Issues with .frd output and loading in PrePoMax

General Questions
1

Hi all,

I am an absolute newbie to PrePoMax (and to Calculix as well). I set up a case in the GUI, exported a .inp and ran a case successfully from the command line. All of my input files are in the attached zip file. However, there some things that I am trying to understand.

  1. The .frd file does NOT load in PrePoMax and I see some errors. See snapshot below.
    ErrorLoadingFRDFile

  2. The .frd file contains node IDs that do NOT even exist in my mesh. See all.msh file in the zip I attached.

  3. I created a MidNode monitor (by created a NodeSet containing only one node 390) and the solver wrote a .dat file that has zero displacements which is incorrect.

Given that I am very new to all of this, I am pretty sure I missed something very fundamental. Any thoughts?

Thanks in advance,
Satish

2

Sorry, I could not attach my files in my previous post. The files may be downloaded from here.

3

This .frd file is really big, did you try reducing its size by saving less output ? I can’t open it in GraphiX as well.

4

Thanks. Actually, you are correct. It does seem to be related to the size of the file. I was able to set up a frequency like as below and the .frd file is loading.

*Node file, FREQUENCY=1000

What I did notice however, is that, my .inp has a shell section defined with the mesh having around 97 nodes. When I load the .frd file, I have double the nodes and a shell displayed fine with as a solid with thickness. There are two issues here though:

  1. Once the .frd file is loaded in PrePoMax, I am unable to create any History Outputs. When I RMB on it and click ‘Create’, nothing seems to happen.

  2. The node numbers in the .frd file are totally different from what they are in the .inp file due to the solid representation of the shell in PrePoMax. In the .inp file, when I use the following commands to write out U at node 506 (this node is in the .frd output), the .dat file is totally blank. When I used the a node number from my original mesh, then, the .dat file was not blank but the displacements were all set to 0. Any idea what I am missing here?

*NSET,NSET=MidNode
506
*Node print, Nset=MidNode
U

Thanks in advance,
Satish

5

In CalculiX shell elements are internally expanded to solids and that’s what may cause confusion in this case. Here’s a figure from the documentation showing how it’s done for triangular elements:

shell ccx
shell ccx719×474 28.5 KB

You can use *EL FILE, OUTPUT=2D if you want to see the results on two-dimensional representation (the internal expansion will take place anyway though). PrePoMax 1.2.0 has this setting available without the need to modify keywords.

At the moment history output can’t be created during the postprocessing stage. You have to define it before the analysis and then you can view it with the results.

Again, this is related to internal expansion. But, as I’ve mentioned above, you can at least switch the display to 2D in the current version of PrePoMax.

By the way, recently a true shell element named US3 was added to CalculiX. It’s new and has not been tested thoroughly yet but you can give it a try.

6

Thank you! All of it makes sense.