yade-users team mailing list archive

[Luc Sibille <luc.sibille@xxxxxxxxxxxxxx>]

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
> condition.

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.

Best,

   Luc

>  
> Mahmud
>
>
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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

Tel: +33 (0)2 40 17 81 78