Using ForceEngine to break a single JCFpm bond

Asked by Yaniv Fogel on 2019-09-09


I'm a new user to YADE and I'm in the process of learning about the JCFpm model. I'm currently trying to break a bond between two particles using the ForceEngine. As described in the code bit below, I'm trying to apply and increasing force until a break occurs between the two particles. The bottom particle is fixed.

If I got the documentation right, the force when the breakage should happen is:
FnMax = tensileStrength * pi*Rmin^2 [1],[2] -> FnMax = 1e6 * np.pi * pow(0.005,2) = 78.539 N

First question -
For the first trials, I tried using addF manually, using the code below (after running the script). I found that the bond breaks around O.forces.addF(1,(0,0,700)). (I first assumed that addF uses Newtons, but now I'm not so sure...). So, did I calculate FnMax correctly or not?

Second question -
After that, I tried using the ForceEngine (same code, just uncomment #ForceEngine & #PyRunner), increasing the force on the particle, but I can't get it to break. Am I using the engine correctly?

Third question -
I also looked at the InterpolatingDirectedForceEngine [3], where there is a magnitude for the force, but what is the difference between force and magnitudes in the engine (Again, I tried playing with it, with increasing magnitudes, but I still couldn't get it to break)

I would like your help. Sorry if this is too long or if my understanding of vector physics is a bit lacking :)

### Forces Test 1, YADE ###

from yade import pack, plot
import numpy as np


# Define geometry
r = 0.005
intR = 1.0

# Define material
idRockTest = O.materials.append(JCFpmMat(type=1,

# add spheres
    sphere((0,0,0),r,material='Rock',color=(0.019, 0.529, 1),fixed=True),
    sphere((0,0,2*r),r,material='Rock',color=(1, 0, 0))

# Simulation loop



    # Apply gravity force to particles.

    # Apply force on top particle



# Define time step
#O.dt = 0.5*utils.PWaveTimeStep()

def recorder():



#### manage interaction detection factor during the first timestep and then set default interaction range
### initializes the interaction detection factor

# Define time step
O.dt = 0.5*utils.PWaveTimeStep()


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