Yade

Simple shear test

Asked by Metehan Karslioglu

Hello Yade users!

I would like to ask something about the tutorial example of periodic simple shear. With defining "O.cell.velGrad = Matrix3(0, 0, .1, 0, 0, 0, 0, 0, 0)" constant-rate distorsion is applied on the periodic cell by this way we can get information about shear stress and shear strains.

My question is that the sample volume stays constant while shearing in this simulation. Does it affect shear stress and shear strain? Because the test procedures for simple shear I've seen have horizontal displacement and volumetric change during shearing.

Best regards
Metehan Karslioglu

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Jérôme Duriez
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Winters (winters1q) said : 		#1

First, simple shear tests are performed in dry and saturated conditions and the results compared in terms of shear strength and volumetric response. Then, wetting tests – under constant vertical stress or constant shear stress – are performed. The experimental results are presented and the future research is outlined.
https://www.mysainsburys.net/

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Jérôme Duriez (jduriez) said : 		#2

Hi,

I think this belongs to the so-called "loading path" influence onto the response of granular materials. A constant-volume shear will not induce the same shear stresses than a constant-normal-stress shear. So, I guess the answer to your question (if I understand it correctly) is Yes.

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Metehan Karslioglu (zmetehans) said : 		#3

Thanks a lot for your answer. Is there any other possibilities or examples to create a simple shear simulation with constant normal stresses. By this way it would be possible also to see the volumetric change.

Thanks in advance again

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Best Jérôme Duriez (jduriez) said : 		#4

Outside periodic boundaries, there is https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.KinemCNLEngine which performs that constant normal stresses control. Sticking to periodic boundaries might be better though, if you want to reach large shear strains (for homogeneity reasons).

And then, I have no precise example in mind at the moment but it should be possible to servo-control O.cell.velGrad in order to maintain by yourself the constant normal stress. Maybe this has been discussed before on the list.

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Metehan Karslioglu (zmetehans) said : 		#5

Thanks Jérôme Duriez, that solved my question.