Tutorial 1: Mill 2D

Mill

This tutorial details the simulation of a process with granular non-cohesive material, concretely a Mill, using a simplified geometry and mesh. Advanced and specific aspects should be clarified during training seminars using the present document as reference.

Important aspects:

- Wizard Interface

- Element Types

- Mesh Properties

- Kinematic Conditions

- Contacts

- Mesh Generation

- Output

- Running the Simulation

- Results

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Tutorial 1: Mill 2D

Graphical Preferences

General Preferences

Previous GiD commands:

1. New GiD project

2. Open GiD project

3. Save GiD project

4. GiD preferences

5. Zoom in

6. Zoom out

7. Zoom frame

8. Redraw

9. Rotate trackball

10. Pan dynamic

Basic GiD colours criterion:

• Points: Black

• Lines: Blue

• Surfaces: Purple

• Volumes: Cyan

• Nodes: Black

• Elements: Green

Attention: To accept the conditions assigned the user has to push the Esc button of the keyboard

Meshing Preferences

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Tutorial 1: Mill 2D

Access to the wizard menu:1. Open GiD 102. Select the desired DEMPack problem type3. Select the case to simulate.4. Select the dimension1.5. Begin the problem simulation.

Notes:1. Rock Cutting Disc an Pick are only available

in 3D2. Once inside the wizard interface, there is a

menu access available3. Help button gives access to DEMPack User

Manual2

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Tutorial 1: Mill 2D

Notes:1. To create more complex geometries use the

GiD geometry toolbar2. The geometry can be imported from CAD

formats accepted by GiD (IGES, DXF…)3. To create the lines, two points are needed4. To create the surfaces, a closed line contour

is needed5. All normals should point to DEM material

Basic tools to create the geometry1,2.

PointsLines3

Surfaces4

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Geometry: Basic Available Tools – Normals Control

Lifter detail

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Tutorial 1: Mill 2D

Notes:1. The Problem Dimension is fixed. It has been

defined by the user before2. The DOF selection modifies other steps of the

wizard interface. See Kinematics, Loads…3. This is the final simulation time4. The user can define the Time Step, but the

Automatic option is recommended

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Problem Data: General Problem Data Assign

File text associated to the GiD model

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Tutorial 1: Mill 2D

Notes:

Create a new layer

Create a new folder with one layer inside

Delete the selected layers

Send entities to selected layer

Color of the layer

Activate / Desactivate layer. It shows the layer entities

Freeze / Unfreeze layer. It doesn’t allow to modify the entities frozen

Four different layers have been created:• MillCenter: contains the central point of the mill• GranularMaterial: contains sand and grinding elements• Mill: contains the mill surface/volume• OuterCrown: contains the outer part of the mill

IMPORTANT: Write the names of layers, curves, materials, and such without spaces, in order to assure a proper functioning of the program.

Layers: Available Options

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Tutorial 1: Mill 2D

Notes:1. Discrete elements: Granular Material and

Grinding Elements2. Finite elements – Triangle: Mill3. If Mill is non deformable, Rigid Walls must be

assigned

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Mill

Granular Material – 1

Granular Material – 2Granular Material – 3

Grinding Elements

Element Types:Discrete, Finite Elements and Rigid Walls Assignation

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Tutorial 1: Mill 2D

Notes:1. There are three different kinds of curves2. The user can add pairs of Time-Value points

or copy the columns from an external file3. These curves are used for the velocities and

loads description

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Lineal

Sinoidal

By Points

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Curves: Loads and Velocities Curves Definition

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Tutorial 1: Mill 2D

Notes:1. Assign DEM to Granular Material and

Grinding Elements2. Assign FEM to Mill3. This table is automatically assigned and

shows the Mesh Type and which Layers have that Mesh Type

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Mesh Properties: DEM and FEM meshes Assignation

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Tutorial 1: Mill 2D

GranularMaterial

Materials: DEM Materials Assignation

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Tutorial 1: Mill 2D

GrindingMaterial

Materials: DEM Materials Assignation

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Tutorial 1: Mill 2D

Materials: DEM Materials Assignation

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Tutorial 1: Mill 2D

Notes:1. To Draw all the model materials in colors, the

user has to open the materials definition window

2. The user can Edit and Delete materials using the appropriate buttons.

Materials: Draw Assigned Materials

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Tutorial 1: Mill 2D

Notes:1. In 2D, the Fixed DOF condition can be

assigned to Points, Lines or Surfaces2. The condition is assigned to the Mill Central

node. The rest of the Mill will be defined as Slave

3. There is no DEM Fixed DOF in this model4. There is no Initial Conditions in this model

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Kinematics Conditions: DOF Restrictions Assignment

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Tutorial 1: Mill 2D

Notes:1. The condition is assigned to the Mill Centre2. There is not any DEM Prescribed Velocity in

this model

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Kinematics Conditions: Master Node and Rotation Movement Assignment

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Tutorial 1: Mill 2D

Notes:1. This is not an assignation button, it only

selects the Master node. To assign the condition the user has to push the Assign button

2. There are available all the model layers, select OuterCrown layer to properly define condition.

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Kinematics Conditions: Master Node Assignment

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Tutorial 1: Mill 2D

Notes:1. Name of the contact automatically defined

with the form: MasterLayer-SlaveLayer2. Bounding box is automatically defined, but can

be modified by the user3. Allows the used to to Delete and Edit a pair of

contactNOTE: Layer names must NOT have any space in

order to guarantee a proper assignation of the problem data.

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Contacts: Creation and Parameters Assignment

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Tutorial 1: Mill 2D

Notes:1. This model has no External Loads

Gravity Direction

Loads: Gravity and External Loads Assign

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Tutorial 1: Mill 2D

Notes:1. The damping force is proportional to the

acceleration.2. The user can find detailed description of the

parameters is shown in DEMPack User Manual

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Damping: Mode Selection and Assign

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Tutorial 1: Mill 2D

Notes:1. The Sphere mesher options parameters could

vary depending on the model requests2. This is the desired FEM size3. To really assign the element size the user has

to select Esc and then push the Close button of the window

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Mesh Generation: DEM Parameters Mesher and FEM Assign Sizes

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Tutorial 1: Mill 2D

Notes:1. The user has to define the diameter of the

circles in each DEM mesh2. The assignment procedure is the same as in

definition of FEM element size

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Mesh Generation: DEM Assign Sizes

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Tutorial 1: Mill 2D

Notes:1. This value is only useful for the surfaces with

no previous element size assignment

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Mesh Generation: View Mesh Options

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Tutorial 1: Mill 2D

A

Mesh Quality Options

A

B

B

A

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Tutorial 1: Mill 2D

Notes:1. This is the interval time between two

simulation results. This time must be proportionally to the final time

2. This is the total number of simulation results in the simulation

3. The Displacement Output is always selected4. The other Outputs selected will be shown in

the simulation postprocess

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PostProcess Options

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Tutorial 1: Mill 2D

Notes:1. Before Calculate the model the user should

save it2. During the model calculation the user can see

the results through the postprocess button

Calculate: Process Info and Results Control