Kinematic keyword definition

1

I am writting my model and I have doubts about the correct use of this keyword.

I have a reference node connected to a surface (in this case the inner surface of a gear middle circle) with a coupling constraint:

*Coupling, Ref node=500, Surface=RBE2_P_CNS, Constraint name=Constraint-pinion

I want to apply a moment in z axis. it is a 2D analysis, what should I write in my Kinematic keyword? This is correct?

*Kinematic
2

How do I decide if I write 1, 2 or 3? I read the user guide but did not understand what it said about th d.o.f.

Thank you very much for your help

2

A kinematic constraint specifies that the displacement in a certain direction i at a node corresponds to the rigid body motion of this node about a reference node.

the degrees of freedom entered immediately below the *KINEMATIC card (these are the degrees of freedom i which take part in the rigid body motion) …

So with the numbers under *KINEMATIC you choose the degrees of freedom to be constrained by kinematic coupling to follow the motion of the reference node. You can just specify all so that the comstraint acts on all DOFs.

Then another thing is which DOF you use to apply BC or load via the constraint. It can be any of the constrained DOFs and it’s specified under *BOUNDARY or *CLOAD card.

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3

Thank you so much @Calc_em!!

Great, in that case I think it is the most suitable! In that case, how should I do that?

*Kinematic
1,2,3

or

*Kinematic
1
2
3

4

Hi Aurea,

At the end of each keywork explanation in the manual there is a reference to some examples that can also be downloaded from the main ccx page.
coupling2 is the right one for you.

imagen
imagen1149×566 106 KB

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5

as i understand coupling type kinematic in CalculiX has only translational dof’s and the case of rotational in force loads can refers to type of distributing.

some examples by simple model to test is available in PrePoMax forums.

6

The syntax for this data line is:

• first degree of freedom (only 1, 2 or 3 allowed)
• last degree of freedom (only 1, 2 or 3 allowed); if left blank the last degree of freedom coincides with the first degree of freedom.

Repeat this line if needed to constrain other degrees of freedom.

So I would just write:

*KINEMATIC
1,3
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