scholarly journals Deviation Effect of Coaxiality on the Rock Brazilian Split

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Zenghui Zhao ◽  
Mingzhong Zhang ◽  
Qing Ma ◽  
Baosen Chen
Keyword(s):  
Tensile Strength ◽  
Numerical Calculation ◽  
Stress Distribution ◽  
Rock Fracture ◽  
Splitting Method ◽  
Maximum Tensile Stress ◽  
Analytic Solutions ◽  
Calculation Error ◽  
Splitting Test ◽  
Variable Function

Tension failure is one of the main forms of instability in geotechnical engineering. Aiming at the calculation error caused by the loading direction deviation of the Brazilian disc splitting method, a mechanical model of a disc under chord loading was constructed firstly. Based on the theory of complex variable function, the analytic solutions of stresses in a circular disc were deduced, and the calculation error of the tensile strength under chord loading was characterized by defining the error impact rate. And the stress distribution of a disc and the law of rock fracture under chord loading were detailed analyzed through numerical calculation. Through numerical calculation, the stress distribution of the disc and rock failure law under chordwise loading are discussed in detail. The results show that the stress concentration near the loading point is stronger under the chordwise loading comparing with the radial loading, which makes the disc more vulnerable to produce compression failure near the loading point. The disc exhibits a maximum tensile stress and a minimum compressive stress at the intersection of the loaded string and the horizontal diameter, so that tensile rupture damage is likely to occur here. With the increase of deviation angle, the tensile strength measured by the Brazilian splitting test decreases gradually, and the influence rate of error increases significantly. The proposed analytical solution under chord loading provides theoretical guiding significance for nonradial splitting failure of a disc.

scholarly journals Study on Mechanical Features of Brazilian Splitting Fatigue Tests of Salt Rock

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Weichao Wang ◽  
Mengmeng Wang ◽  
Xiliang Liu
Keyword(s):  
Tensile Strength ◽  
Failure Modes ◽  
Splitting Method ◽  
Fatigue Tests ◽  
Test Machine ◽  
Salt Rock ◽  
Tablet Splitting ◽  
Splitting Test ◽  
Fracturing Process ◽  
Brazilian Splitting

The microtest, SEM, was carried out to study the fracture surface of salt rock after the Brazilian splitting test and splitting fatigue test were carried out with a servo-controlled test machine RMT-150B. The results indicate that the deviation of using the tablet splitting method is larger than that of using steel wire splitting method, in Brazilian splitting test of salt rock, when the conventional data processing method is adopted. There are similar deformation features in both the conventional splitting tests and uniaxial compression tests. The stress-strain curves include compaction, elasticity, yielding, and failure stage. Both the vertical deformation and horizontal deformation of splitting fatigue tests under constant average loading can be divided into three stages of “loosening-tightness-loosening.” The failure modes of splitting fatigue tests under the variational average loading are not controlled by the fracturing process curve of the conventional splitting tests. The deformation extent of fatigue tests under variational average loading is even greater than that of conventional splitting test. The tensile strength of salt rock has a relationship with crystallization conditions. Tensile strength of thick crystal salt rock is lower than the bonded strength of fine-grain crystals.

scholarly journals Analytical and Modelling Study on the Spatial Stress Distribution and Failure Process of Disc Specimen in the Brazilian Splitting Test

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Wei Zhang ◽  
Wei-yao Guo ◽  
Zhi-qi Wang
Keyword(s):  
Tensile Strength ◽  
Stress Distribution ◽  
Failure Process ◽  
Spatial Effect ◽  
Diameter Ratio ◽  
Disc Specimen ◽  
Radial Bearing ◽  
Splitting Test ◽  
Brazilian Splitting ◽  
Spatial Stress

To correctly obtain the spatial stress distribution and failure process of disc specimen in the Brazilian splitting test, an analytical solution of three-dimensional stress is deduced. Then, the effects of height-diameter ratio and clamp radian on the spatial stress distribution and failure process are analyzed and studied combined with numerical modelling. At last, the influence of spatial effect on the tensile strength of disc specimen is discussed. The results show that the cracks firstly generate at the two ends of the specimen in the axial direction and then extend due to the nonuniform distribution of tensile stress. The macrocracks coalescence does not mean the capacity loss of radial bearing. The maximum radial bearing capacity of the disc specimen decreases with the increase of height-diameter ratio due to the spatial effect. The tensile strength obtained by the two-dimensional calculation formula is significantly smaller. Therefore, when the commonly-used height-diameter ratio of 0.5 is used in the Brazilian splitting test, a correction factor k = 1.15 − 1.25 is suggested.

scholarly journals Modeling for Distribution of Compressive Stress from Loading Platens in Diametrical Compression Test

2018 ◽  
Vol 250 ◽  
pp. 01009 ◽  
Author(s):  
Yukari Higashi ◽  
Shinnosuke Yoshinaga ◽  
Rini Asnida Abdullah ◽  
Takashi Tsutsumi
Keyword(s):  
Tensile Strength ◽  
Stress Distribution ◽  
Compressive Stress ◽  
Compression Test ◽  
Contact Area ◽  
Stress Function ◽  
Fourier Expansion ◽  
Complex Stress ◽  
Concentrated Loading ◽  
Indirect Tests

Diametrical Compression test is one of indirect tests to investigate the tensile strength of brittle materials. This test is spread because of easiness to perform. However, results from this test are not stable. Traditionally, calculations for this test are performed under a pair of opposite concentrated loading on the diameter of specimen. However, contact areas appear just before fracture of specimen in the fact and the stress distribution from loading platens is not obvious. It seems be one of reasons why the result from this test is not stable. In this study, the attempt to establish the modeling for distribution on loading platens in the diametrical compression test is shown. The aim of this modeling is to calculate stresses and displacement of specimen using complex stress function by Lekhnitskii. Therefore, this model is expanded in Fourier expansion. Accuracy of calculation using Fourier expansion depends on the number of terms. Therefore, the influence of contact area and number of terms to accuracy is also discussed.

scholarly journals Cracking Tendency Prediction of High-Performance Cementitious Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Ke Chen ◽  
Hui Hu ◽  
Ke Chen ◽  
Zhaohui Chen ◽  
Xin Wang
Keyword(s):  
Tensile Strength ◽  
Analytical Method ◽  
High Performance ◽  
Environmental Parameters ◽  
Drying Shrinkage ◽  
Maximum Tensile Stress ◽  
Cementitious Materials ◽  
Hydration Heat ◽  
Ring Test ◽  
Split Tensile Strength

The constraint ring test is widely used to assess the cracking potential for early-age cementitious materials. In this paper, the analytical expressions based on elastic mechanism are presented to estimate the residual stresses of the restrained mortar ring by considering the comprehensive effects of hydration heat, autogenous and drying shrinkage, creeping, and restraint. In the present analytical method, the stress field of the restrained ring is treated as the superposition of those caused by hydration heat, external restraint, autogenous and drying shrinkage, and creep. The factors including the properties of materials, environmental parameters such as relative humidity and temperature, the geometry effect of specimen, and the relative constraint effects of steel ring to mortar ring, are taken into account to predict the strain development with age of mortar. The temperature of the ring, the elastic modulus, the creep strain, and the split tensile strength are measured to validate the model. The age of cracking is predicted by comparing the estimated maximum tensile stress of the restrained mortar ring with the measured split tensile strength of specimen. The suitability of the present analytical method is assessed by comparing with the restraint ring test and a soundly good agreement is observed.

Residual Stress Distribution in Pure Bending Beam Subjected to Tensile Failure on One Side

2006 ◽  
Vol 524-525 ◽  
pp. 253-258
Author(s):  
X.B. Wang
Keyword(s):  
Residual Stress ◽  
Tensile Strength ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Strain Localization ◽  
Tensile Strain ◽  
Residual Stress Distribution ◽  
Neutral Axis ◽  
Residual Tensile Stress ◽  
Pure Bending

The stress distribution on the midsection of a pure bending beam where tensile strain localization band initiates on the tensile side of the beam and propagates within the beam is analyzed. Using the static equilibrium condition on the section of the midspan of the beam and the assumption of plane section as well as the linear softening constitutive relation beyond the tensile strength, the expressions for the length of tensile strain localization band and the distance from the tip of the band to the neutral axis are derived. After superimposing a linear unloading stress distribution over the initial stress distribution, the residual stress distribution on the midsection of the beam is investigated. In the process of strain localization band’s propagation, strain-softening behavior of the band occurs and neutral axis will shift. When the unloading moment is lower, the length of tensile strain localization band remains a constant since the stress on the base side of the beam is tensile stress. While, for larger unloading moment, with an increase of unloading moment, the length of tensile strain localization band decreases and the distance from the initial neutral axis to the unloading neutral axis increases. The neutral axis of midsection of the beam will shift in the unloading process. The present analysis is applicable to some metal materials and many quasi-brittle geomaterials (rocks and concrete, etc) in which tensile strength is lower than compressive strength. The present investigation is limited to the case of no real crack. Moreover, the present investigation is limited to the case that the length of strain localization band before unloading is less than half of depth of the beam. Otherwise, the residual tensile stress above the elastic neutral axis will be greater than the tensile strength, leading to the further development of tensile strain localization band in the unloading process.

Determination of Rock Fracture Toughness K IIC and its Relationship with Tensile Strength

2011 ◽  
Vol 44 (5) ◽  
pp. 621-627 ◽  
Author(s):  
Yan Jin ◽  
Jianbo Yuan ◽  
Mian Chen ◽  
K. P. Chen ◽  
Yunhu Lu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Rock Fracture ◽  
Rock Fracture Toughness

Shape of a Wire in a Centrifugal Field—Application to Quasi-Circular Bare Filament Flywheels

1983 ◽  
Vol 105 (2) ◽  
pp. 221-226 ◽  
Author(s):  
G. Genta
Keyword(s):  
Numerical Calculation ◽  
Stress Distribution ◽  
Numerical Integration ◽  
Equilibrium Equation ◽  
Series Solution ◽  
Field Application ◽  
Centrifugal Field ◽  
Low Speed ◽  
Theoretical Results ◽  
Good Agreement

In order to calculate the stress distribution in bare filament rotors it is necessary to evaluate with good approximation the shape taken by the wires in the centrifugal field (sometimes referred to as “polar catenary”). This problem is usually solved via a numerical integration of the equilibrium equation of the wire. In this paper a series solution of the same equilibrium equation is obtained. The calculation of the stress distribution in the rotor, which is an interative one and requires the evaluation of the shape of each wire several times, becomes faster and can be performed also in those conditions in which the numerical calculation failed (i.e., at low speed, when the “subcircularity” of the wires is too great to be taken into account in that way). Photographic and photoelastic tests are in good agreement with theoretical results.

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