scholarly journals Energy Dissipation and Electromagnetic Radiation Response of Sandstone Samples with a Pre-Existing Crack of Various Inclinations under an Impact Load

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1363
Author(s):  
Zesheng Zang ◽  
Zhonghui Li ◽  
Yue Niu ◽  
He Tian ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Energy Consumption ◽  
Energy Dissipation ◽  
Electromagnetic Radiation ◽  
Stress Wave ◽  
Impact Load ◽  
Radiation Energy ◽  
Radiation Response ◽  
Main Frequency ◽  
Red Sandstone

Various primary fissures and defects are widely present in a rock mass and have a significant impact on the stability of the rock mass. We studied the influence of the crack inclination angle on the energy dissipation and electromagnetic radiation (EMR) response of sandstone under an impact load. Impact tests were conducted on red sandstone samples with different inclination angles, in addition to test energy dissipation and EMR signals. The results showed that as the energy of the stress wave increased, the energy consumption density and damage variables of the sample gradually increased, and the electromagnetic radiation energy also increased. As the crack inclination increased, the energy consumption density first decreased and then increased, while the damage variable and electromagnetic radiation energy first increased and then decreased. In the process of impact damage, the main frequency of EMR was 0~5 kHz. As the energy of the stress wave increased, the dominant frequency band of the main frequency expanded from low frequency to high frequency, and the amplitude signal gradually increased; the α = 45° specimen frequency domain was the widest, and the amplitude was the largest. The crack inclination significantly changed the failure state of the sample, resulting in changes in the energy dissipation and the electromagnetic radiation response of the sample.

scholarly journals Investigations of Damage Characteristics in Rock Material Subjected to the Joint Effect of Cyclic Loading and Impact

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2154 ◽  
Author(s):  
Yanlong Chen ◽  
Haoshuai Wu ◽  
Hai Pu ◽  
Kai Zhang ◽  
Feng Ju ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Cyclic Load ◽  
Rock Specimen ◽  
Impact Load ◽  
Particle Diameter ◽  
Damage Variable ◽  
Average Particle ◽  
Red Sandstone ◽  
Initial Damage ◽  
Combined Action

Investigation of the damage characteristics of rock material under the combined effect of cyclic load and impact load is extremely crucial for many mining engineering applications. Based on energy dissipation theory, we considered factors such as circulation times, the cyclic stress of a uniaxial cyclic load test, and the impact pressure (strain rate) of a split Hopkinson pressure bar (SHPB) test, studying the damage mechanism of red sandstone under the combined action of a uniaxial cyclic and impact loads. We found that when the load stress is 60%, 70%, and 80% of the uniaxial compressive strength (UCS) of red sandstone, the stress can still promote the development of microcracks and the generation of new cracks in the rock, increasing the inner damage of the rock so that it reduces the rock strength. As the cyclic time increases, the energy dissipation ratio presented a trend of decreasing dramatically and then maintaining basically no change, and the peak strain and the damage variable of the rock both increased first and then tended to remain relatively constant. The damage variable of the rock specimen under the combined action of the uniaxial cyclic loading and impact load had a significant corresponding relationship with the initial damage. As the rock specimen initial damage increases, the damage variable and the peak stress of the rock specimen both decreases almost linearly with initial damage. Meanwhile, the average particle diameter of the rock specimen after breakage gradually increased, showing a positively correlated tendency. The ratio between the fragment quality of the bigger particle diameter in the total rock specimen quality gradually increased. Under the conditions of the same initial damage, a higher impact pressure resulted in smaller rock fragment average particle diameters.

scholarly journals Analysis of Energy Dissipation Characteristics of Damaged Sandstone under Impact Load

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Feng Wang ◽  
Haibo Wang ◽  
Ying Xu ◽  
Bing Cheng ◽  
Qianqian Wang
Keyword(s):  
Rock Mass ◽  
Energy Dissipation ◽  
Cyclic Loading ◽  
Dynamic Load ◽  
Impact Load ◽  
Peak Strain ◽  
Dissipation Energy ◽  
Cyclic Loading And Unloading ◽  
Damage Degree ◽  
Loading And Unloading

Before rock burst, coal, and gas outburst dynamic load, rock mass in geotechnical engineering has been an indifferent degree of damage. The dissipation energy of rock mass under dynamic load reflects the difficulty of rock breaking. In view of the energy dissipation of damaged rock mass under dynamic load, the cyclic loading and unloading test is carried out to make sandstone in different damage states, and the damage degree of sandstone is characterized by the change of longitudinal wave velocity before and after cyclic loading and unloading. Then, the rock with different damage degrees is tested by adopting the split Hopkinson pressure bar (SHPB). Finally, the energy dissipation characteristics of damaged rock under impact load are analyzed. The results show that the damage factor of sandstone increases with the increase of the upper limit of stress after cyclic static loading. The dynamic strength and peak strain of damaged sandstone increase with the increase of impact pressure and decrease with the increase of damage degree. With the increase of damage degree of sandstone, the reflection energy and dissipation energy of sandstone increase, while the transmission energy decreases.

