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["Alexander Eulitz \[Eugen\]" <question238696@xxxxxxxxxxxxxxxxxxxxx>]

Question #238696 on Yade changed:
https://answers.launchpad.net/yade/+question/238696

Alexander Eulitz [Eugen] posted a new comment:
Hi Bruno,
do you know of some papers dealing with your last remark?
"...(but it should not be used for impact problems)."
I'd like to cite that in my master thesis.
So is modelling of a bulk a impact problem, too? Or what is the definition of impact problem? At the end it all goes down to impacts. I think you're pointing out, that if you are interested in contact forces of certain impacts and not only in the overall behaviour then you need to use diffrent contact law like Hertz Mindiln, don't you?

Thanks,
Alex

-----Ursprüngliche Nachricht-----
Von: bounces@xxxxxxxxxxxxx [mailto:bounces@xxxxxxxxxxxxx] Im Auftrag von Bruno Chareyre
Gesendet: Freitag, 8. November 2013 13:21
An: Eulitz, Alexander
Betreff: Re: [Question #238696]: Time step

Question #238696 on Yade changed:
https://answers.launchpad.net/yade/+question/238696

Bruno Chareyre posted a new comment:
Reflecting contact damping in time-step determination is relatively easy in the context of GlobalStiffness (though not implemented).
The derivation has been explained by Emanuele Catalano (page 59 in [1]). For Emanuele it was fluid viscosity instead of contact viscosity, but the equations are similar if you replace V (eq. 4.9) by a global viscosity matrix reflecting existing contacts on a given body.

For the record, Cundall's non-viscous damping [2] is not modifying the
timestep (but it should not be used for impact problems).

Bruno

[1] https://yade-dem.org/publi/Catalano_Thesis.pdf
[2] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.NewtonIntegrator.damping

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