yade-users team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

> I got that 
> the final stage is achieved according to the sigmaIsoCompation (isotropic 
> stress) value I choose. But in this case I cannot control the value of porosity 
> (I mean, the porosity and the isotropic stress are not independent, but here I 
> choose to get a specific value of isotropic stress that will correspond to a 
> certain porosity).
No. This is a common mistake. You cannot control porosity via stress. 
Well... you can, but it is not some realistic mechanics.
In reality, when you want to densify a sand, you don't apply a static 
stress on it, you do something else (vibrations, height of 
pluviation,...). The "elastic" change of porosity is very small compared 
to the range of possible porosities.
Actually, the obtained porosity is a function of contact friction and 
particles sizes distribution.

>  My question is: is it possible, with the second method 
> (expansion method), to choose a final target porosity? In my case I would like 
> to run the triaxial test starting with a certain value of porosity.
>
>   
No. The two methods are exactly the same on this point. You impose a 
stress, which has little - if any - influence on the final porosity.

> Then I see 
> that there is another flag called isotropicCompaction. Well, could you explain 
> how it works? Since, actually it seems not working when I try to use it.
>
>   
Somebody else introduced this flag. I don't remember why, sorry. If you 
don't activate it, you will have isotropic compression anyway.

Bruno
































> Thanks a lot,
>
> Chiara
>
>
>
>
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Chareyre Bruno
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