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Re: clumps


Hi, all.
Is anybody uses clumps for now?
I don't, but I would like to soon.
Seems that clumps incorrectly implemented now.
For example, in NewtonDampedLaw.cpp line 28:
00028         const Vector3r& m=ncb->bex.getTorque(memberId); const
Vector3r& f=ncb->bex.getForce(memberId);

so m and f in global coord. But line 31:

00031         Vector3r

clumpRBP in local clumps coord.

I would not be surprised to find mistakes or inconsistencies here and there as I think Vaclav developped the framework but did not really use it for now.

If nothing changed since last time we discussed that in Grenoble, you could also find the definition of clumps inertia a bit weird : it is the inertia of a sphere of equivalent mass (I suggested that for quasi-static problems it would be an acceptable approximation, and it was easier to code, so...).

Consequence of that : clumpRBP->inertia is an isotropic matrix, independant on the coordinate system, and equations above are correct. :)

If somebody takes time to compute the correct inertia matrix, then inertia will have to be rotated, I agree.


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Chareyre Bruno
Maître de Conférences

Grenoble INP
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BP 53 - 38041, Grenoble cedex 9 - France
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