FE modeling of fuselage frames

[Andries]

Good Day Colleagues,

I noticed that in two different aircraft company finite element manuals the light frames typically used in airliner fuselages
are represented by Nastran CRODS for the flanges of the stringer and a single QUAD4 element representing the web.
Surely a single QUAD4 will be too stiff?
Any views on this?

Thanks.

Andries

 

[SWComposites]

Presumably that is for a loads FE model only, and not a stress FE model. And that sounds like a 1980's modelling approach when computing power was much less; likely that current FEMs are more detailed.

 

[GregLocock]

I suspect that once a method has been correlated then it will be used in perpetuity.

Cheers

Greg Locock


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[Andries]

Thanks Gentlemen,

Yes, it is for a loads model.

Regards,

Andries

 

[SAITAETGrad]

There are some great notes from Ian Taig on this around. This is a reliable means. Complexity leads to error. Review Cook.

 

[Andries]

Thanks SAITAETGrad,

I fortunately have Cook's book and copies of Taig's notes; they really get down to the nitty-gritty of FE modeling.
(As far as FE text books go Cook et al is one of the best.)
On further reflection and the replies above I can now understand the use of a single CQUAD4 as a frame web.
I do think, however, that for spar webs one should have more CQUAD4s, say 4 - 6, down the depth of the web, as mentioned in earlier threads.

Thanks again to all the respondents.

Regards,

Andries