yade-users team mailing list archive

["Luc SIBILLE" <Luc.Sibille@xxxxxxxxxxxxxx>]

Hi Nejib,

You cannot do that directly with the 3DTriaxialEngine, you need to modify
it to perform the following thing:

1/compute de radial stress sigma_r (there is a function for that in
TriaxialStressController).
2/ adjust the axial stress sigma_a such that sigma_a = q - sigma_r, where
q is the value of the deviatoric stress you want to impose for your stress
control.
3/ finally impose the radial strain epsilon_r to verify the undrained
condition with epsilon_r = - epsilon_a / 2.

Best,

  Luc

>
> Controlling in strains only does not lead the specimen to a brutal
> failure, I want to see what happens to the specimen if I add a small
> axial load at a given state of the unstable zone.
>
>
>
>
>
> Le jeudi 15 avril 2010 à 18:46 +0200, Jerome Duriez a écrit :
>> I would say that the simplest is to control in strain only (set
>> stressControl_1=stressControl_2=stressControl_3=False), and to set
>> directly values of strain_rate1, strain_rate2, strain_rate3 such that
>> strain_rate1+strain_rate2+strain_rate3=0
>>
>> What do you think about this ?
>>
>> Jerome
>>
>>
>> nejib hadda a écrit :
>> > Hi Jerome,
>> >
>> >   I'm using the ThreeDtriaxialengine, and it gives the possibility to
>> > control in stress and strain at the same time. And using your notation
>> > downhere, I would like to make E22 and E33 follow E11 in such a way
>> that
>> > Ev=0.
>> >
>> >
>> > Le jeudi 15 avril 2010 à 16:04 +0200, Jerome Duriez a écrit :
>> >
>> > > Hello Nejib,
>> > >  From a general point of view if we note 1(=axial for ex), 2,3
>> > > (=laterals) the directions of the space, L1, L2, L3 the size of your
>> > > specimen in these three directions, and v1, v2 and v3 the speeds at
>> > > which you displace your walls in these three directions I would say
>> that
>> > > you will be at a constant volume if you keep v1/L1 + v2/L2 + v3/L3
>> =0
>> > > (No more stress control by this way, your test will be fully strain
>> > > controlled)
>> > >
>> > > Jerome
>> > >
>> > > nejib hadda a écrit :
>> > >
>> > > > Hi,
>> > > >
>> > > > I like to make the sum of the lateral strains equal to the
>> opposite of
>> > > > the axial strain so that the volumetric strain is null (Undrained
>> > > > triaial test).
>> > > > stains' computing depend on the 3 axes, is it possible to compute
>> the
>> > > > lateral strains function of the axial one (stress controlled) or
>> it
>> > > > would have an impact on the results?
>> > > >
>> > > > if not, I'll appreciate any other alternative to perform an
>> undrained
>> > > > triaxial test.
>> > > >
>> > > > thanks
>> > > >
>> > > >
>> > > >
>> > > > _______________________________________________
>> > > > Mailing list: https://launchpad.net/~yade-users
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>> > > >
>> > > >
>> > > >
>> >
>> >
>>
>> --
>> Jérôme Duriez
>> ATER Iut 1 Grenoble, département GMP - Laboratoire 3S-R
>> 04.56.52.86.49 (ne pas laisser de messages sur le répondeur)
>> _______________________________________________
>> Mailing list: https://launchpad.net/~yade-users
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>
>
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-- 
Luc Sibille
Université de Nantes - Laboratoire GeM

Adresse/address:
IUT de Saint Nazaire - Département de Génie-Civil
58, rue Michel-Ange - BP 420
44606 Saint-Nazaire Cedex   France

Tel: +33 2 40 17 81 78