X Force X32 Exe Inventor Nastran 2017 Portable
Vannina Keasley
That is correct. You should have two beams that are connected together because the sketch lines are connected together. Contact is not required. The point where the two beams (two sketch lines) are connected is where you can apply a force.
If that is what you are doing, the sum of the two is incorrect because you are summing the same nodes twice. Instead, you should get the node numbers for contact pair 1 and 2, remove the duplicate nodes per the article, and then get the sum of the contact force. This sum should be correct.
The stress results (and all the other results) are correct because there is only one contact force at the node. There is not one contact force at the node for contact pair 1 and a different contact force at contact pair 2.
A similar thing happens when looking at the SPC Summation in Inventor Nastran. The result shown is not the result at the selected constraint. The result shown is the reaction force in all directions at the nodes on the selected geometry. For example, this image shows 3 symmetry constraints on 3 faces. When looking at the SPC Summation for constraint 1 (Z symmetry), the nodes along edge A are also fixed in the X direction, so those nodes contribute an X reaction force. The nodes along edge B are also fixed in the Y direction, so those nodes contribute a Y reaction force. So although you have selected "constraint 1", the SPC summation has reactions in X, Y, and Z.
What I see is that if I have a contact pair with no shared nodes, the summed results for Master nodes and Slave nodes are virtually exactly the same (opposite signs though). This should of cause be the case; the total forces on one side of the contact must be the same as the sum on the other side.
But if there are shared nodes on one of the sides in a contact pair, the sum of forces is not "correct", i.e if I want to know how much force is transferred from Part 2 to Part 1 via Contact pair 1 I can't use the results obtained for Contact pair 1 Master, because the values for contact forces on nodes along edge A will be influenced by Contact pair 2 (net force sum for each node I assume??).
I think I understand your description. I think the problem is you need to use the contact force components and exclude directions that do not make sense. (Just like with the my constraint example. You cannot use the total SPC summation for the X symmetry constraint because the total reaction force on face 2 includes Z reaction force, and it is incorrect to use the Z reaction when trying to report the X reaction.)
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