Solid elements with rotational dofs 1

[Cmfg]

Does anybody know a paper or location in the web where I could find the formulation for a FEM solid element with 6 dof per node?

Thanks,

CMFG

 

[corus]

Solid elements don't have 6 dof, shell elements do. You should be able to find a book on the subject easily enough.

corus

 

[Cmfg]

CORUS:

Some solid elements do have 6 dofs like Solid73 implemented by ANSYS. I am looking for the shape funtions of this element.

CMFG

 

[Drej]

There is no such element in the latest ver of ANSYS - it was removed with its tetrahedral counterpart (solid72) from v5.7 (approx) onwards I think due to efficiency (too many DOFs i.e. 48 DOF per element!) and element-coupling errors (erroneous results even with consistent DOF). Shells and beams NEED 6 DOF, as mentioned above, and implementing a 6 DOF element would be wasteful, frankly. RIP solid72/3.

 

[Drej]

Correct my wording slightly: shells do not necessarily NEED 6, some shells only have 5 DOF etc. which give reduced runtimes.

Cheers,

-- drej --

 

[Cmfg]

Drej:

I am no specifically looking for that element (SOLID73), which I also heard that performed very badly, but any solid element that permits using shells, beams, and solids all together.

CMFG

 

[Drej]

You can use all the standard solids together with shells, beams etc. but you need to write constraint equations to tie the DOF together. If you use ANSYS use the CE command to do this, otherwise check the literature for ways of writing these (*EQUATION etc. for example in ABAQUS).

-- drej --

 

[happypap]

A number of solid element formulations with rotational DOFs exist and have been proposed over the years.

Cmfg, this paper might help:

"Hybrid stress tetrahedral elements with Allman's rotational D.O.F.s", K. Y. Sze, Y. S. Pan
You can find it in the International Journal for Numerical Methods in Engineering