Yade

Rolling Resistance

Asked by bruna

Hello everyone!

I am trying to simulate a shear test. The rolling resistance is very important for my testing. I don't know if I have understood wrong but my attempts to simulate the rolling resistance didn't work.

I am using Ip2_FrictMat_FrictMat_MindlinPhys(en=0.5,es=0.7,krot=valorKrot,eta=valorEta) and Law2_ScGeom_MindlinPhys_Mindlin(includeMoment=True) but as I determine values for krot and eta nothing different happens when I compare to results without this parameters. In other words, with or without krot and eta the results are the same.

What could I be doing wrong? Have I missed something?
Which would be the magnitude order of this parameters? I am simulating a low resistance granite.

Thanks a lot!

Question information

Language:
English Edit question
Status:
Answered
For:
Yade Edit question
Assignee:
No assignee Edit question
Last query:
Last reply:
Revision history for this message
Luc Sibille (luc-sibille) said : 		#1

Hello Bruna,

I never used Mindlin contact law, but did you defined the rolling resistance properties in the material properties associated to bodies? If not, try and see if it solves the problem.

Luc

Revision history for this message
bruna (brunamot) said : 		#2

Hello Luc, thank you very much for your answer.

I am using FrictMat for my materials. The property that more would approach is the friction angle and it is already defined. If I am not wrong, there isn't a rolling resistance property for FrictMat.
I thought I could maybe change my material to CohFrictMat using cohesion = 0 but in this case I would have to change my Mindlin contact law. Would it be a good ideia?

Thanks again.

Bruna.

Revision history for this message
Jérôme Duriez (jduriez) said : 		#3

Hi,

Indeed, you may check from [1] that Ip2_FrictMat_FrictMat_MindlinPhys.krot directly equals the rolling stiffness MindlinPhys.kr
In the end, there is no rolling resistance parameters for Mindlin model in the "Material" class (not the usual way in YADE, I would say), as you got it. In particular, the friction angle Material parameter is for another purpose.

This being said, I am not used to Mindlin model either. You may try defining Ip2_FrictMat_FrictMat_MindlinPhys.ktwist as well, in order to activate another type of rolling resistance. For now, with "krot", you're only restricting --- if things go as planned --- one kind of rolling relative movement.

You may also try with a two spheres example to check if your definition of contact law/parameters actually leads to resisting moment at the particle interaction scale.

[1] https://github.com/yade/trunk/blob/6d4a0d1689c6bad2dbdd6e27d1653418f7fc6498/pkg/dem/HertzMindlin.cpp

Can you help with this problem?

Provide an answer of your own, or ask bruna for more information if necessary.

To post a message you must log in.