scholarly journals Comparison of Experimentally Determined Two-Dimensional Strain Fields and Mapped Ultrasonic Data Processed by Coda Wave Interferometry

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 4023
Author(s):  
Felix Clauß ◽  
Niklas Epple ◽  
Mark Alexander Ahrens ◽  
Ernst Niederleithinger ◽  
Peter Mark
Keyword(s):  
Test Specimen ◽  
Crack Depth ◽  
Mechanical Strain ◽  
Ultrasonic Waves ◽  
Bending Test ◽  
Coda Wave ◽  
Strain Fields ◽  
Zero Crossing ◽  
Ultrasonic Signals ◽  
Coda Wave Interferometry

Due to the high sensitivity of coda waves to the smallest structural alterations such as strain, humidity or temperature changes, ultrasonic waves are a valid means to examine entire structures employing networks of ultrasonic transducers. In order to substantiate this ex ante assessment, the viability of measuring ultrasonic waves as a valid point of reference and inference for structural changes is to be further scrutinized in this work. In order to investigate the influence of mechanical strain on ultrasonic signals, a four-point bending test was carried out on a reinforced concrete beam at Ruhr University Bochum. Thus, measurements collected from a network of selected transducer pairings arranged across the central, shear-free segment of the test specimen, were correlated to their respective strain fields. Detected ultrasonic signals were evaluated employing Coda Wave Interferometry. Such analysis comprised the initial non-cracked state as well as later stages with incremental crack depth and quantity. It was to ascertain that the test specimen can in fact be qualitatively compartmentalized into areas of compression and tension identified via Relative Velocity Changes presented in Attribute Maps. However, since results did not entail a zero crossing, i.e., neither positive nor negative values were to be calculated, only relative changes in this work displayed staggered over the height of the object under test, are discussed. Under the given methodological premises, additional information is currently required to make quantitative assertions regarding this correlation of ultrasonic and strain results. This holds true for the comparability of the ultrasonic and strain results for both non-cracked and even the cracked state.

scholarly journals Damage Detection at a Reinforced Concrete Specimen with Coda Wave Interferometry

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5013
Author(s):  
Stefan Grabke ◽  
Felix Clauß ◽  
Kai-Uwe Bletzinger ◽  
Mark Alexander Ahrens ◽  
Peter Mark ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Reinforced Concrete ◽  
Damage Detection ◽  
Concrete Specimen ◽  
Bending Test ◽  
Coda Wave ◽  
Multiple Cracks ◽  
Ultrasonic Signals ◽  
Significant Difference ◽  
Coda Wave Interferometry

Reinforced concrete is a widely used construction material in the building industry. With the increasing age of structures and higher loads there is an immense demand for structural health monitoring of built infrastructure. Coda wave interferometry is a possible candidate for damage detection in concrete whose applicability is demonstrated in this study. The technology is based on a correlation evaluation of two ultrasonic signals. In this study, two ways of processing the correlation data for damage detection are compared. The coda wave measurement data are obtained from a four-point bending test at a reinforced concrete specimen that is also instrumented with fibre optic strain measurements. The used ultrasonic signals have a central frequency of 60 kHz which is a significant difference to previous studies. The experiment shows that the coda wave interferometry has a high sensitivity for developing cracks and by solving an inverse problem even multiple cracks can be distinguished. A further specialty of this study is the use of finite elements for solving a diffusion problem which is needed to state the previously mentioned inverse problem for damage localization.

scholarly journals Estimation of Stresses in Concrete by Using Coda Wave Interferometry to Establish an Acoustoelastic Modulus Database

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 4031 ◽  
Author(s):  
Hanyu Zhan ◽  
Hanwan Jiang ◽  
Chenxu Zhuang ◽  
Jinquan Zhang ◽  
Ruinian Jiang
Keyword(s):  
Experimental Study ◽  
Coda Wave ◽  
Structural Stress ◽  
Stress Monitoring ◽  
Ultrasonic Signals ◽  
Uniaxial Load ◽  
Laboratory Conditions ◽  
Before And After ◽  
High Degree ◽  
Coda Wave Interferometry

This article presents an experimental study of estimating stresses in concrete by applications of coda wave interferometry to establish an acoustoelastic modulus database. Under well-controlled laboratory conditions, uniaxial load cycles were performed on three groups of 15 × 15 × 35-cm concrete prisms, with ultrasonic signals being collected continuously. Then, the coda wave interferometry technique, together with acoustoelastic and Kaiser theories, are utilized to analyze the stress-velocity relations for the distinct ranges before and after historical maximum loads, forming an acoustoelastic modulus database. When applied to different concrete samples, their stresses are estimated with a high degree of accuracy. This study could be used to promote the development of novel nondestructive techniques that aid in structural stress monitoring.

scholarly journals Direct Modeling of the Mechanical Strain Influence on Coda Wave Interferometry

2018 ◽  
Vol 123 (4) ◽  
pp. 3160-3177 ◽  
Author(s):  
J. Azzola ◽  
J. Schmittbuhl ◽  
D. Zigone ◽  
V. Magnenet ◽  
F. Masson
Keyword(s):  
Mechanical Strain ◽  
Coda Wave ◽  
Direct Modeling ◽  
Coda Wave Interferometry

scholarly journals Detection of Multiple Cracks in Four-Point Bending Tests Using the Coda Wave Interferometry Method

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1986 ◽  
Author(s):  
Xin Wang ◽  
Joyraj Chakraborty ◽  
Antoine Bassil ◽  
Ernst Niederleithinger
Keyword(s):  
Fiber Optics ◽  
Large Scale ◽  
Early Stage ◽  
Image Correlation ◽  
Bending Test ◽  
Coda Wave ◽  
Multiple Cracks ◽  
Rc Structures ◽  
Four Point Bending ◽  
Coda Wave Interferometry

The enlargement of the cracks outside the permitted dimension is one of the main causes for the reduction of service life of Reinforced Concrete (RC) structures. Cracks can develop due to many causes such as dynamic or static load. When tensile stress exceeds the tensile strength of RC, cracks appear. Traditional techniques have limitations in early stage damage detection and localisation, especially on large-scale structures. The ultrasonic Coda Wave Interferometry (CWI) method using diffuse waves is one of the most promising methods to detect subtle changes in heterogeneous materials, such as concrete. In this paper, the assessment of the CWI method applied for multiple cracks opening detection on two specimens based on four-point bending test is presented. Both beams were monitored using a limited number of embedded Ultrasonic (US) transducers as well as other transducers and techniques (e.g., Digital Image Correlation (DIC), LVDT sensors, strain gauges, and Fiber Optics Sensor (FOS)). Results show that strain change and crack formation are successfully and efficiently detected by CWI method even earlier than by the other techniques. The CWI technique using embedded US transducers is undoubtedly a feasible, efficient, and promising method for long-term monitoring on real infrastructure.

Monitoring medium changes in an intraplate setting with coda wave interferometry

2013 ◽  
Author(s):  
Virginie D'Hour ◽  
Aderson F. do Nascimento ◽  
Heleno C. de Lima Neto ◽  
Joaquim M. Ferreira ◽  
Martin Schimmel
Keyword(s):  
Coda Wave ◽  
Coda Wave Interferometry

scholarly journals Sensitivity of Ultrasonic Coda Wave Interferometry to Material Damage—Observations from a Virtual Concrete Lab

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4033
Author(s):  
Claudia Finger ◽  
Leslie Saydak ◽  
Giao Vu ◽  
Jithender J. Timothy ◽  
Günther Meschke ◽  
...  
Keyword(s):  
Elastic Moduli ◽  
Concrete Specimen ◽  
Coda Wave ◽  
Velocity Change ◽  
Damage Scenarios ◽  
Different Types ◽  
Source Signal ◽  
The Impact ◽  
Structural Scale ◽  
Coda Wave Interferometry

Ultrasonic measurements are used in civil engineering for structural health monitoring of concrete infrastructures. The late portion of the ultrasonic wavefield, the coda, is sensitive to small changes in the elastic moduli of the material. Coda Wave Interferometry (CWI) correlates these small changes in the coda with the wavefield recorded in intact, or unperturbed, concrete specimen to reveal the amount of velocity change that occurred. CWI has the potential to detect localized damages and global velocity reductions alike. In this study, the sensitivity of CWI to different types of concrete mesostructures and their damage levels is investigated numerically. Realistic numerical concrete models of concrete specimen are generated, and damage evolution is simulated using the discrete element method. In the virtual concrete lab, the simulated ultrasonic wavefield is propagated from one transducer using a realistic source signal and recorded at a second transducer. Different damage scenarios reveal a different slope in the decorrelation of waveforms with the observed reduction in velocities in the material. Finally, the impact and possible generalizations of the findings are discussed, and recommendations are given for a potential application of CWI in concrete at structural scale.

Coda Waves for Health Monitoring of Composites Under Low-Velocity Impact

2021 ◽  
Author(s):  
Subal Sharma ◽  
Vinay Dayal
Keyword(s):  
Ultrasonic Waves ◽  
Coda Waves ◽  
Low Velocity Impact ◽  
Coda Wave ◽  
Low Velocity ◽  
Fibrous Composite Material ◽  
Velocity Impact ◽  
Isotropic Composite ◽  
The Impact ◽  
Impact Damages

Abstract Coda waves have been shown to be sensitive to lab-controlled defects such as very small holes in fibrous composite material. In the real world, damages are subtler and more irregular. The main objective of this work is to investigate coda wave capability to detect low-velocity impact damages. The emphasis is to detect the presence of barely visible impact damages using ultrasonic waves. Detection of incipient damage state is important as it will grow over the life of the structure. Differential features, previously used in similar work, have been utilized to detect realistic impact damages on carbon fiber composites. Quasi-isotropic composite laminates were subjected to low-velocity impact energy ranging from 2J to 4.5J. Two differential features reported could be used detect the presence of damage. It is also observed that ply orientation can be a deterministic factor for indicating damages. The size and shape of the impact damage has been characterized using ultrasonic C-scans. Results indicate that coda waves can be used for the detection of damage due to low-velocity impact.

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