scholarly journals Structural Health Monitoring of Timber Using Electromechanical Impedance (EMI) Technique

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Fang Han ◽  
Quanjing Zhang ◽  
Chengfeng Wang ◽  
Guangtao Lu ◽  
Jinwei Jiang
Keyword(s):  
Lead Zirconate Titanate ◽  
Low Cost ◽  
Damage Index ◽  
Stress Waves ◽  
Impedance Method ◽  
Size Factor ◽  
Location Factor ◽  
Electromechanical Impedance ◽  
Damage Location ◽  
Impedance Technique

Nowadays, the electromechanical impedance method has been widely used in the field of structural healthy monitoring, especially for the concrete and steel materials. However, the electromechanical impedance studies on damage detection for timber are limited due to the anisotropic and ununiform biomaterial properties. As a low-cost and environment-friendly building material, timber has been widely used in the construction. Thus, it is beneficial to develop electromechanical impedance technique for structural healthy monitoring of timber so as to ensure the stability and safety of the entire timber structures. In this paper, two damage factors, i.e., the damage location factor and the damage size factor of timber specimens are investigated by using the electromechanical impedance method. The method is implemented by using a patch of Lead Zirconate Titanate transducer both as an actuator to generate stress waves and a sensor to detect stress waves after propagating across the timber specimens. Then, the damage index-root mean square deviation is employed to evaluate the damage severity of the timber specimens. The results indicate that the damage index changes consistently with the change of damage location and size factors, and the proposed method using electromechanical impedance technique can efficiently estimate the damage and its severity.

Non Destructive Evaluation Based on Impedance Method Using Embedded PZT Sensor

2009 ◽  
Vol 79-82 ◽  
pp. 35-38 ◽  
Author(s):  
Dong Yu Xu ◽  
Xin Cheng ◽  
Shi Feng Huang ◽  
Min Hua Jiang
Keyword(s):  
Structural Damage ◽  
Crack Depth ◽  
Impedance Method ◽  
Impedance Spectra ◽  
Electromechanical Impedance ◽  
Non Destructive Evaluation ◽  
Increasing Trend ◽  
Impedance Technique ◽  
Impedance Curve ◽  
Non Destructive

The structural damage of mortar caused by simulated crack was evaluated using embedded PZT sensor combining with dynamic electromechanical impedance technique. The influence of embedded PZT sensors layout on detecting structural damage induced by the simulated cracks was also investigated. The results indicate that with increasing the simulated crack depth, the impedance real part of PZT sensors shift leftwards accompanying with the appearance of new peaks in the spectra. When more simulated cracks occur, the shift of the impedance curve becomes more obvious, and the amounts of new peaks in the impedance spectra also increase. RMSD indices of the structures with PZT sensors embedded in them with different layout can show the structural incipient damage clearly. With increasing more simulated cracks in the mortar structures, RMSD values of the structures with different PZT sensors layout become larger, under the same depth, RMSD indices of the structures with PZT sensor embedded transversely and horizontally in them show the increasing trend.

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.

scholarly journals Damage Detection of Common Timber Connections Using Piezoceramic Transducers and Active Sensing

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2486 ◽  
Author(s):  
Fang Han ◽  
Jinwei Jiang ◽  
Kai Xu ◽  
Ning Wang
Keyword(s):  
Damage Detection ◽  
Lead Zirconate Titanate ◽  
Failure Modes ◽  
Low Cost ◽  
Energy Levels ◽  
Stress Waves ◽  
Active Sensing ◽  
Timber Structures ◽  
Signal Energy ◽  
Timber Connections

Timber structures have been widely used due to their low-cost and environmental-friendly properties. It is essential to monitor connection damage to ensure the stability and safety of entire timber structures since timber connection damage may induce catastrophic incidents if not detected in a timely manner. However, the current investigations on timber connections focus on mechanical properties and failure modes, and the damage detection of timber connection receives rare attention. Therefore, in this paper, we investigate the damage detection of four common timber connections (i.e., the screw connection, the bolt connection, the decussation connection, and the tooth plate connection) by using the active sensing method. The active sensing method was implemented by using a pair of lead zirconate titanate (PZT) transducers: one PZT patch is used as an actuator to generate stress waves, and the other works as a sensor to detect stress waves after propagating across the timber connection. Based on the wavelet packet energy analysis, the signal energy levels of received stress waves under different damage extent are quantified. Finally, by comparing the signal energy between the intact status and the damage status of the timber connection, we find that the energy attenuates with increasing severity of the connection damage. The experimental results demonstrate that the active sensing method can realize real-time monitoring of timber connection damage, which can guide further investigations.

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.

scholarly journals Electromechanical Impedance Based Self-Diagnosis of Piezoelectric Smart Structure Using Principal Component Analysis and LibSVM

2021 ◽  
Author(s):  
Xie Jiang ◽  
Xin Zhang ◽  
Tao Tang ◽  
Yuxiang Zhang
Keyword(s):  
Principal Component Analysis ◽  
Lead Zirconate Titanate ◽  
Comprehensive Evaluation ◽  
Principal Component ◽  
Component Analysis ◽  
Smart Structure ◽  
Identification Accuracy ◽  
Impedance Method ◽  
Sensor Faults ◽  
Electromechanical Impedance

Abstract The long-term use of a piezoelectric smart structure make it difficult to judge whether the structure or piezoelectric lead zirconate titanate (PZT) is damaged when the signal changes. If the sensor fault occurs, the cases and degrees of the fault are unknown based on the electromechanical impedance method. Therefore, after the principal component analysis (PCA) of six characteristic indexes, a two-component solution which could explain 99.2% of the variance in the original indexes was obtained to judge whether the damage comes from the PZT. Then LibSVM was used to make an effective identification of four sensor faults (pseudo soldering, debonding, wear, and breakage) and their three damage degrees. The result shows that the identification accuracy of damaged PZT reached 97.5%. The absolute scores of PCA comprehensive evaluation for structural damages are less than 0.5 while for sensor faults are greater than 0.6. By comparing the scores of the samples under unknown conditions with the set threshold, whether the sensor faults occur is effectively judged; the intact and 12 possible damage states of PZT can be all classified correctly with the model trained by LibSVM. It is feasible to use LibSVM to classify the cases and degrees of sensor faults.

