scholarly journals Simulation of Motion Behavior of Concrete in Pump Pipe by DEM

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Ji Hao ◽  
Caiyun Jin ◽  
Yue Li ◽  
Zigeng Wang ◽  
Jianglin Liu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Coarse Aggregate ◽  
Flow Behavior ◽  
Static Friction ◽  
Rolling Friction ◽  
Pumping Test ◽  
Movement Trajectory ◽  
Test Results ◽  
Aggregate Gradation ◽  
Dem Model

In this paper, the mesocalibration test was used to measure the contact parameters (restitution coefficient, rolling friction coefficient, static friction coefficient, and surface energy) between coarse aggregate particles and mortar particles in Discrete Element Method (DEM) model of concrete. Then, the DEM model of concrete slump was established according to the coarse aggregate gradation to study the flow behavior of coarse aggregate in fresh concrete. The slump test result was compared with the output of the slump DEM model with high consistent, indicating the promising reliability of the mesocalibration test. Finally, based on the mesocalibration test results, the DEM model of pumping concrete was established. It was obtained that the pumping pressure calculated by the numerical model was similar to that of the pumping test with satisfactory accuracy better than the concrete pumping pressure calculated according to the rheological test results of concrete and lubricating layer. On this basis, the movement trajectory of coarse aggregate in the pump pipe was analyzed and the influence of coarse aggregate on the pumping performance of concrete was revealed.

scholarly journals ANALYSIS AND CALIBRATION OF QUINOA GRAIN PARAMETERS USED IN A DISCRETE ELEMENT METHOD BASED ON THE REPOSE ANGLE OF THE PARTICLE HEAP

2020 ◽  
Vol 61 (2) ◽  
pp. 77-86 ◽  
Author(s):  
Fei Liu ◽  
Dapeng Li ◽  
Tao Zhang ◽  
Zhen Lin
Keyword(s):  
Friction Coefficient ◽  
Discrete Element Method ◽  
Static Friction ◽  
Rolling Friction ◽  
Optimal Parameters ◽  
Dem Simulation ◽  
Static Friction Coefficient ◽  
Dem Model ◽  
Rolling Friction Coefficient ◽  
Element Method

An optimization method based on a regression model was established by combining physical experiments, and an extended distinct element method (EDEM) simulation was proposed to address the difficult problem of obtaining the contact characteristic parameters used in the discrete element method (DEM) model of quinoa grains and for calibrating the parameters of the quinoa DEM model. The Plackett-Burman test was designed using Design-Expert software to screen the parameters of the quinoa DEM model, and the quinoa-quinoa static friction coefficient, quinoa-polylactic acid (PLA) static friction coefficient and quinoa-quinoa rolling friction coefficient were found to have significant effects on the repose angle. The optimal value intervals of the parameters with a significant impact on the repose angle were determined using the steepest ascent test. A regression model of the repose angle and the parameters with a significant impact on the repose angle was then established with the Box-Behnken design and further optimized, and the combination of optimal parameters was as follows: 0.26 for the quinoa-quinoa static friction coefficient (E), 0.38 for the quinoa-PLA static friction coefficient (F), and 0.08 for the quinoa-quinoa rolling friction coefficient (G). Lastly, the optimal combination was used in the verification performed by the DEM simulation, and the error between the simulated repose angle and the target repose angle was 0.86%. These findings indicated that it was feasible to use the response surface optimization to calibrate the parameters required for quinoa DEM simulation and that the combination of optimal parameters can provide a reference for selecting the characteristic contact parameters used in quinoa DEM simulation.

scholarly journals Calibration of the Discrete Element Method Parameters in Living Juvenile Manila Clam (Ruditapes philippinarum) and Seeding Verification

2021 ◽  
Vol 3 (4) ◽  
pp. 894-906
Author(s):  
Hangqi Li ◽  
Guochen Zhang ◽  
Xiuchen Li ◽  
Hanbing Zhang ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Discrete Element Method ◽  
Static Friction ◽  
Discrete Element ◽  
Rolling Friction ◽  
Manila Clam ◽  
Average Error ◽  
Verification Test ◽  
Dem Model ◽  
Element Method

