EDEM TUTORIAL

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EDEM Tutorial:Conveyor Simulation


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EDEM Tutorial: Conveyor

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Copyrights and Trademarks

Copyright2014 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 purchasers personal use without written permission.

DEM Solutions

49 Queen StreetEdinburgh

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 isbased in part on the work of the Independent JPEG Group. EDEM uses the Mersenne Twister

random number generator, Copyright1997 - 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.


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Introduction

Through this introductory tutorial we can learn how to set-up and analyze an EDEMsimulation. 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 particleshape is defined using particle CAD templates, which can be imported toEDEM 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 propertiesin 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.


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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 Modelin 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 howelements behave when they come into contact with one another.

1. Select Particle to Geometry from theInteraction drop-down list in the Physicssection.

2. Click the button then select the Moving

Planecontact model.3. Select Moving Plane in the list of models

then click the up button , so that MovingPlane is calculated before Hertz-Mindlin:


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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 Installexternal libraries to My Documents.

2. When you navigate My Documents folder you will notice that new folderEDEM_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_2.6.0folder in My Documents.

5. Select materialsDB.ddb and click OK.

When you use EDEM later, the database would already be imported so you do nothave 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 particularmaterial. All materials and the interactions between them must be defined in theMaterials section.

1. Check that Gravity is set to -9.81m/s2in the z-direction.

2. Click the button in the Materialssection to create a new material.

3. Click the button and rename thematerial to rock. Click OK.

4. Set the Poisson's Ratio, ShearModulus and Density as shown below:

Now define the conveyor material. The conveyor is made of steel a material verysimilar to the high-stiffness material defined in EDEMs materials databaseand it canbe transferred from there.

1. Click the Transfer button. TheMaterial/Interactions Transfer dialog willappear

2. Expand the Materials tree in theMaterials Database window and selecthigh-stiffness.

3. Click the left arrow to copy the materialinto your model. Click OK to close thewindow.

4. Select the high-stiffness material and

click the button to rename the

material to steel.


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Define the interactions between the materials

1. Select rockfrom 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 madeof steel.

5. Set the coefficients as follows:


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Step 2: Define the Base Particles

All types of particles used in a model are defined in the Particles pane. These are thebase or prototype particles.

Create a new particle type

1. Click the Particles tab.

2. Click the button in Select Particle section in order to create a new particletype.

3. Click the button and rename the particle type to rock part ic le.

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 isthe 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 atthe default values and click OK.

If Quality was selected instead of Curvature, then a smooth mesh of muchhigher 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 beperfectly smooth.

5. Click the button and rename the template to Rock Templatethen click OK.

Curvature Quality


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6. Go back to Particles tab in Creator panel.

Set the Radius of the surface to 18 mmand 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. InParticles section check the Show Templatebox:

8. Click the button in the Surfaces section to create a second surface.

9. Set the Radius of this surface to 18 mmand 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 todistinguish the surfaces:


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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 mmand 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 Templateoption inthe dialog that appears.

When using the imported template option, mass, volume and inertia are calculatedfrom the CAD template. Alternatively you could use the Surfacesoption to CalculateProperties from the group of spheres.

15. Click OK.


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Step 3: Define the Geometry

Next step is to define the conveyor geometry used in the model.

Import the conveyor geometryThe conveyor geometry has been created in a CAD package and it is ready to beimported into EDEM.

1. Click on the Geometry tab.

2. Click the Import button in the Sections part.

3. Navigate to the file conveyor_hopper.stland 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 atthe default values and click OK.

The conveyor will appear in the Viewer. It is made up of five sections, which arelisted 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_toplower_hopper,hopper

7. In Details tab, set Type to Physical and change the Material to steel for allsections.

Configure the moving plane

The conveyor model uses the Moving Plane contact model. This model simulates alinear motion of a geometry section, where the whole section moves at the samevelocity. The contact model adds this linear velocity to the velocity of the geometrysection only within the contact model. In other words, the geometry section does notactually move.

1. Go back the Globals tab.

2. Select the Moving Planecontact model then click the configure button .

3. In the dialog that appears, click the button to add the belt_topas the movingplane. Set the Linear Velocity as follows and click OK.


