scholarly journals Influence of Cyclic Impact Loading and Axial Stress on Dynamic Mechanical Properties of Burst-Prone Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-10 ◽  
Author(s):  
Shuang Gong ◽  
Zhen Wang ◽  
Lei Zhou ◽  
Wen Wang
Keyword(s):  
Mechanical Properties ◽  
Impact Loading ◽  
Coal Sample ◽  
Impact Load ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Cyclic Impact Loading ◽  
Cyclic Impact ◽  
The Impact

High in-situ stress and frequent dynamic disturbances caused by the mining process in deep coal mines can easily induce dynamic disasters such as coal burst. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst-prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst-prone and burst-resistant coal samples. The mineral components, organic macerals, and dynamic mechanical features of both burst-prone and burst-resistant coal samples were comparatively analyzed based on the obtained X-ray diffraction (XRD), optical microscope observations, and dynamic compressive stress-strain curves, respectively. The results of the microstructure analysis indicated a larger difference between the minimum and maximum reflectances of vitrinite for burst-prone coal. Compared to the burst-resistant coal samples, the burst-prone coals contained less corpocollinite and fusinite. While applying a high axial static load combined with cyclic impact load, the coal samples showed the characteristics of fatigue damage. The results also demonstrated that preaxial stress affected the burst resistance of coal samples. The greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst-resistant coal sample, the burst-prone coal sample showed a larger dynamic compressive strength and a lower deformation. They were also more positively capable of the propagation and activation of the coal burst. We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst-prone coals. The results are also beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load.

scholarly journals Effect of Microstructure Refinement on Surface Morphology and Dynamic Mechanical Properties of W-Cu Alloys

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4615
Author(s):  
Fei Ding ◽  
Jinglian Fan ◽  
Liqiang Cao ◽  
Qidong Wang ◽  
Jun Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Impact Loading ◽  
Dynamic Mechanical Properties ◽  
Fracture Probability ◽  
Coarse Grained ◽  
Tungsten Alloy ◽  
Dynamic Mechanical ◽  
Cu Alloys ◽  
The Impact

Two ultrafine-grained W-Cu alloys and two coarse-grained W-Cu alloys were prepared to study the effect of tungsten grain refinement on the interface characteristics between coating and W-Cu alloys. The experimental results show that in the coarse-grained W-Cu alloys, the tungsten phase near the surface is easy to form pits and cracks during impact loading, while the fine-grained tungsten alloy is not prone to this phenomenon. Simulations show that refining tungsten grains can not only reduce the impact absorption energy, but also increase the contact area of tungsten and copper phases, thereby reducing the fracture probability of tungsten phases and improving the dynamic mechanical properties of the W-Cu alloys under impact loading. The tested results show that the shear strength of gold studs on the coating is increased by about 33%, after grain refinement for the W-Cu alloys.

scholarly journals Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7298
Author(s):  
Shumeng Pang ◽  
Weijun Tao ◽  
Yingjing Liang ◽  
Shi Huan ◽  
Yijie Liu ◽  
...  
Keyword(s):  
Stress Wave ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Stress Waves ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.

Research on the dynamic mechanical properties of C-plane sapphire under impact loading

2018 ◽  
Vol 44 (8) ◽  
pp. 9839-9847 ◽  
Author(s):  
Feng Jiang ◽  
Xiaosheng Luan ◽  
Ningchang Wang ◽  
Xipeng Xu ◽  
Xizhao Lu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Loading ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical

scholarly journals Dynamic Mechanical Compression Impulse of Lithium-Ion Pouch Cells

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2105 ◽  
Author(s):  
Alon Ratner ◽  
Richard Beaumont ◽  
Iain Masters
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Lithium Ion ◽  
Rate Sensitivity ◽  
Dynamic Mechanical Properties ◽  
Impact Testing ◽  
Significant Feature ◽  
Dynamic Mechanical ◽  
The Impact

Strain rate sensitivity has been widely recognized as a significant feature of the dynamic mechanical properties of lithium-ion cells, which are important for their accurate representation in automotive crash simulations. This research sought to improve the precision with which dynamic mechanical properties can be determined from drop tower impact testing through the use of a diaphragm to minimize transient shock loads and to constrain off-axis motion of the indenter, specialized impact absorbers to reduce noise, and observation of displacement with a high speed camera. Inert pouch cells showed strain rate sensitivity in an increased stiffness during impact tests that was consistent with the poromechanical interaction of the porous structure of the jellyroll with the liquid electrolyte. The impact behaviour of the inert pouch cells was similar to that of an Expanded Polypropylene foam (EPP), with the exception that the inert pouch cells did not show hysteretic recovery under the weight of the indenter. This suggests that the dynamic mechanical behaviour of the inert pouch cells is analogous to a highly damped foam.

scholarly journals Study on Dynamic Mechanical Properties of Limestone Under Impact Loading

2019 ◽  
Vol 300 ◽  
pp. 022150
Author(s):  
Renliang Shan ◽  
Yongwei Song ◽  
Haochen Zhang ◽  
Mengnan Wang ◽  
Xiaolin Hao
Keyword(s):  
Mechanical Properties ◽  
Impact Loading ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical

scholarly journals Dynamic Fracture Experiment of Fractured Rock under Dynamic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Yanbing Wang ◽  
Xingyuan Zhou ◽  
Ji Kong ◽  
Bingbing Yu
Keyword(s):  
Mechanical Properties ◽  
Energy Loss ◽  
Dynamic Loading ◽  
Split Hopkinson Pressure Bar ◽  
Fractured Rock ◽  
Dynamic Mechanical Properties ◽  
Dynamic Crack ◽  
Loading Test ◽  
Dynamic Mechanical ◽  
The Impact

In order to examine the dynamic mechanical properties, dynamic crack proposition process, and energy loss of fractured rock under dynamic loading, the specimens with different fracture dig angles were processed with Φ50 mm × 50 mm cylindrical sandstone, the impact loading test was conducted on 50 mm stem diameter split Hopkinson pressure bar (SHPB) experiment platform, and the whole process of crack propagation and dynamic failure was recorded using a high-speed camera. As a result, the dynamic mechanical properties such as stress wave fluctuation characteristics, peak strength and stress-strain relationship, crack initiation angle, stress and other dependencies with prefabricated fracture angle of the prefabricated fracture specimens under high strain rate were obtained, and the incident energy, absorbed energy, and energy absorption rates were compared to investigate the energy loss law in the dynamic loading; on the contrary, the effects of different loading rates on the dynamic mechanical properties of the sandstone specimens were identified, and finally a set of findings were presented.

Study on Impact Resistance of Silica Fume Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 211-214
Author(s):  
Chao Zhang ◽  
Wei Wu ◽  
Yong Li
Keyword(s):  
Mechanical Properties ◽  
Optimal Design ◽  
Silica Fume ◽  
Impact Loading ◽  
Impact Resistance ◽  
Dynamic Mechanical Properties ◽  
Practical Significance ◽  
Test Device ◽  
Dynamic Mechanical ◽  
Shpb Test

It has important practical significance to research dynamic mechanical properties of silica fume concrete with silica fume concrete widely applying in civil engineering. Mechanical properties of silica fume concrete under impact loading were studied with the SHPB test device ofφ74mm to get its optimal design project and provided important bases and references for engineering applications.

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