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Re: Yade-users Digest, Vol 24, Issue 4

To: yade-users@xxxxxxxxxxxxxxxx
From: kan <nicessgg@xxxxxxxxx>
Date: Sat, 7 Jun 2008 01:07:24 -0600
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Thank you all.
I appreciate it.

Kan

On Fri, Jun 6, 2008 at 4:01 AM, <yade-users-request@xxxxxxxxxxxxxxxx> wrote:

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> Today's Topics:
>
>   1. Re: How is the cohesion treated in YADE? (Bruno Chareyre)
>   2. Re: How is the cohesion treated in YADE? (V?clav ?milauer)
>   3. Re: How is the cohesion treated in YADE? (kan)
>   4. How to reset a body's velocity? (sega)
>   5. Re: How to reset a body's velocity? (Lionel Favier)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 05 Jun 2008 12:14:03 +0200
> From: Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>
> Subject: Re: [Yade-users] How is the cohesion treated in YADE?
> To: yade-users@xxxxxxxxxxxxxxxx
> Message-ID: <4847BC6B.60705@xxxxxxxxxxx>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> CohesiveFrictionalContactLaw is indeed the law you need, Kan.
> Janek added bending/twisting moments to this contact law recently.
> Moments are only elastic for now, but implementing plasticity for
> moments would be just few lines as you have all kinematic variables
> defined already (like the relative bending/twisting rotations between
> bodies).
> 2 Remarks :
> -you need to set collider->haveDistantPersistent=true if you want
> interactions with tensile forces (overlap<0)
> -you will have to set interaction->isReal=true in the contact law if you
> want the collider to delete lost interactions (loss of contact means
> adhesive properties are lost and overlap<0, this is equivalent to
> contactForce=0).
>
> Bruno
>
>
>
>
>
> Jerome Duriez a ?crit :
> >
> >>
> >> is the cohesion property of some kind of material (like rock) treated
> >> in YADE?
> >> if so, how it is modeled? bonded model?
> >>
> >     Hello. It depends on the contact law you use...
> >     For example you could have cohesion in
> > CohesiveFrictionalContactLaw (see the files in
> > pkg/dem/Engine/StandAloneEngine/). For each interaction a value of
> > cohesion "c"  named in fact "shearAdhesion" is computed depending on a
> > caracteristic "shearCohesion" (member of the class
> > "CohesiveFrictionalRelationships) and on the radii of the bodies in
> > contact.
> > This value of cohesion will then be used for computing a maximum value
> > of tangential contact force : Ftmax = c + Fn * tan(phi).
> >
> > Jerome
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Yade-users mailing list
> > Yade-users@xxxxxxxxxxxxxxxx
> > https://lists.berlios.de/mailman/listinfo/yade-users
> >
>
>
> --
>
> _______________
> Chareyre Bruno
> Maitre de conference
>
> Institut National Polytechnique de Grenoble
> Laboratoire 3S (Soils Solids Structures) - bureau E145
> BP 53 - 38041, Grenoble cedex 9 - France
> T?l : 33 4 56 52 86 21
> Fax : 33 4 76 82 70 43
> ________________
>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 05 Jun 2008 14:15:29 +0200
> From: V?clav ?milauer <eudoxos@xxxxxxxx>
> Subject: Re: [Yade-users] How is the cohesion treated in YADE?
> To: yade-users@xxxxxxxxxxxxxxxx
> Message-ID: <4847D8E1.4010202@xxxxxxxx>
> Content-Type: text/plain; charset=UTF-8
>
> There is the brefcom model (in extra) that is supposed to do just that
> (cohesion) and is formulated using continuum mechanics (strain/stress)
> rather than particles and there is code to make the transition from
> displacements/positions etc to normal strain, shear strain and back from
> stresses to forces. The material model itself cannot be disclosed, but
> you can easily add your own. It is pretty much work in progress now,
> however.
>
