SOLIDWORKS SIMULATION TECH TIP: Flexibility in Non-linear Fixtures

There’s a feature I always suspected was in COSMOS/SolidWorks Simulation Premium, but I never needed it badly enough to do more than a web search to a dead end and give up. Well, I finally had the need: it was an analysis of a clip/pin system.The goal: Determine plastic deformation and insertion/retention forces during the pin installation/removal process solved in sequence.

1. The “C” clip is first installed on the housing.

2. Then then pin is inserted into the housing deforming the clip.

There was one problem: with the clip in the As Installed position, the shrink fit wouldn’t solve due to the large amount of interference. How could I accurately model this sequence of events?

One option: Thermally expand the clip at time = 0 and then reduce the temperature. That can involve a fair amount of trial and error.

Another option: I could use an advanced fixture to move my clip into place with relative computational efficiency. However, my fixtures would then be artificially constraining the clip when the pin is installed.

After a little bit of research and some great support from SolidWorks, I learned that you can actually release constraints in Simulation Premium. In this particular case, after I move the clip into position using an advanced fixture, I then give that fixture a value of “1e8” and the constraint will be removed.

Now, when the pin is inserted into the clip, it is not being artificially held by the fixture anymore. So far I have only used this with a dynamic simulation, since the “upset” to the stiffness matrix will make it very difficult for the static solver to converge. I have been very pleased with the results so far!

Take a look at a couple examples here: