Nastran press-fit analysis

[daniel_luescher]

Hi everyone,

I have a question about the press-fit contact, I didn't find an answer in this link:

https://knowledge.autodesk.com/support/inventor-nastran/troubleshooting/caas/sfdcarticles/sfdcarticl...

How fast are the two surface (with initial penetration) connected? By fast I mean how many iterations are needed. Looking at the results it seems that the surfaceces are in contact after the first iteration of the subcase, the link above says you should have 8-10 iterations.

In my model there are other contacts, "getrennt" (in german) and I assume that this other contacts need the whole 10 iterations in order to be calculated/merged.

Is there a problem if one contact (press-fit) are closed after the first iteration and the other contact at the last.

Thanks in advance!

[John_Holtz · Accepted solution]

Hi,

The recommendation to use 8 iterations is for the shrink fit contact although some models can get accurate results with fewer iterations. The analysis can adjust the stiffness of the shrink fit contact on each iteration in order to obtain the specified press fit. The question is how do you know which models require fewer iterations (2? 3?) and which ones require more iterations.

You could run every model using 3 iterations, check the results to see if the shrink fit contact has settled down (stress, displacement, and contact force has stabilized), and run the model a second time with all of the subcases and loads (using either 3 iterations for the shrink fit because it did stabilize, or using 8 iterations for the shrink fit because it did not stabilize).