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.

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 Modeling of Bimodular Bone Specimen under Four-Point Bending Fatigue Loading

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 474
Author(s):  
Yufan Yan ◽  
Xianjia Meng ◽  
Chuanyong Qu
Keyword(s):  
Compressive Strain ◽  
Fatigue Loading ◽  
Degradation Process ◽  
Neutral Axis ◽  
Image Correlation ◽  
Bending Test ◽  
Correlation Technique ◽  
Fatigue Process ◽  
Four Point Bending ◽  
Bone Properties

The fatigue damage behavior of bone has attracted significant attention in both the mechanical and orthopedic fields. However, due to the complex and hierarchical structure of bone, describing the damage process quantitively or qualitatively is still a significant challenge for researchers in this area. In this study, a nonlinear bi-modulus gradient model was proposed to quantify the neutral axis skewing under fatigue load in a four-point bending test. The digital image correlation technique was used to analyze the tensile and compressive strains during the fatigue process. The results showed that the compressive strain demonstrated an obvious two-stage ascending behavior, whereas the tensile strain revealed a slow upward progression during the fatigue process. Subsequently, a theoretical model was proposed to describe the degradation process of the elastic modulus and the movement of the neutral axis. The changes in the bone properties were determined using the FEM method based on the newly developed model. The results obtained from two different methods exhibited a good degree of consistency. The results obtained in this study are of help in terms of effectively exploring the damage evolution of the bone materials.

scholarly journals Nondestructive Monitoring Techniques for Crack Detection and Localization in RC Elements

2020 ◽  
Vol 10 (9) ◽  
pp. 3248 ◽  
Author(s):  
Marco Domaneschi ◽  
Gianni Niccolini ◽  
Giuseppe Lacidogna ◽  
Gian Paolo Cimellaro
Keyword(s):  
Crack Detection ◽  
Visual Observation ◽  
Image Correlation ◽  
Bending Test ◽  
Nondestructive Monitoring ◽  
Integrated Monitoring ◽  
Four Point Bending ◽  
Initiation And Propagation ◽  
Detection And Localization ◽  
Good Agreement

This paper presents the structural and damage assessment of a reinforced concrete (RC) beam subjected to a four-point bending test until yielding of reinforcing steel. The deterioration progress was monitored using different nondestructive testing (NDT) techniques. The strain was measured by distributed fiber optic sensors (FOSs), embedded prior to concrete pouring. The initiation and propagation of cracks were monitored by acoustic emission (AE) sensors attached to the surface of the material. The recorded AE activity results in good agreement with FOS strain measurements. The results of the integrated monitoring system are confirmed by visual observation of the actual crack pattern. At different loading steps, digital image correlation (DIC) analysis was also conducted.

scholarly journals Investigation of Interlaminar Defects and their Influence on Interlaminar Strength

1996 ◽  
Vol 5 (4) ◽  
pp. 096369359600500
Author(s):  
J Ziao ◽  
J Tao
Keyword(s):  
Tensile Strength ◽  
Large Scale ◽  
Peel Strength ◽  
Test Method ◽  
Bending Test ◽  
Four Point Bending ◽  
Transverse Tensile ◽  
Interlaminar Shear ◽  
Transverse Tensile Strength ◽  
Set Up

In this paper, we directed our attention to the interlaminar defects and their influence on the interlaminar strengths. With the aid of a S-570 scanning electron microscope, the morphology and distribution of interlaminar defects were inspected and documented. According to their shape, size and cause of formation, the defects were classified into five types: flakiness void, irregular shaped debond, local imperfectly cured resin, debond in two multi-directional plies, and inhomogeneous fibers and the large scale debond by these fibers. The cause of defects formation was discussed by analyzing the manufacturing process of composites. The influence of defects on the interlaminar strength and its mechanism was analyzed experimentally and theoretically. The results indicate that these defects, with different effects, decrease the interlaminar strength because they form interlaminar cracks, and the interlaminar shear strength is less affected than interlaminar tensile strength, which is measured according to GB4944 test method. To comprehend defects distribution effect, a four-point-bending test method was introduced to measure the interlaminar peel strength, and a discussion was made on the correlation between the interlaminar tensile strength, interlaminar peel strength and in-plane transverse tensile strength. Finally the concept of interlaminar defect coefficient, which can be used to characterize the defects, was set up and the formula to calculate it was proposed.

scholarly journals Simulations of the large-scale four point bending test using Rousselier model

2017 ◽  
Vol 178 ◽  
pp. 497-511 ◽  
Author(s):  
Sutham Arun ◽  
Andrew H. Sherry ◽  
Mike C. Smith ◽  
Mohammad Sheikh
Keyword(s):  
Large Scale ◽  
Bending Test ◽  
Four Point Bending ◽  
Four Point Bending Test

scholarly journals Hanging glacier monitoring with icequake repeaters and seismic coda wave interferometry: a case study of the Eiger hanging glacier

2021 ◽  
Author(s):  
Małgorzata Chmiel ◽  
Fabian Walter ◽  
Lukas Preiswerk ◽  
Martin Funk ◽  
Lorenz Meier ◽  
...  
Keyword(s):  
Large Scale ◽  
Wave Attenuation ◽  
Seismic Velocity ◽  
Swiss Alps ◽  
Coda Wave ◽  
Diurnal Cycles ◽  
Ice Surface ◽  
Novel Approach ◽  
Seismic Coda ◽  
Coda Wave Interferometry

