yade-dev team mailing list archive

[François <francois.kneib@xxxxxxxxx>]

Hi,

I'm currently dealing with handling the contact between a ViscElMat and a
FrictMat.
To do this, and as I said some days ago, ViscElMat will have a Young
Modulus and Stiffnesses. If both are set by the user, young modulus will be
ignored (so the actual scripts will still work).

I'm wondering about massMultiply. By default it is True and the resulting
stiffness of the contact is K=k1*m1*k2*m2/(k1*m1+k2*m2), and the viscous
factors are multiplied by the mass too. If the user sets stiffnesses, I
understand that the masses comes into consideration when computing the
resulting stiffness. But to my mind, if the user sets Young/Poisson, then
ki=2*Ei*ri and the "particles shapes" are already taken into account, so we
should not use massMultiply. That's not true for the viscous coefficient
that should be computed the same way if the user sets stiffnesses or
young/poisson.

What I propose in the case the user sets young/poisson and
massMultiply=true is : don't multiply for the stiffness calculation, but
multiply for the viscous coefficients. In addition, by doing this, the
behaviour will be the same than for the FrictPhys, which seems essential.

Do you agree with this ? Of course, all this modifications will be
described in the documentation.

François