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dem simulation of granular segregation in two-compartment system under zero gravity

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Chinese Physics B 2017年第4期26卷 238-244页

作者：王文广周志刚宗谨厚美瑛 Key Laboratory of Soft Matter Physics Beijing National Laboratory for Condense Matter PhysicsInstitute of PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences

In this paper,granular segregation in a two-compartment cell in zero gravity is studied numerically by dem *** the simulation using a virtual window method we find a non-monotonic flux,a function which governs the segregation.A parameter is used to quantify the *** effect of three parameters：the total number of particles N,the excitation strength F,and the position of the window coupling the two compartments,on the segregation and the waiting time%are *** is found that the segregation observed in zero gravity exists and does not depend on the excitation strength *** waiting time T,however,depends strongly on F：the higher the F,the lower the waiting time V,The simulation results are important in guiding the SJ-10 satellite microgravity experiments.

关键词： dem simulation granular gas microgravity segregation

Quantitative Analysis of Discharging Speed of a Horizontally Rotating Drum with Internal Baffles by Using dem simulation

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Quantitative Analysis of Discharging Speed of a Horizontally...

Quantitative Analysis of Blending Speed of a Horizontally Rotating Drum with Internal Baffles by Using dem simulation

作者： Zhongke Tian Haiyong Yu Congcong Han College of Electromechanical Engineering Qingdao University of Science and Technology

Although the concept seems simple,the motion of bulk materials in a rotating drum is rather *** this paper,the process of throwing the evenly mixed materials out of a horizontally rotating mixing tank with internal baffles was *** reasonable rotary speeds for the discharging process as well as the ideal process durations were quantitatively determined by running simulations based on the Discrete Element Method（dem） software PFC3 *** particle-counting codes,developed in PFC3 D built-in programming language FISH,took important roles in evaluating the corresponding effects of different process parameters,which overcame the uncertainty of usual qualitative analysis of simulation results.

关键词： Rotating drum Internal baffles Discharging process dem simulation

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Quantitative Analysis of Blending Speed of a Horizontally Ro...

Kinetic model of vibration screening for granular materials based on biological neural network

作者： Zhong-ke TIAN Cong-cong HAN Hai-yong YU College of Electromechanical Engineering Qingdao University of Science and Technology

How to get the best uniformity in the shortest time has always been a hot and difficult point in the quantitative analysis of bulk mixing process using rotating drum. With the advent of Discrete Element Method（dem）, the mixing behavior of particle material in blender has been extensively studied these years. In this paper, the reasonable rotary speeds for blending process as well as the ideal process durations of a horizontally rotating drum with internal baffles in batch mode are quantitatively determined by running simulations based on dem software PFC3D. The particle-counting codes, developed in PFC3D built-in programming language FISH, take important roles in evaluating the corresponding effects of different process parameters, which overcomes the uncertainty of usual qualitative analysis of simulation results.

关键词： Rotating drum Internal baffles Blending process dem simulation

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Particuology 2024年第5期88卷 98-106页

作者： Zhan Zhao Yan Zhang Fang Qin Mingzhi Jin School of Agricultural Engineering Jiangsu UniversityZhenjiang212013China Shandong Academy of Agricultural Machinery Sciences Ji'nan250100China

The kinetic model is the theoretical basis for optimizing the structure and operation performance of vibration screening *** this paper,a biological neurodynamic equation and neural connections were established according to the motion and interaction properties of the material under vibration *** material feeding to the screen and the material passing through apertures were considered as excitatory and inhibitory inputs,respectively,and the generated stable neural activity landscape was used to describe the material distribution on the 2D screen *** dynamic process of material vibration screening was simulated using discrete element method(dem).By comparing the similarity between the material distribution established using biological neural network(BNN)and that obtained using dem simulation,the optimum coefficients of BNN model under a certain screening parameter were determined,that is,one relationship between the BNN model coefficients and the screening operation parameters was *** screening parameters were randomly selected,and the corresponding relationships were established as a ***,with straw/grain ratio,aperture diameter,inclination angle,vibration strength in normal and tangential directions as inputs,five independent adaptive neuro-fuzzy inference systems(ANFIS)were established to predict the optimum BNN model coefficients,*** training results indicated that ANFIS models had good stability and *** flexibility and adaptability of the proposed BNN method was demonstrated by modeling material distribution under complex feeding conditions such as multiple regions and non-uniform rate.

