Is arragement of nodes in RigidLink or equalDOF important?

[mohsenVazirizade]

I modeled 4 cantilever columns. Then, push them with a force in node 5.

node 1 0. 0. 0.
node 2 4. 0. 0.
node 3 0. 4. 0.
node 4 4. 4. 0.
node 5 0. 0. 5.
node 6 4. 0. 5.
node 7 0. 4. 5.
node 8 4. 4. 5.
fix 1 1 1 1 1 1 1
fix 2 1 1 1 1 1 1
fix 3 1 1 1 1 1 1
fix 4 1 1 1 1 1 1

pattern Plain 1 Linear {
load 5 100. 0. 0. 0. 0. 0.
}

when we use
rigidLink bar 5 6 or equalDOF 5 6 1 2 3
as we expected, the force is distributed between them equally.
reaction for nodes 1 to 4
-50 0 0 0 -250 0
-50 0 0 0 -250 0
0 0 0 0 0 0
0 0 0 0 0 0
displacement for nodes 5 to 8
0.0013 0 0 0 0.0004 0
0.0013 0 0 0 0.0004 0
0 0 0 0 0 0
0 0 0 0 0 0


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And, if we use (5 is the master for both commands)
rigidLink bar 5 6 or equalDOF 5 6 1 2 3
rigidLink bar 5 7 or equalDOF 5 6 1 2 3
as we expected, the force is distributed between all these three nodes, 5 6 7, equally.
reaction for nodes 1 to 4
-33.3333 0 0 0 -166.6670 0
-33.3333 0 0 0 -166.6670 0
-33.3333 0 0 0 -166.6670 0
0 0 0 0 0 0
displacement for nodes 5 to 8
1.0e-03 *
0.8333 0 0 0 0.2500 0
0.8333 0 0 0 0.2500 0
0.8333 0 0 0 0.2500 0
0 0 0 0 0 0
_________________________________________________________________
After all, the question is why do we meet the following results when we change the arrangement of nodes as the following (first 6 is the master and then 5 is the master node):
rigidLink bar 6 5 or equalDOF 6 5 1 2 3
rigidLink bar 5 7 or equalDOF 5 6 1 2 3

reaction for nodes 1 to 4
-52.0930 0 0 0 -246.5120 0
-47.9070 0 0 0 -239.5350 0
0 -13.9535 0 69.7674 0 0
0 0 0 0 0 0
displacement for nodes 5 to 8
0.0012 0 0 0 0.0003 0
0.0012 0 0 0 0.0004 0
0 0.0003 0 -0.0001 0 0
0 0 0 0 0 0


As we can see, the results are completely changed. And I cannot understand where these results come from.

[fmk]

the Transformation constraint handler does not follow constraints, i.e. 5 constrained to 6 and 6 to 7 .. not sure why you did not see a warning message .. it is in the doc.

if need this type of constraints use Penalty.

[mohsenVazirizade]

Thanks for your response.
In order to sum up for others:
The earlier example is analyzed by constraints Transformation. In other words, if one uses constraints Transformation should not define the node A in a command as the master node and in another comment as the slave node.

However, we do not encounter this problem if we use all other constraints handler:
constraints Plain
constraints Lagrange
constraints Penalty 1.0e14 1.0e14