yade-users team mailing list archive

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

Hi,

during the triaxial test I should maintain the same lateral stress value 
during the analysis, while the axial stress is increasing. The fact is that 
from my simulation actually I see from the results that the lateral stress is 
not kept constant, but it is increasing. How can I fix it? Am I wrong 
somewhere?

Thanks a lot.

Nejib, I can confirm that with the boolean 
autoCompressionActivation at the false value you stop the simulation right 
after the isotropic compression phase.

Chiara






>----Messaggio 
originale----
>Da: luc.sibille@xxxxxxxxxxxxxx
>Data: 10/12/2009 14.17
>A: <yade-
users@xxxxxxxxxxxxxxxxxxx>
>Ogg: Re: [Yade-users] (no subject)
>
>Hi Nejib,
>

>In the TriaxialCompressionEngine, I think there is a booleen that you 
>can 
swith from 1 to 0 to stop the computation when the compaction is 
>finished. I 
don't remember the name of the booleen, but it should be 
>something like 
"AutoCompressionActivation".
>
>About the stress deviator q: generally 
speaking, during the compaction 
>phase Yade tries to reach the same stress 
value for the three space 
>direction. During the compaction, sigma_1, sigma_2 
et sigma_3 may be a 
>little bit different, thus you can compute a non 
vanishing q value 
>(negative or positive), but q value should be very small 
(and it is not 
>really a problem).
>Does it solve your problem?
>
>   Luc
>
>

>nejib hadda a écrit :
>> I don't see how to seperate these two phases on yade.

>> In fact what I want to do is to compact my specimen before launching the
>> 
calculus so that I get the density I wish to have.
>> But here, yade do both 
phases simultaniously, and the phase at which q
>> takes negatives values is 
the phase of compaction which corresponds to
>> the first ietrations.
>> 
>> 

>> Le mardi 08 décembre 2009 à 17:55 +0100, Luc Sibille a écrit :
>>> For which 
phase have you got negative q values? The compaction phase, 
>>> the deviatoric 
phase, ... ?
>>>
>>> Hadda Nejib a écrit :
>>>> I don’t know if it is common in 
YADE to have negative values for the 
>>>> deviatoric stress q   in both 
triaxial test and triaxial test water for 
>>>> the first iterations (numerical 
problem) until the specimen is 
>>>> stabilized. I have also always had this 
sudden fall in the value of 
>>>> sigma22 after some iterations at the 
beginning of my simulations.
>>>>
>>>> Shall I take the initial value of 
sigmaisocompactation near to value of 
>>>> the confining pressure to avoid 
such problem ?
>>>>
>>>>  
>>>>
>>>>  
>>>>
>>>>
>>>> 
------------------------------------------------------------------------
>>>>

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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
>

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