Implementation of Charged Particle Behavior in Discrete Element Method (DEM) Simulations

2021 ◽  
Author(s):  
James R. Phillips ◽  
Hao Wang ◽  
Alexander Hillegass ◽  
Annelisa Esparza ◽  
Adrienne R. Dove ◽  
...  
Keyword(s):  
Charged Particle ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Particle Behavior ◽  
Dem Simulations ◽  
Element Method

scholarly journals A Discrete Element Method Study of Solids Stress in Cylindrical Columns Using MFiX

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 60
Author(s):  
Filippo Marchelli ◽  
Renzo Di Felice
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Solid Particles ◽  
Static System ◽  
Bottom Pressure ◽  
Filling Rate ◽  
Dem Simulations ◽  
Source Program ◽  
Detailed Assessment ◽  
Element Method

Friction phenomena play a key role in discrete element method (DEM) modeling. To analyze this aspect, we employed the open-source program MFiX to perform DEM simulations of cylindrical vertical columns filled with solid particles. These are still associated with and described by the pioneering model by the German engineer H.A. Janssen. By adapting the program’s code, we were able to gather numerous insights on the stress distribution within the solids. The column was filled with different amounts of solids and, after the system had stabilized, we assessed the pressure in the vertical and radial directions and the distribution of the friction force for all particles. An analysis of the bottom pressure for varying particle loads allowed us to infer that the program can correctly predict the expected asymptotical behavior. After a detailed assessment of the behavior of a single system, we performed a sensitivity analysis taking into account several of the variables employed in the simulations. The friction coefficient and filling rate seem to affect the final behavior the most. The program appears suitable to describe friction phenomena in such a static system.

scholarly journals Discrete Element Method Modelling of the Diametral Compression of Starch Agglomerates

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 932
Author(s):  
Józef Horabik ◽  
Joanna Wiącek ◽  
Piotr Parafiniuk ◽  
Mateusz Stasiak ◽  
Maciej Bańda ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Potato Starch ◽  
Discrete Element ◽  
Contact Model ◽  
Ductile Material ◽  
Diametral Compression ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Dem Simulations ◽  
Element Method

Starch agglomerates are widely applied in the pharmaceutical, agricultural, and food industries. The formation of potato starch tablets and their diametral compression were simulated numerically and verified in a laboratory experiment to analyse the microscopic mechanisms of the compaction and the origins of their breakage strength. Discrete element method (DEM) simulations were performed using EDEM software. Samples comprised of 120,000 spherical particles with radii normally distributed in the range of 5–36 μm were compacted in a cylindrical die with a diameter of 2.5 cm. The linear elastic–plastic constitutive contact model with a parallel bonded-particle model (BPM) was used to model the diametral compression. DEM simulations indicated that the BPM, together with the linear elastic–plastic contact model, could describe the brittle, semi-brittle, or ductile breakage mode, depending on the ratio of the strength to Young’s modulus of the bond and the bond-to-contact elasticity ratio. Experiments confirmed the findings of the DEM simulations and indicated that potato starch (PS) agglomerates can behave as a brittle, semi-brittle, or ductile material, depending on the applied binder. The PS agglomerates without any additives behaved as a semi-brittle material. The addition of 5% of ground sugar resulted in the brittle breakage mode. The addition of 5% gluten resulted in the ductile breakage mode.

Ballast Support Condition Affecting Crosstie Performance Investigated Through Discrete Element Method

2018 ◽  
Author(s):  
Wenting Hou ◽  
Bin Feng ◽  
Wei Li ◽  
Erol Tutumluer
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Force Transmission ◽  
Support Condition ◽  
Normal Stress Distribution ◽  
Binding Condition ◽  
Polyhedral Particles ◽  
Dem Simulations ◽  
Support Conditions ◽  
Element Method

This paper reports on the ballast layer mesoscale behavior, tie-ballast interaction, and ballast-subgrade interaction under five crosstie support conditions, namely full support, lack of rail seat support, lack of center support, high center binding, and severe center binding condition. Discrete Element Method, an effective technique to study particulate natured unbound aggregate materials, i.e., ballast, was adopted in this study. The DEM simulations included one-tie spacing geometry, approximately 11,000 polyhedral particles. The ballast gradation used in DEM models was according to the AREMA No. 3 and No. 4A specifications. The shape properties of ballast particles in DEM models was consistent with field collected samples. The pressure distributions along tie-ballast interface under rail seat load of 10-kips predicted by DEM simulations were in good agreement with the results backcalculated from laboratory tests, which validated the DEM models. Next, DEM simulations considered rail seat loads of 20-kips and 25-kips. The predicted results indicated that support condition is a key factor for predicting normal stress distribution and force transmission within ballast layer. Ballast particles in shoulders and areas with poor support indicated low or negligible contact stresses. Extremely high normal stresses observed in some support conditions often exceeded single particle crushing load limit and thus would cause ballast particle breakage and layer degradation under repeated loading. Further, the tie-ballast pressure captured in some scenarios could be higher than allowable maximum pressure of 85-psi under concrete tie in AREMA standard. Finally, the pressure at bottom of the ballast layer obtained from the DEM simulations were compared with top of subgrade pressure calculated from analytical/empirical equations such as Talbot equation and AREMA manual.

scholarly journals Comparisons of Inter-tablet Coating Variability under Different Tablet Shapes and Filling Levels by Using DEM Simulations

2018 ◽  
Vol 238 ◽  
pp. 04008
Author(s):  
Qiushuang Zhang ◽  
Hui Wan ◽  
Bin Jian ◽  
Guoming Hu
Keyword(s):  
Discrete Element Method ◽  
Coating Thickness ◽  
Discrete Element ◽  
Tablet Coating ◽  
Dem Simulations ◽  
Spherical Surfaces ◽  
Thickness Variability ◽  
Coating Mass ◽  
Contact Models ◽  
Element Method

The purpose of this paper is to investigate inter-tablet coating thickness variability based on different tablet shapes and filling levels. To achieve this goal, the Discrete Element Method (DEM) is applied, and efforts are made as following: For the first step, four different tablet shapes, referred to as Sphere, SRC (Standard Round Concave), Oval and Triangular, are built by importing three (except Sphere) CAD templates to create one or more spherical surfaces. Furthermore, a spray zone in the coating pan is presented to monitor the change of the “coating mass”, by virtue of which we calculate the inter-tablet coating variability. And to complete this work, custom contact models and properties are created to describe coating. Then, three different filling levels are added to the simulation. Eventually, the compared results are analyzed between three diverse filling degrees among tablet particles with four discrepant shapes.

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