The Manila Clam is an important economic shellfish in China’s seafood industry. In order to improve the design of juvenile Manila Clam seeding equipment, a juvenile clam discrete element method (DEM) particle shape was established, which is based on 3D scanning and EDEM software. The DEM contact parameters of clam-stainless steel, and clam-acrylic were calibrated by combining direct measurements and test simulations (slope sliding and dropping). Then, clam DEM simulation and realistic seeding tests were carried out on a seeding wheel at different rotational speeds. The accuracy of the calibrated clam DEM model was evaluated in a clam seeding verification test by comparing the average error of the variation coefficient between the realistic and simulated seeding tests. The results showed that: (a) the static friction coefficients of clam-acrylic and clam-stainless steel were 0.31 and 0.23, respectively; (b) the restitution coefficients of clam-clam, clam-acrylic, and clam-stainless steel were 0.32, 0.48, and 0.32, respectively. Furthermore, the results of the static repose angle from response surface tests showed that when the contact wall was acrylic, the coefficient rolling friction and static friction of clam-clam were 0.17 and 1.12, respectively, and the coefficient rolling friction of clam-acrylic was 0.20. When the contact wall was formed of stainless steel, the coefficient rolling friction and static friction of clam-clam were 0.33 and 1.25, respectively, and the coefficient rolling friction of clam-stainless steel was 0.20. The results of the verification test showed that the average error between the realistic and simulated value was <5.00%. Following up from these results, the clam DEM model was applied in a clam seeding simulation.

Two-step validation process of particle mixing in a centrifugal mixer with vertical axis

2016 ◽  
Vol 232 (1) ◽  
pp. 29-37
Author(s):  
Matej Zadravec ◽  
Blaž Orešnik ◽  
Matjaž Hriberšek ◽  
Jure Marn
Keyword(s):  
Numerical Simulation ◽  
Friction Coefficient ◽  
Numerical Simulations ◽  
Static Friction ◽  
Vertical Axis ◽  
Rolling Friction ◽  
Angle Of Repose ◽  
Discrete Elements ◽  
Power Characteristics ◽  
Centrifugal Mixer

Two-step approach of validation is proposed to validate a numerical model, capable of accurate prediction of mixing power characteristics of a centrifugal mixer with vertical axis. Two sets of experiments and two sets of numerical simulations are presented—the first set to determine physical characteristics of the particles comparing the numerical simulations results with experimental data, and the second set to validate predicted behavior of anchor type vertical axis impeller for mixing of same particles. Zeolite particles were used for actual calculations. After determining shear modulus, coefficient of interaction, static friction coefficient, and rolling friction coefficient through optimization process based on numerical simulations with subject function of diameter and angle of repose derived from experiment, using these values in numerical simulation of impeller mixer mixing zeolite particles led to results, which were in good agreement with results of the second set of experiments. The obtained zeolite material parameter values can therefore serve as a solid basis for discrete elements method based numerical simulation of zeolite granular materials.

Calibration and Experimental Validation of Contact Parameters for Oat Seeds for Discrete Element Method Simulations

2021 ◽  
Vol 37 (4) ◽  
pp. 605-614
Author(s):  
Lingxin Geng ◽  
Jiewen Zuo ◽  
Fuyun Lu ◽  
Xin Jin ◽  
Chenglong Sun ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Discrete Element Method ◽  
Static Friction ◽  
Discrete Element ◽  
Rolling Friction ◽  
Angle Of Repose ◽  
Static Friction Coefficient ◽  
Contact Parameters ◽  
Rolling Friction Coefficient ◽  
Element Method

