EDEM TUTORIAL

EDEM Tutorial: Conveyor Simulation

EDEM Tutorial: Conveyor

Copyrights and Trademarks ©

Copyright 2014 DEM Solutions. All rights reserved.

Information in this document is subject to change without notice. The software described in this document is furnished under a license agreement or nondisclosure agreement. The software may be used or copied only in accordance with the terms of those agreements. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or any means electronic or mechanical, including photocopying and recording for any purpose other than the purchaser’s personal use without written permission.

DEM Solutions 49 Queen Street Edinburgh EH2 3NH UK

www.dem-solutions.com

®

EDEM incorporates CADfix translation technology. CADfix is owned, supplied by © and Copyright TranscenData Europe Limited, 2007. All Rights Reserved. This software is based in part on the work of the Independent JPEG Group. EDEM uses the Mersenne Twister © random number generator, Copyright 1997 - 2002, Makoto Matsumoto and Takuji Nishimura, All rights reserved. EDEM includes CGNS (CFD General Notation System) software. See the Online Help for full copyright notice.

®

®

®

®

®

EDEM EDEM Creator , EDEM Simulator , EDEM Analyst and Particle Factory are registered trademarks of DEM Solutions. All other brands or product names are the property of the respective owners.

Page 2 of 19


Introduction Through this introductory tutorial we can learn how to set-up and analyze an EDEM simulation. The exercise is directed at beginners to get a basic understanding of the software. The model used here is a conveyor belt that transports material to a hopper. The main focus in on: 

Creation of materials for Particles and Geometry.



Creation of Particles with a User Defined Size distribution



Creation a Particle Prototype from multiple spheres. The multi-sphere particle shape is defined using particle CAD templates, which can be imported to EDEM and manually filled with spherical particles.



Use of the Moving Plane contact model, which provides movement for the conveyor belt.



Creation of bin groups in the Analyst to analyze particles and their properties in specified regions.



Export of simulation data to a .csv (text) file.

1. Start EDEM. 2. Go to File > Save As… 3. Select a location on the local machine (e.g. C:\EDEM_Tutorials). 4. Enter a file name (e.g. Conveyor_Tutorial.dem) and click Save.

Page 3 of 19


EDEM Creator: Setting up the model Step 1: Set the Global Model Parameters Choose the units The first step in creating the model is to set the units used throughout EDEM. 1. Go to the Tools > Options… menu and select the Units tab. 2. Change the following measurement units: 

Angle to degrees (deg)



Angular acceleration to deg/s2



Angular velocity to deg/s



Length to mm



Mass to kg



Mass Flow Rate to kg/s

3. Click OK.

Enter the model title and description The model title and description will appear in the Data Browser window. 1. Click on the Globals tab in the Tabs pane. 2. Enter the title Conveyor Model in the Title field in the Simulation section. 3. Enter the description in the Description field.

Set the contact models The Physics section lists contact models and forces. A contact model describes how elements behave when they come into contact with one another. 1. Select Particle to Geometry from the Interaction drop-down list in the Physics section. 2. Click the button then select the Moving Plane contact model. 3. Select Moving Plane in the list of models then click the up button , so that Moving Plane is calculated before Hertz-Mindlin:

Page 4 of 19


Install the EDEM materials database The materials database is supplied with EDEM, but it must be installed first. 1. In Windows go to Start > DEM Solutions > EDEM 2.6 and select Install external libraries to My Documents. 2. When you navigate My Documents folder you will notice that new folder EDEM_2.6.0 was created. To make sure that the materials database is already available in your new simulation: 3. Go back to EDEM and navigate to: Tools > Options… > File Locations. 4. In Materials Database section, click Browse button and go to EDEM_2.6.0 folder in My Documents. 5. Select materialsDB.ddb and click OK. When you use EDEM later, the database would already be imported so you do not have to install libraries every time you run EDEM.

Set the gravity and define the materials Every particle or section of geometry used in a model is made of a particular material. All materials and the interactions between them must be defined in the Materials section. 1. Check that Gravity is set to -9.81m/s2 in the z-direction. 2. Click the button in the Materials section to create a new material. 3. Click the button and rename the material to rock. Click OK. 4. Set the Poisson's Ratio, Shear Modulus and Density as shown below: Now define the conveyor material. The conveyor is made of steel – a material very similar to the high-stiffness material defined in EDEM’s materials database and it can be transferred from there. 1. Click the Transfer button. The Material/Interactions Transfer dialog will appear 2. Expand the Materials tree in the Materials Database window and select high-stiffness. 3. Click the left arrow to copy the material into your model. Click OK to close the window. 4. Select the high-stiffness material and click the button to rename the material to steel.

