calculix node number issue

cubayang

Hi,

I used calculix for FSI simulation of a flexible plate. The plate is discretized with S6 shell element, and the number of node and element of the plate is 3645 and 1760. However, as attached below, the number of nodes becomes 116285 and I don't know where it comes from. Could anyone help with this?

Thanks in Advance,
Yang

prop_design

I've been thrown off by that too. note it says the numbers below are estimates. unfortunately, the screen output from ccx isn't good.

cubayang

Thanks, @prop_design. Does that mean there is some problem for my case setup? I have used calculix for FSI simulation before, but for those cases, the screen output is correct.

prop_design

I'm not sure what the estimates are there for. i just ignore that part of the screen output now. if your model is running as expected then it's probably set up ok. victor helped me understand this when I had the same issue. he or others here may have some more insight.

disla

Hi,

I have created an S6 element and calculix says number of nodes 70 while mecway says the correct number (15 after expansion to solid).
1760 S6 * 70 = 123200 Nodes - Shared nodes. Seems it is close to what is showing to you (116285).

The number of nodes in Mecway is shown in the lower left corner of the GUI (15)

¿Why Calculix shows upper bounds 70 for a 15-node element? , no idea. In the manual says:

"These upper bounds are used in the subsequent allocation statements in ccx 2.17.c. This procedure might seem slightly awkward, however, since the subroutines reading the input later on are in FORTRAN77, a reallocation is not possible at that stage. Therefore, upper bounds must have been defined.".

Maybe a Crack Opens or the system splits and new nodes are required to describe the model as they are not shared anymore. Calculix needs to foresee as FORTRAN don't allow it later ? ...?¿?.Not sure sorry.

JohnM

Calculix expands beams and shells into solids, so you will find a lot of new nodes.


This discussion may help:

https://mecway.com/forum/discussion/1014/exporting-deformed-mesh-of-shell-model

cubayang

Thanks for your information, @disla, it's very helpful.

cubayang

Thanks a lot, @JohnM. Like you said, the reason is the expansion of the shell elements.