Computation of V-notch shape factors in four-point bend specimen for fracture tests on brittle materials

Ayatollahi, M.R.; Dehghany, M.; Kaveh, Z

doi:10.1007/s00419-012-0654-0

Cited by 8 publications

(4 citation statements)

References 39 publications

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“…Table summarizes the obtained fracture loads for each specimen and the corresponding dimensionless fracture parameters obtained in the previous section. In this table, a parameter called the notch mode mixity parameter

M_{V}^{e} = \frac{2}{π} \tan^{prefix- 1} ((), \frac{Y_{I}^{V}}{Y_{I I}^{V}})

has also been employed to define the state of mode mixity around the notch tip quantitatively . The next section is devoted to the discussion on the obtained experimental results.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, these techniques are often complicated and need lengthy calculations. Hence, some studies have tried to provide the NSIFs of experimental notched specimens for a wide range of geometry and loading conditions to remove the need for these cumbersome calculations. However, none of these investigations have reported the coefficients of the first non‐singular terms and hence cannot be employed for evaluating the effects of these terms on fracture evaluation of the notched bodies.…”

Section: Introductionmentioning

confidence: 99%

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The role of first non‐singular stress terms in mixed mode brittle fracture of V‐notched components: an experimental study

Dehghany

Googarchin

Aliha

2016

Fatigue Fract Eng Mat Struct

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This paper investigates the effects of the first non‐singular stress terms on the fracture assessment of sharp V‐notches under mixed mode loading. First, numerical studies have been performed on a fracture test configuration called single V‐notched ring (SVR) specimen. Then, the notch stress intensity factors as well as the coefficients of the first non‐singular stress terms, which are vital parameters in brittle fracture of V‐notched components, were calculated via a finite element over‐deterministic algorithm for a wide range of loading and geometry conditions. The obtained results demonstrate that the SVR specimen is able to provide a complete range of mode mixities from pure mode I to pure mode II loading conditions. The numerical results, next, have been converted to dimensionless parameters and are illustrated in several graphs. Indeed, these graphs can be easily employed by the engineers for rapid calculation of the corresponding notch stress intensity factors and the coefficients of the first non‐singular stress terms in the SVR specimen. The obtained fracture parameters are then submitted to the maximum tangential stress criterion to assess the effects of the first non‐singular terms on fracture behaviour of the specimen. Finally, an experimental study has been performed on the SVR specimen made of Nayriz Marble rock for two notch angles with a complete range of mode mixities. The obtained experimental data confirm the significant role of the first non‐singular stress terms. In fact, these results show that considering only the singular stress terms may induce an average error of 38% in the predicted fracture loads, which can be decreased to about 12% just by adding the contribution of the first non‐singular terms to the maximum tangential stress criterion.

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M_{V}^{e} = \frac{2}{π} \tan^{prefix- 1} ((), \frac{Y_{I}^{V}}{Y_{I I}^{V}})

has also been employed to define the state of mode mixity around the notch tip quantitatively . The next section is devoted to the discussion on the obtained experimental results.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of first non‐singular stress terms in mixed mode brittle fracture of V‐notched components: an experimental study

Dehghany

Googarchin

Aliha

2016

Fatigue Fract Eng Mat Struct

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“…In lab experiments, three-point (Dong et al 2017;Stavrakas et al 2016) and four-point (Ayatollahi et al 2013;Efimov 2011;Koudelka et al 2020) loading are generally used to provide bending loads for rock beams. AE (Acoustic Emission) test is a very effective method to study the fracture of rock beams.…”

Section: Introductionmentioning

confidence: 99%

Research on mechanical properties and acoustic emission characteristics of rock beams with different lithologies and thicknesses

Zhao

Zhang

Guo

et al. 2021

Lat. Am. j. solids struct.

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The lithology and thickness of the rock beam affect its mechanical properties and acoustic emission characteristics when it is fractured. In this study, three-point bending tests of rock beams were carried out. Then, we proposed to utilize the percentage of peak energy to characterize the intensity of energy release during fracture. Finally, the energy release mechanism of coal roof fracture was discussed. The evolution process of acoustic emission includes five stages. The acoustic emission amplitude distribution of rock beams has three typical patterns. Most of the cracks after fracture are tensile cracks, the proportion of tensile cracks is positively correlated with the elastic modulus. The percentage of peak energy is positively correlated with thickness and elastic modulus. More energy is released when thick and hard roof fractures. When necessary, measures such as reducing the thickness or the strength of the roof could be taken to improve the safety of mining.

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“…Therefore, problems of brittle fracture of structural components with sharp V-notches have been considered in numerous papers, see e.g. [1][2][3][4]. Cracks can be regarded as a special case of V-notch with zero opening angle.…”

Section: Introductionmentioning

confidence: 99%

Critical Value for Crack Propagation from Sharp V-Notch

Náhlík

Štegnerová

Hutař

et al. 2013

KEM

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The contribution is focused on estimation of a critical value of generalized stress intensity factor for crack propagation from sharp V-notches. Stress distribution around the tip of the V-notch is described on the base of generalized linear elastic fracture mechanics, because V-notch is a singular stress concentrator with stress singularity exponent different from 0.5 (depending on V-notch opening angle). Then also stability criteria based on strain energy density factor and average critical stress are generalized for the stress singularity different from 0.5. Using FE analysis the critical stresses for crack initiation was estimated and compared with experimental data from the literature.

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Computation of V-notch shape factors in four-point bend specimen for fracture tests on brittle materials

Cited by 8 publications

References 39 publications

The role of first non‐singular stress terms in mixed mode brittle fracture of V‐notched components: an experimental study

The role of first non‐singular stress terms in mixed mode brittle fracture of V‐notched components: an experimental study

Research on mechanical properties and acoustic emission characteristics of rock beams with different lithologies and thicknesses

Critical Value for Crack Propagation from Sharp V-Notch

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