yade-dev team mailing list archive

[eudoxos <eudoxos@xxxxxxxx>]

> Hi, Vaclav.
> In certain circumstance it would break simulation.
> For example, when a sphere is moved from one side corner to the other
> side.
> See attached file. So, please, keep it optional if it need.
> 
> ps/ In my opinion, if the overlap is more than the radius, it said too
low
> stiffness and an error in the physical model... Or is there another
> reasons?

Yes, it is an error in the simulation setup: extreme velocities and
inertia. I will try to avoid this by using logarithmic compressive strain
definition so that e.g. if 2 spheres initially in touching contact overlap,
their strain goes to -∞ as their center approach. One can define
ε=ln(ε₀+1) if ε₀<1, where ε₀=d/d₀-1. The adverse side is that
rigidity is effectively increased and timestep has to be decreased. I was
told afterwards that such definitions are used in some large-strain
formulations. Someone has any experience?

I will make it optional (and perhaps remove it altogether later, it
logstrain works), but give me a few day until I will be able to commit
(firewall).

Best, Vaclav