yade-dev team mailing list archive

[Chareyre <bruno.chareyre@xxxxxxxxxxxxxxx>]

Vaclav, I was just sarcasticaly playing the role of the contact law
freak. Horrible idea apparently.

Speaking seriously then :

You didn't get the implicit in the sarcasm. In my vision, your model
belongs to the family of "multibody systems" even if interactions
reflect the microscale behaviour of a continuum (which perhaps makes it
somehow hybrid). Did I criticize that once? I remember writing it was
consistent.

#3 Is not an option. It would make the current normal inward, which both
of us dislike.

For sign convention, I observe the former devs choosed the one that was usual in DEM litterature (Trubal, PFC, SDEC, Cundall, Thornton, etc.). When you started working with yade, you decided to change this convention in your code, and now you think it should apply for everybody else's code.
If you make it a casus belli, I'll not oppose. Changing signs everywhere in my code is a very cheap due for what the main dev's achieved. And if one ask me why this unusual sign convention in Yade, I'll say it's been inspired by you, while you were deeply rationalizing continuum-discrete modelling.

Cheers.

-- 
NormalShearInteraction::{normalForce,shearForce} has undefined orientation
https://bugs.launchpad.net/bugs/493102
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developers, which is subscribed to Yade.

Status in Yet Another Dynamic Engine: Confirmed

Bug description:
NormalShearInteraction::{normalForce,shearForce} should contain forces on the interaction, which can be used for various purposes by other functions. However, different functors use them with different sign

ef2_Spheres_Elastic_ElasticLaw (a.k.a. ElasticContactLaw):

   applyForceAtContactPoint(-currentContactPhysics->normalForce-shearForce, ... )

Law2_Dem3DofGeom_CpmPhys_Cpm:

   applyForceAtContactPoint(BC->normalForce+BC->shearForce, ...)

This is a convention issue, but must be fixed. Should normalForce and shearForce be oriented as it applies on id1 (first case) or id2 (second case)? 2nd case is nicer WRT applyForceAtContactPoint syntax, but that one is arbitrary as well.