> For cohesion, make sure you use enable distant contacts in
> PersistentSAPCollider and
> InteractingSphere2InteractingSphere4SpheresContactGeometry. The old
> approach would use persistentContacts, but there are (by general
> consensus) deprecated and will be removed.
>
> Vaclav
> > Hi,
> >
> > is the cohesion property of some kind of material (like rock) treated
> > in YADE?
> > if so, how it is modeled? bonded model?
> >
> > Thanks.
> > Kan
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Yade-users mailing list
> > Yade-users@xxxxxxxxxxxxxxxx
> > https://lists.berlios.de/mailman/listinfo/yade-users
> >
>
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 5 Jun 2008 09:26:57 -0500
> From: kan <nicessgg@xxxxxxxxx>
> Subject: Re: [Yade-users] How is the cohesion treated in YADE?
> To: yade-users@xxxxxxxxxxxxxxxx
> Message-ID:
>        <45213f870806050726m1a4b293am4851fa35823034f2@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset="utf-8"
>
> Hi, Dear Jerome,
>
> Thank you for your instruction.
> In my contact model, I use the bonded-particle model, so I just assume the
> cohension force is modeled in the bond. In that case, the parameter of
> cohension c is not explicit shown in the model. maybe it is the problem of
> my code.
> I will read the code and study how it is modeled in YADE.
>
> Thanks a lot.
> kan
>
>
> On 6/5/08, yade-users-request@xxxxxxxxxxxxxxxx <
> yade-users-request@xxxxxxxxxxxxxxxx> wrote:
> >
> > Send Yade-users mailing list submissions to
> >        yade-users@xxxxxxxxxxxxxxxx
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> >        https://lists.berlios.de/mailman/listinfo/yade-users
> > or, via email, send a message with subject or body 'help' to
> >        yade-users-request@xxxxxxxxxxxxxxxx
> >
> > You can reach the person managing the list at
> >        yade-users-owner@xxxxxxxxxxxxxxxx
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of Yade-users digest..."
> >
> >
> > Today's Topics:
> >
> >   1. How is the cohesion treated in YADE? (kan)
> >   2. Re: How is the cohesion treated in YADE? (Jerome Duriez)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 4 Jun 2008 14:56:28 -0500
> > From: kan <nicessgg@xxxxxxxxx>
> > Subject: [Yade-users] How is the cohesion treated in YADE?
> > To: yade-users@xxxxxxxxxxxxxxxx
> > Message-ID:
> >        <45213f870806041256y5d8b36e0oba36e625340746e5@xxxxxxxxxxxxxx>
> > Content-Type: text/plain; charset="utf-8"
> >
> > Hi,
> >
> > is the cohesion property of some kind of material (like rock) treated in
> > YADE?
> > if so, how it is modeled? bonded model?
> >
> > Thanks.
> > Kan
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL:
> >
> https://lists.berlios.de/pipermail/yade-users/attachments/20080604/2009b6ab/attachment-0001.html
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Thu, 05 Jun 2008 10:21:44 +0200
> > From: Jerome Duriez <duriez@xxxxxxxxxxxxxxx>
> > Subject: Re: [Yade-users] How is the cohesion treated in YADE?
> > To: yade-users@xxxxxxxxxxxxxxxx
> > Message-ID: <4847A218.8040504@xxxxxxxxxxxxxxx>
> > Content-Type: text/plain; charset="utf-8"
> >
> >
> > >
> > > is the cohesion property of some kind of material (like rock) treated
> > > in YADE?
> > > if so, how it is modeled? bonded model?
> > >
> >    Hello. It depends on the contact law you use...
> >    For example you could have cohesion in CohesiveFrictionalContactLaw
> > (see the files in pkg/dem/Engine/StandAloneEngine/). For each
> > interaction a value of cohesion "c"  named in fact "shearAdhesion" is
> > computed depending on a caracteristic "shearCohesion" (member of the
> > class "CohesiveFrictionalRelationships) and on the radii of the bodies
> > in contact.
> > This value of cohesion will then be used for computing a maximum value
> > of tangential contact force : Ftmax = c + Fn * tan(phi).
