Monitoring concrete by means of embedded sensors and electromechanical impedance technique

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.

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Fatigue damage diagnosis and prognosis using electromechanical impedance technique

Structural Health Monitoring (SHM) in Aerospace Structures ◽

10.1016/b978-0-08-100148-6.00015-9 ◽

2016 ◽

pp. 429-446 ◽

Cited By ~ 4

Author(s):

C.-K. Soh ◽

Y.Y. Lim

Keyword(s):

Fatigue Damage ◽

Damage Diagnosis ◽

Electromechanical Impedance ◽

Diagnosis And Prognosis ◽

Impedance Technique

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Method for removing temperature effect in impedance-based structural health monitoring systems using polynomial regression

Structural Health Monitoring ◽

10.1177/1475921720917126 ◽

2020 ◽

pp. 147592172091712 ◽

Cited By ~ 1

Author(s):

Bárbara M Gianesini ◽

Nicolás E Cortez ◽

Rothschild A Antunes ◽

Jozue Vieira Filho

Keyword(s):

Structural Health Monitoring ◽

Damage Detection ◽

Temperature Effect ◽

Health Monitoring ◽

Monitoring Systems ◽

Electromechanical Impedance ◽

Structural Health ◽

Detection Systems ◽

Impedance Technique ◽

Health Monitoring Systems

Structural health monitoring systems are employed to evaluate the state of structures to detect damage, bringing economical and safety benefits. The electromechanical impedance technique is a promising damage detection tool since it evaluates structural integrity by only measuring the electrical impedance of piezoelectric transducers bonded to structures. However, in real-world applications, impedance-based damage detection systems exhibit strong temperature dependence; therefore, variations associated with temperature changes may be confused as damage. In this article, the temperature effect on the electrical impedance of piezoelectric ceramics attached to structures is analyzed. Besides, a new methodology to compensate for the temperature effect in the electromechanical impedance technique is proposed. The method is very general since it can be applied to nonlinear (polynomial) temperature and/or frequency dependences observed on the horizontal and vertical shifts of the impedance signatures. A computer algorithm that performs the compensation was developed, which can be easily incorporated into real-time damage detection systems. This compensation technique is applied successfully to two aluminum beams and one steel pipe, minimizing the effect of temperature variations on damage detection structural health monitoring systems in the temperature range from −40°C to 80°C and the frequency range from 10 to 90 kHz.

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Modelling of the electromechanical impedance technique for prediction of elastic modulus of structural adhesives

Structural Health Monitoring ◽

10.1177/1475921720916924 ◽

2020 ◽

pp. 147592172091692

Author(s):

Zi Sheng Tang ◽

Yee Yan Lim ◽

Scott T Smith ◽

Ricardo Vasquez Padilla

Keyword(s):

Tensile Strength ◽

Elastic Modulus ◽

Model Updating ◽

Dynamic Elastic Modulus ◽

Curing Process ◽

Electromechanical Impedance ◽

Structural Adhesives ◽

Reinforced Polymer ◽

Impedance Technique ◽

Fibre Reinforced Polymer

In order to strengthen and repair existing concrete structural elements, fibre-reinforced polymer composites are often externally bonded using structural adhesives. It is thus desirable to monitor the in situ performance of the sandwiched adhesive layer in such fibre-reinforced polymer–strengthened systems via its stiffness and strength gain throughout the curing process. The electromechanical impedance technique, which relies upon the utilisation of piezoelectric sensors, offers this capability. Although the technique has been verified experimentally in the laboratory, no known electromechanical impedance–based modelling study has been reported. This study, therefore, proposes the first electromechanical impedance–based finite element and analytical models to monitor the curing of structural adhesives. The dynamic elastic modulus of structural adhesives during curing can be determined from the developed models via a model updating process. Semi-empirical relationships were then developed to determine the tensile strength of structural adhesives from the resonance frequency obtained from the electromechanical impedance technique. This was made possible by correlation between static tensile tests on structural adhesives and the dynamic elastic modulus. These electromechanical impedance–based models were found to perform equally well when compared to the previously developed wave propagation–based models. This study shows the robustness of the electromechanical impedance technique for non-destructively predicting the dynamic elastic modulus and tensile strength of adhesives throughout the curing process.

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