defining transverse frames cross sections.

[suslu13]

Hi all

I would like to ask a question about definening airframe section.

The first thing is obtaining the Free body forces frem global FEM with defined elements and nodes setsor section cut.
Then define the cross section( j, i beam, z , channel)and calculate geometric properties. ( ıf its possible, obtain the geometric properties values like inertia, beam length etc.. from GFEM)
Third step is failure criteria check, cripling, buckling etc.....

Finally choosing the best cross-section for frame.

The things is how do you do this loop?

I planned to use Hypermesh to obtain free body forces then use these forces in excel for calculation .

Any better idea?

Best Regards
Seçkin

 

[Sparweb]

This may be OK in concept, but only for the first pass.
The crippling/buckling stresses will be affected by the product of inertia of the stiffener sections, which are not symmetrical. The simplified model is symmetrical so it will overestimate the buckling strength.

http://www.sparweb.ca

 

[suslu13]

Thanks for answer.

Which software do you use for this procedure?

 

[rb1957]

the fem modelling is fine, quite typical. I suspect you'll use RODs for the outer cap and BEAMs for the inner cap; webs can be QUADs or SHEARs depending.

for analysis, lateral buckling of the frame inner cap is an issue. There should be analysis for this in Bruhn or Niu.

another day in paradise, or is paradise one day closer ?

 

[SWComposites]

software? Once you get the loads from the FEM you use hand calcs for margins.

 

[rb1957]

most OEMs have proprietary programs for automating the section analysis.

another day in paradise, or is paradise one day closer ?