Microcrack modelling of Brazilian tensile tests with the boundary element method

Lanaro, Flavio; Sato, Toshinori; Stephansson, Ove

doi:10.1016/j.ijrmms.2008.11.007

Cited by 66 publications

(28 citation statements)

References 22 publications

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“…Recently, theoretical and numerical results indicate that friction between the platen and the specimen can affect the stress distribution in the immediate vicinity of the contact rim. But the stress field at the disc's centre is totally insensitive to the exact distribution of radial pressure and also to the presence or absence of friction (Lavrov and Vervoort 2002;Lanaro et al 2009;Markides et al 2010Markides et al , 2011Markides and Kourkoulis 2013). Thus, the specimens were placed directly between the loading platens and friction was ignored.…”

Section: Test Apparatus and Schemementioning

confidence: 99%

“…Previous researches (Lanaro et al 2009;Markides et al 2010Markides et al , 2011Markides and Kourkoulis 2013;Zhou et al 2012) on static and dynamic BD tests have all shown that the BD test can give accurate strength results once the following conditions are met: (1) the stress/ force equilibrium should be satisfied before the specimen fails and (2) the crack should initiate from the disc centre and propagate along the loading direction diametrically. In dynamic BD tests, the stress field of the specimen under dynamic loads is similar to that of the specimen under static loads, when the stress/force balance has been achieved on both ends of the BD specimen.…”

Section: Tensile Strength Of Rock Under Coupled Loadsmentioning

confidence: 99%

“…Then, the local friction affects the stress distribution of the specimen and leads to premature failure at the contact zone of the bar/specimen. The presence of the foregoing cracks far from the disc centre affects the stress distribution and deformability of the specimen, so that a crushed strap forms, rather than a central split (Lanaro et al 2009;Markides et al 2010;Markides and Kourkoulis 2013). As the crack does not initiate from the specimen centre, the results of this type of failure should be avoided for strength analysis.…”

Section: Failure Pattern Of Specimensmentioning

confidence: 99%

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Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

et al. 2013

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Rocks in underground projects at great depth, which are under high static stresses, may be subjected to dynamic disturbance at the same time. In our previous work (Li et al. Int J Rock Mech Min Sci 45(5):739-748, 2008), the dynamic compressive behaviour of pre-stressed rocks was investigated using coupled-load equipment. The current work is devoted to the investigation of the dynamic tensile behaviour of granite rocks under coupled loads using the Brazilian disc (BD) method with the aid of a high-speed camera. Through wave analyses, stress measurements and crack photography, the fundamental problems of BD tests, such as stress equilibrium and crack initiation, were investigated by the consideration of different loading stresses with abruptly or slowly rising stress waves. The specially shaped striker method was used for the coupled-load test; this generates a slowly rising stress wave, which allows gradual stress accumulation in the specimen, whilst maintaining the load at both ends of the specimen in an equilibrium state. The test results showed that the tensile strength of the granite under coupled loads decreases with increases in the static pre-stresses, which might lead to modifications of the blasting design or support design in deep underground projects. Furthermore, the failure patterns of specimens under coupled loads have been investigated. Travelling time of the stress wave (s) r t Dynamic tensile strength of the specimen (MPa) r c Dynamic compressive strength of the specimen (MPa) r 0 Amplitude of the assumed stress pulse (MPa) P Static force applied on the specimen (N) P c Equivalent force applied on the specimen under coupled loads (N)

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Section: Test Apparatus and Schemementioning

confidence: 99%

Section: Tensile Strength Of Rock Under Coupled Loadsmentioning

confidence: 99%

Section: Failure Pattern Of Specimensmentioning

confidence: 99%

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Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

et al. 2013

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“…by Hoek and Martin (2014) based on the conclusions stated in the paper by Fairhurst (1964). The simple processing of samples enables a quick experimental check-up of the theoretical presumptions and their numerical analyses (Hiramatsu and Oka, 1966;Barla and Innaurato 1973;Sundaram and Corrales 1980;Lavrovetal, 2002;Yue et al, 2003;Yu et al, 2006;Lanaro et al, 2009;Yu et al, 2009;Markides and Kourkoulis, 2012;Li and Wong, 2013;). However, the sensitivity to the testing conditions requires a careful explanation of the material behaviour during the testing and finding the solutions for removal of the flaws (Hobbs, 1964(Hobbs, , 1965(Hobbs, , 1967.…”

Section: Discussionmentioning

confidence: 99%

Current Cognition of Rock Tensile Strength Testing by Brazilian Test

Briševac

Kujundžić

Čajić³

2015

MGPB

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Tensile strength of intact rock materials has been determined by the indirect method more frequently than by the direct method. This paper presents a historical review of the development of the indirect method called the Brazilian test, comprising the period from 1943 to the present day. It stresses some aspects which are essential for interpreting the results of the Brazilian test due to the different degrees of stress during the testing and the direct method of determining tensile strength. The estimate of the direct tensile strength and the influence of sample saturation on the results of indirect tensile strength testing have been specifically elaborated.

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“…These publications were critically examined, but did not reveal any references to the aspects emphasised here. It is also worth mentioning the contributions of Lanaro et al (2009), Andreev (1991, Markides et al (2012), Erarslan et al (2012) and Aydin and Basu (2006), Yang et al (2015), Haeri et al (2014), Choupania et al (2015), Cai et al (2015), which addressed the issue of the Brazilian test, either theoretically or experimentally, or even applied. However, none of them investigated the foundations raised from Timoshenko and Goodier (1970), in which the problem of methodological character examined in this work was found.…”

Section: Introductionmentioning

confidence: 99%

Superposition of Stress Fields in Diametrically Compressed Cylinders

Rocha

Wahrhaftig

2016

Lat. Am. j. solids struct.

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The theoretical analysis for the Brazilian test is a classical plane stress problem of elasticity theory, where a vertical force is applied to a horizontal plane, the boundary of a semi-infinite medium. Hypothesizing a normal radial stress field, the results of that model are correct. Nevertheless, the superposition of three stress fields, with two being based on prior results and the third based on a hydrostatic stress field, is incorrect. Indeed, this work shows that the Cauchy vectors (tractions) are non-vanishing in the parallel planes in which the two opposing vertical forces are applied. The aim of this work is to detail the process used in the construction of the theoretical model for the three stress fields used, with the objective being to demonstrate the inconsistency often stated in the literature.

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Microcrack modelling of Brazilian tensile tests with the boundary element method

Cited by 66 publications

References 22 publications

Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

Current Cognition of Rock Tensile Strength Testing by Brazilian Test

Superposition of Stress Fields in Diametrically Compressed Cylinders

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