Combine stress data from same mesh

ParaView Support
1

Hi there,

I am quite new to Paraview, so go easy on me! :smile:
I have two d3plot files from LS-DYNA corresponding to the same mesh but with different material parameters. What I want to do is combine the stresses of both solutions into one and divide them element-wise, as to have a measure of how much larger the stresses of one of the solutions are with respect to the other. I appreciate any help provided and thanks in advance!

2

Hi,

After loading the two d3plot files, perform the following steps:

  1. Select the two you have loaded while holding down the Ctrl key in the Pipeline Browser.
  2. Click Filters > Alphabtical > Append Attributes
  3. Click the Calculator icon calculator on the toolbar
  4. Write “your_material_name / your_material_name_1” and click Apply
3

I follow more or less what you say. If I try to plot the proportion of von-mises stresses I have to previously define it in the Calculator (d3plots apparently do not import von-mises stress), but Paraview just recognizes one “Stress_XX”, “Stress-YY” , etc, from one of the d3plots. I guess what I want to say I don´t quite understand how the Append Attributes works and sepparates the variables from both files. Which is the easy way to plot such a proportion? Thanks.

4

Paraview just recognizes one “Stress_XX”, “Stress-YY” , etc, from one of the d3plots.

Does it mean that ParaView cannot load “Stress_XX”, “Stress-YY”, etc., which should be contained in one of the d3plots files?

Is it possible to share those files? It is easier to understand the situation

5

Does it mean that ParaView cannot load “Stress_XX”, “Stress-YY”, etc., which should be contained in one of the d3plots files?

I mean that in “AppendAttributes1” there appears to be a single variable with this names. I guess this is related to this post, that both files have the stresses and strains with the same names and when appending only one of the two is taken.

Is it possible to share those files? It is easier to understand the situation.

I am sorry, I don’t think I am allowed to. I hope this is enough for you to understand the issue… thanks!

6

Are you experiencing the same problem as the linked post? Also, are you using an older version of ParaView? This issue has already been resolved, so you may not have a problem with the latest version of ParaView.

7

I think I know where the issue is. When looking at the info of both files, they have the same number of cells but different number of points, which I don’t understand since I used the exact same mesh. Hence, I Append Atributtes only takes the attributes of the first selected file if they don’t have the same number of cells and points. Also, I have noticed that even though the number of cells is the same as number of elements, in any case the number of points corresponds to the number of nodes. Are you aware of any issue related to that?

8

If the problem with the different number of points is due to LS-DYNA’s analysis settings or output options, unfortunately, I do not have that knowledge.

9

Opening the files with LS-PrePost gives the same number of nodes and elements as the mesh should have, yet for some reason when it is opened in Paraview, more nodes are created…

10

Below is a description of the vtkLSDynaReader that ParaView uses to read the d3plot file. It may give you some hints.

https://vtk.org/doc/nightly/html/classvtkLSDynaReader.html#details

11

If the numerical results are confidential then it would be best to create two simple, fictitious, representative, files that demonstrate the problem. It is impossible to prescribe a solution without tangible data.