Re: [Paraview] How to indicate the pressure data in paraview ( I use LS-DYNA)

Thu, 26 Sep 2013 07:55:33 -0700 

Yusuke-san,
I am very sorry; I am not a LS-Dyna user and therefore not so familiar with how one directs LS-Dyna to write the stress component array [Sigma_ij] to the d3plot-file. 

[Sigma_ij] is the 3x3 symmetric array

| Sigma_xx Sigma_xy Sigma_xz |
| Sigma_xy Sigma_yy Sigma_yz |
| Sigma_xz Sigma_yz Sigma_zz |




You noted that "resultant" components were in the d3plot-file. This 
suggests to me at least two possibilities:



Case(1). Your model is using 3D solid finite elements that are 
internally configured to behave as shell elements (the word "resultant" 
is commonly used to describe the stress components in shell 
formulations), or



Case(2). Your model is using 3D solid finite elements that use a 
multiple-point volume integration rule and, therefore, has multiple 
stress-strain evaluations within each element. Post-processors like 
ParaView typically use only a single set of stress components per 
element and, thus, some form of volume averaging is required to provide 
a set of 'mean' stress values.



Be aware that "Resultant" can have different definitions in Case(1) and 
Case(2). Only someone very familiar with LS-Dyna can tell you what is 
done internally in LS-Dyna to get these values.



You may be able to see in ParaView a single interior pressure value by 
doing the following replacement:


Sigma_XX ==> NormalResultant_X

Sigma_YY ==> NormalResultant_Y

Sigma_ZZ ==> NormalResultant_Z


In either Case(1) or Case(2) above, you will be examining an average 
pressure in each element, however, this pressure will not be at the 
surface of the finite element.



To get surface pressure values, the components listed as 
"BendingResultant_X,Y,Z" must be combined with "NormalResultant_X,Y,Z" 
values in a very particular way. Please find a colleague that 
understands shell formulations to explain the process.


Best regards,

Sam Key



On 9/25/2013 7:43 PM, Yusuke wrote:

Samuel Key <samuelkey <at> bresnan.net> writes:



     Yusuke-san,
     If the components of the stress tensor supplied by the LS-DYNS
     d3plot file have the following names: Sigma_XX, Sigma_XY, Sigma_XZ,
     Sigma_YY, ...
     then one can use the Calculator filter with the formula
     Pressure = (Sigma_XX + Sigma_YY + Sigma_ZZ)/3.0
     Note: (1) Pressure replaces the temporary "Results" name, (2)
     just the formula (Sigma_XX + Sigma_YY + Sigma_ZZ)/3.0
     is used in the "blank line" above the key-pad, and (3) be sure to
     use the stress component names supplied by  d3plot in place of my
     guessed names above.
     Hope this helps,
     SamOn 9/23/2013 7:47 PM,
       uverworld_1016 <at> yahoo.co.jp wrote:


Hi Mr. Samuel
Thank you to answer my question!
I found BendingResultant_X,Y,Z , NormalResultant_X,Y,Z , ShearResultant_X,Y.
However I can't find Sigma_XX,XY,XZ.......and Results.
Maybe these are not Sigma and results.
Should I set calculation files to output sigma and results??
But I don't know  how to do ....

Thank you
Best regards
Yusuke



       
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<div>
     Yusuke-san,<br><br><br>
     If the components of the stress tensor supplied by the LS-DYNS
     d3plot file have the following names: Sigma_XX, Sigma_XY, Sigma_XZ,
     Sigma_YY, ...<br><br>
     then one can use the Calculator filter with the formula <br><br>
     Pressure = (Sigma_XX + Sigma_YY + Sigma_ZZ)/3.0<br><br>
     Note: (1) Pressure replaces the temporary "Results" name, (2)<br>
     just the formula (Sigma_XX + Sigma_YY + Sigma_ZZ)/3.0<br>
     is used in the "blank line" above the key-pad, and (3) be sure to
     use the stress component names supplied by  d3plot in place of my
     guessed names above.<br><br>
     Hope this helps,<br><br>
     Sam<br><br><div class="moz-cite-prefix">On 9/23/2013 7:47 PM,
       <a class="moz-txt-link-abbreviated" href="mailto:uverworld_1016 <at>

yahoo.co.jp">uverworld_1016 <at> yahoo.co.jp</a> wrote:<br>

</div>
     <blockquote cite="mid:340485.43466.qm <at>

web100905.mail.kks.yahoo.co.jp" type="cite">

       <div>
         <div>Hi! All! </div>
         <div>I'm sorry to ask a lot of questions.</div>
         <div><br></div>
         <div>I use LS-DYNA and I input d3plot file to paraview.</div>
         <div>If I use ls-prepost, I can indicate pressure but there is
           not pressure data in paraview.</div>
         <div>So, I can't indicate pressure  in paraview.</div>
         <div><br></div>
         <div>Should I use some filters?? </div>
         <div><br></div>
         <div>Thank you a lot. </div>
         <div>Best regards</div>
         <div>Yusuke</div>
       </div>
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