Abstract. Driven by the force of gravity, hanging glacier instabilities can lead to catastrophic rupture events. Reliable forecasting remains a challenge as englacial damage leading to large-scale failure is masked from modern sensing technology focusing on the ice surface. The Eiger hanging glacier, located in the Swiss Alps, was intensely monitored between April and August 2016 before a moderate 15,000 m3 break-off event from the ice cliff. Among different instruments, such as an automatic camera and interferometric radar, four 3-component seismometers were installed on the glacier. A single seismometer operated throughout the whole monitoring period. It recorded over 200,000 repeating icequakes showing strong englacial seismic coda waves. We propose a novel approach for hanging glacier monitoring by combining repeating icequake analysis, coda wave interferometry, and attenuation measurements. Our results show a seasonal 0.1 % decrease in relative englacial seismic velocity dv/v and an increase in coda wave attenuation Qc−1 (Qc decreases from ~50 to ~30). Comparison of dv/v and Qc with air temperature suggests that these changes are driven by a seasonal increase in the glacier’s ice and firn pack temperature that might affect the top 20 m of the glacier. Diurnal cycles of Qc−1, repeating icequake activity, and the velocity of the glacier front shift from cosinusoidal to sinusoidal variations under the presence of meltwater. The proposed approach extends the monitoring of the hanging glacier beyond the ice surface and allows for a better understanding of the glacier’s response to time-dependent external forcing, which is an important step towards improved break-off forecasting systems.

scholarly journals Distributed Fiber Optics Sensing and Coda Wave Interferometry Techniques for Damage Monitoring in Concrete Structures

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 356 ◽  
Author(s):  
Antoine Bassil ◽  
Xin Wang ◽  
Xavier Chapeleau ◽  
Ernst Niederleithinger ◽  
Odile Abraham ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Fiber Optics ◽  
Asset Management ◽  
Crack Opening ◽  
Concrete Structures ◽  
Reinforced Concrete Beam ◽  
Coda Wave ◽  
Reinforced Concrete Structures ◽  
Detection And Localization ◽  
Coda Wave Interferometry

The assessment of Coda Wave Interferometry (CWI) and Distributed Fiber Optics Sensing (DFOS) techniques for the detection of damages in a laboratory size reinforced concrete beam is presented in this paper. The sensitivity of these two novel techniques to micro cracks is discussed and compared to standard traditional sensors. Moreover, the capacity of a DFOS technique to localize cracks and quantify crack openings is also assessed. The results show that the implementation of CWI and DFOS techniques allow the detection of early subtle changes in reinforced concrete structures until crack formation. With their ability to quantify the crack opening, following early detection and localization, DFOS techniques can achieve more effective monitoring of reinforced concrete structures. Contrary to discrete sensors, CWI and DFOS techniques cover larger areas and thus provide more efficient infrastructures asset management and maintenance operations throughout the lifetime of the structure.

Modeling of Deformation and Fracture of Concrete Structures with FRP Reinforcement

2015 ◽  
Vol 752-753 ◽  
pp. 685-688
Author(s):  
Andrey Benin ◽  
S.G. Semenov ◽  
Artem S. Semenov
Keyword(s):  
Image Correlation ◽  
Bending Test ◽  
Four Point Bending ◽  
Reinforced Plastic ◽  
Deformation And Fracture ◽  
Different Types ◽  
Loading Case ◽  
Frp Reinforcement ◽  
Four Point Bending Test ◽  
Frp Bars

Carrying capacity and fracture modes of concrete beams reinforced by different types of fiber reinforced plastic (FRP) bars are analyzed experimentally and numerically. The four-point-bending test is used as a typical loading case for this purpose. Synchronous registration of loading level, displacements and strains is performed by using InstronTM servohydraulic machine, LVDT sensors, strain gauges and digital image correlation Vic3DTM system. The experimental data and results of finite element simulations are compared and discussed.

Four Points Bending Test on an EPR Type DMW Pipe Containing a Through-Wall Defect: Experimental and Numerical Analysis From Small Specimens Until Pipe Scale

2014 ◽  
Author(s):  
M. Bourgeois ◽  
S. Chapuliot ◽  
S. Marie ◽  
O. Ancelet ◽  
Y. Kayser
Keyword(s):  
Numerical Analysis ◽  
Ferritic Steel ◽  
Large Scale ◽  
Bending Test ◽  
Small Scale ◽  
Narrow Gap ◽  
Fracture Test ◽  
Ductile Tearing ◽  
Four Point Bending ◽  
Four Point Bending Test

Within the framework of European project STYLE [1], a fracture test on a pipe containing a through wall crack in a narrow gap Inconel Dissimilar Metals weld (welds named hereafter DMW) has been performed. The work is focusing on the Inconel - ferritic steel interface which is the weakest area of such welded pipes in front of ductile tearing. The study temperature is 300°C, which covers typical temperatures in components like hot pipes in the primary coolant system of pressurized water reactors. The four point bending test was carried out by the French Atomic Energy Commission and Alternative Energies (CEA), in order to study the mechanical properties and integrity of component such as the DMW pipes provided and designed by AREVA France. The observations made post-mortem showed a small 2.5 mm ductile tearing at the interface of Inconel and ferritic steel, and after this point, a large crack that has deviated from the interface to propagate in the Inconel and then in the stainless steel. The DMW Mock-up is presented with previous results concerning the mechanical characterizations of his constitutive materials. The second part of this paper is devoted to the four point bending test at 300°C: procedure, instrumentation and interpretation of large-scale test in terms of initiation and propagation of cracks. A comparison is made with tests performed at a smaller scale on multi-material CT specimens. The third part deals with first numerical analysis of fracture test. The results are interpreted on a small scale using finite element analysis to obtain the parameters of damage models that are needed for global approach. Finally, numerical approaches is presented and applied to simulate the fracture of the large-scale pipe. The aim of this paper is to propose and discuss the validity of new assessment methods of ductile propagation in a large scale pipe containing a through wall crack in a narrow gap dissimilar metal weld.

Sign in / Sign up

Export Citation Format

Share Document