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Solid elements with rotational dofs

Solid elements with rotational dofs

Solid elements with rotational dofs

(OP)
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

RE: Solid elements with rotational dofs

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

corus

RE: Solid elements with rotational dofs

(OP)
CORUS:

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

CMFG

RE: Solid elements with rotational dofs

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.

RE: Solid elements with rotational dofs

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

Cheers,

-- drej --

RE: Solid elements with rotational dofs

(OP)
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

RE: Solid elements with rotational dofs

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 --

RE: Solid elements with rotational dofs

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

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