Bulk Material Interaction

Starting in version 2019.1, MotionSolve supports co-simulation with the bulk material simulation interface EDEM® (now part of Altair). Through EDEM, users can simulate interaction of multi-bodies with granular materials such as stones, sand, grass, capsules etc.

Pre-requisites

  1. HyperWorks 2019.1 or later
  2. EDEM 2019.1 or later

Broad Steps for Co-simulation

  1. Define the system model in MotionView.
  2. Define the bulk material modeling in EDEM. Please refer to the EDEM manual (http://www.edemsimulation.com/resources-learning) for additional information on how to use EDEM.
  3. Use the EDEM Subsystem utility in MotionView to create a sub-system that contains the entities needed for the co-simulation. The sub-system entails all components that interact with the bulk material. Optionally, the graphics from MotionView can be transferred to EDEM using the same utility.
  4. Turn on the coupling server in EDEM while being in the Simulate mode.
  5. Start the MotionSolve simulation from the Run panel in MotionView.


Figure 1. The user-interface for creating an instance of the MotionSolve-EDEM interaction

Build Model using EDEM Subsystem

The EDEM subsystem tool defines the co-simulation settings between MotionSolve and EDEM. Within the tool, you can:
  • Transfer graphics from MotionView into EDEM.
    Note: This is particularly useful in cases where the model contains a large number of components, such as a chain drive. This resolves the need to remodel the same components in EDEM. MotionView generates an STL in the background and transfers to EDEM through an EDEM Coupling server.
  • Choose if EDEM runs locally or on a separate server.
  • Define the communication parameters if EDEM runs on a separate server.
  • Define simulation settings, such as the communication interval and simulation start time of EDEM.
  • Choose if EDEM should export the results into the H3D format automatically after simulation.

From HyperWorks v2020, the interface is supported on Windows as well as Linux platforms. The interface can be used in cross-platform scenarios (HyperWorks on Windows and EDEM on Linux or vice-versa).

To invoke the tool, click on the EDEM Subsystem icon from the Bulk Material Interface toolbar to bring up the panel as shown below:


Figure 2. EDEM Subsystem Panel
  1. Activate the Graphics collector and pick the graphics that will interact with the bulk material in EDEM. Graphics of type Box, Cylinder, Sphere, Ellispoid, CADGraphics, FileGraphics can be selected from the graphics area.
    Tip: Use the Select a Graphic dialog to pick multiple graphics simultaneously (double click on the collector to display this dialog).


    Figure 3. Select a Graphic Dialog
  2. To control the coarseness of the tessellation of the graphics (CADGraphics and Primitives) that go into EDEM, click the Mesh Refinement button.
    Maximum facet width ratio Maximum width of elements in meters.
    Curve chord tolerance factor Tolerance factor that controls chordal deviation along curved edges.
    Surface plane tolerance factor Tolerance factor that controls surface deviation along curved surfaces.
  3. Select the EDEM server:
    1. Local if EDEM are running on the same local machine as MotionView and MotionSolve.
    2. Remote if EDEM is running on a different machine.
      1. EDEM IP address - Specify the IP address of the machine where EDEM application is running. Default is set to 127.0.0.1 which refers to the local machine.
      2. MotionView Export directory – This is applicable only for transferring geometry to EDEM on a remote server. Select a shared directory which is accessible by both machines. MotionView will use this directory as a temporary location to transfer the geometry.
      3. EDEM Import directory – Path string of the same shared directory as above but as recognized by the machine running EDEM.
  4. Specify the communication interval between MotionSolve and EDEM.
  5. To transfer geometry to EDEM, with the EDEM GUI on and coupling server turned ON , click on Transfer to EDEM to transfer the selected graphics as geometries to EDEM.
  6. Start EDEM simulation at time - Enter a time at which the EDEM simulation is starting. The coupling between MotionSolve and EDEM will be established once MotionSolve reaches the specified time. Default is 0.0.
  7. Export H3d for EDEM particles - With this option turned ON, an H3d will be generated for the EDEM particle simulation. Turn off this check box if EDEM H3d generation is not desired.
  8. Click on Create EDEM System to add a DEM system to the MotionView model. This system contains the requisite entities for MotionSolve’s coupling with EDEM.
    Note: To change the IP address of the machine, the communication interval, or Start EDEM simulation at time after the system is created, use the dataset 'DataSet_1' within the system.


    Figure 4. DataSet within the EDEM system
The model is now ready for co-simulation with EDEM.
Note: The components in EDEM can be created independently. The names for the components should have names as component_0000, component_0001 and so on. The naming sequence should match with the sequence of graphics selection in the tool.

Analyze Model

Once the model is defined, the solution process is identical to performing a “MotionSolve-only” simulation.

Use the Run Solver panel in MotionView/MotionSolve to start the simulation. MotionView will launch MotionSolve.

MotionSolve will connect to EDEM in the specified machine as a sub-process and start the communication. From here on, no additional user intervention is required to analyze the system.
Note: EDEM allows you to run at a variable or fixed step size. It is recommended that you run the simulation at a fixed step (usually 1e-4 or 1e-5 is adequate). Furthermore, you should ensure that the communication interval is exactly divisible by the step-size you selected. This will ensure that the EDEM solver will be exactly at the time required to communicate its forces to MotionSolve.


Figure 5. The user-interface for running a MotionSolve + EDEM simulation
Tip: The MS/EDEM cosimulation in batch mode utility is available under the EDEM menu if the cosimulation needs to be run in batch mode.

Review Results

Once the simulation is complete, an H3D file containing the EDEM results is generated. MotionSolve and EDEM results are written to two separate H3D files. MotionSolve H3D (runfile.h3d) contains the system-level information. EDEM H3D (runfile_edem.h3d) contains the bulk material information.
  1. Once the simulation is complete, use the Animate button in the MotionView Run panel to load the MotionSolve H3D into a HyperView window.
  2. Overlay the runfile_edem.h3d in HyperView using the Overlay option in the Load Model and Results panel to visualize the entire system in one environment.


Figure 6. The user-interface for overlaying a MotionSolve + EDEM simulation result
Note: Animation H3D for EDEM particles can also be generated separately using the Generate H3D from EDEM results tool located under the EDEM menu.

Known Limitations

  1. MotionSolve supports up to 1024 components to interact with EDEM.
  2. Multiple instances of EDEM coupling is not supported.
  3. Flexbodies and NLFE Bodies are not supported.
  4. Certain graphics when transferred to EDEM may appear un-merged as several components. Use the “Merge Geometry” tool in EDEM to merge them into one component.
  5. Interfacing with graphics belonging to Ground Body is not currently supported. The graphics may be transferred separately to EDEM (using the Discrete Element Method) without being included while creating the system in MotionView.
  6. Save/Load in MotionSolve, in conjunction with corresponding operations in EDEM, is not supported.
  7. Quasi-static and Linear analysis are not supported with this connection.
  8. On Windows if Microsoft C++ 2010 SP1 Redistributable Package (x64) is not available, then the co-simulation will fail with an error "Failed to load edem.dll".
Refer to Discrete Element Simulation in MotionSolve for more information about MotionSolve’s co-simulation and post-processing.

See Also

MV-7021: MotionSolve/EDEM Co-Simulation

www.edemsimulation.com