yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 18 March 2010 16:54, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

>
>
>> shearForce = (phys.ks*dt+phys.cs)*shearVelocity;
>>
>> but should not be:
>>
>> shearForce += (phys.ks*dt+phys.cs)*shearVelocity;
>>
>>
> Both wrong I think... If spring and dashpot are in parallel it should be
> something like :
>
> elasticShearF += shearVel*phys.ks*dt;//check plasticity condition on that
> one ...
> viscousShearF = shearVel*phys.cs;
> shearForce = elasticShearF + viscousShearF;//... or that one, depends on
> your constitutive model
>
> The solid (elastic) force can accumulate with increments, the viscous one
> is uniquely defined as a function of current velocity (no history).
>
> Oh yes, I agree with you in this sense. Bruno, what about the shear
velocity? Do you agree that the way we define it is related to a local
system? This is simple to see, just try to invert the ids and you will see
what I mean.


>
>  Moreover once we rotate the force we have:
>>
>> shearForce -= shearForce.Cross(axis);
>>
>>  Still the same, the rigid body rotation is not impacted by the
> constitutive equations.
>
> Bruno
>
>
>
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