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.

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.

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.

Research on the Joint of Concrete-Filled Steel Tubular Column and Steel Beam

2013 ◽  
Vol 351-352 ◽  
pp. 174-178
Author(s):  
Ying Zi Yin ◽  
Yan Zhang
Keyword(s):  
Energy Dissipation ◽  
Failure Mechanism ◽  
Compression Ratio ◽  
Seismic Behavior ◽  
Strength Degradation ◽  
Steel Beam ◽  
Failure Characteristics ◽  
Static Test ◽  
Axial Compression Ratio ◽  
Energy Dissipation Capacity

With the pseudo-static test of 4 concrete-filled square steel tubular column and steel beam joint with outer stiffened ring, this paper discusses the failure characteristics, failure mechanism and seismic behavior of joints under different axial compression ratio. The analysis of the testing results shows: when reached the ultimate strength, the strength degradation and stiffness degradation of joints are slowly and the ductility is also good, the energy dissipation capacity of joints is much better.

Propagation velocity model of stress waves in larch wood (Larix gmelinii) three-dimensional space with different moisture contents

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6680-6695
Author(s):  
Xiwen Wei ◽  
Liping Sun ◽  
Hongjv Zhou ◽  
Yang Yang ◽  
Yifan Wang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wave Velocity ◽  
Stress Wave ◽  
Propagation Velocity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Stress Waves ◽  
Moisture Contents ◽  
Direction Angle ◽  
Stress Wave Velocity

Based on the effects of stress wave propagation in larch (Larix gmelinii) wood, the propagation mechanism of stress wave was explored, and a theoretical model of the propagation velocity of stress waves in the three-dimensional space of wood was developed. The cross and longitudinal propagation velocities of stress wave were measured in larch wood under different moisture contents (46% to 87%, 56% to 96%, 20% to 62%, and 11% to 30%) in a laboratory setting. The relationships between the propagation velocity of stress waves and the direction angle or chord angle with different moisture contents were analyzed, and the three-dimensional regression models among four parameters were established. The analysis results indicated that under the same moisture content, stress wave velocity increased as the direction angle increased and decreased as chord angle increased, and the radial velocity was the largest. Under different moisture contents, stress wave velocity gradually decreased as moisture content increased, and the stress wave velocity was more noticeably affected by moisture content when moisture content was below the fiber saturation point (FSP, 30%). The nonlinear regression models of the direction angle, chord angle, moisture content, and the propagation velocity of stress wave fit the experiment data well (R2 ≥ 0.97).

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

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.

scholarly journals Comparative Analysis of the Energy Dissipation of Steel Buildings with Concentric and Eccentric Braces

2015 ◽  
Vol 9 (1) ◽  
pp. 295-307 ◽  
Author(s):  
Edelis del V. Marquez A. ◽  
William Lobo-Q ◽  
Juan C. Vielma
Keyword(s):  
Energy Dissipation ◽  
Shear Failure ◽  
Numerical Models ◽  
Deformation Energy ◽  
Seismic Zone ◽  
Deformation Capacity ◽  
Building Structures ◽  
Steel Buildings ◽  
High Deformation ◽  
Energy Dissipation Capacity

A comparative study has been done to analyze the behavior of regular steel building structures of 4, 6, 8 and 10 stories, located in seismic zone 5 and soil type S1. The structures were upgraded with different brace configurations according to current Venezuelan codes. A total number of 24 numerical models were analyzed considering non-linear static and incremental dynamic analysis (IDA). The buildings were initially designed as moment resisting frames, and upgraded with six different bracing configurations: concentric braces in “X” and inverted “V”; eccentric braces inverted "V" with horizontal links, inverted “Y” and “X” with vertical links. Short length links were used to ensure a shear failure. The used methodology is based on obtaining the capacity, IDA curves, and bilinear approximations of these curves that allow the determination of yield and ultimate capacity points, in order to estimate important parameters of seismic response: overstrength and ductility; and considering these areas under the curves to estimate elastic deformation energy, energy dissipated by hysteretic damping and equivalent damping. According to the results, the cases with no brace enhancement showed the lowest lateral strength and lateral stiffness and high deformation capacity. On the other hand, the concentric bracing cases, resulted with the highest stiffness and strength and the lowest deformation capacity, therefore they have low ductility and energy dissipation capacity under seismic loading. Structures with links showed intermediate stiffness and strengths, resulting in the best performance in terms of ductility and energy dissipation capacity. The present study provides a better understanding of the benefits of eccentrically braced systems.

scholarly journals Experimental study on deformation and failure characteristics of discontinuous prefabricated fractured tuff

2019 ◽  
Vol 16 (5) ◽  
pp. 862-874
Author(s):  
Yang Song ◽  
Heping Wang ◽  
Meng Ren
Keyword(s):  
Shear Failure ◽  
Failure Process ◽  
Dissipated Energy ◽  
Uniaxial Compression Test ◽  
Tensile Shear ◽  
Joint Spacing ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Peak Intensity ◽  
Dip Angle

Abstract To study more fully the characteristic law of deformation and failure of tuff jointed rock mass of prefabricated parallel discontinuous joint test specimens, the uniaxial compression test was used. The stress–strain curve, peak intensity, deformation parameters, energy characteristics, etc., of the rock test specimens were systematically studied under different combinations of joint dip angle and joint spacing. The research found that: (1) during the failure process of tuff, the peak intensity and elastic modulus followed a U-shaped change pattern and the minimum value was reached when α = 60°; (2) the fracture modes of test specimens with different joint dip angles were different. When α = 30° and 45°, failure characteristics were mixed modes of tensile or tensile shear failure. When α = 60°, failure characteristics were shear. At α = 75°, the failure characteristic was tensile shear failure. (3) The absorbed and dissipated energy of the rock increased nonlinearly at each stage of deformation. (4) We quantified rock energy damage through a correlation between dissipated energy and absorbed energy of the rock in the process of energy evolution, and obtained an evolution of the relationship between the dissipated energy ratio, crack dip angle and crack spacing. Based on different fracture distribution methods and according to the strain equivalence principle, the constitutive equation of the pre-peak rock damage was obtained.

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