I was actually thinking about implementing contact geometry classes from
scratch, both incremental and non-incremental versions, in such way that
deformations (normal, shear, twist, bending) would be precomputed in the
Ig2_* functor, and then just accessed directly from the constitutive law.
It would make sense. I don't remember why the updateShearForce code was
moved to interaction geometry. Rotating the force in geometry is ok, but
computing the shear force increment should be done in ElasticContactLaw.
There has been a bit of over-splitting actually, since the incremental
ElasticContactLaw can fit in almost 15 lines of code in total
(geometry+physics+constitutiveLaw). I don't think it will change anytime
soon though.
The InteractionGeometry classes themselves would be the same, only the
functor would make the distinction of absolute/incremental. There already
was 6dof contect implemented (Dem6Dof_Sphere_Sphere), but it is commented
out currently; and guess what, it is much cleaner code than the horrible
mess (sorry) in CohesiveFrictionalContactLaw.
I though I would start from this Dem6Dof next time I have to implement a
new law. But you know, it is always the same problem : I know the
CohesiveFrictional code and I tested it. Learning new notations will
take time, while it needs only few minutes to do what I want with the
old code. At least, I'll recommend new users to start with Dem6Dof if
they want to derive a new constitutive law (which is not what they seem
to do unfortunately).
"Mess" is a relative concept : it took me approximately the same time to
understand Galizzi's SortCollider and Smilauer's one. I'm not sure which
one is better. Well, I tend to think yours is, but the biggest part is
different coding styles from different developpers.
I'm not trying to say CohesiveFrictionalContactLaw is well written
though. It was not very well structured from the very beginnning, and
Janek added tests for snow creep, which doesn't help. I'll clean that
eventually, but the code can't be simpler than the algorithm.
Bruno
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