Highlights The static friction coefficient and rolling friction coefficient of oat seeds were calibrated by the discrete element method. Two representative oat varieties were selected. The hollow cylinder method and sidewall collapse method were used together to reduce the test error. Abstract . Hulless and shelled oat are two types of oat with major differences in physical appearance. To study the contact parameters between the two different oat seed types, these parameters were delineated with the discrete element method and graphic image processing technology. Using plexiglass as the contact material, the experiments used two different angle of repose measurement methods—hollow cylinder and collapse sidewall devices, to perform bench and simulation experiments on the two different oats. Under different measurement methods, bench experiments measured the angles of repose of the two oat seed types at 33.19°, 33.82° and 22.45°, 23.57°; the static friction coefficient and rolling friction coefficient were the experimental factors, and the angle of repose was the experimental indicator in the simulation. The steepest climbing experiment determined the optimal range of the experimental factor, and the regression equation between the static friction coefficient, rolling friction coefficient and angle of repose was established by a quadratic orthogonal rotation combination experiment. Finally, the angles of repose measured by the bench experiment with the two different measurement methods were treated as target values, the coefficient of static friction and the coefficient of rolling friction were solved; the coefficient of static friction between hulless oats was 0.36, and the coefficient of rolling friction between hulless oats was 0.052; the coefficient of static friction between shelled oats was 0.24, and the coefficient of rolling friction between shelled oats was 0.036. The obtained contact parameters between seeds were input into EDEM, the simulation and bench experiment results were verified. The difference between the simulation results and the actual values was within 3%. The angle of repose of oats after calibration was close to the actual situation, and the calibration results had high reliability and provided a referencefor the measurement of contact parameters between other agricultural crop seeds. Keywords: Calibration, Contact parameters, Discrete element method, Oat.

Experimental Research on the Influence of Pebble Aggregate Gradation on Concrete Strength

2013 ◽  
Vol 438-439 ◽  
pp. 179-182
Author(s):  
Xiu Hai Yin ◽  
Ling Lu
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Experimental Research ◽  
Bending Strength ◽  
Coarse Aggregate ◽  
Concrete Strength ◽  
Test Results ◽  
Aggregate Gradation ◽  
Cement Ratio ◽  
Maximal Size

By changing the grading of pebble and water cement ratio, the influence of pebble grading on the compressive strength and flexural strength of concrete is studied at the same pebble content. Test results show that the compression strength and bending strength of concrete decrease with the increasing of the maximal size of coarse aggregate, while the maximal size (Dmax) of pebble aggregate achieves 10mm, 20mm, 40mm and 60mm. And concrete strength decreases significantly when Dmax is 60mm. Meanwhile, the influence of aggregate gradation is obviously with the increase of age time.

Determination of the friction coefficient of coal particles by discrete element simulation and experimentation

2020 ◽  
Author(s):  
Jinrong CHAI ◽  
Shifeng WANG ◽  
Zihao ZHOU ◽  
Guohua LI ◽  
Xunan LIU
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Static Friction ◽  
Discrete Element ◽  
Rolling Friction ◽  
Angle Of Repose ◽  
Discrete Element Simulation ◽  
Element Simulation ◽  
Coal Particles ◽  
Rolling Friction Coefficient

Abstract The friction coefficient of coal is the main factor influencing the results of discrete element simulation. In this study, the friction coefficient of coal was determined using a self-made testing instrument for measuring the static friction coefficient and an automatic cylinder lifting device on the basis of discrete element simulation, image processing, and orthogonal testing. The correlations between the angle of repose of coal particles, the rolling friction coefficient between coal particles, and the rolling friction coefficient between the coal particles and stainless steel were evaluated by linear regression analysis. Results indicated that the dependent variable (angle of repose of coal particles) was linearly correlated to the two independent variables (rolling friction factor between the coal particles, as well as the rolling friction factor between the coal and the stainless steel). The angle of repose of the coal particles was largely affected by the rolling friction coefficient between the coal particles but not by the rolling friction coefficient between the coal particle and stainless steel. Moreover, the static friction coefficient between the coal particles was 0.53, and that between the coal particle and the stainless steel was 0.38. The rolling friction coefficient between the coal particles was 0.048, and that between the coal particles and the stainless steel was 0.03. These friction coefficients were used to simulate the bottomless cylinder test of the coal particles. The angle of repose in the simulation test was 30.77°, whereas that in the real test was 31.47°; the relative error was 2.22%. Therefore, no significant difference in the results was indicated between the simulation test and the real test, verifying the effectiveness of the method used to determine friction coefficients. The aforementioned technique can be applied to determine the friction coefficient of lump coal particles.

scholarly journals Discrete Element Analysis of Friction Coefficient on Granular Accumulation

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.

