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Re: [Question #693631]: Ip2_CohFrictMat_CohFrictMat_CohFrictPhys

 

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

nobody posted a new comment:
Hi Jan,

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

You are right, there are more parameters. I just want to mention that
under this class there is also one friction angle parameter.

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

If I understand correctly, for this ip2 class. we can define the material properties and then get the properties of the contacts. 
###############################
For instance, I set the material properties as follows:
young=4e8
finalcompFricDegree=19.5
sphereMat=O.materials.append(CohFrictMat(young=young,poisson=0.3,frictionAngle=radians(finalcompFricDegree),isCohesive=False,alphaKr=0.2,alphaKtw=0,etaRoll=0.5,momentRotationLaw=True,density=2648)) #####(material properties)
###############
Then, by using this Ip2 class (Ip2_CohFrictMat_CohFrictMat_CohFrictPhys), the properties of the contact will be calculated automatically. these properties are the properties that contained under the CohFrictPhys <For example, the kn, ks, kr )
put it simply, we use the young and Poisson of the material to calculate the kn, ks, kr of the contacts (interactions).
the material properties here are properties that the user can modify it, while the interaction properties (kn, ks, kr) are read-only parameters here  (however, these parameters can be changed by advanced manipulation).
##########################################
InYADE, the physical properties can be set through the material properties and the contact properties, or both.
(1) In the above case, we set the material properties to get the contact properties.
(2) for this case( Law2_ScGeom_MindlinPhys_Mindlin), we can set the contact properties in this class.

for example: Ip2_FrictMat_FrictMat_MindlinPhys(gamma=40e-3, betan = 0.6, betas = 0.3)
(3) we can also set the material properties for this class (Law2_ScGeom_MindlinPhys_Mindlin )
#######################################################################
#######################################################################
As for the friction angle, here is my understanding.
we set the friction angle for the materials and then we use the criteria (Ip2_CohFrictMat_CohFrictMat_CohFrictPhys() -----this is the criteria) to determine the friction angle of the contacts (interactions) ( IPhys.tangensOfFrictionAngle ).
If there is just one kind of material, the friction angle of the material will be the friction angle of the contacts (interactions).
for example: O.materials[0].frictionAngle=.5 # radians
for i in O.interactions: i.phys.tangensOfFrictionAngle=tan(.5)
################################################
If there are two kinds of materials, we have to use the criteria to determine the friction angle between the interface of material A and material B. 
##############################
the above notes are my humble opinion. Please correct if I was wrong. 

thanks!
Yong



references:[1]https://yade-dem.org/doc/yade.wrapper.html?highlight=ip2%20mindlinphys#yade.wrapper.Ip2_FrictMat_FrictMat_MindlinPhys

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