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[Jan Stránský <question693631@xxxxxxxxxxxxxxxxxxxxx>]

Question #693631 on Yade changed:
https://answers.launchpad.net/yade/+question/693631

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hello,

> If I only search for the whole class: (
Ip2_CohFrictMat_CohFrictMat_CohFrictPhys() )[3] .Under this class, there
is one parameter which is named: frictAngle

I see much more parameters, normalCohesion, shearCohesion, ...

> What is the function of the CohFrictPhys?? (Here, I mean if we set the
sphere's material properties by CohFrictMat.

Simple resolution:

Mat is a property of particle. Usually (but not necessarily) there are a
few materials and many particles share the same material.

Phys is a property of interaction. Always one IPhys instance belongs to
one interaction (interactions does not share IPhys).

Ip2 takes two (possibly different) Materials and create IPhys.

You can modify both Mat and IPhys relatively independently (e.g.
changing b.material has no effect on existing interactions, modifying
i.phys has no effect on Material)

> How can we use the properties under the CohFrictPhys??
> For example, where should I add the kn, ks, kr during the simulation?

ideally nohow and nowhere, as it should be determined "automatically".
If you need to modify it, then it is an "advanced" manipulation, assuming you know what you are doing.

> 2: If I set the frictionangle in CohFrictMat, what is the purpose of the frictAngle in Ip2 class?
> For instance, if I set this class like this: Ip2_CohFrictMat_CohFrictMat_CohFrictPhys (frictAngle = 30).

Concerning frictAngle, doc says "Instance of MatchMaker determining how to compute interaction’s friction angle. If None, minimum value is used."
Please be more specific, what is not clear.

In this case, Ip2.firctAngle determines, how to set IPhys.tangensOfFrictionAngle according to Material(s).frictionAngle.
The interaction can connect bodies with different materials, with different values of firctionAngle. What should be the fractionAngle of the interaction? minimum? average? There is something default (minimum here for friction angle, but e.g. for stiffness it is a harmonic mean ) and for certain properties there is an option to adjust this behavior (using MatchMaker)

> Does this mean there are two friction angle for this kind of
material??

see above for Ip2, Material and IPhys "definitions".

If you have just one material, it may seem that some of the values and properties are redundant.
But consider interactions connecting bodies with different materials, and the purpose should be clear.

cheers
Jan

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