yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

Luc,



> From my few tests, it seems that the problem is in the computation for 
> the moment law (everything goes fine when the moment is desactivated), 
> and, from this part, CFpm is exactly the same as 
> CohesivefrictionalContactLaw. Have you tested your law with the moment?
Yes I tested and used it many times, but not in the last weeks. I made 
no recent change either IIRC.

> I'm going to test it with and without Eigen in order to try to find out.
Wm3 should compile now.
> ps: was the bug you fixed related to the moment computation?
Not really.

Bruno


> 2010/5/26 Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx 
> <mailto:bruno.chareyre@xxxxxxxxxxx>>
>
>     Hi Luc,
>
>     I've took care of TTWater recently (well, the problems were not
>     due to eigen anyway).
>     For CohesivefrictionalPM, could you compare with and without
>     eigen? Is it really similar to CF law?
>     We fixed a crash in CF law a few days ago. CohesiveTriaxialTest
>     looked correct after a quick look at results but I didn't check
>     details.
>     How do you see there is a problem (sorry but I don't know what I
>     should read in the code you pasted)?
>
>     Bruno
>
>     luc scholtes a écrit :
>
>         Hi Anton,
>
>         Thank you for the link.
>
>         After few tests, it seems that CohesivefrictionalPM does not
>         work in its actual version (is it related to Eigen?...). More
>         particularly, it seems that the problem comes from the part
>         related to the moment rotation law (see the concerned code
>         below). I know that it is a pity to have copy/paste this code
>         from Bruno's work on CohesivefrictionalContactLaw, but I
>         cannot see where is the problem (I tried to follow all the
>         wm3->Eigen conversions, and it seems ok).
>
>         Does anibody have any suggestion? I am stucked...
>
>          Luc
>
>
>            /* Moment Rotation Law */
>            // NOTE this part could probably be computed in ScGeom to
>         avoid copy/paste multiplication !!!
>            Quaternionr delta( b1->state->ori *
>         phys->initialOrientation1.conjugate()
>         *phys->initialOrientation2 * b2->state->ori.conjugate());
>         //relative orientation
>            AngleAxisr aa(angleAxisFromQuat(delta)); // axis of
>         rotation - this is the Moment direction UNIT vector; angle
>         represents the power of resistant ELASTIC moment
>            if(aa.angle() > Mathr::PI) aa.angle() -= Mathr::TWO_PI; //
>         angle is between 0 and 2*pi, but should be between -pi and pi
>                 phys->cumulativeRotation = aa.angle();
>                 //Find angle*axis. That's all.  But first find angle
>         about contact normal. Result is scalar. Axis is contact normal.
>            Real angle_twist(aa.angle() * aa.axis().dot(geom->normal)
>         ); //rotation about normal
>            Vector3r axis_twist(angle_twist * geom->normal);
>            Vector3r moment_twist(axis_twist * phys->kr);
>                 Vector3r axis_bending(aa.angle()*aa.axis() -
>         axis_twist); //total rotation minus rotation about normal
>            Vector3r moment_bending(axis_bending * phys->kr);
>            Vector3r moment = moment_twist + moment_bending;
>
>            Real MomentMax =
>         phys->maxBend*std::fabs(phys->normalForce.norm());
>            Real scalarMoment = moment.norm();
>
>            /*Plastic moment */
>            if(scalarMoment > MomentMax)
>            {
>              Real ratio = 0;
>              ratio *= MomentMax/scalarMoment; // to fix the moment to
>         its yielding value
>              moment *= ratio;             moment_twist *=  ratio;
>              moment_bending *= ratio;
>            }
>
>            phys->moment_twist = moment_twist;
>            phys->moment_bending = moment_bending;
>                 rootBody->forces.addTorque(id1,-moment);
>            rootBody->forces.addTorque(id2, moment);
>
>         or maybe from the
>
>
>         2010/5/26 Anton Gladky <gladky.anton@xxxxxxxxx
>         <mailto:gladky.anton@xxxxxxxxx> <mailto:gladky.anton@xxxxxxxxx
>         <mailto:gladky.anton@xxxxxxxxx>>>
>
>
>            Hi, Luc!
>
>            Have a look here:
>            https://yade-dem.org/wiki/Wm3%E2%86%92Eigen
>
>            Eigen is a actively developed mathematical library. Wm3 is,
>         as I
>            know, does not develops now. Eigen gives a great functionality
>            through API and well-supported.
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>     -- 
>     _______________
>     Bruno Chareyre
>     Associate Professor
>     Grenoble INP
>     Lab. 3SR
>     BP 53 - 38041, Grenoble cedex 9 - France
>     Tél : 33 4 56 52 86 21
>     Fax : 33 4 76 82 70 43
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--
_______________
Bruno Chareyre
Associate Professor
Grenoble INP
Lab. 3SR
BP 53 - 38041, Grenoble cedex 9 - France
Tél : 33 4 56 52 86 21
Fax : 33 4 76 82 70 43
________________