The Effect of Coarse Aggregate Gradation Degradation on the Mechanical Behavior of Asphalt Mixture

2013 ◽  
Vol 811 ◽  
pp. 223-227
Author(s):  
Yong Ye ◽  
Hong Kai Chen ◽  
Yi Zhou Cai
Keyword(s):  
Compressive Strength ◽  
Creep Behavior ◽  
Coarse Aggregate ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Test Results ◽  
Creep Tests ◽  
Aggregate Gradation ◽  
Coarse Aggregates ◽  
Static Creep

The objective of this study is to investigate and evaluate the effect of coarse aggregates (aggregate size bigger than 2.36 mm) on the compressive strength and creep behavior of asphalt mixture. The variable that is mainly considered in the study is the gradation degradation of coarse aggregates. A kind of standard aggregate gradation and three kinds of degraded aggregate gradation mixture specimens are used. Uniaxial compression and static creep tests were realized at different loading conditions and temperatures. The test results on asphalt mixture showed that the compressive strength and creep behavior of asphalt mixture are significant affected by the different coarse aggregate gradations.

scholarly journals Calibration of the Interaction Parameters between the Proppant and Fracture Wall and the Effects of These Parameters on Proppant Distribution

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2099
Author(s):  
Mingzhong Li ◽  
Chunting Liu ◽  
Guodong Zhang
Keyword(s):  
Friction Coefficient ◽  
Critical Role ◽  
Three Dimensional ◽  
Static Friction ◽  
Calibration Method ◽  
Rolling Friction ◽  
Interaction Parameters ◽  
Wall Roughness ◽  
Proppant Transport ◽  
Equilibrium Height

Saltation and reputation (creep) dominate proppant transport rather than suspension during slickwater fracturing, due to the low sand-carrying capacity of the slickwater. Thus, the interaction parameters between proppants and fracture walls, which affect saltation and reputation, play a more critical role in proppant transport. In this paper, a calibration method for the interaction parameters between proppants and walls is built. A three-dimensional coupled computational fluid dynamics–discrete element method (CFD–DEM) model is established to study the effects of the interaction parameters on proppant migration, considering the wall roughness and unevenly distributed diameters of proppants. The simulation results show that a lower static friction coefficient and rolling friction coefficient can result in a smaller equilibrium height of the sand bank and a smaller build angle and drawdown angle, which is beneficial for carrying the proppant to the distal end of the fracture. The wall roughness and the unevenly distributed diameter of the proppants increase the collision between proppant and proppant or the wall, whereas the interactions have little impact on the sandbank morphology, slightly increasing the equilibrium height of the sandbank.

scholarly journals Simulation of the Flowability of Fresh Concrete by Discrete Element Method

2021 ◽  
Vol 7 ◽  
Author(s):  
Yue Li ◽  
Ji Hao ◽  
Caiyun Jin ◽  
Zigeng Wang ◽  
Jianglin Liu
Keyword(s):  
Friction Coefficient ◽  
Discrete Element Method ◽  
Fresh Concrete ◽  
Flow Behavior ◽  
Ring Test ◽  
Slump Test ◽  
Slump Flow ◽  
Dem Model ◽  
Flow Stage ◽  
Contact Parameters

The discrete element method (DEM) was used to establish the slump model and J-Ring model of concrete to describe the flow behavior in the slump test and J-Ring test. Then, the contact parameters of particle-particle and particle-geometry for the concrete DEM model, including restitution coefficient, rolling friction coefficient, static friction coefficient, and surface energy, were measured. In order to avoid the influence of the shape and size of the aggregate, this paper used high-precision glass spheres as the aggregate of the concrete for meso-calibration test, slump test, and J-Ring test. Comparing the simulation results of DEM model with slump test result, a very high agreement between the initial stage, the rapid flow stage, and the slow flow stage of the slump flow–time curve can be found as well as the final slump and slump flow. Moreover, similar to the slump DEM model, the DEM models of J-Ring test, V-funnel test, and U-channel test were established to study the passing ability and filling ability of concrete with outstanding accuracy. Therefore, the concrete DEM model with contact parameters and JKR model can be adopted to study the flow behavior of the fresh concrete.

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