# Rigid body on the nodes of a "through thickness" shell face

Hello,

I have set up a simple rectangular plate with a circular hole in the center.

Additionally, I have defined a rigid body for the set of nodes located at the lip of that hole. (NSET)

The rectangular plate is clamped on two sides and I’m pulling in the perpendicular direction to the plate with a force F applied to the reference node.

The reference node is at the center of the hole.

The result for Rigid Body shows that the inner lip face rotates allowing a large displacement of the plate.

¿Shouldn’t the lip (Through thickness face in the hole) keep also rigid?

That gives a completely different displacement shape as shown in the picture.

Left side with red top: NODE SURFACE COUPLING RIGID CCX.
Right Side: Same load but constraining surface rotation.

i can not see into detail since there’s no input file in block data of coupling and rigid body.

did you are using coupling type distributing?

For reference, here’s what I got in Abaqus:

Of course, Abaqus doesn’t expand shells to solids.

try to understand the problem by simple recreate the model. below result using rigid body

how about deformation plots in plane direction, did it have the same sign values at outer face of shell element around hole?

Sorry xyont, I should be more explicit.

My main issue is that I’m Mecway user and my experience says that inp files do not always work when I have post them in this forum. Hope this one does.

Here it is the part of the code related with RIGID BODY Definition.

*RIGID BODY,NSET=S_RIGI1,REF NODE=2559,ROT NODE=2562

Here it is the file.

Regards

EDITED: The Lip is rotating as the plot in plane directionis shows

Here are the displacement plots:

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not a problems, i’m only doubt personally since there’s a coupling word in discussion.

regarding to Abaqus result comparisons, it seems CalculiX has different behavior. need rotational restraint to make wall perimeter holes stay plane.

as can be seen above, outer face of shell element (top and bottom) around perimeter holes has the same sign values.

Hi Xyont,

¿Do you mean ccx needs to fix that in the future or that we should set the model different to achieve the Abaqus behavior?

Ccx Manual says:

“The rigid body deﬁnition ensures that the distance between any pair of nodes belonging to the body does not change during deformation. This means that the degrees of freedom are reduced to six: three translational and three rotational degrees of freedom.”

The lip rotation implies that the Lip nodes still keep their rotational DOFs.

¿Could this be the origin of the RIGID BODY problems on shells and beams ?

Regards

Abaqus has two element type of shell, classical (2D) and continuum shell (3D). CalculiX expanded shell may comparable to the last ones, so it’s required to test with Abaqus model at the same condition. varying cases also may help to understand discrepancy, advantages and limitation.

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