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Rigid Link between EDGES - Best way to do it

3 REPLIES 3
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Message 1 of 4
scudelari
741 Views, 3 Replies

Rigid Link between EDGES - Best way to do it

Hello Everyone,

 

I want to simulate an object here that must have a rigid connection between two edges, as shown in the picture below:

Capture.PNG

 

Let me explain what you see there:

1- The pink lines must be rigid links.

2- The pink lines were created using the "Contact Elements" function limiting the maximum size of the connections.

 

Basically each pink line represents a rigid link between the vertices they are connected to.

 

I know it is possible to do it manually, and for that I would have to divide these lines and have them in several different parts.

 

Knowing this, I must know:

 

1- Is it possible to explode this part and create one part for each one of these lines?

2- How can I simulate this rigid link between the vertices on the lower and upper surfaces? What should be the "Surface Rigid Boundary"?

3- Is there another way to go around the fact that "Rigid Link" elements must have all of their lines sharing one central vertice?

 

Thanks in advance for the help!

3 REPLIES 3
Message 2 of 4
John_Holtz
in reply to: scudelari

Hi,

 

How about using beam elements with "large stiffness" instead of rigid elements. Mathematically, the results are the same.

 

Of course, "large stiffness" cannot be so large that the system of equations becomes unstable.

 

Another consideration is the type of elements that are being connected along the edge. From your image, one part appears to be plate elements, so connecting beam elements is not a problem.

 

Nodes on a brick element behave like a pin joint; they do not transmit a moment to any other element connected to them. This can create two problems in some situations:

  1. If the two edges are straight lines, the "rigid links" will act like a hinge.
  2. Since the brick nodes cannot prevent the beam elements from rotating, each beam element is acting like a small shaft and is free to rotate. This would cause problems during the solution.

To get a better understanding of these types of connection problems, please see "Help > Autodesk Simulation > Mesh Models > Mesh Overview > Contact Pairs > Examples of Contact". For a more indepth theoretical background (but still at the beginner level, hopefully), see "Help > Autodesk Simulation > Getting Started > Nodes and Elements".

 

P.S. Well done on using the "contact element" command with the filter on the length to connect your parts together!

 

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


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Message 3 of 4
scudelari
in reply to: John_Holtz

Hello AstorJohn,

 

Thanks for the compliment on using the "Contact Element".

 

Anyway, I'll tell you what I'll do. I am already almost there on creating the lines manually.

 

I'll make the simulation of the model having both the 104 parts of rigid links, and another simulation of it having the surface as beam elements with large stiffness. Then people will be able to compare the results and have this post as future reference, in case someone else stumbles on the same type of problem.

Message 4 of 4
S.LI
in reply to: scudelari

For the way going with beam element, you may consider truss element, which depends on the two edges.

If these edges belong to shell, beam is all right.

If they belong to brick or other regular elements, you will need to add more constrain for rotational DOFs of beam. So in this situation, truss element might be easier and cheaper.

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