[Gmsh] Stress on Gauss Points

Tue Feb 19 23:36:52 CET 2019

Hi Gaetano,

I'm glad it's working for you!
Yes, I think the same code should work, but the data labels will be
incorrect for this new batch.
You can change the calls to gmsh.view.add( name ) to fix this.

Sincerely,
Max

On Tue, Feb 19, 2019 at 10:02 AM Gaetano Camarda <gaetano_18 at live.it> wrote:

> Hi Max,
>
>
>
> Thank you again for your code, I’ve tried it on my unitcell and it work
> great, I’ll send you a picture just for letting you see what I was telling
> about.
>
> I would like to ask you another question, I have same information with
> deformation (strain) information. The matrix is same way as stress:
>
> [ epsx, epsy epsz epsxy epsyz epsxz]
>
>
>
> I was wondering if you think I can use same code for doing this operation,
> what do you think?
>
>
>
> Sincerily,
>
> Gaetano
>
>
>
> Inviato da Posta <https://go.microsoft.com/fwlink/?LinkId=550986> per
> Windows 10
>
>
> ------------------------------
> *Da:* Max Orok <morok at mevex.com>
> *Inviato:* Saturday, February 16, 2019 5:35:43 PM
> *A:* Gaetano Camarda; gmsh at onelab.info
> *Oggetto:* Re: [Gmsh] Stress on Gauss Points
>
> Hi Gaetano,
>
> Here I modified the script to each of the stress values separately as
> scalars.
> The views will all be visible at once by default but can be toggled by
> clicking the "Post-processing" text in the sidebar and then cycled through.
>
> About that displacement question, I just meant I would defer to your
> judgment as to whether the displacement matched the stresses, etc.
>
> Sincerely,
> Max
>
> [image: image.png]
>
> [image: image.png]
> [image: image.png]
>
> On Sat, Feb 16, 2019 at 6:30 AM Gaetano Camarda <gaetano_18 at live.it>
> wrote:
>
>> Hi guys,
>>
>>
>>
>> Yes, the goal for me was to plot the data on Gmsh, but i would like to
>> ask if there’s a way to show sigx, sigy and so on as view in Gmsh
>> Post-processing, it’s look like all the tensor is plotted all together, am
>> I wrong?
>>
>>
>>
>> I will do a little brief on my work, maybe it could be better
>> understanding. I’m sorry in advance if my english is not so perfect.
>>
>> I’m working on a Multiscale RVE, not the one I’,ve send but another one
>> more complex, but I’m working in parallel with this smaller one for having
>> more control on the code and on the operations.
>>
>> First thing first, I’ve generated the mesh on Gmsh and I processed the
>> operation on Matlab, part of the code was made by me, and for the solver
>> I’ve used CalFem function (freeware script for matlab and python for
>> studying FEM). The .txt file with stress matrix in gauss point and nodal
>> forces for each element are the result of the Calfem function’s I’ve used.
>> The Gauss stress matrix I’ve sent as .txt has 8 point for each element,
>> this is why it has 512 row, cause the element are 64 with 8 gauss point =
>> 512.
>>
>>
>>
>> Now the post-processing part, my goal is to plot the data on Gmsh
>> postprocessing, thanks to Max now I’ve understood a little bit more about
>> the input data Gmsh needed, but I would like to plot stress field
>> separately (as sigx view, sigy view and so on); I also have another matrix
>> for strain, but I didn’t sent because I think the process to do is the same
>> for the gauss-points stresses.
>>
>>
>>
>> About this question from Max:
>>
>> “For the displacement, does it seem like it aligns? I don't want to make
>> a mistake in interpreting the data. “
>>
>> I haven’t understand well your question, my english is a little bit
>> limited, what to you mean with “it seem like it alligns?” If I’ve
>> understood the question you mean the fact that displacement are not the
