Seemingly incorrect shear stress-strain curve

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2443631711@qq.com
Posts: 31
Joined: Tue Nov 22, 2022 10:24 am

Seemingly incorrect shear stress-strain curve

Post by 2443631711@qq.com » Wed Mar 22, 2023 2:09 pm

Dear stko team
I have established a very simple model to simulate sand liquefaction, and it seems that the shear stress shear strain curve of post processing is not satisfactory. Is the result option selected by me for post processing incorrect?

The shear strain shear stress curve should look like this (fig1), but my results don't seem quite right

I have attached my model below. Could you help me check where the error occurred?
Attachments
微信图片_20230322220840.jpg
微信图片_20230322220840.jpg (278.27 KiB) Viewed 182 times
1.zip
(129.36 KiB) Downloaded 5 times

STKO Team
Posts: 1811
Joined: Tue Oct 29, 2019 8:45 am

Re: Seemingly incorrect shear stress-strain curve

Post by STKO Team » Thu Mar 23, 2023 11:39 am

The PDMY uses a different convention for 2D (plane strain) stress components:
It gives a 5-components vector like this: [S11, S22, S33, S12, InternalVariable]
But STKO assumes it's a 5-component vector as in Shells (Yes, in OpenSees, Shells gives 5 components because the S33 is zero in shells)


So you should extract it like this:
settings with stress full.png
settings with stress full.png (23.49 KiB) Viewed 162 times

This is what I got:
result_with_restraints.png
result_with_restraints.png (30.94 KiB) Viewed 162 times

2443631711@qq.com
Posts: 31
Joined: Tue Nov 22, 2022 10:24 am

Re: Seemingly incorrect shear stress-strain curve

Post by 2443631711@qq.com » Wed Mar 29, 2023 6:15 am

Therefore, the rules for extracting results should be extracted in the order of [S11, S22, S33, S12, InternalVariable] in the opensees wiki, not in the order marked in stko σ 12, right?

Thank you for answering my question. I always thought there was a problem with my model

STKO Team
Posts: 1811
Joined: Tue Oct 29, 2019 8:45 am

Re: Seemingly incorrect shear stress-strain curve

Post by STKO Team » Tue Apr 11, 2023 8:13 am

Therefore, the rules for extracting results should be extracted in the order of [S11, S22, S33, S12, InternalVariable] in the opensees wiki, not in the order marked in stko σ 12, right?
Yes, but only for this material (and its variations PIMY 02 03 etc...), just because they don't follow the rule of all other materials (and of course STKO is not aware of that)

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