yade-users team mailing list archive

[chiara modenese <c.modenese@xxxxxxxxx>]

On 14 June 2010 17:27, Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx> wrote:

> Thanks. Everything is as expected then, always good to hear.
> For motion engines, I prefer not to use them as we can simply assign
> velocity directly. Soon, you will not have to modify anything in Newton,
> since this behaviour of non-dynamic bodies is currently being implemented.
> Test scripts without Newton is not a good thing IMHO, you are putting
> yourself in a special case wich will never happen in routine simulations. It
> can hide existing problems or create problems that would not exist with
> Newton.
>
I partially agree. I guess it depends on the task. I found quite useful the
use of motion engines to test contact laws.

I would have a question about the ratcheting. I have run the same test also
for HM and of course I do not get the same good result as in the case of the
linear formulation. The reason is that in HM the tangential stiffness
depends on the normal force (or say on the overlapping alike), and this is
different from the initial one once I come back with the rotation (say at
the last step). Hence shear force is not equal to zero although granular
ratcheting is avoided. Do you think this is expected? I have not really
investigated too much the granular ratcheting in the literature. Is this
phenomenon perhaps addressing only the linear elastic case?

Thanks for reply,
Chiara