## Question about Gap Elements

## Question about Gap Elements

(OP)

I want to now if there is a way to use gap elements in linear static analysis, my problem is: I am modeling a mast climbing working platform, the tower is consist of four 2*2 HHS members which are confined in horizontal plane with 8 rollers. there is 1/32Inch gap between rollers and HSS because of the size of model (2 million Dof) we don't want go nonlinear. It seems that the gap element is pulling my structure.(basically I need a kind of gap element that behaves only in compression in linear static analysis)

## RE: Question about Gap Elements

Gap elements are nonlinear so the short answer is, no, unfortunately. A gap in a linear analysis works as a spring, I believe. Your model is large but fairly simple, if I understand things correctly. Why don't you just remove the gaps in tension?

Another thing. I think that in NX Nastran there is a "small" deformation option that runs nonlinear problems in linear mode. Perhaps somebody who knows NX can help you with that part if you have NX.

Good Luck

Thomas

## RE: Question about Gap Elements

sherbrooke,

Gap Elements are nonlinear but a simplified version of elements is available also for linear analysis (SOL 101). It requires just a few changes to your input file and an additional PARAMETER CDITER. The full description of the procedure may be found on NASTRAN Manuals, try and search for 'Gaps in SOL 101' or 'Linear Gap Elements'.

Hope this helps; otherwise let me know.

Regards

DS

'Ability is 10% inspiration and 90% perspiration.'

## RE: Question about Gap Elements

I am using NEi nastran, I tried List/output/query/stresses on gap element, but it dosen't give any result.

any suggestion would be appericiated

## RE: Question about Gap Elements

If you want to avoid nonlinear (due to the large model size), I would recommend replacing the gap elements with springs elements (in the NEiModeler you can do this by creating a spring property, and going to Modify-Update Elements-Type, and choose all the gaps, and then pick the new spring property).

Then run the analysis once, and determine which spring elements are in tension, remove those, and re-run the analysis.

Thank you,

Noran Tech

## RE: Question about Gap Elements

I am also try to use GAP element in linear static analysis. Can you guide me regarding the changes that I have to made in the bdf file.

Thanks

AS

## RE: Question about Gap Elements

## RE: Question about Gap Elements

www.geocities.com/rajsekarann/lingap.pdf

rudi

## RE: Question about Gap Elements

Thank you very much for any help!

## RE: Question about Gap Elements

## RE: Question about Gap Elements