>> same in faces dx and sx? if that’s your meaning, i’ve noticed it too, and I
>> think it depends on the boundary conditions I gave to the element.
>>
>>
>>
>> Sincerily,
>>
>> Gaetano
>>
>>
>>
>>
>>
>>
>>
>> Inviato da Posta
>> <https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgo.microsoft.com%2Ffwlink%2F%3FLinkId%3D550986&data=02%7C01%7C%7C73310a179a5841aab52408d6942cd9da%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636859317703189999&sdata=G7qtTFXlvkUpFI8GnWPOiN4%2B6AtBN1Baj1qFK%2F%2F3sfE%3D&reserved=0>
>> per Windows 10
>>
>>
>> ------------------------------
>> *Da:* Jeremy Theler <jeremy at seamplex.com>
>> *Inviato:* Saturday, February 16, 2019 11:29:03 AM
>> *A:* Max Orok
>> *Cc:* Gaetano Camarda; gmsh at onelab.info
>> *Oggetto:* Re: [Gmsh] Stress on Gauss Points
>>
>> Hey Max
>>
>> On Fri, 2019-02-15 at 11:01 -0500, Max Orok wrote:
>>
>>
>> My impression going in was that the Gauss point steps were part of the
>> simulation and the goal was just to plot the data.
>>
>>
>> Well, there is a fine line here but it can be considered that the
>> modeling [1] is finished when the stresses (or the heat fluxes, etc) are
>> computed at the gauss points.
>>
>> Actually, I think the original question was: "given that I have data at
>> the Gauss points (and not at the nodes nor at the cell centers), how can I
>> plot them on Gmsh?"
>>
>> Indeed, I think Gaetano wanted to have Gmsh to do something like to
>> re-mesh the base grid and have new cells around the gauss points and plot
>> the data as cell-centered values. I do not know if I am clear, but for a
>> 8-node hexa with 2 Gauss points per dimensions that would be to replace the
>> original element with 8 little hexas, one in each octant and then assign a
>> cell value from the dataset to each of them. For other elements it would be
>> more complex.
>>
>> This is definetely in the post-processing step of the worflow.
>>
>>
>> I think for this data set, the shared node data does repeat, but a single
>> element will vary as a function of its nodes.
>>
>>
>> As far as I can see, the data corresponding to the shared nodes does not
>> repeat. Again, this is what is expected from secondary fields computed as
>> derivatives of a primary field at the Gauss points.
>>
>>
>> For any averaging etc., perhaps this could be done during the simulation?
>>
>>
>> Yes, it could. This is why I am interested in this issue, and raised the
>> question on how to average if the solver has to output nodal values of
>> stresses. Weighted average? With the element's volume? With the element's
>> quality?
>>
>>
>>
>> [1] https://www.seamplex.com/blog/say-modeling-not-simulation.html
>> <https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.seamplex.com%2Fblog%2Fsay-modeling-not-simulation.html&data=02%7C01%7C%7C73310a179a5841aab52408d6942cd9da%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636859317703200010&sdata=HyJU40M0h8b0L3zxRw0c6j%2FCJa%2FpwWvLqSSaoxKYNHA%3D&reserved=0>
>>
>>
>> --
>> Jeremy Theler
>> www.seamplex.com
>> <https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.seamplex.com&data=02%7C01%7C%7C73310a179a5841aab52408d6942cd9da%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636859317703210021&sdata=xGwsNp%2BFJ0Z6vASU1zUR5eXqaPNz4pRMgTya%2F%2FxNFks%3D&reserved=0>
>>
>
>
> --
> Max Orok
> Contractor
> www.mevex.com
> <https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.mevex.com&data=02%7C01%7C%7C73310a179a5841aab52408d6942cd9da%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636859317703220026&sdata=v%2FR9k2G3Zec8F1qQcL%2BvNdMB89wmC%2B%2FgNEmzSV%2F3UCQ%3D&reserved=0>
>
>
>

-- 
Max Orok
Contractor
www.mevex.com
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