Modelling Fuselage Frames with CSHEAR

Creator
Creator

I modelled a fuselage using QUAD4's for Skin, CShear for frames and rods for the inner chord, outer chord and stringers. When i run a modal analysis, i get a fatal error and i see all the cshear nodes failing in 1,4,5,6 directions.  The static analysis did run fine but i get the following out of plane displacement at the frames. There are no free edges no duplicate nodes as well. Please let me know if i am missing something.

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4 REPLIES 4

Re: Modelling Fuselage Frames with CSHEAR

Gears Phenom Gears Phenom
Gears Phenom

Hi Kalyan

 

Have you included the flange of the frames using CROD elements that will give the shear panel out of plane stiffness? - is that your chords?

 

Also, see image below detailing interesting comment on using CSHEAR:

 

Frames.JPGshear.JPG

Re: Modelling Fuselage Frames with CSHEAR

Genius
Genius

Stuart_S,

 

That looks like an interesting reference.  Can you post the title/author?

 

Thanks.

Re: Modelling Fuselage Frames with CSHEAR

Gears Phenom Gears Phenom
Gears Phenom
Aircraft Finite Element Modeling

Dr Mohammed Abdo

it is available on scribd so you may have to create an account (unfortunately I cant attach a pdf file here).

It is not the most detailed FEM report, but has interesting foot notes and good examples.

Re: Modelling Fuselage Frames with CSHEAR

Creator
Creator

Hi Stuart,

 

Thank  you for your valuable inputs. I found the mistake. A few of the nodes on both of the frames were out of plane by 0.1 inch and that was the primary reason. I corrected it and now the deflection is quite normal. 

 

Kalyan