A novel method to monitor soft soil strength development in artificial ground freezing projects based on electromechanical impedance technique: Theoretical modeling and experimental validation

2020 ◽  
Vol 31 (12) ◽  
pp. 1477-1494 ◽  
Author(s):  
Chuan Zhang ◽  
Xianfeng Wang ◽  
Qixiang Yan ◽  
Cumaraswamy Vipulanandan ◽  
Gangbing Song
Keyword(s):  
Lead Zirconate Titanate ◽  
Lead Zirconate ◽  
Soil Strength ◽  
Impedance Method ◽  
Strength Development ◽  
Electromechanical Impedance ◽  
Freeze Thaw ◽  
Zirconate Titanate ◽  
Ground Freezing ◽  
Artificial Ground Freezing

The artificial ground freezing is an important technique for soft soil reinforcement and underground water sealing carried out by continuously refrigerating ground. It is of great significance to monitor the soil strength development in artificial ground freezing projects not only for better evaluation of the soil freeze–thaw status but also for predicting and controlling the concurrent adverse effects which may cause serious engineering accidents. In this study, the electromechanical impedance method was explored in monitoring the soil strength development in the freeze–thaw process. The lead zirconate titanate transducer was embedded inside the soil specimen, and changes in the conductance signatures were monitored throughout the soil freeze–thaw process. The experimental results indicate that the resonant frequency of the embedded lead zirconate titanate transducer can serve as a reliable index for assessment of the soil’s dynamic elastic modulus in the freeze–thaw process. More importantly, an analytical model was developed based on the piezo-elasticity theory to characterize the correlation between the electromechanical impedance of the lead zirconate titanate transducer and the soil’s mechanical properties, and its validity was further confirmed by the experimental research. Based on the proposed model, the development of the soil’s strength can be well predicted from the measured conductance signatures. As a nondestructive testing method, the proposed soil testing technique will help save considerable time and resources by avoiding the conventional sampling, specimen preparation, and testing of soil. The theoretical and experimental research will contribute to the future application of the electromechanical impedance method in real-life artificial ground freezing engineering projects.

scholarly journals Anchor Force Monitoring Using Impedance Technique with Single-Point Mount Lead-Zirconate-Titanate Interface: A Feasibility Study

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 382 ◽  
Author(s):  
Thanh-Cao Le ◽  
Duc-Duy Ho ◽  
Thanh-Canh Huynh
Keyword(s):  
Lead Zirconate Titanate ◽  
Single Point ◽  
Lead Zirconate ◽  
Impedance Method ◽  
Electromechanical Impedance ◽  
Zirconate Titanate ◽  
Proposed Model ◽  
Anchoring System ◽  
Force Monitoring ◽  
Anchor Force

As a key load-bearing element in a prestressed structure, the anchor should be appropriately monitored to secure its as-built prestressing force. In previous studies, the impedance-based prestress force monitoring technique through a mountable lead–Zirconate–Titanate (PZT) interface was developed. However, the previous design of the PZT interface uses a two-point mount technique through two bonding layers, causing inconveniences during installation and replacement processes. To address this issue, we propose an alternative PZT interface model for prestress force monitoring based on the impedance method. The proposed model uses a single-point mounting technique that allows it to be more conveniently installed and replaced on a host structure. First, the electromechanical impedance of the proposed PZT interface is theoretically derived. The proof-of-concept of the proposed PZT interface for impedance monitoring is then shown by finite element modelling. Afterwards, a lab-scaled experiment is conducted on an anchoring system to demonstrate the practical application feasibility of the proposed technique. The obtained results show that the proposed technique can produce impedance responses that are highly sensitive to the prestress force. The performance of the proposed model for impedance-based prestress force monitoring is found to be comparable with the previous techniques (the washer-type mount and the two-point mount). Due to its advantage of simple design, the newly designed PZT interface is promising for the future development of the impedance-based anchor force monitoring systems in practice.

scholarly journals A PZT-Based Electromechanical Impedance Method for Monitoring the Soil Freeze–Thaw Process

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1107 ◽  
Author(s):  
Jicheng Zhang ◽  
Chuan Zhang ◽  
Jiahao Xiao ◽  
Jinwei Jiang
Keyword(s):  
Stress Wave ◽  
Lead Zirconate Titanate ◽  
Soil Freezing ◽  
Impedance Method ◽  
Active Sensing ◽  
Freezing And Thawing ◽  
Engineering Structures ◽  
Electromechanical Impedance ◽  
Freeze Thaw ◽  
Wave Signal

