scholarly journals Dynamic Failure Model of Thin Coal and Rock Mass under Uniform Impact Load

Engineering ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 699-714
Author(s):  
Feng Li ◽  
Fangfei Sha ◽  
Minbo Zhang ◽  
Zijian He ◽  
Xinhui Dong ◽  
...  
Keyword(s):  
Rock Mass ◽  
Impact Load ◽  
Dynamic Failure ◽  
Failure Model

Model Testing and Analysis Study on Shear Strength of Rock Mass Containing Multiple Cracks under Compression-Shearing Loading

2008 ◽  
Vol 33-37 ◽  
pp. 617-622
Author(s):  
Wei Shen Zhu ◽  
Bin Sui ◽  
Wen Tao Wang ◽  
Shu Cai Li
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Rock Sample ◽  
Failure Process ◽  
Jointed Rock ◽  
Multiple Cracks ◽  
Test Results ◽  
Failure Model ◽  
Two Phase ◽  
Bridge Failure

Two-phase modelling testing was performed to study the shear strength of rock bridges of jointed rock mass in this paper. The failure process of rock sample containing multiple collinear cracks was observed. Based on theory of fracture mechanics and analytical method, a rock-bridge failure model was proposed and the expression of shear strength was derived. Comparison of calculated shear strength and the model test results was made and they agree well.

scholarly journals Analysis of load of a powered roof support’s hydraulic leg

2018 ◽  
Vol 71 ◽  
pp. 00002 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Rock Mass ◽  
Hydraulic System ◽  
Impact Load ◽  
Load Condition ◽  
Dynamic Impact ◽  
Registration System ◽  
Free Falling ◽  
The Impact ◽  
Impact Mass ◽  
Roof Support

The main purpose of the powered roof support is to protect headings from the impact of the rock mass. The result of such impact is static and dynamic load impacting the support section, which is carried by its construction. The basic elements of the construction of the support are hydraulic legs, whose task is to ensure adequate strength of its setting. Particularly in the case of dynamic impact of the rock mass, these legs are exposed to a very unfavourable load condition. Therefore, it is necessary to conduct tests to determine the parameters of operation for this type of loads. The paper presents the results of tests on the hydraulic leg subjected to impact load with free falling impact mass. The purpose of the research was to determine the parameters of the leg's operation, i.e. the time periods of pressure in the space under the piston and other elements of the hydraulic system. The tests were conducted in compliance with designed methodology and included innovative registration system. The obtained results clearly indicate the correctness of the adopted assumptions. According to the authors, the results should be applied during selection and operation of a powered roof support.

DYNAMIC FAILURE OF A SPOT WELD IN LAP–SHEAR TESTS UNDER COMBINED LOADING CONDITIONS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5527-5532 ◽  
Author(s):  
J. H. SONG ◽  
J. W. HA ◽  
H. HUH ◽  
J. H. LIM ◽  
S. H. PARK
Keyword(s):  
Failure Load ◽  
Spot Weld ◽  
Combined Loading ◽  
Dynamic Failure ◽  
Failure Model ◽  
Dynamic Effects ◽  
Shear Tests ◽  
Loading Rates ◽  
Lap Shear ◽  
Failure Loads

This paper is concerned with the evaluation of the dynamic failure load in the lap-shear tests of a spot weld. Dynamic lap-shear tests of a spot weld in SPRC340R were conducted with different tensile speeds ranging from 5×10-5 m/sec to 5.0 m/sec. Dynamic effects on the failure load of a spot weld are examined based on the experimental data. Experimental results indicate that failure strength increases with increasing loading rates. Finite element analyses of dynamic lap-shear tests were also performed considering the failure of a spot weld. A spot weld is modeled with a beam element and dynamic failure model is utilized in order to describe the failure of a spot weld in the simulation. The failure loads obtained from the analyses are compared to those from the lap-shear tests. The comparison shows that the failure loads obtained from the analyses are close in consistence with those obtained from the experiments.

Development Of A Dynamic Failure Model For Polymeric Adhesives

2021 ◽  
Author(s):  
Harshil H Pisavadia ◽  
Patricia Dolez ◽  
James D Hogan
Keyword(s):  
Dynamic Failure ◽  
Failure Model

Noise effects on the health status in a dynamic failure model for living organisms

2007 ◽  
Vol 40 (13) ◽  
pp. 3319-3328 ◽  
Author(s):  
H Kang ◽  
J Jo ◽  
M Y Choi ◽  
J Choi ◽  
B-G Yoon
Keyword(s):  
Health Status ◽  
Dynamic Failure ◽  
Failure Model ◽  
Noise Effects ◽  
Living Organisms

scholarly journals Study of the Failure Mode of a Jointed Rock Mass due to a Stress Wave

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xi Kun Qian ◽  
Cong Cong Li
Keyword(s):  
Rock Mass ◽  
Failure Mode ◽  
Dynamic Loading ◽  
Stress Wave ◽  
Static Loading ◽  
Failure Process ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Dynamic Failure ◽  
Shear Cracks

The mechanical response and failure process of a jointed rock mass subjected to dynamic loading is very important for the safety and stability of rock engineering projects. In this study, we use RFPA2D-Dynamic, a rock dynamic failure process analysis platform, to establish a two-dimensional impact model of a jointed rock mass to analyze the mechanism of crack propagation in a jointed rock mass with preexisting cracks under dynamic loading. We discuss the influence of the stress wavelength and precrack inclination on the dynamic failure process and mode of the rock mass and compare this failure process with the failure model under static loading. The results show that the dynamic failure process and crack initiation type of a jointed rock mass are closely related to the stress wavelength. For a given peak, as the stress wavelength increases, the failure mode changes from local cracking that occurs above the precracks to a global instability caused by wing cracks. Meanwhile, as the wavelength increases, the shear cracks and mixed tensile-shear cracks generated at the two ends of the precracks are replaced by tensile cracks. The precrack inclination on a jointed rock mass mainly affects the strength of the jointed rock mass and the final failure mode. Specifically, when the joint inclination is small, the rock mass is severely damaged in the region above the precracks because the stress wave forms a region of cracks with a concentrated distribution. As the joint inclination increases, the damaged region becomes larger while the rock mass is less prone to failure; the strength of the rock mass gradually increases, and the wing cracks produced at the two ends of precracks propagate toward the upper and lower ends of the rock mass. However, when the stress wavelength is small, the precracks of different inclinations form cracks in the region above the precracks with a length similar to the precracks. For this condition, the propagation of the cracks is mainly controlled by the stress wavelength, while the influence of the inclination of the precracks is not significant. There is a significant difference between the failure modes of a rock specimen under dynamic loading or static loading because the stress wave produces a reflected tension wave in the direction parallel to the wave attack of the joint plane, which leads to spalling, while the wing cracks are more likely to occur under static loading.

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