2D output in .frd file for shell elements?

Dear Forum,

I would like 2D shell elements output with, for example, 4 node coordinates for each shell rather than 8 node coordinates for each “thickened” shell.

I see the command *EL FILE, OUTPUT=2D. Where do I enter this command for 2D output?

TIA,
–Neal

It’s in the field output request settings:

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Dear FEAnalyst,

When I look at the .frd file, I now see one line for each 3D shell element rather than 2 lines as I saw previously prior to modifying the output to 2D as you directed me above. So I believe that each 3D shell element is now being expressed with 4 nodes (x,y coordinates for each node) rather than 8 nodes for a rectangular prismatic-shaped element.

Here is a screenshot with the 2D element output:

Here is a screenshot with the 3D element output:

What are the numbers? How do I decipher the numbers? My model is only 3050mm in length, so the numbers cannot be lengths. Are these node numbers?

Is there a way to list the x,y coordinates of each node? And if so, will the coordinates be the node locations before or after offsets?

TIA,
–Neal

Frd files are not really suitable for reading directly but the syntax is explained here: https://www.dhondt.de/cgx_2.22.pdf#section.11

It’s much easier to read .dat files generated for history output requests.

There is the COORD output variable but it’s only for integration point coordinates.

Here’s a script to work with .frd files: getResultsFromFRD.py : Extract Results from PrePoMax/CalculiX

Dear FEAnalyst,

Thank you.

–Neal

@nrosenblum Hi,

Hope you solved the issue but in case you did not, screenshots you added means:

-In lines starting with ‘-1’, first number gives you the element ID,
-In lines starting with ‘-2’, numbers are node ID’s attached to the corresponding element ID the line before.

For your first ss, which starts like below,

image

  • In the line starting with ‘-1’, the first ‘1’ after ‘-1’ tells you this is the definition of element ID = 1.
  • In the line starting with ‘-2’, all numbers after ‘-2’ are node ID’s of nodes attached to element ID = 1. (1, 214, 221, 5, 217, 371, 372, 55 for this case.)
    As you can see there are 8 nodes for element ID = 1. Probably it’s a quad element which has midside nodes like this:

    It might show the nodes of before expanding 2D elements to 3D elements.

For your second ss, which starts like below,
image

  • Again, in the line starting with ‘-1’, the first ‘1’ after ‘-1’ tells you this is the definition of element ID = 1.
  • And again, in the lines starting with ‘-2’, all numbers after ‘-2’ are node ID’s of nodes attached to element ID = 1. (26014, 26653, 26674, …and…27127, 26176, 26015, …etc… for this case.)
    This time, there are 20 nodes attached to element ID = 1, it might be a brick element with midside nodes like C3D20/C3D20R or expanded S8/S8R element like below:
  1. These are the meanings of numbers, they’re not lengths.
  2. Yes you can list the x, y, z coordinates of each node. At the beginning of your each screenshot, there is a line starts with 3C… like below:
    image

When it starts with 3C, it means there’re gonna be some element identifications.
Instead of 3C, if you search for ‘2C’ (actually it’s directly at the beginning of the .frd file) you can find the locations of each node like this:

  1. As far as i can remember it gives you the node locations after expansion if you selected 3D for Output (2D/3D).
    image

Have a good day.

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Dear Mhayrettin,

Thank you very much for this explanation and the illustrations. This is extremely helpful.

–Neal