It is important to conduct research on the soil freeze–thaw process because concurrent adverse effects always occur during this process and can cause serious damage to engineering structures. In this paper, the variation of the impedance signature and the stress wave signal at different temperatures was monitored by using Lead Zirconate Titanate (PZT) transducers through the electromechanical impedance (EMI) method and the active sensing method. Three piezoceramic-based smart aggregates were used in this research. Among them, two smart aggregates were used for the active sensing method, through which one works as an actuator to emit the stress wave signal and the other one works as a sensor to receive the signal. In addition, another smart aggregate was employed for the EMI testing, in which it serves as both an actuator and a receiver to monitor the impedance signature. The trend of the impedance signature with variation of the temperature during the soil freeze–thaw process was obtained. Moreover, the relationship between the energy index of the stress wave signal and the soil temperature was established based on wavelet packet energy analysis. The results demonstrate that the piezoceramic-based electromechanical impedance method is reliable for monitoring the soil freezing and thawing process.

Reusable piezoelectric transducer for structural health monitoring using both Lamb wave and electromechanical impedance modes

2020 ◽  
Vol 31 (16) ◽  
pp. 1898-1909
Author(s):  
Qijian Liu ◽  
Yuan Chai ◽  
Xinlin Qing
Keyword(s):  
Structural Health Monitoring ◽  
Lead Zirconate Titanate ◽  
Health Monitoring ◽  
Lamb Wave ◽  
Lead Zirconate ◽  
Aluminum Plate ◽  
Electromechanical Impedance ◽  
Structural Health ◽  
Zirconate Titanate ◽  
Piezoelectric Lead Zirconate Titanate

A variety of structural health monitoring techniques have been developed to support the efficient online monitoring of structural integrity. Moreover, Lamb wave and electromechanical impedance methods are increasingly used for structural health monitoring applications due to their high sensitivity and effectiveness in detecting damage. However, these techniques require transducers to be permanently attached to structures because of the usage of baselines recorded under the condition without damage. In this study, a reusable piezoelectric lead zirconate titanate transducer for monitoring corrosion damage on the aluminum plate is introduced, which can be removed from the test specimen and reused with the repeatability of signals. The reusable piezoelectric lead zirconate titanate transducer is bonded on the aluminum plate using the ethylene-acrylic acid copolymer with an aluminum enclosure. A series of experiments are conducted on an aluminum plate, including the investigation for repeatability of signals and the capability of corrosion detection of the designed piezoelectric lead zirconate titanate transducer through the Lamb wave and electromechanical impedance methods. The simulated corrosion defect with the area of 15 × 15 mm2 is detected during experiments. The experimental results confirm that the reusable piezoelectric lead zirconate titanate transducer can effectively evaluate the corrosion damage to plate structure and can be reused many times.

Detection and Characterization of Fatigue Induced Damage Using Electromechanical Impedance Technique

2009 ◽  
Vol 79-82 ◽  
pp. 2031-2034 ◽  
Author(s):  
Chee Kiong Soh ◽  
Yee Yan Lim
Keyword(s):  
Damage Detection ◽  
Fatigue Damage ◽  
Lead Zirconate Titanate ◽  
Crack Detection ◽  
Tensile Load ◽  
Lead Zirconate ◽  
Electromechanical Impedance ◽  
Zirconate Titanate ◽  
Impedance Technique

In this paper, the feasibility of damage detection and characterization using the EMI technique on high cycles fatigue induced damage is investigated. Cyclic tensile load is applied on a lab sized aluminium beam up to failure. Piezo-impedance transducer in the form of PZT patch (lead zirconate titanate) is surface bonded on the specimen for crack detection. Progressive shift in admittance signatures measured by the PZT patch corresponding to increase of loading cycles reflects effectiveness of the EMI technique in tracing the process of fatigue damage progression.

