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[Anton Gladky <gladky.anton@xxxxxxxxx>]

It can be related to https://bugs.launchpad.net/yade/+bug/577581

______________________________

Anton Gladkyy


2010/5/26 luc scholtes <lscholtes63@xxxxxxxxx>

> 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>
>
> 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.
>> ______________________________
>>
>>
>