yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 26 April 2010 11:49, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

>
>>  Prescribing displacement (even by fixing position of
>> support) means that energy might disappear from the system...
>>
> This is what I was trying to find out, I mean, _why_ that happens..

>
>>
>>
>
> By definition, you impose displacement on a non-equilibrated body. So that
> if you impose a displacement "du" on body "i", you provide energy
> du*force[i] to the system, which is in turn transformed into elastic,
> plastic, or kinetic (in other bodies) energy.
> Not sure I understood the point, though. I must admit I still don't
> understand how a velocity can be imposed to dynamic bodies.

Would not just be simply an initial velocity you assign, which might change
once your body hits another one, isn't it? We could ideally also define a
coefficient of restitution, that would be equal to one if no dissipation
occurs during the impact. Why do you think this is not understandable?


> Also, kinetic energy of velocity/displacement controlled bodies should not
> count in the total kinetic energy, only prescribed-force bodies should.
>
I cannot see why not..

>
> Chiara, did you try the blockedDOF trick?
>
I try. I let you know.
Chiara

>
> Bruno
>
>
>
>
>
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