> >
> > Jerome
> >
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL:
> >
> https://lists.berlios.de/pipermail/yade-users/attachments/20080605/2829f7c9/attachment-0001.html
> >
> > ------------------------------
> >
> > _______________________________________________
> > Yade-users mailing list
> > Yade-users@xxxxxxxxxxxxxxxx
> > https://lists.berlios.de/mailman/listinfo/yade-users
> >
> >
> > End of Yade-users Digest, Vol 24, Issue 3
> > *****************************************
> >
> -------------- next part --------------
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> ------------------------------
>
> Message: 4
> Date: Fri, 6 Jun 2008 12:31:35 +0400
> From: sega <dorofeenko@xxxxxxxxx>
> Subject: [Yade-users] How to reset a body's velocity?
> To: yade-users@xxxxxxxxxxxxxxxx
> Message-ID: <200806061231.35876.dorofeenko@xxxxxxxxx>
> Content-Type: text/plain;  charset="iso-8859-1"
>
> Hi!
> I need to reset a body's velocity to zero when this body is reloaded into a
> simulation.
> Now can I do it?
> As me seems, a velocity of body is sets _only_ by
> LeapFrogPositionIntegrator or NewtonsDampedLaw.
> Both have a firsts vector but different parents...
>
> --
> Best regards, Sergei D.
>
>
> ------------------------------
>
> Message: 5
> Date: Fri, 06 Jun 2008 13:15:26 +0200
> From: Lionel Favier <lfavier@xxxxxxxxxxxxxxx>
> Subject: Re: [Yade-users] How to reset a body's velocity?
> To: yade-users@xxxxxxxxxxxxxxxx
> Message-ID: <48491C4E.3060306@xxxxxxxxxxxxxxx>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> sega a ?crit :
> > Hi!
> > I need to reset a body's velocity to zero when this body is reloaded into
> a simulation.
> > Now can I do it?
> > As me seems, a velocity of body is sets _only_ by
> LeapFrogPositionIntegrator or NewtonsDampedLaw.
> > Both have a firsts vector but different parents...
> >
> >
> Hi Sega,
>
> If you need to do that during the simulation with a body which has a
> current velocity, acceleration .. Maybe you could add these lines in
> "LeapFrogPositionIntegrator" (additions in italics)
>
>    Real dt = Omega::instance().getTimeStep();
>
>    /ParticleParameters * p = YADE_CAST<ParticleParameters*>(b.get());/
>
> /    if (p->vel_nulle)
>    {
>        p->acceleration = Vector3r(0,0,0);
>        prevVelocities[id] = Vector3r(0,0,0):
>    }/
>
>    if (!firsts[id])
>        p->velocity = prevVelocities[id]+((Real)0.5)*dt*p->acceleration;
>
> You have also to declare the parameter /vel_nulle/ as a boolean in
> "ParticleParameter"
>
> finally you can initialise your velocity by adding a line, for example
> in "VelocityRecorder.cpp" (additions in italics)
>
>    for(  ; bi!=biEnd ; ++bi )
>    {
>        shared_ptr<Body> body = *bi;
>        if( body->isDynamic )
>        {
>            size+=1.0;
>            ParticleParameters* pp =
> YADE_CAST<ParticleParameters*>(body->physicalParameters.get());
>
>           /pp->vel_nulle = true;/
>
>            x+=pp->velocity[0];
>            y+=pp->velocity[1];
>            z+=pp->velocity[2];
>        }
>    }
>
> Normally it works, I just don't know if that is really fits YADE
> philosophy, maybe the YADE's big boss could comment.
>
> good luck
>
> Lionel
>
> //
>
> --
> Lionel FAVIER
> Doctorant
> Laboratoire Sols Solides Structures, Risques (3S-R)
> Equipe Risques et Vuln?rabilit? (RV)
>
> Domaine Universitaire - BP 53
> 38041 Grenoble Cedex 9
> France
>
> T?l: +33 (0)4 56 52 86 36
> lionel.favier@xxxxxxxxxxx
>
>
>
> ------------------------------
>
> _______________________________________________
> Yade-users mailing list
> Yade-users@xxxxxxxxxxxxxxxx
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>
> End of Yade-users Digest, Vol 24, Issue 4
> *****************************************
>

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