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Plate theory Kirchhoff/Mindlin

Creator
Creator

Hi everyone,

 

Today I got asked a question regarding the used plate theory in Femap + NX Nastran, which I couldn't answer. I can see (when selecting element type PLATE and under 'formulation' that under 'Femap structural options' the plate theory is set to 0..default

 

My questions are:

-Which theory is used when selecting the default option?

-Does making a choice in theory type affect the calculation when I model flat plates with a thickness/span ration of around 1/100?

 

The help is greatly appreciated!

 

 

Michael van Telgen

2 REPLIES

Re: Plate theory Kirchhoff/Mindlin

Valued Contributor
Valued Contributor

With the default formulation, FEMAP should write out CQUAD4 elements.

 

From the NX Nastran Element Library PDF:

---

CQUAD4 and CTRIA3 Elements
The formulation of the CQUAD4 and CTRIA3 elements are based on the Mindlin-Reissner shell
theory. These elements do not provide direct elastic stiffness for the rotational degrees-of-freedom
which are normal to the surface of the element.

------

 

With the mindlin theory, transverse shear is allowed, with kirchoff, no transverse shear is allowed. For a very thin plate, which it seems like what you are modeling, the transverse shear should be negligible. 

 

 

 

 

 

Re: Plate theory Kirchhoff/Mindlin

Creator
Creator

Thank you! I didn't know a PDF existed for the Nastran elements.

 

This helped a lot!