Page 5 of 19


Define the interactions between the materials 1. Select rock from the drop-down list at the top of the Materials section. 2. Click the button in the Interaction section. Select rock when prompted. This will define the interaction between elements both made of the material rock. 3. Set the coefficients as follows:

4. Click the Interaction button again and select the material steel. This will define interaction between elements made of rock with elements made of steel. 5. Set the coefficients as follows:

Page 6 of 19


Step 2: Define the Base Particles All types of particles used in a model are defined in the Particles pane. These are the base or prototype particles.

Create a new particle type 1. Click the Particles tab. 2. Click the type.

button in Select Particle section in order to create a new particle

3. Click the

button and rename the particle type to rock particle.

Define the surfaces and properties Particles are made up of one or more spherical surfaces. In this case we import a CAD template of a rock and fit 4 spheres to the template shape. 1. Select Tools > Options… > Particle Display. 2. Click the Import button then import the particle template rock_particle.stl. This is the mesh file to use as a particle template. 3. When Import Options dialog appears, set the measurement units to Millimeters (mm) and click OK. 4. When the Geometry Import Parameters dialog appears, leave all the settings at the default values and click OK. If Quality was selected instead of Curvature, then a smooth mesh of much higher resolution would be used, as can be seen below. Curvature is selected here as the shape will be filled with spheres, therefore it does not need to be perfectly smooth.

Curvature 5. Click the

Quality button and rename the template to Rock Template then click OK.

Page 7 of 19

EDEM Tutorial: Conveyor 6. Go back to Particles tab in Creator panel. Set the Radius of the surface to 18 mm and the Position X, Y, Z to (0, -3, 0) mm. 7. To view the template, go to Viewer Controls on the right of the screen. In Particles section check the Show Template box:

8. Click the

button in the Surfaces section to create a second surface.

9. Set the Radius of this surface to 18 mm and the Position to be (-13, 0, 0) mm. The second surface is offset from the first. 10. Check the Highlight Surface box in Viewer Controls section to be able to distinguish the surfaces:

Page 8 of 19

EDEM Tutorial: Conveyor 11. Create a third surface, setting the Radius to 18 mm, the Position to (0, 4, 0) mm.

12. Create a final surface of Radius 18 mm and the Position (12, 0, 0) mm.

13. In Properties section, set the Material to rock. 14. Click the Calculate Properties button and pick the Imported Template option in the dialog that appears. When using the imported template option, mass, volume and inertia are calculated from the CAD template. Alternatively you could use the Surfaces option to Calculate Properties from the group of spheres. 15. Click OK.

Page 9 of 19


Step 3: Define the Geometry Next step is to define the conveyor geometry used in the model.

Import the conveyor geometry The conveyor geometry has been created in a CAD package and it is ready to be imported into EDEM. 1. Click on the Geometry tab. 2. Click the Import button in the Sections part. 3. Navigate to the file conveyor_hopper.stl and import it. 4. When prompted to, set the Units of measurement to Millimeters. 5. When the Geometry Import Parameters dialog appears leave all the settings at the default values and click OK. The conveyor will appear in the Viewer. It is made up of five sections, which are listed in the Sections drop-down list. When any is selected it is highlighted in red. 6. Select and rename each section in the drop-down list. Name them appropriately: guide_1, guide_2, belt_top lower_hopper, hopper 7. In Details tab, set Type to Physical and change the Material to steel for all sections.

Configure the moving plane The conveyor model uses the Moving Plane contact model. This model simulates a linear motion of a geometry section, where the whole section moves at the same velocity. The contact model adds this linear velocity to the velocity of the geometry section only within the contact model. In other words, the geometry section does not actually move. 1. Go back the Globals tab. 2. Select the Moving Plane contact model then click the configure button

.

3. In the dialog that appears, click the button to add the belt_top as the moving plane. Set the Linear Velocity as follows and click OK.

Page 10 of 19


Create the particle factory plate Particle factories are used to define where, when and how particles appear in a simulation. All factories must be based on a section of geometry (whether 'real' or 'virtual'). This defines the area or volume in the model that produces the particles. 1. Return to the Geometry tab. 2. Click the

button in the Sections section and select Polygon.

3. Click the

button and rename the section factory_plate.

4. Click on the Details tab and set the type to Virtual, since the plate is not a physical part of the machinery. 5. Click on the Polygon tab and set the Number of Edges, X/Y/Z Center and Dimensions of the polygon as follows:

Page 11 of 19


Step 4: Create the Particle Factory Particle factories are used to define where, when and how particles appear in a simulation.

Create the particle factory 1. Click on the Factories tab. 2. Click the

button to create a new factory.

Set the factory’s particle creation values In this model, rock particles are to be created at a rate of 50 kg per second. 1. Set the Factory Type to dynamic. 2. Select Total Mass and set the value to 500 kg. 3. In the Generation Rate section, select Target Mass and set the rate to 50 kg/sec.

Set the factory’s initial parameters 1. In the Parameters section, select the factory_plate from the Section pull-down. 2. Set the Size to user defined and click the configure button Defined Size Distribution box 3. Select the

to open the user

button 4 times and input the following distribution, followed by OK:

4. Set the Position to random to ensure that the particles are randomly created over the entire plate area. 5. Set the Velocity to fixed and click the configure button direction to -2 m/s. 6. Select File > Save.

Page 12 of 19

to set the velocity in z-


EDEM Simulator: Running Simulation Once the model has been set-up in the Creator we move to the Simulator to run it. 1. Click on the Simulator button

on the toolbar.

Step 1: Set the Time options Set the time step The time step is the amount of time between iterations (calculations) in the Simulator. The particles in this model are loosely packed for the majority of the simulation, so set a time step of 0.00015 s (~19% of the Rayleigh Time Step). To find out more about Rayleigh time step, refer to Appendix A: Estimating Simulation Time of the EDEM Help. 1. Set the Fixed Time Step lower box to 0.00015 s. The percentage of Rayleigh time step would be calculated automatically.

Set the simulation time and data write-out frequency The simulation time is the amount of real time your simulation represents. 1. In Simulation Time section, set the Total Time to 10s. 2. Set the Target Save Interval to 0.02s to specify write-out frequency. It is not usually necessary to write a data point for every iteration in a simulation. Doing so would result in a slow simulation and a very large amount of data being collected.

Step 2: Set the Grid options The grid options are used to optimize the simulation. 1. Set the Cell Size to 3 Rmin. (Rmin = smallest particle radius in simulation) Note the number of grid cells (Approx. Number of Cells) is stated below. The simulation results are not affected by the number of grid cells, only the time taken to reach them. The more grid cells a simulation uses the more system RAM is required. It is necessary to find a balance between RAM usage and simulation performance. For simulations with a narrow size distribution the ideal value will be between 2 – 3 Rmin, but for wider size distributions this will increase.

Step 3: Run the Simulation You are now ready to start the simulation. 1. Click the start Progress button

at the bottom of the simulation window.

2. In Viewer Controls, click the Refresh Viewer button or enable Auto Update at any point to update the Viewer and see how the simulation is progressing.

Page 13 of 19


EDEM Analyst: Analyzing Your Results The Analyst is used to review, examine and analyze the results of the simulation. 1. Click on the Analyst button

on the toolbar.

2. Use the controls below the main window to rewind the simulation to the first timestep. 3. Click the play button to play through each time step of your simulation.

Step 1: Configuring the Display The options in the Model pane are used to configure how the different elements in your model appear.

Configure the geometry 1. Click on the Model tab to open the Model pane. 2. Experiment with altering the geometry display: For example, try making the hopper transparent, the guides a mesh and the belt fully opaque. To do that in Geometry section change Type and then modify the Display options. Display Mode can be chosen to be Filled, Mesh or Points. The Opacity can take values 0-1, with 0 being completely transparent and 1 being solid. 3. Before finishing, make sure the factory_plate Display box is unchecked, so it is not visible in the Viewer. 4. Other sections should be displayed as Filled with 0.5 opacity.

Configure the particles The display of the particles can be altered in a similar way to that of the geometry. In addition, the particles can be represented using a number of different forms. One such form is the template originally used to create the particle. 1. In the Particles section of the Model tab, select Template from the Representation pulldown menu. 2. Click the Options button then set the Template to Rock Template. 3. Click OK to close the dialog, then click Apply. In large simulations, a template representation can put a high demand on system resources. 4. Watch the simulation step by step, zooming at particles. 5. Set the Representation back to Default before proceeding and click Apply. 6. Watch the simulation. Page 14 of 19


Step 2: Coloring Elements The particles, geometry and contacts within your model can be colored in a variety of ways. Any section of geometry, particle, contact type or selection group can be colored independently.

