Joint in 2D model

[bob3535]

Hello
Does anybody know how to make a joint connection between two surfaces with holes?
In the attached file you can see my problem.
This is a 2D model of an excavator arm and I don't know how to connect these two parts.
Thanks for help

 

[Onda]

You can use two RBE2 with a central coincident grid point.
then, use a CBUSH on the gridpoint with correct stiffness, keeping a very low stiffness in the correct rotation direction.
pay attention that the two RBE2 shall have the indipendent grid point coincident.
Extend the RBE2 on the mesh for the dimension of the bushing.
regards

 

[bob3535]

Thanks for your reply!

I'm quiet new in Patran, so still I don't know how to do it...
By RBE2 did you mean MPC element connecting a central node with nodes on the circle (hole)? Where should the CBUSH element be located?

Is there any tutorial?

 

[Onda]

You are correct, RBE2 are rigid element connecting, in your case a central grid point to the peripheral nodes (the ones that are on the circles).
You have to make one RBE2 for each hole. The central grid point (the independent one) shall be coincident with the other RBE2.
then you should connect the two coincident grid point by a CBush element, giving very high stiffness, except in the direction of free rotation.

 

[bob3535]

Thanks for your time
More questions...
The two central points should have the same XYZ coordinates or only coincident in one plane for example XY?
If coincident in XYZ, how to connect these points?

In my case there is a distacne between these surfaces, so I made 2 RBE2 and a curve from 1st to 2nd central independent point.
Then I'm trying to set BUSH property in that cuvre, but it doesn't work. What orientation should I set if I want it to rotate around this curve (parallel to global Z) and where give the stiffness?

 

[Onda]

the two central point shall be coincident to let the bush work in the right way. thy shall be connect each other with the cbus and to the respective part with the rbe2.
To set the cbush you have to create an element bar piking the two coincident grid point and then set the cbush property.
when you set the property for the cbus, get the global Coordinate system as orientation (coord 0) and set a very low stiffness or 0 stiffness on the 6th input