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[Luc Scholtès <question403846@xxxxxxxxxxxxxxxxxxxxx>]

Question #403846 on Yade changed:
https://answers.launchpad.net/yade/+question/403846

    Status: Open => Answered

Luc Scholtès proposed the following answer:
Hello Luis,

Firstly, you don't need to have 2 Ip2_JCFpmMat_JCFpmMat_JCFpmPhy
functors defined in your script (actually, the script that you provided
does not work due to the following line that you should remove:
[Ip2_JCFpmMat_JCFpmMat_JCFpmPhys(cohesiveTresholdIteration=1,alpha=0.3,tensileStrength=1e6,cohesion=1e6,jointNormalStiffness=1e7,jointShearStiffness=1e7,jointCohesion=1e6,jointFrictionAngle=radians(20),jointDilationAngle=0.0)],)

Secondly, you should consider the physics in the test that you defined.
The 2 particles move apart tangentially. With the strength properties
that you defined, it appears that bond failure occurs due to a shear
mechanism. The maximum shear force is actually reached before the
maximum normal force. Running 2 tests with Poisson equal to 0.4 and 0.7
respectively, you will see that, effectively, the maximum shear force is
equal to ~3e6 in both cases, the difference between the 2 cases being
that it is reached sooner (for smaller displacement) in the case where
Poisson = 0.7 because the shear stiffness is bigger in this case. Now,
regarding your concern, when the maximum shear force is reached, the
bond breaks and the normal force is set to zero as well because there is
no interaction anymore but, you have to keep in mind that the driving
failure mechanism is shear so that the normal force at failure will be
different and will be a function of the relative normal displacement
between the particles.

I would suggest that you run a similar test defining the relative
movement of the particles in the direction normal to the contact so that
failure will occur due to a tensile/normal mechanism.

Luc

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