piezoelectric ceramic patch directly bonded on the rebar used for reinforcement and another one embedded in the concrete surrounding the rebar. The sensing capability of the proposed metal foil configuration is clearly evident from the coupled admittance signature quantitatively vis-à-vis the other configurations. As a preliminary analysis, root mean square deviation values are employed to monitor the hydration process quantitatively. A piezo-equivalent mechanical model is also developed wherein the piezo-identified mass, stiffness and damping parameters are investigated for the cement hydration process so as to chalk out rigorous quantifiers of hydration progression. The employability of the proposed configuration is further proven by explanation of the physio-chemical products developed during various stage of hydration with step-by-step explanation along with corelation of the piezo-identified mass, stiffness and damping parameters. Overall, the proposed reusable configuration carries a high potential for field deployment in concrete industry for early detection of physio-chemical changes.