Using Kn Kt instead of Young Modulus

Submitted by andrea.pasquali on Tue, 05/31/2011 - 15:25

Hi,
I'm trying to use Kn and Kt instead Young Modulus. I wrote:

pair_style gran/hooke/history/stiffness 3 0
pair_coeff * *
...
fix m9 all property/global kn peratomtypepair 1 5000000
fix m10 all property/global kt peratomtypepair 1 5000000
fix m11 all property/global gamman peratomtypepair 1 0.7
fix m12 all property/global gammat peratomtypepair 1 0.7

But LIGGGHTS crashes without error message.
What I'm missing?

Thanks for any help

Andrea

Forums:

andrea.pasquali | Wed, 06/01/2011 - 14:11

Ok no problem,
I will try to obtain my Kn value by formula:

Kn = 4/3 * Y_star * sqrt( R_star * delta_n)

I have some question:
- for Y_star and R_star i can calculate them from 1/Y_star and 1/R_star, true?
- delta_n = d -r = R1+R2 -r. If r > d there is no contact. But what is really "r", the skin value?
- If I have 3 particles with R1 R2 R3, should I set Kn (in this case Young) for 11 12 13 21 22 23 31 32 33 ?

Thanks

Andrea