Clump inertia and orientation
Hi,
while seeking for solution to Rohit John's problem [1], I got confused by inertia and orientation of clumps. I have found a discussion [2] explaining that:
> inertia is defined in the space of principal axes
> The orientation is internally stored as a quaternion
I modified John's code [1] where he uses eccentricAxisEn
Two observations are odd:
1) For both clumps inertia and orientation are the same. If I understand the convention properly, the orientations should be different ( Quaternion(
2) The two pendulums have different periods of oscillations - the one that is x axis aligned move slower (T=3.4s) while the y axis aligned pendulum has period T=2.5s.
I think that may be a potential bug, but I would like to confirm this first.
Cheers,
Karol
[1] https:/
[2] https:/
# -------
from math import *
from yade import *
from yade import utils, geom
from yade import plot
# -------
sph1 = sphere((0, 2, 0), radius=.5)
sph2 = sphere(center=(0, 0, 0), radius=.5)
sph3 = sphere((2, 5, 0), radius=.5)
sph4 = sphere(center=(0, 5, 0), radius=.5)
sph1_id = O.bodies.
sph2_id = O.bodies.
sph3_id = O.bodies.
sph4_id = O.bodies.
g = Vector3([0,0,-10])
stiffnes = 1e7
# -------
clump1_id = O.bodies.
clump2_id = O.bodies.
# -------
O.engines = [
),
]
# -------
def eccentricAxisEn
pos_01 = O.bodies[
pos_02 = O.bodies[
force1 = -stiffnes*pos_01
force2 = -stiffnes*
O.forces.
O.forces.
def addPlotData():
h1 = O.bodies[
h2 = O.bodies[
plot.addData(t = O.time, m1_height = h1, m2_height = h2)
# -------
O.dt = .5e-2 * PWaveTimeStep()
#
plot.plots=
plot.plot(subPlots =False)
### print information about clumps
print("
print(O.
print("
print(O.
print("
print(O.
print("
print(O.
Question information
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- Solved by:
- Jan Stránský
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