Node numbering and fatigue
We have a simple model (plate with hole)
It has 2 loadsets, Loadset 1 and Loadset 2.
We create and save the mesh
We then carry out a linear static study first with loadset 1 - Analysis1. Then with Loadset 2 - Analysis2. i.e. 2 distinct analyses (not summed or combined).
and the constraints are unchanged
The saved mesh is reused and therefore we now have 2 results directories with consistent mesh.
We can then carry out a fatigue analyis using the results from analysis 1 and then 'append' a fatigue analysis using results from analysis 2.
(sometimes loads move about, hence 2 analyses. The real study requires many more load positions than 2 but this is keeping it simple and manually debug-able using the ascii output)
Now a description of the problem encountered ...
The h-element section of the .neu files, first 6 elements:
| h-elements | 840 | Analysis1 | |||||||
| 1 | 6 | 22884 | 23759 | 23753 | 23762 | 0 | 0 | 0 | 0 |
| 2 | -12 | 23759 | 23943 | 23753 | 23762 | 23954 | 23946 | 0 | 0 |
| 3 | 6 | 23759 | 23758 | 23943 | 23954 | 0 | 0 | 0 | 0 |
| 4 | -12 | 23758 | 23945 | 23943 | 23954 | 23952 | 24165 | 0 | 0 |
| 5 | 6 | 23758 | 23757 | 23945 | 23952 | 0 | 0 | 0 | 0 |
| 6 | -12 | 23757 | 23756 | 23945 | 23952 | 23766 | 23951 | 0 | 0 |
| h-elements | 840 | Analysis2 | |||||||
| 1 | 6 | 23368 | 24237 | 24231 | 24240 | 0 | 0 | 0 | 0 |
| 2 | -12 | 24237 | 24421 | 24231 | 24240 | 24432 | 24424 | 0 | 0 |
| 3 | 6 | 24237 | 24236 | 24421 | 24432 | 0 | 0 | 0 | 0 |
| 4 | -12 | 24236 | 24423 | 24421 | 24432 | 24430 | 24643 | 0 | 0 |
| 5 | 6 | 24236 | 24235 | 24423 | 24430 | 0 | 0 | 0 | 0 |
| 6 | -12 | 24235 | 24234 | 24423 | 24430 | 24244 | 24429 | 0 | 0 |
Why oh why oh why has Mechanica changed the node numbers !!!
Third party fatigue solvers don't like this ,,,, and these are the ones that are supposed to work with Mechanica.
Apart from the pair highlighted which have a difference of 484 in the node numbers, all other pairs of node numbers have the difference of 478.
From the h-node section of the .neu file the pairs of node numbers have the same co-ordinates (reasonable proof that the mesh is consistent)
I have only just started this investigatation into why our life contours are poor and am hoping for a revelation regarding this. Do I really have to write code to work on the output files to change this? what is the obvious user error?
Anyone? (even PTC development he asks tentatively)
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