yade-users team mailing list archive

["chiara.modenese@xxxxxxxxx" <chiara.modenese@xxxxxxxxx>]

I didn't want to say that I can control porosity via stress, but that they are 
not independent (am I wrong anyway?).
So, having a specific particle size 
distribution, the contact stiffnesses, the angle of friction, is it possible to 
get a specific value of porosity for the specimen? How can I do it with Yade?

Sorry if I continue on this point, but I am a little bit confused on it.

Thank 
you very much,

Chiara





>----Messaggio originale----
>Da: bruno.
chareyre@xxxxxxxxxxx
>Data: 08/12/2009 14.57
>A: <yade-users@lists.launchpad.
net>
>Ogg: Re: [Yade-users] Compaction_phase/Triax
>
>
>> 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
>
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>> Thanks a lot,
>>

>> Chiara
>>
>>
>>
>>
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>
>
>-- 
> 

>_______________
>Chareyre Bruno
>Maître de Conférences
>
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