How "Partitions" are used with Inspire Motion Contacts

First, you should understand that motion-based contacts in Inspire Motion can be analytical or mesh-based, depending on the type of geometry at the contact interface. Inspire Motion automatically chooses which method is appropriate for the given geometry representation. If the geometry is representative of, for example, a cylinder contacting another cylinder, analytical contact might be used.  On the other hand, if the geometry is complex, such as one cam surface following another cam surface, a mesh-based contact is used.

Mesh-based contact candidate contact pair:

With mesh-based contacts, the entire body is meshed at the time of solve.  The mesh is used to help in the detection of the contact surfaces by constantly checking their proximity to one another.  Similar to meshes used for FEA, a finer contact mesh tends to produce better contact results than a coarse mesh, but potentially at the expense of solve time.

Now, back to Partitions – Partitions  have many useful options, one of which is helping simplify a mesh-based motion Contact problem by segmenting the contact regions into separate (smaller) bodies.  For example, imagine one cam surface following along another.  The bodies containing the contacting surfaces can be partitioned into a smaller sub-region of the main body.

Partitioned regions: 

Then, the smaller body is used in the contact definition to help reduce the size of the mesh. In short, Partitions can be used to help define a separate contact body which is large enough to capture the contact region, but small enough to help save time of unnecessary meshing - why mesh areas of the entire body that will never contact another body?

Final Partition mesh.  The Non-partitioned portion is not a mesh but instead normal graphics tessellation:

When partitioning a part, the Partition can be used to either add or subtract a region of material from a body. If a body is partitioned for purposes of using in a motion contact, the Partition should be joined back to its parent body with a Rigid Group so that mass and inertia is collectively the same as if they were a single part.

Some Notes:

• The mesh is not visible inside Inspire Motion.  However, the user may "Include All Data" under the Run Settings and then, when the solve is complete, open the Run Folder on the Analyze Motion icon and access the .H3D file, which can then be viewed in HyperView.

• If the intent is to eventually analyze stress in either part using loads from the Inspire Motion run, the partition will be bonded to the parent part with FEA contacts during the structural FEA solve.  

The following 1minute video shows the process of creating partitions and placing them into a Rigid Group: