Stress extraction problem

Altair Forum User

Hello guys,

I'm writing to you today because I encounter a weird problem with HyperView.
So here is the case. I'm an intern in a French company dealing with automotive and aeroplanes, and I have to develop a tool in order to calculate damages.
Here is where I'm stuck, I have to compare RMS stress given by the old tool with the RMS stress given by the new tool I developped. In order to do that, I isolated a weld of my structure with a set I created on Hypermesh.
I'll take the longitudinal case but I have the same problems in transversal and vertical ones.

So for both case (old tool and new tool), I extract the RMS stress this way:

- Result Type: RMS STRESS
- Layers : Max
- Resolved in: Global System (proj: none)
- Averaging method: None

Once I configured that (for XX, YY and ZZ stress), I query the stress and export it in a CSV file.

 

A quick comparison of the results has been made for 9 elements (on 106) but as I told before I have the same problem on majority of them.

 

<?xml version="1.0" encoding="UTF-8"?>

 

 

As you can see, It seems that the coordinates system has been change during the extraction or even wehn I plotted it, but we can see that the stresses are really close but not in the good axis (for example element 65942). And for some elements, the stress are good (for example element 65637).

How can I be sure that I'm extracting the stress in the same coordinate system? I do'nt really understand why I do have this problem because the extraction process was exactly the same.

The results from the fist tool are obtained with a xml file which also give us the PSD. So we used the PSD and verified, with matematical formula, if the RMS stress was good after calculation and the answer is Yes. So it seems that the problem comes from the second tool, for which the results are obtained with OP2 file.


If you need any other informations don't hesitate.


thank you for your answer.


Francois.B

Altair Forum User

Hi,

 

Which solver are you using for RMS analysis?

 

All the simulation happens with solver and the results are stored in result based on user input.

 

Altair Forum User

Hi,

We are using OptiStruct as solver.

Altair Forum User

Hi @francois.B

 

I will check and will update to you soon. 

Altair Forum User

Hi Prakash Pagadala,

Thank you for your time, waiting for your answer.

Best regards