Nastran SOL400 normal modes analysis with touching contact

catalina29 · May 14, 2024

Hi,
I'm trying to run a SOL400 modal (or normal modes) analysis using Nastran 2017. I have two deformable bodies with touching contact between them. The analysis ignores the tuching contact and the two bodies go through eachother.
I did try the same analysis but wit glue contact and it seems to be working and the bodies are moving together, but the glue does not reflect the reality.
Is there a setting that I should make that would help Nastran remember the contact?

I attached the .bdf file.

Thaks!

karachun · May 22, 2024

I am not familiar with this exact type of Nastran solver - SOL400 but in general Normal Modes is linear solution only. You can find modes either for closed or open gap. You can use prestressed state from nonlinear static analysis but it still represent only one contact state - either open o closed. That`s how its works.

If you realy realy need to investigate gap behavior you can run nonlinear transient analysis and apply some excitation force to force gap to open and close repeatedly but this is much more complex analysis by means of computational cost, setup time and interpretation of results.

If gap is not so critical than you can find modes for open and closed gap in separate runs and assume that real model normal modes will be somewhere in between.

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Nastran SOL400 normal modes analysis with touching contact

catalina29

Aerospace

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karachun

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