Color the particles according to their mass 1. Click on the Coloring tab to open the Coloring pane. 2. In the Select Element section, set: 

Element to Particle



Color by to Type



Type to All

3. In the Attribute Coloring section, set the Attribute to Mass. 4. Set the Min, Mid and Max colors to the Blue, Green and Red respectively. 5. Click the buttons next to the Min and Max Value fields – this reads the current values from the point in the simulation being displayed in the Viewer at the moment. Unselect Auto Update and set Min to 0 kg and Max to 0.8 kg. 6. Click the Apply button to color the particles. 7. Check the Show Legend checkbox then click Apply. 8. Click the Play button to view the distribution of mass over time. Notice that in the picture below, the color of geometry has been changed to Dark Grey.

Page 15 of 19


Step 3: Creating Selections Selections allow data to be extracted from a particular area or element in the domain. Using selections, you can monitor any element passing through a particular area (known as a “bin”) or track particular elements when they move within the domain. You can then display, color, graph or export data based on the selections.

Create a grid bin group We can compare the total mass of particles that fall off the end of the conveyor belt with mass of particles falling out at the bottom of the lower hopper. To do so, create two grid bin groups each containing one bin. 1. Click on the Selection tab. 2. Click the

button then select Grid Bin Group. Rename it Conveyor_group

3. Set the properties of the bin group as follows then click Apply:

4. Click the button one more time to create a second Grid Bin Group. Rename it Hopper_group. 5. Set the properties of the bin group as follows then click Apply:

Page 16 of 19


Define selection group queries A query is used to define a single element attribute, for example particle velocity, total force on a geometry section or number of collisions. To compare the total mass of particles passing through the first bin group with the number passing through the second: 1. Set the Current Time (using the control in the top of the Viewer Control pane at the right of the screen) to about 5s. This is the last time-step before any particles leave the conveyor belt. 2. Select the Conveyor_group from the drop-down list. 3. In the Options section click the Queries Edit button:

The Selection Query Editor is displayed. 4. Expand the Particle tree then select Mass. 5. Set Type to rock particle and Query Type to Total. 6. Select the Total Over Time option then click the displayed in the list at the bottom of the dialog:

button. The query is

7. Click OK. 8. Repeat the above steps to define an identical query for the Hopper_group.

Page 17 of 19


Set selection group display options 1. Select the Conveyor_group from the drop down list then in the Representation section, click the Display Options Edit button.

The Display Options window is displayed. 2. Tick the On Screen Query checkbox to display the mass in the viewer:

3. Repeat the above steps to for the Hopper_group. 4. Click the play button to view the results in real time. As playback continues through the time-steps, bin group data is collected and displayed.

Page 18 of 19


Step 4: Extracting Data Data collected during your simulation can be exported for analysis. Data can be exported from a single time step or a range of time steps; from all elements in a model or just from a selection or bin group.

Create an export configuration 1. Select File > Export > Results Data. The Export Results Data dialog will appear. 2. Click the button to create a new configuration. A single configuration can contain multiple queries and can be reused at any point in your model. 3. Set the Export format to Text to extract data to a .csv file. 4. Enter the file name Conveyor then set the save location to the tutorial folder.

Define a query to export bin group data Export Total Over Time queries for each bin group. 1. In File > Export > Results Data dialog, go to General tab. 2. Tick the Output Averages, Maximums, Minimums and Totals in Columns checkbox. 3. In Time Steps section, uncheck All then set the range to start at about 5s. 4. Click the Queries tab to open the Queries pane. This is where you define the data to be exported. 5. Click the

button to create a new query.

6. Click on the Particle element in the list then select Mass. 7. Select Conveyor_group as the Selection. 8. Set the Type to rock particle and Query Type to Total Over Time. 9. Repeat the instructions 5-8 to add a second query for the Hopper_group.

Export the data 1. Click the Export button to export the data to the pre-defined file. 2. Open the file in an external application (such as a spreadsheet) and review the data.

Page 19 of 19

EDEM TUTORIAL

Recommend Documents