Tutorial 2: Rock Cutting Disc 3D. Rock Cutting Disc

Transcription

1 Rock Cutting Disc This tutorial details the simulation of a process with granular non-cohesive material, concretely a Mill. 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

2 Previous GiD commands:. 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 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 0. Pan dynamic General Preferences Graphical Preferences Meshing Preferences

3 Access to the wizard menu:. Open GiD 0 2. Select the Problem Type DEMPack v.0 3. Select the case to simulate. 4. Select the dimension. 5. Begin the problem simulation Rock Cutting Disc an Pick are only available in 3D 2. Once inside the wizard interface, there is a menu access available 3. Help button gives access to DEMPack User Manual

4 Geometry: Basic Available Tools Normal s Control Basic tools to create the geometry,2. Points Lines 3 Surfaces 4. To create more complex geometries use the GiD geometry toolbar 2. The geometry can be imported from CAD formats accepted by GiD (IGES, DXF ) 3. To create the lines, two points are needed 4. To create the surfaces, a closed line contour is needed 5. The geometric model can be imported using CAD formats accepted by GiD Disc detail

5 Geometry: Basic Available Tools Normal s Control Pick all the surfaces with bad normal orientation in order to change its sense Good Disc normal s orientation means that all normals should point in the same direction (in or out of the surfaces) in surface local axes. 2. Bad Disc normal s orientation 2. All normals should point to DEM material

6 Problem Data: General Problem Data Assign 2 File text associated to the GiD model 3 4. The Problem Dimension is fixed. Rock Cutting Disc simulation has only sense in 3D 2. The DOF is fixed as 6 3. This is the final simulation time 4. The user can define the Time Step, but the Automatic option is recommended

7 Layers: Available Options Example of Layers managing Four different layers have been created: Central point of the Disc (Point) Rock (Volume) Cutting Disc (Volume) DiscRing (Internal surface of Disc) Important : Unselect also lower entities. Create a new layer 2. Create a new folder with one layer inside 3. Delete the selected layers 4. Send entities to selected layer 5. Color of the layer 6. Activate / Desactivate layer. It shows the layer entities 7. Freeze / Unfreeze layer. It doesn t allow to modify the entities frozen Push finish button or Esc in your keyboard to complete the entities transfer to the selected Layer

8 Element Types:Discrete, Finite Elements and Rigid Walls Assignation 2 Disc 3 2. Discrete elements: Rock 2. Finite elements Tetrahedra: Disc 3. To save computational time and if Disc behavior is not important, the Disc surfaces can be meshed as Rigid Walls

9 Curves: Loads and Velocities Curves Definition Lineal Sinoidal. There are three different kinds of curves 2. The user can add pairs of Time-Value points or copy the columns from an external file 3. These curves are used for the velocities and loads description 2 By Points

10 Mesh Properties: DEM and FEM meshes Assignation. Assign DEM to Rock 2. Assign FEM to Disc 3. This table is actualized automatically and shows the Mesh Type and which Layers have that Mesh Type 3 2

11 Materials: DEM Materials Assignation. Available material models

12 Materials: DEM Materials Assignation

13 Materials: Draw Assigned Materials 2. 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.

14 Kinematics Conditions: DOF Restrictions Assignment 2. In 3D, the Fixed DOF condition can be assigned to Points, Lines, Surfaces or Volumes 2. The DEM condition is assigned to the base surface of the Rock.

15 Kinematics Conditions: DOF Restrictions Assignment. In 3D, the Fixed DOF condition can be assigned to Points, Lines, Surfaces or Volumes 2. The FEM condition is assigned to the Disc Central node. The layer DiscRing will be defined as Slave

16 Kinematics Conditions: Initial Conditions Assignment 2. All entities with initial conditions must be asigned because master-slave only involve vector properties so initial conditions will not be transmited to disk if them are only assigned to central point. 2. There is not any Initial Velocity in this model

17 Kinematics Conditions: Initial Conditions Assignment

18 Kinematics Conditions: Master Node and Rotation Movement Assignment 2. The condition is assigned to the Disc Centre 2. There is not any DEM Prescribed Velocity in this model 3. The Curve selected is the defined in Curves Definition step

19 Kinematics Conditions: Master Node Assignment 3 Master-slave condition let user to transmit some kinematic conditions from a reference point to higher entities (in this case from the disk center to DiskRing surfaces (and also to disk volumes because they are conected)) 2. 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. The Master Point is the Centre of the Disc 3. There are available all the model layers.

20 Contacts: Creation and Parameters Assignment 2. Name of the Contact automatically defined with the form: MasterLayer- SlaveLayer 2. Bounding box is automatically defined, but can be modified by the user 3. Allows the user to Delete and Edit a pair of contact 3

21 Loads: Gravity and External Loads Assign Gravity Direction. This model has no External Loads

22 Concentrated Mass: Equivalent Mass and Inertia Assignment. The center node has not material properties and it needs mass and inertia in order to be integrated in the calculations

23 Damping: Mode Selection and Assign. The damping force is proportional to the acceleration 2. The user can find detailed description of the parameters is shown in DEMPack User Manual

24 Mesh Generation: DEM Parameters Mesher and FEM Assign Sizes 2. The Sphere mesher options parameters could vary depending on the model requests 2. This is the desired DEM spheres diameter Push Esc button to assign element size

25 Mesh Generation: Meshing points with kinematic conditions applied. It is necessary to mesh the points with any assigned condition to translate them correctly to mesh (and also to output calculation file).

26 Mesh Generation: DEM Assign Sizes. The meshing conditions in surfaces have to be applied in the 4 master surfaces that make up the volumes

27 Mesh Generation: FEM Assign Sizes As can be seen two different sizes have been assigned to surface lines. The process must be repeated for sized lines. These sizes have to be applied on the 4 master surfaces as well. Select 4 Disc volumes. Semistrutured mesh allows user to extrude a master surface in a prescribed direction. In this case every volume will have 20 divisions in radial direction or,in other words, every radial line is divided in 20 parts.

28 Mesh Generation: Semistrutred mesh parameters Only one of the above meshed surfaces has to be choosen as master surface.

29 Mesh Generation: View Mesh Options. Element size introduced on the text box will be applied only to elements with random mesh parameters (entities without mesh conditions assigned)

30 Mesh Quality Options 2. DEM radius distribution 2. Tetrahedra minimum edge distribution

31 PostProcess Options 2 3. 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 selected 4. The other Outputs selected will be shown in the simulation postprocess

32 Calculate: Process Info and Results Control. Before Calculate the model the user should save it 2. During the model calculation the user can see the results through the postprocess button