Modeling and electromechanical performance of improved smart aggregates using piezoelectric stacks

Abstract

Smart aggregates (SAs) are often formed by embedding lead zirconate titanate (PZT) patches into concrete or marble blocks, which not only have the advantages of low cost, quick response, high reliability, and long service life, but also possess the comprehensive actuating and sensing abilities, and have been widely used in structural health monitoring in the field of civil engineering. However, due to the plate-like geometry of the PZT patch and the limited number of layers, the SAs have relatively short sensing range. To solve the problem of short sensing range, a new kind of smart aggregates using piezoelectric stacks was developed. Theoretical modeling of this new transducers was established, and three prototypes were fabricated. Comparisons between the theoretical predications and the experimental results were presented, and good agreements can be found. Effects of the key parameters, including the total height of specimen, the elastic modulus of cement, the radius of piezoelectric stack, the thickness of piezoelectric layer, and the number of piezoelectric layers in piezoelectric stack, on the electromechanical properties were analyzed, and the guidelines for optimal design were presented. In addition, the improved and the traditional SAs were used to monitoring the water content in the soil specimens based on the electromechanical impedance (EMI) technique. The results showed that the improved SAs using piezoelectric stacks is more sensitive than the traditional ones, which have promising potential in structural health monitoring in the field of civil engineering.

Monitoring of soil water content using spherical smart aggregates based on electromechanical impedance (EMI) technique

“…The EMI technique mainly utilizes the direct and inverse piezoelectric effects of various piezoelectric transducers. In the test, the piezoelectric transducers are usually coupled to the structure by embedding them into the main structure or gluing them on the surface, and they are simultaneously employed as the actuators and the sensors [52][53][54][55]. On the one hand, the dynamic voltage is applied to the piezoelectric transducers to activate the whole structure by using the impedance analyzer.…”

An electromechanical impedance measurement-based solution for monitoring fresh concrete maturity

“…The coupling theory and the impedance method (Xu et al, 2022) are revisited in this section to explain the working principle of the proposed EIM-SMA. According to the electromechanical coupling theory, the dynamic characteristics of a piezoelectric structure are governed by the interactions between the piezoelectric element and the structure.…”

Monitoring of crack repair in concrete using spherical smart aggregates based on electromechanical impedance (EMI) technique

“…Based on smart aggregates (SAs), the SW method is used for evaluating the repair effect through wavelet packet-based energy analysis as SW propagation in concrete is highly influenced by cracks on the wave path and cracks will attenuate the SW [29,31]. Due to the plate-like geometry of the inner piezoelectric transducers, SAs have a relatively short sensing range and the SW is unidimensional [32], which lead to the limitations of the described method. In recent years, the electromechanical impedance (EMI) technique has been widely used in structural health monitoring (SHM), such as metal corrosion monitoring [33,34], concrete early-age strength monitoring [35,36], concrete damage assessment [37,38], soil freeze-thaw process monitoring [39,40], and grinding process monitoring [41,42].…”

“…The TSA can generate radially uniform SWs which is suitable for damage detection in planar structure [46], and has been used for damage detection in two-dimensional (2D) concrete slab under laboratory conditions [47,48]. The SSA has a broader sensing range and is more sensitive in damage diagnosis for three-dimensional concrete structures compared to traditional SAs [32,49]. The SSA was first prepared by Kong et al [50,51] and the study on the vibration characteristics of SSA had been implemented by Wang et al [52].…”