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Create the particle factory plate

Particle factories are used to define where, when and how particles appear in asimulation. 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 aphysical part of the machinery.

5. Click on the Polygon tab and set the Number of Edges, X/Y/Z Center andDimensions of the polygon as follows:


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Step 4: Create the Particle Factory

Particle factories are used to define where, when and how particles appear in asimulation.

Create the particle factory

1. Click on the Factories tab.

2. Click the button to create a new factory.

Set the factorys 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 factorys initial parameters

1. In the Parameters section, select the factory_platefrom the Section pull-down.

2. Set the Size to user definedand click the configure button to open the userDefined Size Distribution box

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

4. Set the Position to randomto ensure that the particles are randomly created overthe entire plate area.

5. Set the Velocity to fixedand click the configure button to set the velocity in z-direction to -2 m/s.

6. Select File > Save.


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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, soset a time step of 0.00015 s (~19% of the Rayleigh Time Step). To find out moreabout 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 0.02sto 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 beingcollected.

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. Thesimulation results are not affected by the number of grid cells, only the time taken toreach 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 3Rmin, 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 Updateatany point to update the Viewer and see how the simulation is progressing.


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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 time-step.

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 inyour 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 thehopper transparent, the guides a mesh and the belt fully opaque. To do that inGeometry section change Type and then modify the Display options. DisplayMode can be chosen to be Filled, Meshor Points. The Opacity can take values0-1, with 0 being completely transparent and 1 being solid.

3. Before finishing, make sure the factory_plate Displaybox is unchecked, so it isnot visible in the Viewer.

4. Other sections should be displayed as Filled with 0.5opacity.

Configure the particles

The display of the particles can be altered in a similar way to that of the geometry. Inaddition, the particles can be represented using a number of different forms. Onesuch form is the template originally used to create the particle.

1. In the Particles section of theModel tab, select Templatefrom the Representation pull-down menu.

2. Click the Options button thenset the Template to RockTemplate.

3. Click OK to close the dialog,then click Apply.

In large simulations, a templaterepresentation can put a highdemand on system resources.

4. Watch the simulation step bystep, zooming at particles.

5. Set the Representation back to Defaultbefore proceeding and click Apply.6. Watch the simulation.


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Step 2: Coloring Elements

The particles, geometry and contacts within your model can be colored in a variety ofways. Any section of geometry, particle, contact type or selection group can becolored 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,Greenand Redrespectively.

5. Click the buttons next to the Min and Max Value fields this reads thecurrent values from the point in the simulation being displayed in the Viewer atthe moment. Unselect Auto Updateand set Min to 0 kgand Max to 0.8 kg.

6. Click the Apply button to color the particles.

7. Check the Show Legendcheckbox 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 DarkGrey.


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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 beltwith mass of particles falling out at the bottom of the lower hopper. To do so, createtwo 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. Renameit Hopper_group.

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


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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 massof particles passing through the first bin group with the number passing through thesecond:

1. Set the Current Time (using the control in the top of the Viewer Control pane atthe right of the screen) to about 5s. This is the last time-step before any particlesleave the conveyor belt.

2. Select the Conveyor_groupfrom 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 particleand Query Type to Total.

6. Select the Total Over Time option then click the button. The query isdisplayed in the list at the bottom of the dialog:

7. Click OK.

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


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Set selection group display options

1. Select the Conveyor_groupfrom the drop down list then in the Representationsection, 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 continuesthrough the time-steps, bin group data is collected and displayed.


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Step 4: Extracting Data

Data collected during your simulation can be exported for analysis. Data can beexported from a single time step or a range of time steps; from all elements in amodel 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 cancontain multiple queries and can be reused at any point in your model.

3. Set the Export format to Textto extract data to a .csv file.

4. Enter the file name Conveyorthen 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 Columnscheckbox.

3. In Time Steps section, uncheck Allthen set the range to start at about 5s.

4. Click the Queries tab to open the Queries pane. This is where you define the datato 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_groupas the Selection.

8. Set the Type to rock particleand 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 thedata.