topic Help with "Fatal error E5004" in Inventor Forum

Help with "Fatal error E5004"

597199 — Tue, 13 Feb 2024 22:25:41 GMT

Hi,

I'm a student working on my bachelor's degree within mechanical engineering, and as part of my bachelor's assignment, we are tasked with doing some structural analysis of a model we've created.

I don't have much experience with Inventor Nastran, but I've tested it on simple structures before.

In this case, we're analyzing a triangle connection commonly used within agriculture, to see the stresses within certain loads. I've applied two loads, one on each side of the triangle, negatively in the Y-axis, of 1000N. (Not visible in the model).

I also created some pinned constraints in the "eyes" on the bottom side of the model and checked the surface contacts.

Whatever I do, I can't get rid of the E5004 error... Any ideas?

Any help is greatly appreciated!

Re: Help with "Fatal error E5004"

magnusn — Tue, 13 Feb 2024 13:44:02 GMT

This should go to the Nastran forum, but do you have a sufficiently tight mesh at the contact areas? If you checked that all surface contacts are ok then that could be the problem.

This link could help you solve the issue too:

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Error-FATAL-ERROR-E5004-STIFFNESS-MATRIX-SINGULAR-OR-NON-POSITIVE-DEFINITE-when-running-an-analysis-in-Nastran-In-CAD.html

Re: Help with "Fatal error E5004"

597199 — Tue, 13 Feb 2024 19:29:29 GMT

Hi! Thanks for your answer, that article helped me find out what I did wrong.
I completely neglected to actually place a bolt in the "eyes" to constrain the triangle. As soon as I placed bolts there and tried to run it, it worked!