Brazilian disc test study on tensile strength-weakening effect of high pre-loaded red sandstone under dynamic disturbance

2020 ◽  
Vol 27 (10) ◽  
pp. 2899-2913
Author(s):  
Feng-qiang Gong ◽  
Wu-xing Wu ◽  
Le Zhang
Keyword(s):  
Tensile Strength ◽  
Dynamic Disturbance ◽  
Brazilian Disc ◽  
Red Sandstone ◽  
Brazilian Disc Test ◽  
Test Study

scholarly journals A numerical and experimental study on the tensile behavior of plasma shocked granite under dynamic loading

2017 ◽  
Vol 50 (2) ◽  
pp. 41-62
Author(s):  
Ahmad Mardoukhi ◽  
Timo Saksala ◽  
Mikko Hokka ◽  
Veli-Tapani Kuokkala
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Mechanical Behavior ◽  
Thermal Shock ◽  
Dynamic Loading ◽  
Split Hopkinson Pressure Bar ◽  
Tensile Behavior ◽  
Brazilian Disc ◽  
Brazilian Disc Test ◽  
Plasma Shock

This paper presents a numerical and experimental study on the mechanical behavior of plasma shocked rock. The dynamic tensile behavior of plasma shock treated Balmoral Red granite was studied under dynamic loading using the Brazilian disc test and the Split Hopkinson Pressure Bar device. Different heat shocks were produced on the Brazilian disc samples by moving the plasma gun over the sample at different speeds. Microscopy clearly showed that as the duration of the thermal shock increases, the number of the surface cracks and their complexity increases (quantified here as the fractal dimension of the crack patterns) and the area of the damaged surface grows larger as well. At the highest thermal shock duration of 0.80 seconds the tensile strength of the Brazilian disc sample drops by approximately 20%. In the numerical simulations of the dynamic Brazilian disc test, this decrease in tensile strength was reproduced by modeling the plasma shock induced damage using the embedded discontinuity finite element method. The damage caused by the plasma shock was modeled by two methods, namely by pre-embedded discontinuity populations with zero strength and by assuming that the rock strength is lowered and conform to the Weibull distribution. This paper presents a quantitative assessment of the effects of the heat shock, the surface microstructure and mechanical behavior of the studied rock, and a promising numerical model to account for the pre-existing crack distributions in a rock material.

scholarly journals Energy Dissipation Characteristic of Red Sandstone in the Dynamic Brazilian Disc Test with SHPB Setup

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Fengqiang Gong ◽  
Jian Hu
Keyword(s):  
Energy Dissipation ◽  
Incident Energy ◽  
Split Hopkinson Pressure Bar ◽  
Critical Energy ◽  
Dissipated Energy ◽  
Brazilian Disc ◽  
Red Sandstone ◽  
Rock Materials ◽  
Brazilian Disc Test ◽  
Dissipation Characteristic

In order to quantitatively investigate the energy dissipation characteristic during the dynamic tension failure of rock materials, the dynamic Brazilian disc tests on red sandstone were conducted using the split Hopkinson pressure bar (SHPB) setup. The states of the specimens after different incident energies can be divided into three forms (i.e., the unruptured state, the ruptured state, and the broken state), and the failure processes of the specimens were recorded by using a high-speed camera. The results show that the ruptured state of the specimen corresponds to the critical failure strain. Taking the critical incident energy as a turning point, two positive linear fitting relations between the dissipated energy and incident energy before and after the point are obtained, and the dynamic linear dissipation law is found. When the incident energy is less than the critical energy, specimens were unruptured after impact. When the incident energy is greater than the critical energy, specimens will be broken after impact. According to the obtained linear energy dissipation law, the dynamic tensile energy dissipation coefficient (DTEDC) was introduced for quantitatively describing the dynamic energy dissipation capacity of rock materials in the dynamic Brazilian disc test. When the specimen is in the unruptured state, the ideal DTEDC is a constant value. When the specimen is in a broken state, the DTEDC increases with the increase of incident energy.

scholarly journals Numerical Analysis of Flattened Brazilian Disc Test Based on the Cusp Catastrophe Theory

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Min Wang ◽  
Ping Cao
Keyword(s):  
Tensile Strength ◽  
Catastrophe Theory ◽  
Poisson’S Ratio ◽  
Equivalent Stress ◽  
Poisson's Ratio ◽  
Fracture Plane ◽  
Cusp Catastrophe ◽  
Brazilian Disc ◽  
Brazilian Disc Test ◽  
Cusp Catastrophe Theory

The Brazilian disc test is a simple and useful technique to determine the tensile strength of rock materials. By using FLAC3D, 63 numerical simulations in total were performed when flattened Brazilian disc coefficient and Poisson’s ratio were different. Based on Griffith theory, the corresponding FISH language was compiled to record the Griffith equivalent stress. Through analysis of numerical simulation results, it is indicated that fracture plane was not the plane going through center of the Brazilian disc, which was in good agreement with the references. In addition, the flattened Brazilian disc coefficients had greater influence on tensile strength than Poisson’s ratio. Based on cusp catastrophe theory, the flattened Brazilian disc coefficient should not exceed 0.035 for the flattened Brazilian disc tests. Consequently, a tensile strength empirical formula considering flattened Brazilian disc coefficient by utilizing the flattened Brazilian disc test was established, which wasσt=0.9993 exp (-11.65ε)2p/πDt,ε≤0.035.

scholarly journals Comparative Study on the Test Method for Tensile Elastic Modulus of Rock Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Yan Zhang ◽  
Dawei Yu
Keyword(s):  
Elastic Modulus ◽  
Comparative Investigation ◽  
Test Method ◽  
Bending Test ◽  
Brazilian Disc ◽  
Rock Materials ◽  
Brazilian Disc Test ◽  
Test Operation ◽  
Uniaxial Compressive Test ◽  
Tensile Elastic Modulus

Rock material has different mechanical behaviors under compressive and tensile loading. Correspondingly, there are two types of elastic modulus: compressive elastic modulus Ec and tensile elastic modulus Et, respectively. To distinguish which indirect test methodology, including three-points bending test and Brazilian disc test, is more suitable to measure the tensile elastic modulus Et of rock materials, a series of uniaxial compressive test (UCT), direct tensile test (DTT), three-points bending test, and Brazilian disc test are performed for three typical types of rock: marble, granite, and sandstone. Comparative investigation on the reliability of measurement results of tensile elastic modulus Et is systematically conducted. Finally, it is found that Brazilian disc test could be a suitable method to measure tensile elastic modulus of rock materials, due to the excellent agreement with that measured by DTT and the simplicity of sample preparation, as well as test operation.

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