scholarly journals Energy Dissipation and Failure Characteristics of Layered Composite Rocks under Impact Load

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Wenjie Liu ◽  
Ke Yang ◽  
Wei Zhen ◽  
Xiaolou Chi ◽  
Rijie Xu ◽  
...  
Keyword(s):  
Particle Size ◽  
Energy Dissipation ◽  
Stress Wave ◽  
Shear Failure ◽  
Impact Load ◽  
Layered Composite ◽  
Stress Waves ◽  
Quadratic Functions ◽  
Failure Characteristics ◽  
Rock Samples

Horizontal layered composite rock samples composed of white and black sandstones with large differences in physical and mechanical properties were tested to explore the dynamic characteristics of layered composite rocks under impact load. Using the split Hopkinson pressure bar test system, the dynamic compression tests of two incident states of stress waves, that is, stress waves from white sandstone to black sandstone (W⟶B) and from black sandstone to white sandstone (B⟶W), were designed and carried out under different impact velocities. Combining the ultrahigh-speed photography system and digital photogrammetry for deformation measurement (DPDM), we obtained the stress wave propagation characteristics, failure characteristics, and particle size distribution characteristics of broken rocks of the composite rocks under the two conditions. The experimental results were compared and analyzed, while stresses and strength conditions at the interface of the composite rock samples were theoretically assessed, yielding the following main findings. The energy dissipation pattern of composite rock had an obvious strain rate effect. The reflected energy and fragmentation energy density of composite rock increased approximately as quadratic functions of the incident energy. Affected by the wave impedance matching relationship, the W⟶B and B⟶W samples were significantly different in terms of the stress wave shape, energy dissipation, average particle size, and fractal dimension of the broken rocks at low impact velocities. However, with an increase in the impact velocities, the two gradually shared the same behavior. When composite rock samples deformed and failed, the macrocracks mostly initiated from the white sandstone. When the crack tip stress of the white sandstone at the interface exceeded the strength of the weakened black sandstone, the crack continued to develop through the two-phase rock interface due to the difference in Poisson’s ratios. The damage degrees and failure modes of the two parts of composite rocks were different: black sandstone was prone to tensile splitting with local shear failure, while white sandstone exhibited shear failure with local tensile splitting. The damage degree of white sandstone exceeded that of black sandstone.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

Integrated Flexible Ga 2 O 3 Deep UV Photodetectors Powered by Environmental Electromagnetic Radiation Energy

2021 ◽  
Vol 6 (3) ◽  
pp. 2000945
Author(s):  
Tao Wang ◽  
Huili Liang ◽  
Zuyin Han ◽  
Yanxin Sui ◽  
Zengxia Mei
Keyword(s):  
Electromagnetic Radiation ◽  
Radiation Energy ◽  
Uv Photodetectors ◽  
Deep Uv

scholarly journals Fragmentation Characteristic and Energy Dissipation of Coal under Impact Load

2021 ◽  
Vol 21 (5) ◽  
pp. 04021057
Author(s):  
Xiaohan Yang ◽  
Ting Ren ◽  
Lihai Tan ◽  
Alex Remennikov
Keyword(s):  
Energy Dissipation ◽  
Impact Load

Modeling the kinetic energy dissipation of road system considering actual weather conditions

2019 ◽  
Vol 33 (07) ◽  
pp. 1950073
Author(s):  
Lei Huang ◽  
De-Yong Guan ◽  
Xin-Hong Qiang
Keyword(s):  
Energy Consumption ◽  
Friction Coefficient ◽  
Energy Dissipation ◽  
Kinetic Energy ◽  
Traffic Management ◽  
Weather Conditions ◽  
Flow Speed ◽  
Flow Density ◽  
Cellular Automata Model ◽  
Density Flow

Traffic flow dynamics and energy consumption differs under dissimilar weather conditions, while seldom investigations have been conducted with a cellular automata model. In this paper, the friction coefficient between ground and tire is considered as the quantitative label of weather, a dynamic safe gap based on friction coefficient to avoid rear-end crash is introduced. We developed a safer one-dimensional model to examine the kinetic energy consumption under different weathers. Numerical results show that previous models overestimated the kinetic energy consumption in medium density flow (density [Formula: see text]0.5). In medium flow, speed limit will not reduce energy consumption on rainy and snowy days in most cases, but is necessary for prevention of accidents. Inversely, the effect of speed control on energy consumption is obvious under extreme weather. Our work can promote a better understanding of traffic dynamics, reduce energy dissipation and be applied to real traffic management.

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