Wednesday, March 9, 2011

Ansys: The Pinball Region

Bonded Details (Pinball Region)
When specifying a contact between two bodies or two surfaces such as Bonded, No Separation, Frictional, or Frictionless you can specify the distance that the contact surface, line, or point and the target line or surface. The way that you specific the distance is either Program Controlled, Automatic Detection Value, or Pinball Region.

The Pinball Region allows you to specify a distance and view a little blue ball so that you know if the Contact will actually find the Target. This is important because in manufacturing geometric design and tolerance of parts means that in a CAD model the parts will not actually touch, and may be rather separated, even though in real life they may be welded or bolted together. Additionally, many assemblies are modeled as mid-surface extractions because that drastically reduces the number of elements in the simulation as well as allowing the user to quickly change the thickness, which means different designs can quickly be tried to find the thinest gage of steel or other metal used, and thus reduce cost. Mid-surfaces further separate the surfaces, or lines, for desired contact so that a larger pinball region is necessary. Parts can sometimes be separated by up to half an inch after mid-surfacing!

In the Automatic Detection Value below you can see that the distance in all directions from the Contact Surface reach those of the target surface (the thin line on the left of the green surface). This is what you desire. In this case the Program Controlled or Automatic Detection Value detected the the target surface and no further modification was needed.
Automatic Detection Value (Acceptable Pinball Region)
Adjusting the Pinball region manually in this case to .1 inches allowed the contact sphere (pinball region) to shrink so that the contract surface would not find the target surface. If you saw this happen when you were using Program Controlled or Automatic Detection you would have to adjust the pinball region to a larger number.
A pinball region that is too small for the contact surface to reach the target surface

For clarification, a diagonal view of the two mid-surface extractions show the two small circles that are bonded in this case with the Automatic Detection Value shown. 
Diagonal view of Automatic Detection Pinball Region with two circular contact surfaces shown

The program used for this tutorial was ANSYS Workbench v11.0.


  1. Good stuff man. Keep the FEA stuff coming! (ANSYS in particular)

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