Hello everyone,
I have two questions regarding Hertz contact model used in Liggghts. I would be very grateful if some one could help me clear this up.
https://www.cfdem.com/media/DEM/docu/gran_model_hertz.html
(1) The force in Hertz model set to be equal to Normal force + Tangential force.
These two forces are in two different directions, so how can they be added to each other ? (mathematically not right)
(2) I am trying to find the relation between damping (gamma_n) and overlap (delta_n) based on the correlation of Sn=2Y*sqrt (R*delta_n).
Can some one give me a reference to how these correlations are originally driven please?
Thanks in Advance
Regards,
Luton
mschramm | Tue, 10/09/2018 - 23:46
Change of orientation
They are added because they are originally found for the normal and tangents directions. This means that the normal force has components in the x, y, and z directions, as do the tangents force. So Fnx + Ftx is the total force acting in the x direction.
Daniel Queteschiner | Wed, 10/10/2018 - 12:42
Hertz-Mindlin contact model
(1) The normal, tangential and total forces are 3d vectors.
(2) Read for example:
Y. Tsuji, T. Tanaka, T. Ishida, "Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe", Powder Technol. 71, 3, 1992
DOI
and
D. Antypov and J. A. Elliott, "On an analytical solution for the damped Hertzian spring", EPL 94, 5, 2011
DOI
as well as the 2 papers by Di Renzo and Di Maio given in the manual