yade-dev team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

I see this is not linked to milestone 0.5. Perhaps it is not an urgent need,
maybe we just keep it in mind for the future.
cheers, Chiara

On 23 May 2010 19:54, Chiara Modenese <c.modenese@xxxxxxxxx> wrote:

> In Classical Mechanics the convention is compression negative and
> tension positive. However, in Contact Mechanics (see Hertzian theory as
> well as Johnsons et al.) the convention holds a positive sign for
> compression and a negative one for tension (e.g. adhesion normal force
> is negative whether presents). I would warmly suggest to follow the
> latter convention, hence as positive the force applied by b1 on b2 if
> normal is b1->b2.
>
> --
> NormalShearInteraction::{normalForce,shearForce} has undefined orientation
> https://bugs.launchpad.net/bugs/493102
> You received this bug notification because you are a member of Yade
> 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.
>
>
>
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