Measurement and evaluation of soft soil strength development during freeze-thaw process based on electromechanical impedance technique

2020 ◽  
Vol 32 (2) ◽  
pp. 025113
Author(s):  
Chuan Zhang ◽  
Qixiang Yan ◽  
Xianfeng Wang ◽  
Guru Prasad Panda ◽  
Cumaraswamy Vipulanandan ◽  
...  
Keyword(s):  
Soft Soil ◽  
Soil Strength ◽  
Strength Development ◽  
Electromechanical Impedance ◽  
Freeze Thaw ◽  
Impedance Technique ◽  
Measurement And Evaluation

A novel electromechanical impedance–based model for strength development monitoring of cementitious materials

2017 ◽  
Vol 17 (4) ◽  
pp. 902-918 ◽  
Author(s):  
Xubin Lu ◽  
Yee Yan Lim ◽  
Chee Kiong Soh
Keyword(s):  
Lead Zirconate Titanate ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Lead Zirconate ◽  
Cementitious Materials ◽  
Electromechanical Impedance ◽  
Zirconate Titanate ◽  
Dynamic Modulus Of Elasticity ◽  
Impedance Technique ◽  
Host Structure

Strength monitoring of early age concrete improves the efficiency of construction as it provides information on the optimum time for shoring removal and pre-stress transferring. Electromechanical impedance technique has been proven to be a useful tool for strength monitoring of cementitious materials. One of the key limitations of this technique is the lack of physical models, which resulted in strong reliance on statistical analysis tools to quantify the strength of structure being monitored. In this proof-of-concept study, a novel electromechanical impedance–based model with the potential of monitoring the strength of cementitious materials using the concept of Smart Probe is proposed. Instead of directly bonding a lead zirconate titanate patch on the host structure, a lead zirconate titanate was first surface-bonded on a pre-fabricated aluminum beam, which is termed Smart Probe. The Smart Probe was then partially embedded into cementitious materials for strength monitoring. The structural resonant frequencies of the Smart Probe can be identified from the conductance signatures measured from the lead zirconate titanate patch throughout the curing process and serve as strength indicator. By modeling the cementitious material as an elastic foundation supporting the Smart Probe, an analytical model was developed to predict the dynamic modulus of elasticity of cementitious materials based on the resonance frequency of the Smart Probe. Experimental study was carried out on a mortar slab specimen to verify the model and to investigate the performance of the Smart Probe. It was found that the dynamic modulus of elasticity of the host structure could be predicted from the conductance signatures using the proposed model. Compressive strength assessment was achieved by establishing an empirical relation with the dynamic modulus. The proposed electromechanical impedance–based model with Smart Probe is physically parametric in nature and shows high repeatability, which renders its superiority over the conventional statistical method–based electromechanical impedance technique for strength monitoring of cementitious materials.

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

2012 ◽  
Vol 24 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Suresh Bhalla ◽  
Sumedha Moharana
Keyword(s):  
Lead Zirconate Titanate ◽  
Adhesive Layer ◽  
Lead Zirconate ◽  
Shear Lag ◽  
Adhesively Bonded ◽  
Lag Effects ◽  
Electromechanical Impedance ◽  
Zirconate Titanate ◽  
Bond Layer ◽  
Lag Model

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.

Convergent-bceam diffraction studies on lead zirconate titanate Ceramics

1986 ◽  
Vol 44 ◽  
pp. 482-483
Author(s):  
M.L.A. Dass ◽  
T.A. Bielicki ◽  
G. Thomas ◽  
T. Yamamoto ◽  
K. Okazaki
Keyword(s):  
Lead Zirconate Titanate ◽  
Direct Proof ◽  
Lead Zirconate ◽  
Subsolidus Phase ◽  
Pzt Ceramics ◽  
Subsolidus Phase Diagram ◽  
Zirconate Titanate ◽  
Two Phases ◽  
Cbd Method ◽  
Titanate Ceramics

Lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), ceramics are ferroelectrics formed as solid solutions between ferroelectric PbTiO3 and ant iferroelectric PbZrO3. The subsolidus phase diagram is shown in figure 1. PZT transforms between the Ti-rich tetragonal (T) and the Zr-rich rhombohedral (R) phases at a composition which is nearly independent of temperature. This phenomenon is called morphotropism, and the boundary between the two phases is known as the morphotropic phase boundary (MPB). The excellent piezoelectric and dielectric properties occurring at this composition are believed to.be due to the coexistence of T and R phases, which results in easy poling (i.e. orientation of individual grain polarizations in the direction of an applied electric field). However, there is little direct proof of the coexistence of the two phases at the MPB, possibly because of the difficulty of distinguishing between them. In this investigation a CBD method was found which would successfully differentiate between the phases, and this was applied to confirm the coexistence of the two phases.

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