AnsweredAssumed Answered

Different behaviour when you apply a force on a node and a force on an edge

Question asked by Alessandro Tornincasa on Apr 30, 2008
Latest reply on Apr 30, 2008 by Anthony Botting
I've created an example to investigate COSMOSWorks new functionality that allows you to apply a force on a reference point (and therefore on a node).
In picture named model.jpg you can see the example: It's a surface model where three equally spaced (25 mm) reference point have been created. This model will be meshed with draft quality shell elements with 25 mm dimension, in order that each reference point exactly corresponds to a node.

The model is fixed on one edge and forces will be applied on the other edge.

I've analized 3 cases:
- case 1 (shown on case1.jpg) where a 10000N force is applied to the entire edge
- case 2(shown on case2.jpg) where a 2000 N force is applied on the 3 reference points and the two vertexes: this way a 2000 N force is applied on each node
- case 3 (shown on case3.jpg) where a 1250 N force is applied on the top and bottom edge and a 2500 N force is applied on the three middle reference points.

For what concerns the results:
- case 1 (shown on case1-results.jpg) shows that more or less all nodes are displacing the same quantity
- case 2 (case2-results.jpg) shows that the outer nodes are displacing more than the inner nodes (load is unbalanced because on external nodes force acts only on one element)
- case 3 (case3-results.jpg) shows a situation that is similar to case 2, but the outer nodes are displacing much less than in the previous case.

What is interesting to see is that when you apply a force on an edge COSMOSWorks perfectly balances forces on the nodes.

Have you ever performed similar tests, and in that case did you get similar results ?

Best regards,
Alessandro Tornincasa