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[Jan Stránský <question237006@xxxxxxxxxxxxxxxxxxxxx>]

Question #237006 on Yade changed:
https://answers.launchpad.net/yade/+question/237006

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hello Nguyen,


> 1. List all the contact orientation inside a specimen (and after that show
> it on a polar diagram to validate its isotropic state) under a vector form
> (Vector3)
> I read in the documents that sumForces might be helpful, right?
>

If you are interested in contact orientation, not the forces itself, then
sumForces does not seem like the right approach.. The list of contact
orientation can be got by

contactOris = []
for i in O.interactions:
   if not i.isReal: continue
   contactOris.append(i.geom.normal)

or alternatlively with list comprehension one line command:

contactOris = [i.geom.normal for i in O.interactions if i.isReal]


>
> 2. Currently I also want to export all the contact force with the branch
> vector that goes with that contact, in order to calculate the internal
> stress following the Love-Weber formula, which allows us to calculate the
> internal stress by the multiplication of force vector and branch vector.
> Here I have the script to export the normal force +  shear force
>
> for i in O.interactions:
>         if not i.isReal: continue
>         fn = i.phys.normalForce
>         fs = i.phys.shearForce
>
> How to export it with the branch vectors?
>

see previous comment, branch=i.geom.normal. What would you like to achieve?
stress tensor of each particle, or stress tensor of whole assembly? There
exists functions
utils.bodyStressTensors # returns list of stress of each particle
utils.getStress # returns stress of whole assembly
so you can use these functions. You can of course use the approach you
wrote in your questions :-) or use both (yours and predefined in utils
module) to check the correct values.

HTH
Jan

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