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How would I model a thin, curved , Double layer shell in nx nastran?

Creator
Creator

Double Layer Curved Plate.pngDouble Layer Plate(white - 0.5mm Green 1.0mm) and Connected by Spotwelding(Solid chexa) &RBE3 ( This photo captured in hypermesh not in NX nastran just for my convenience)

Hi everyone

 

I want to get some advices because Experimental modal analysis results and analysis results are not well correlated. ( Mode Frequency and.. Mode shape)

 

The structure that I want to analyze is as shown in the picture above, and a double Curved shell is attached by spot welding.
(The white part has a thickness of 0.5mm and the green part has a thickness of 1.0mm

Both lengths are long enough. For example, The horizontal length of the white shell part is about 600 mm and the vertical length is about 250 mm)

 

I modeled these structures using cquad elements and pshell cards.
(In fact, I do not know if it is right to model such a thin curved shell like this.)

 

In my opinion, the white shell is too thin, so I should consider the geometric nonlinearity effects like stress stiffening effects(Coupling between membrane stress and lateral displacements associated with bending)

 


My question is as follows..

 

 

1.nastran sol103 does not consider this membrane stiffness(i.e. Stress stiffening effects)?

 


2.If so, is it possible to consider membrane stiffness in sol 103 using the mid4 of the Pshell card?
   So how do I configure zoffs to use mid4?

 

 

3.I wonder if there is a mode analysis method considering this membrane stiffness effect.

 

 

You may be busy, but even a few answers will help me a lot. Thank you.

2 REPLIES 2
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Re: How would I model a thin, curved , Double layer shell in nx nastran?

Gears Phenom Gears Phenom
Gears Phenom

I think to take into account what you want to have to run a previous static analysis and then the modal. "prestressed modal analysis". In this way the stiffness matrix is "preloaded" before modal analysis.

 

hope it helps

Re: How would I model a thin, curved , Double layer shell in nx nastran?

Creator
Creator

dear jon_morga

very thx for your reply Smiley Very Happy