Know of Shell Element Formulations with Differential Stiffness Matrix?

[ESPcomposites]

Does anyone of know shell element formulations (tri and quad) that have an associated differential stiffness matrix (geometric stiffness matrix)? The MITC elements are quite popular, but we can not find the associated differential stiffness matrix. The objective is to incorporate these formulations so we can do buckling analysis for the MYSTRAN project. This is probably the most lacking aspect of MYSTRAN at this point. Alternatively, does anyone know how to derive a differential stiffness matrix from an existing shell formulation (this way we could use the MITC shell as the base since it has a published formulation).

Brian

http://www.mystran.com

 

[dmapguru]

Section 7 of the Nastran Theoretical Manual discusses the theory behind differential stiffness, and there is a section on plate elements.
DG

 

[Ali baba Sx]

I don't understand why you cannot derive the geometric stiffness matrix for the MITC elements. I agree that you will not find it in close form in any paper. But you should find all the relevant information to derive the matrix by yourself. This element is used in non linear analysis in ADINA for instance.

I wrote an article a year ago about the MITC element, it may help for your application (you can refer to thread727-468911). You can also consult the original paper about the MITC4 element, it discusses the large displacement derivation from where you should be able to derive the geometric stiffness matrix.

Ali