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Coda wave interferometry for monitoring the fracture process of concrete beams under bending test

Knak Magdalena, Wojtczak Erwin, Rucka Magdalena

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 3

art. no. e144118

EN

Early detection of damage is necessary for the safe and reliable use of civil engineering structures made of concrete. Recently, the identification of micro-cracks in concrete has become an area of growing interest, especially when it comes to using wave-based techniques. In this paper, a non-destructive testing approach for the characterization of the fracture process was presented. Experimental tests were performed on concrete beams subjected to mechanical degradation in a 3-point bending test. Ultrasonic waves were registered on a specimen surface by piezoelectric transducers located at several points. Then, the signals were processed taking advantage of wave scattering due to micro-crack disturbances. For early-stage damage detection, coda wave interferometry was used. The novelty of the work concerns the application of the complex decorrelation matrix and the moving reference trace approach for better distinguishment of sensors located in different parts of a crack zone. To enhance coda wave-based damage identification results, optical imaging of crack development was performed by means of digital image correlation measurement. The results obtained showed that the coda wave interferometry technique can be successfully used as a quantitative measure of changes in the structure of concrete. The results also indicated that the course of decorrelation coefficient curves enabled the identification of three stages during degradation, and it depended on the location of acquisition points versus the crack zone.

2

Application of cohesive model in fracture mechanics by WARP3D

Gałkiewicz J.

Journal of KONES

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2008

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Vol. 15, No. 1

69-77

EN

In the paper cohesive model implemented in WARP3D code and an example simulation of crack growth analysis ispresented. Cohesive model is an effective tool for a crack growth analysis and it was a main reason to invent it. For the "dassica" constitutive equation the crack growth simulation in the finite element method (FEM) is not possible without an additional crack growth criterion. In the commercial FEM codes cohesive model is not very popular unfortunately. Usually it can be applied as user implemented elements. However there is a code free of charge with high reliability acknowledged in the literature with cohesive elements in standard library. This program is WARP3D and it is dedicated to numerical simulations of three dimensional fracture mechanics problems. The Dugdale's model, void creation, the cellular model of material, the cohesion-decohesion curve, behaviour of cohesive element, comparison of curve shapes for brittle and ductile fracture, the profile of the cohesive element in WARP3D, specimen geometry, changes of crack shape under increasing load, opening stress distribution in the uncracked ligament are presented in the paper.

3

Effect of aggregate structure on fracture process in concrete using 2D lattice model

Kozicki J., Tejchman J.

Archives of Mechanics

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2007

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Vol. 59, nr 4-5

365-384

EN

The 2d lattice model was used to analyse fracture processes in concrete at the meso-level. Concrete was described as a three-phase material (aggregate, interfacial transition zone and cement matrix). The calculations were carried out for concrete specimens subject mainly to uniaxial extension. The effect of the aggregate density investigated, In addition, a deterministic size effect was studied, The advantages and disadvantages of the model were outlined.

4

Development of fracture processes in Silesian Carboniferous sandstones

Łukaszewski P.

Geological Quarterly

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2003

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Vol. 47, No 1

29-38

EN

The development of fracture processes in selected Carboniferous rocks from the Upper Silesian Coal Basin is described, with particular regard to the behaviour of rock specimens in the post-failure stage. The fracture processes were monitored using the stress-strain relations, coupled with acoustic emission, recorded during loading. Energy accumulation and dissipation phenomena were observed during rock loading. Cracking was recorded on the stress-strain curves as deformation loops, accompanied by significant stress decreases, and as cyclic increases in acoustic emission activity. Observing and analysing stages of high acoustic emission and stress drops enabled determination of three ways ("schemes") in which fracture originated and developed during the post-critical stage. Scheme I is damage and movement of grains and rock cement, scheme II is destruction of single rock grains of particular resistance, and scheme III is a dislocational and slide deformation of the rock medium.

5

Monitoring of optical transmission loss through optical fiber embedded in SiC fiber reinforced aluminum composite during tensile test

Asanuma H., Du H.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 1

7-18

EN

This paper describes a trial of monitoring fracture processes of SiC fiber reinforced aluminum composites with embedded optical fiber. It was embedded in composites reinforced with SiC fiber of different volume fractions by the interphase forming/bonding method using copper insert. These composites were tensile tested with measuring optical transmission loss. The results show that breakage of optical fiber starts at smaller strain than that of SiC fiber. The embedded optical fiber works as an optical path even after severe multiple fractures. Optical transmission loss is dependent on the number of optical fiber breakages. As fracture of SiC fiber enhances that of optical fiber and is reflected on optical transmission loss, fractures of SiC fibers can be detected by monitoring of optical transmission loss. It can also reflect the type of fracture process of the composite, that is, cumulative or non-cumulative.

6

Typy niszczenia kompozytowych butli wysokociśnieniowych

Błażejewski W.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

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1999

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Z. 68, t. 1

37--44

PL

W pracy opisano badania butli ES (epoksydowo-szklanych) ciśnieniem niszczącym. Posłużono się metodą tablicową do: projektowania, analizy nawijania i doboru nawoju dla butli ciśnieniowych. Przygotowano trzy rodzaje butli, o różnej strukturze przeplotów, które były obciążane ciśnieniem wewnętrznym do zniszczenia W czasie obciążania prowadzono pomiar emisji akustycznej (EA) oraz odkształcenia płaszcza nośnego w wybranych punktach. Wyniki badań pozwalają stwierdzić, iż liczba i rozmieszczenie przeplotów mają wpływ na sposób niszczenia płaszcza nośnego butli kompozytowej.

EN

In this paper a GRP vessel (epoxy resin and glass fibre) have been tested until destroying pressure. The table method has been used of: design, winding analysis and choice the wound for a pressure vessel. Three kinds of pressure vessels with a different structure of the interleave have been prepared. Vessels have been loaded by internal pressure. The acoustic emission and strain have been measured in a few selection point. Pressure test proved that the number and distribution of interleaves has a effect upon pressure vessel strength.