关键词： Kinetic model Material distribution Vibration screening Biological neural network dem simulation Adaptive neuro-fuzzy inference systems

Constitutive relations for the shear band evolution in granular matter under large strain

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Particuology 2008年第6期6卷 501-505页

作者： Stefan Luding Multi Scale Mechanics TS CTW UTwente P.O. Box 217 7500 AE Enschede Netherlands

A so-called ＂split-bottom ring shear cell＂ leads to wide shear bands under slow, quasi-static deformation. Unlike normal cylindrical Couette shear cells or rheometers, the bottom plate is split such that the outer part of it can move with the outer wall, while the other part （inner disk） is immobile. From discrete element simulations （dem）, several continuum fields like the density, velocity, deformation gradient and stress are computed and evaluated with the goal to formulate objective constitutive relations for the powder flow behavior. From a single simulation, by applying time- and （local） space-averaging, a non-linear yield surface is obtained with peculiar stress dependence. The anisotropy is always smaller than the macroscopic friction coefficient. However, the lower bound of anisotropy increases with the strain rate, approaching the maximum according to a stretched exponential with a specific rate that is consistent with a shear path of about one particle diameter.

关键词： Ring shear cell Shear bands dem simulation Micro-macro transition Objective constitutive relations Yield stress fluid

Discrete numerical modeling of granular materials considering crushability

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Journal of Mountain Science 2017年第4期14卷 758-770页

作者： QIAN Jian-gu GU Jian-bo GU Xiao-qiang HUANG Mao-song Key Laboratory of Geotechnieal and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Department of Geotechnical Engineering Tongji UniversityShanghai 200092China

The aim of this study is to numerically investigate the influence of particle breakage on the mechanical behavior of granular materials using a discrete element method(dem). To enable particle crushing, non-crushable elementary particles are boned together to represents the granular aggregates which can be crushed when the external force exceeds its strength. The flaw of the aggregate was also modeled by randomly distributed void. Single particle crushing tests were carried out to determine the distribution of particle strength. The results of single particle crushing tests illustrate that the simulated single particle fracture strength and pattern agree well with the Weibull's distribution *** oedometer tests, drained monotonic and cyclic triaxial tests were also carried out to investigate the crushing of the aggregates and the associated mechanical behaviors. The effect of confining pressure on the crushing of aggregates and the mechanical behavior was also analyzed. It was found that the peak stress and dilation decrease significantly when particle crushing was *** deformation behavior of the specimen is essentially controlled by two factors: particle rearrangement-induced dilation and particle crushing-induced contraction. The increase of permanent strain and the reduction of dilation were observed during cyclic loading and they tend to reach a stable state after a certain number of cycles. The crushing of aggregate is most significant in the first two cycles. The results also indicated that for the same axial strain the volumetric strain and the bound breakage in the cyclic loading tests are significantly larger than that in the monotonic loading tests,especially at high cyclic stress ratio.

关键词： dem simulation Granular materials Crushing Monotonic and Cyclic triaxial test

COLLISION PROCESS DETAILS CONTROL THE HYDRODYNAMICS AND HEAT TRANSFER IN FLUIDIZED BED REACTORS

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China Particuology 2005年第1期3卷 18-18页

作者： Masayuki Horio Department of Chemical Engineering Tokyo University of Agriculture and Technology Koganei Tokyo 184-8588 Japan

In the '90s dem simulation research was successful in exploring its potential in the simulation of fluidization phenomena and in its application to the design of fluidized-bed processes. Nevertheless, not much progress has been made regarding the realistic treatment of collision processes that are critical in determining macroscopic mode of fluidization. All through the second half of the '90s, the author investigated/demonstrated the issue by introducing different surface interactions caused by formation of liquid and/or solid bridges, van der Waals force and the existence of surface roughness. In the first part of the presentation these are to be summarized and the tasks remaining are discussed. In the second part, are presented the results from a newly developed force-deformation meter to demonstrate the significance of the surface roughness and its elasto-plastic characteristics.

关键词： FLUIDIZED BED surface roughness different surface dem simulation mode of