Discrete Element Analysis of The Impact of Transition Structure Inside The Drill Tool on Simulated Lunar Soil Mesoscopic Behavior

Abstract Slit dam is an open-check barrier structure widely used in mountainous regions to resist the destructive impacts of granular flows. To examine the dynamics of granular flow impact on slit dams, a numerical study by discrete element method (DEM) is presented in this article. The study considers dry granular materials flowing down a flume channel and interacts with slit dams installed at the lower section of the flume. The particle shape is explicitly considered by particle clumps of various aspect ratios. The slit dams are modeled as rigid and smooth rectangular prisms uniformly spaced at in the flume. Four key stages of granular flow impact on the slit dams have been identified, namely, the frontal impact, run up, pile up, and static deposition stages. In the impact process, the kinetic energy of the granular flow is dissipated primarily by interparticle friction and damping. The trapping efficiency of the slit dams decreases exponentially with the relative post spacing, while it increases with the particle clump aspect ratio. The numerical results can provide new insights into the optimization of relative post spacing for slit dam design.

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Discrete Element Analysis of Friction Coefficient on Granular Accumulation

Advanced Engineering Forum ◽

10.4028/www.scientific.net/aef.2-3.894 ◽

2011 ◽

Vol 2-3 ◽

pp. 894-899

Author(s):

Qin Liang Li ◽

Bin Zhao ◽

Bo Wang ◽

Bang Chun Wen

Keyword(s):

Friction Coefficient ◽

Static Friction ◽

Discrete Element ◽

Rolling Friction ◽

Point Of View ◽

Angle Of Repose ◽

Element Analysis ◽

Dem Analysis ◽

The Impact ◽

Rolling Friction Coefficient

Discrete element method (DEM) is applied to study the granular accumulation problem. Using Herz-Mindlin (no slip) model to simulate particles and container model is also established by software. When the container elevates, the process of granular falling and collision can be ob-served. Detailed analysis of that the impact of static and rolling friction coefficient for particles - particles, particles - flat on angle of repose is accomplished. The variation law is also further val-idated from the energy point of view. The results show that rolling friction has a greater impact on angle of repose than static friction, and rolling friction coefficient among particles play the more prominent role in the two kinds of rolling friction. The research method and results provide a the-oretical reference for the granular movement and DEM analysis.

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Thematic maps in the scientific studies of the moon

Geodesy and Cartography ◽

10.22389/0016-7126-2019-943-1-68-75 ◽

2019 ◽

Vol 943 (1) ◽

pp. 68-75

Author(s):

S.G. Pugacheva ◽

E.A. Feoktistova ◽

V.V. Shevchenko

Keyword(s):

Natural Resources ◽

Thermal Inertia ◽

High Growth ◽

Lunar Soil ◽

Nature Management ◽

The Moon ◽

Surface Cooling ◽

Laser Altimeters ◽

Space Infrastructure ◽

The Impact

The article presents the results of astrophysical studies of the Moon’s reflected and intrinsic radiation. We studied the intensity of the Moon’s infrared radiation and, thus, carried out a detailed research of the brightness temperature of the Moon’s visible disc, estimated the thermal inertia of the coating substance by the rate of its surface cooling, and the degree of the lunar soil fragmentation. Polarimetric, colorimetric and spectrophotometric measurements of the reflected radiation intensity were carried out at different wavelengths. In the article, we present maps prepared based on our measurement results. We conducted theresearch of the unique South Pole – Aitken basin (SPA). The altitude profiles of the Apollo-11 and Zond-8 spacecrafts and the data of laser altimeters of the Apollo-16 and Apollo-15 spacecrafts were used as the main material. Basing upon this data we prepared a hypsometric map of SPA-basing global relief structure. A surface topography map of the Moon’s Southern Hemisphere is given in the article. The topography model of the SPA topography surface shows displacement centers of the altitude topographic rims from the central rim. Basing upon the detailed study of the basin’s topography as well as its “depth-diameter” ratio we suggest that the basin originated from the impact of a giant cometary body from the Orta Cloud. In our works, we consider the Moon as a part of the Earth’s space infrastructure. High growth rates of the Earth’s population, irrational nature management will cause deterioration of scarce natural resources in the near future. In our article, we present maps of the natural resources on the Moon pointing out the most promising regions of thorium, iron, and titanium. Probably in 20 or 40 years a critical mining level of gold, diamonds, zinc, platinum and other vital rocks and metals will be missing on the Earth.

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Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

Biogeosciences ◽

10.5194/bg-12-5871-2015 ◽

2015 ◽

Vol 12 (19) ◽

pp. 5871-5883 ◽

Cited By ~ 7

Author(s):

L. A. Melbourne ◽

J. Griffin ◽

D. N. Schmidt ◽

E. J. Rayfield

Keyword(s):

Climate Change ◽

Finite Element ◽

Structural Integrity ◽

Geometric Model ◽

Algal Growth ◽

Coralline Algae ◽

Rocky Shores ◽

Element Analysis ◽

Scan Data ◽

The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

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Impact Load Buffering Method Based on Stress Wave Attenuation Principle

International Journal of Applied Mechanics ◽

10.1142/s1758825119500194 ◽

2019 ◽

Vol 11 (02) ◽

pp. 1950019 ◽

Cited By ~ 2

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.

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Discrete Element Analysis of High-Pressure Zones of Sea Ice on Vertical Structures

Journal of Marine Science and Engineering ◽

10.3390/jmse9030348 ◽

2021 ◽

Vol 9 (3) ◽

pp. 348

Author(s):

Xue Long ◽

Lu Liu ◽

Shewen Liu ◽

Shunying Ji

Keyword(s):

High Pressure ◽

Sea Ice ◽

Failure Mode ◽

Contact Area ◽

Loading Rate ◽

Discrete Element ◽

Offshore Platforms ◽

Marine Structures ◽

Element Analysis ◽

Ice Pressure

In cold regions, ice pressure poses a serious threat to the safe operation of ship hulls and fixed offshore platforms. In this study, a discrete element method (DEM) with bonded particles was adapted to simulate the generation and distribution of local ice pressures during the interaction between level ice and vertical structures. The strength and failure mode of simulated sea ice under uniaxial compression were consistent with the experimental results, which verifies the accuracy of the discrete element parameters. The crushing process of sea ice acting on the vertical structure simulated by the DEM was compared with the field test. The distribution of ice pressure on the contact surface was calculated, and it was found that the local ice pressure was much greater than the global ice pressure. The high-pressure zones in sea ice are mainly caused by its simultaneous destruction, and these zones are primarily distributed near the midline of the contact area of sea ice and the structure. The contact area and loading rate are the two main factors affecting the high-pressure zones. The maximum local and global ice pressures decrease with an increase in the contact area. The influence of the loading rate on the local ice pressure is caused by the change in the sea ice failure mode. When the loading rate is low, ductile failure of sea ice occurs, and the ice pressure increases with the increase in the loading rate. When the loading rate is high, brittle failure of sea ice occurs, and the ice pressure decreases with an increase in the loading rate. This DEM study of sea ice can reasonably predict the distribution of high-pressure zones on marine structures and provide a reference for the anti-ice performance design of marine structures.

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Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

Acta Geotechnica ◽

10.1007/s11440-020-01119-z ◽

2021 ◽

Author(s):

Antonio Pol ◽

Fabio Gabrieli ◽

Lorenzo Brezzi

Keyword(s):

Mechanical Response ◽

Steel Wire ◽

Discrete Element ◽

Wire Mesh ◽

Steel Plates ◽

Loading Conditions ◽

Element Analysis ◽

In Situ Conditions ◽

Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

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