contact stiffness in samples
Dear yade users,
I made a bouncing of 4 spheres with different diameters.
I varied the value of the damping (0.1 and 0.7) and I get the different value of contact stiffness (kn) used in the simulation.
My question:
How do you compute the contact stiffness? Is it kn is computed from the firs contact detected between the spheres?
Your answer would be appreciated. Thank you
I give you my script:
# -*- coding: utf-8 -*-
from yade import pack, plot
# basic simulation showing sphere falling ball gravity,
# bouncing against another sphere representing the support with cohesive contact law
# DATA COMPONENTS
# Geometry parameter to adapt
rad1 = 0.2
rad2 = 0.4
rad3 = 0.6
rad4 = 0.8
young_val = 1e7 # normal contact stiffness (N/m2)
pois_val = 1.0 # shear contact stiffness (N/m2)
dens_sp = 2600 # density of the spheres (kg/m3)
angle_frict = 30.0 # friction angle (in degree)
c_normal = 1e6 # normal cohesion in contact (N/m2)
c_shear = 1e6 # shear cohesion in contact (N/m2)
## create materials for spheres and plates
O.materials.
young=young_val,
poisson=pois_val,
density=dens_sp,
frictionAngle=
normalCohesion
shearCohesion=
momentRotation
isCohesive=True,
alphaKr=0.0,
alphaKtw=0.0,
etaRoll=0.0,
label='spheres'))
# Blocked certain degress of freedom to make 2D-Model in plane-XZ
for k in O.bodies:
if isinstance(k.shape, Sphere): k.state.
# add 2 particles to the simulation
# they the default material (utils.defaultMat)
O.bodies.append([
# fixed: particle's position in space will not change (support)
utils.
# this particles is free, subject to dynamics
utils.
# this particles is free, subject to dynamics
utils.
# this particles is free, subject to dynamics
utils.
])
# FUNCTIONAL COMPONENTS
# simulation loop -- see presentation for the explanation
O.engines=[
ForceResetter(),
InsertionSor
InteractionLoop(
[
[
[
),
# apply gravity force to particles
GravityEngin
# damping: numerical dissipation of energy
NewtonIntegr
]
# set timestep to a fraction of the critical timestep
# the fraction is very small, so that the simulation is not too fast
# and the motion can be observed
O.dt=.5e-
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- Solved by:
- Jan Stránský
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