Experimental analysis of the feasibility of deep slide monitoring with low-cost piezoelectric diaphragms-based EMI technique

2021 ◽  
pp. 1045389X2110386
Author(s):  
Jianchao Wu ◽  
Yunsheng Yao ◽  
Gang Yang ◽  
Min Yu ◽  
Weijie Li
Keyword(s):  
Lead Zirconate Titanate ◽  
Slip Surface ◽  
Low Cost ◽  
Front Surface ◽  
Lead Zirconate ◽  
Slope Instability ◽  
Back Surface ◽  
Soil Slope ◽  
Electromechanical Impedance ◽  
Time Deformation

Slope instability, especially the soil slope instability, is a common occurrence in mountainous areas. It poses a huge threat to people’s lives and properties under the slope body. Effective slope monitoring techniques can provide detailed information and precursor about the real-time deformation, which is of great importance to provide early warning to the public. In this paper, a novel electromechanical impedance (EMI)-based slope deep slide monitoring bar (DSMB) was proposed. The main purpose was to investigate the application of the EMI technique for deep slide detection. In this study, a small soil slope specimen with a DSMB embedded inside it was fabricated in laboratory. To verify the practicality of the low-cost piezoelectric diaphragms (commonly known as buzzers), four conventional lead zirconate titanate (PZT) patches and four buzzers were bonded onto the front surface and back surface of the bar at specific positions, respectively. The slope specimen was then subjected to a horizontal thrust to initiate an interlayer slide along the slip surface. The whole process was monitored with a precision impedance analyzer by measuring the admittance of these transducers at specific sliding displacement. In order to reduce the error and increase the reliability, the experiment was repeated three times under the same conditions. It was concluded that the conventional PZT patches and buzzers have similar sensitivities to interlayer slide damage. The results indicate that both the severity and sliding location could be identified via the two metrics including root mean square deviation (RMSD) and correlation coefficient deviation (CCD). The experimental results verify the feasibility and practicality of using novel and low-cost piezoelectric diaphragm-based EMI technique to detect the deep slide in soil slope.

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.

The Study on Piezoelectric Impedance Technique Used in Loading Damage Identification

2010 ◽  
Vol 139-141 ◽  
pp. 2612-2615 ◽  
Author(s):  
Jun Zhang ◽  
Zi Jian Qin
Keyword(s):  
Material Property ◽  
Health Monitoring ◽  
Damage Identification ◽  
Damage Index ◽  
Impedance Method ◽  
Frequency Range ◽  
Impedance Analyzer ◽  
Testing Frequency ◽  
Impedance Technique ◽  
Piezoelectric Impedance

The superiority and feasibility of piezoelectric impedance method used in damage detecting was expounded, and the research status of the technical was summarized. Then, the rationale of the basic theory of the technique used in damage identification and health monitoring was analyzed here. The experiment of the damage change of loaded beam was researched. The experiment of the beam which was loaded by a material property, the value of the beam was got by an impedance analyzer, while the beam with different pull force. The research indicates that while the testing frequency range should elect as 300k-800k, with the increasing of loading force, the value of real part impedance is descending, the damage index of beam is increasing. PZT can sensitively catch the influence brought by stress varying

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.

Monitoring of pin connection loosening using eletromechanical impedance: Numerical simulation with experimental verification

2018 ◽  
Vol 29 (9) ◽  
pp. 1964-1973 ◽  
Author(s):  
Shuli Fan ◽  
Weijie Li ◽  
Qingzhao Kong ◽  
Qian Feng ◽  
Gangbing Song
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Lead Zirconate Titanate ◽  
Numerical Study ◽  
Element Model ◽  
Impedance Method ◽  
Experimental Investigations ◽  
Detection Accuracy ◽  
Practical Applications ◽  
Electromechanical Impedance

Pin connection, as an important structural connection mechanism, is widely used in various structures, especially spatial structures. In this article, numerical and experimental investigations are performed for monitoring the loosening of pin-connected structures using the electromechanical impedance technique. For this purpose, a finite element model for a pin-connected structure considering the contact interfaces between the pin and the support base is proposed to study the effect of pin connection loosening on the electromechanical impedance signatures. A multi-physics analysis is conducted to simulate the electromechanical behavior of lead zirconate titanate transducers bonded on the pin head and the steel base. The relationship between the force applied on the pin connection and the variation in electromechanical impedance signatures is established. Experiments are carried out to verify the accuracy of the proposed finite element model. The results show that the changes in the electromechanical impedance signatures consist of frequency shifts and peak splitting. The contact condition of the pin connection can be assessed by observing the changes in the electromechanical impedance signatures. The location of the piezoelectric patch has significant effect on the sensitivity of the electromechanical impedance signatures. The numerical study in this research helps to optimize the design of sensor placement and improve the detection accuracy of the electromechanical impedance method in practical applications of detecting the loosening of pin-connected structures.

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