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Re: Re. Hybrid control of boundary stress


mmsarani@xxxxxxx a écrit :
Thanks Luc and vaclav. I have verified the engine performance using a 400
particle sample for stress controlled triaxial test and it seems, the
ThreeDTriaxialEngine.cpp is not working. First, I have made two
isotropic samples (Sigma1=Sigma2=Sigma3=100 kPa)having different
densities ( I have designated them dense and relatively loose).
Then, I run the triaxial test simulation by setting Sigma1=Sigma3=100 kPa and
Sigma2=200 kPa. The stress-strain curves are attached here with. Relatively
loose sample can reach the target stress, however, the dense sample
cannot. However, the results for both the cases look abnormal. Do I have any mistake?

Did you try to perform a classical triaxial test: first an isotropic compression up to Sigma1=Sigma2=Sigma3=100 kPa, then a deviatoric compression with Sigma1=Sigma3=100 et by imposing a given strain rate in direction 2 ? In addition you should perform this test with a little bit more particles, for instance 1000 particles (400 particles is very few, it corresponds only to about 7 particles in the width of the sample).

I am sorry that my explanation is not good enough. I should be more precise. However, I think, you get what I want to mean. I want to adjust the stress in two directions with respect to stress value in the third direction. I want to fix the stress relations as Sigma2=a*Sigma1+b*Sigma3, where a and b are non-dimensional coefficients and will be determined by user or by any

Ok, so you have to write your own engine, based for instance on the ThreeDTriaxialEngine, and calling the StressControllerEngine where the value of Sigma2 you want to reach is not fixed as an input parameter given by the operator but computed by the relation Sigma2=a*Sigma1+b*Sigma3, where a et b are input parameters given by the operator, and Sigma1 and Sigma3 are the stress values computed by Yade at each time step.





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Luc Sibille

Université de Nantes - Laboratoire GeM UMR CNRS

IUT de Saint Nazaire
58, rue Michel-Ange - BP 420
44606 Saint-Nazaire Cedex, France

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