SCM and contact friction

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Klaus Kivekäs

Jun 21, 2022, 10:14:56 AMJun 21
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I have been looking into using the SCM deformable terrain and rigid mesh tire models in my tractor-related research. I am using the dev branch of Chrono, currently on a version downloaded on June 7.

Is it possible to somehow change the coefficient of friction used in the contact force calculations between the tire and soil when using SCM and RigidMeshTire? Changing the friction value of the tires in their JSON file or using a FrictionFunctor don’t seem to do anything even though both work when using a rigid terrain. Am I possibly doing something wrong or is this intended behavior?


Radu Serban

Jun 22, 2022, 8:00:55 AMJun 22
to ProjectChrono

Hi Klaus,


You are not doing anything wrong. 

Indeed, the coefficient of friction specified on an object that interacts with SCM terrain is currently not taken into account.   This is because the friction is embedded in one of the SCM terrain parameters (Mohr_friction, passed in degrees to SCMDeformableTerrain::SetSoilParameters, and used in the Janosi-Hanamoto formula for tangential forces).


Try varying that value and see if you obtain the desired effect. 


I thought about also taking into consideration the coefficient of friction specified on the impactor object (e.g., a rigid tire) and may do that in the future.  Note however that that would have to be used in conjunction with two different sets of SCM parameters (for soil-soil and tire-soil interactions) and with the ability in the Chrono SCM implementation of optionally specifying both (see



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Klaus Kivekäs

Jun 22, 2022, 3:06:49 PMJun 22
to ProjectChrono
Hey Radu,

Thanks for the response! I will play around with the Mohr friction and see how it affects my simulations.

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