yade-dev team mailing list archive

[Vincent Richefeu <richefeu@xxxxxxxxx>]

Le 25 févr. 2011 à 11:38, Chiara Modenese a écrit :

> Yes, I agree. I think I was confused by Vincent's words such as: "let say that the critical time step determined for non-viscous contact will be smaller that the effectively minimum time step". Vincent, maybe you could clarify this point?

Oh sorry! Obviously I've made a mistake! I wanted to say that if the time step is ok without viscous damping, it will necessary be ok with the damping. My sentence was so complicated... just to say simple things...

With Pascal Villard (at Grenoble), we found a "problem" with viscous damping in the case of multi-contacts when considering balances of half a body. I don't really remember the demo but I will search it in the papers piled on my desktop. Viscous damping at contact is ok if you only want to stabilize your simulation. Anyway it's million times better than the so called Cundall damping which must be proscribed (in my own opinion) when the inertial number is to high (say > 10e-4 ?).

I don't know your topic, but if you want to dissipate a certain rate of energy (defined as the ratio of energy = e_n^2) you could simply multiply the force (even non-linear with respect to the overlap) by this rate during unloading...
Think about it...

Vincent