To illustrate the advantages of coupling Rocky with Ansys Motion, we will first create a simple motion setup using Rocky's built-in motion tools. In this example, we will define basic geometry movements by importing pre-defined motion profiles from .csv files through Rocky Motion Frames Time Series feature. Although functional, you will notice that this approach quickly becomes complex and impractical when dealing with highly coordinated or intricate movements, highlighting the benefits of using the Ansys Motion coupling method discussed later Part B.

The primary benefits of 2-Way Coupling Rocky with Ansys Motion as compared to using the standard Rocky Motion Frames method are explained in the table below.

For simplicity, this basic setup will consider only the geometries Bucket.stl and Ground.stl:

To begin the steps for this tutorial, do the following:

For the Geometries step, we will import the .

For the Materials step, we will:

Once the Motion Frame is created, it can be assigned to the respective geometry.

For the Particles step, we will create a sphere-shaped particle group with some added rolling resistance.

For the Inlets and Outlets step, we will create a Particle Custom Inlet and import a .csv file that defines an already-filled pit of particles.

The Simulation Summary screen appears (as shown), then processing begins.

We used Rocky’s built-in motion tools to create a simple geometry motion using CSV-based Motion Time Series.

During this tutorial, it was possible to:

While functional, this approach highlighted the challenges of manually controlling complex, multi-body motions.

What's Next? If you completed this part successfully, then you are ready to move on to Part B and set up and process the Rocky portion of this coupled simulation.

The main purpose of this tutorial is to set up 2-Way Coupling abilities between Rocky and Ansys Motion.

We will then use Ansys Motion to export pre-defined geometry movements into a Functional Mock-Up Unit (FMU) file that will later be coupled with Rocky.

The scenario considered in this tutorial is evaluating the performance of a backhoe loader's bucket as it scoops material out of a pit in the ground.

In Part A of this tutorial, you will learn how to:

Later in Part C you will learn how to import the FMU file into Rocky, and run the 2-Way coupled simulation.

To complete this tutorial, you are required to have on a Windows machine both of the following programs:

The geometries in this tutorial are composed of:

Ansys Motion Coupling enables you to use motions defined in Ansys Motion within the DEM simulation you set up and run in Rocky.

Motions are exported into an "all-in-one" Functional Mock-Up Unit (FMU) file.

This FMU is then imported into Rocky, defining both geometries and motions.

Exporting and importing the FMU requires the installation of two modules' one for Ansys Motion and one for Rocky.

Both are bundled into one .exe file that is available on the Ansys Customer Portal.

STEP 1: Download and install the Ansys Motion Coupling module.

STEP 2: Open the Ansys Motion project you want to couple with Rocky.

For Ansys Motion Coupling to work, we need to ensure that the gravity direction exactly matches what we will use in Rocky.

To verify that gravity is set in the Y direction, do the following:

We also must ensure that the simulation time in Ansys Motion is equal to or greater than the one we will use in Rocky.

We plan to have a 12s simulation in Rocky. Verify that the simulation time in Ansys Motion is greater than this by doing the following:

STEP 4: Export the files needed for Ansys Motion Coupling.

This version of Ansys Motion Coupling supports particle interactions on only rigid bodies without beam elements.

Part of the exporting files step is choosing how body components are treated during coupling. Specifically:

For this tutorial, we want all bodies to have motions in Rocky, but only the Bucket body to collect particle forces.

This completes Part B of this tutorial.

For further information on Ansys Motion Coupling with Rocky, we suggest searching the Modules Manual. To access it, do the following:

We used Ansys Motion to set up and export geometry movements that will later be coupled with Rocky.

During this tutorial, it was possible to:

What's Next? If you completed this part successfully, then you are ready to move on to Part C and set up and process the Rocky portion of this coupled simulation.

The purpose of this tutorial is to use the information we exported out of Ansys Motion in Part B to set up and process the 2-Way Coupled simulation in Rocky.

In Part B of this tutorial, you will learn how to:

To complete this tutorial, you are required to have on a Windows machine both of the following programs:

In addition, you must have already downloaded and installed the Ansys Motion Coupling module.

As a reminder, the geometries in this tutorial are composed of:

Whether or not you completed Part B of this tutorial, do the following:

For the Modules step, we will be enabling the Ansys Motion Coupling functionality and turning on the collection of boundary-related collision data.

Stresses: Rocky will collect the normal and tangential stress values measured by each individual geometry triangle. This can be useful for analyzing the distribution of load due to particle collisions on a geometry.

We will use the first module to import the FMU file we exported out of Ansys Motion in Part B. As a reminder:

Once the Select file to import dialog closes without error, this indicates that the FMU file was successfully imported.

For the Geometries step, we will import the exact same FMU file that we used earlier.

Because we want to analyze particle forces on the Bucket component later, we must also refine its mesh.

And lastly, we'll import the ground and pit geometry as an .stl file.

For the Materials step, we will:

For the Particles step, we will create a sphere-shaped particle group with some added rolling resistance.

For the Inlets and Outlets step, we will create a Particle Custom Inlet and import a .csv file that defines an already-filled pit of particles.

With a 3D View window opened, your Data panel and Workspace should look similar to the below image.

The Simulation Summary screen appears (as shown), then processing begins.

After processing is complete, we can analyze the particle forces on the bucket component.

For example, we can plot the Instantaneous Force in the Y direction:

Results show the reaction force of the particles over the bucket surface during the ground digging phase (1-3 s) and the weight of the scooped material until the unloading phase (3-10 s).

Let's next evaluate the draw efficiency of the bucket by using a Cube User Process and a Time Plot to analyze the carried Particle Mass.

This results in a Cube (blue outline, as shown) encompassing the full bucket.

Now, let's use Output variables to view the max value at 8 s.

The updated value shows that the Particle Mass in the Bucket reaches about 750 kg before it is dumped.

You can also visualize stresses on the Bucket geometry in a 3D View window:

This analysis shows the shear stress caused by the interactions between particles and the bucket geometry, and therefore identifies zones that are prone to wear.

Extension: You can extend this analysis even farther by creating a Time Statistics Property on the Bucket and then plotting a contour of wear.

This completes Part C of this tutorial.

For further information on Ansys Motion Coupling with Rocky, we suggest searching the Modules Manual. To access it, do the following:

Rocky was used to set up, process, and post-process a simulation of a backhoe loader with movements defined in Ansys Motion.

During this tutorial, it was possible to:

What's Next? If you completed this tutorial successfully, then you are ready to move on to next tutorial.