4 noded shell element with 6dof

hi,

please help in writting matlab program for a cylinder using 4-noded shell element having 6dof per node.

[Grzegorz Knor]

And what's your problem?

[GOPIKA]

i want to get the rotations and displacements in each node while applying a point load at one node.

[Tim O]

PLEASE Knor, Could you help me with program on bending analysis of circular plates with following boundary conditions 1. Simply supported 2. Clamped edge 3. Half clamped and half simply supported. LOADINGS Uniformly distributed load on both and centre concentrated load on both. Thanks hope to hear from you soon Tim O

Answer 1

[Sean de Wolski]

A starting point for an element stiffness matrix

K_el = zeros(24);  %4nodes@6dof/node

This will be a very weak element until you populate it with stiffness values derived from the shell element equations.

[GOPIKA]

do you have any idea about stiffness matrix formulation of shell elements??

[Sean de Wolski]

I have an idea, but there are many different types of shells and you probably know a whole lot more about what you want for your _specific_ case.

[GOPIKA]

ya..my problm is to model a circular footing with a central vertical load using shell elements and finally i want to know the resulting deflections and moments.

Answer 2

[KSSV]

Implementing shell element formulation in matlab is bit tough. You must have good experience in FEM formulation in MATLAB. For shell there are many formulations in FEM:

1. Plate elements combine bending and plane stress.

2. Degenerated shell elements

3. Assumed Natural strain shell elements etc..

It involves many transformations. I found one implementation of shell element in mathworks. (<http://www.mathworks.com/matlabcentral/fileexchange/11905)>.

To use this one should have good idea on FEM. You can refer to Finite Element Method - Cook for the formulation.

Sreenu

https://sites.google.com/site/kolukulasivasrinivas/

[GOPIKA]

thank you..now im trying 1st method,as a combination of plate element and plane stress element.

[KSSV]

Hello

You must remember that, in this combination of plate element and plane stress element, there will be five degrees of freedom. And the sixth one is included as drilling degrees of freedom. You have to fix the value of drilling degrees of freedom such that whole solution is not effected. Refer the elemental formulation and then put into code. Refer FEM - zienkowicz. It is given nice in that as well....

Sreenu

https://sites.google.com/site/kolukulasivasrinivas/