yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 18 June 2010 16:39, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

> Writing the 6x6 stiffness matrix of each body is like examining sub-blocs
> of the global stiffness matrix of the system (which is very sparse and can
> be put as a thin band matrix). Read PFC3D doc, or this paper for a special
> case where there is no rotational inertia
> http://dx.doi.org/10.1061/(ASCE)0733-9399(2005)131:7(689)<http://dx.doi.org/10.1061/%28ASCE%290733-9399%282005%29131:7%28689%29>
> .
> Better discuss in my office because I don't understand all questions below.
> A mistake on a sqrt(2) factor is always possible, though I would be
> surprised.
>
> Bruno
>

In fact there is no sqrt(2) factor in PFC manual if we consider the MDOF
system. They take an equivalent system where the stiffness is equal to 4k
being k the stiffness of each spring. At the end there is no sqrt(2) factor
in the computation of the time step.

Chiara