scholarly journals Numerical Study of Mechanical Characteristics and Crack Evolution Law of Coal-Rock With Different Fracture-Hole Defects By Particle Model

2019 ◽  
Vol 21 (2) ◽  
pp. 30-30
Author(s):  
Longgang Tian ◽  
Xiao Wang ◽  
Qi Zhang
Keyword(s):  
Mechanical Characteristics ◽  
Numerical Study ◽  
Particle Model ◽  
Crack Evolution ◽  
Evolution Law ◽  
Coal Rock ◽  
Hole Defects

scholarly journals Experimental Research on the Mechanical Characteristics and the Failure Mechanism of Coal-Rock Composite under Uniaxial Load

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ke Yang ◽  
Zhen Wei ◽  
Xiaolou Chi ◽  
Yonggang Zhang ◽  
Litong Dou ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Elastic Modulus ◽  
Crack Propagation ◽  
Failure Mechanism ◽  
Poisson’S Ratio ◽  
Mechanical Characteristics ◽  
Poisson's Ratio ◽  
Energy Value ◽  
Coal Rock

Due to the influence of the component structure and combination modes, the mechanical characteristics and failure modes of the coal-rock composite show different characteristics from the monomer. In order to explore the effect of different coal-rock ratios on the deformation and the failure law of the combined sample, the RMT rock mechanics test system and acoustic emission real-time monitoring system are adopted to carry out uniaxial compression tests on coal, sandstone, and three kinds of combined samples. The evolution rules of the mechanical parameters of the combined samples, such as the uniaxial compressive strength, elastic modulus, and Poisson’s ratio, are obtained. The expansion and failure deformation characteristics of the combined sample are analyzed. Furthermore, the evolution laws of the fractal and acoustic emission signals are combined to reveal the crack propagation and failure mechanism of the combined samples. The results show that the compressive strength and elastic modulus of the combined sample increase with the decrease of the coal-rock ratios, and Poisson’s ratio decreases with the decrease of the coal-rock ratios. The strain softening weakens at the postpeak stage, which shows an apparent brittle failure. The combined sample of coal and sandstone has different degrees of damages under load. The coal is first damaged with a high degree of breakage, with obvious tensile failure. The acoustic emission energy value presents different stage characteristics with increasing load. Crackling sound occurs in the destroy section before the sample reaches the peak, along with small coal block ejection and the partial destruction. The energy value fluctuates violently, with the appearance of several peaks. At the postpeak stage, the coal samples expand rapidly with a loud crackling sound in the destroy section, and the energy value increases dramatically. The crack propagation induces the damage in the sandstone; when the energy reaches the limit value, the instantaneous release of elastic energy leads to the overall structural instability.

scholarly journals Numerical Study on the Effect of Non-Sinusoidal Motion on the Energy Extraction Performance of Parallel Foils

2019 ◽  
Vol 9 (3) ◽  
pp. 384
Author(s):  
Yulu Wang ◽  
Fahui Zhu ◽  
Yonghui Xie
Keyword(s):  
Lift Force ◽  
Numerical Study ◽  
Average Power ◽  
Power Coefficient ◽  
Energy Extraction ◽  
Pitching Motion ◽  
Evolution Law ◽  
Sinusoidal Motion ◽  
Oscillation Process ◽  
Extraction Performance

The effect of non-sinusoidal motion which influences the energy extraction performance of foil is considered in this paper. Two oscillation motions, the combined non-sinusoidal plunging and sinusoidal pitching motion, as well as the combined non-sinusoidal pitching and sinusoidal plunging motion, are selected to investigate the oscillation process of two-dimensional parallel foils numerically. The optimal oscillation motion and average power coefficient at different combined motions are gained. The effects of the plunging motion and pitching motion at different oscillation motions are analyzed, and the evolution law of the foil lift force and vortex field are obtained. It is indicated that the non-sinusoidal motion has a significant influence on energy extraction. When the motion is combined (non-sinusoidal plunging and sinusoidal pitching motion), the best extraction performance is gained at Kh = −0.5. The maximal CPm is 0.375 and the maximal η is 0.188. When the motion is combined (non-sinusoidal pitching and sinusoidal plunging motion), the maximal CPm is 0.623 and the maximal η is 0.312 which appear at Kθ = 2. For the same frequency, the more the plunging motion is similar to the sinusoidal motion, the more energy is extracted by foils. While the more the pitching motion approximates to the square wave, the worse the achieved extraction performance is.

Analysis of energy dissipation and crack evolution law of sandstone under impact load

2020 ◽  
Vol 132 ◽  
pp. 104359 ◽  
Author(s):  
Yi Luo ◽  
Gang Wang ◽  
Xinping Li ◽  
Tingting Liu ◽  
Abhay Kumar Mandal ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Impact Load ◽  
Crack Evolution ◽  
Evolution Law
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