Yade

Shear Force calculation code

Asked by Andy Torres

Hi to all,
I'm trying to figure out where I'm doing a miss interpretation of the GUI information.
I can't adjust the shear force given by Yade for a viscoelastic material contact , to the equation given by Pourin [ec (11) in PRE-2001] in wich the shear force is ( I alrready know that the value of Ks and Cs are not the same than in the paper)

Fs=Ks*sum(shear displacement increment during the contact)+ Cs*(shear displacement/dt)

so my question is: where can i found the calculation of the shear force (for viscoelastic material) in the code (which file) or how should I make the calculation properly with the provided GUI data?
thanks in advance
Andy

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Anton Gladky
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Jérôme Duriez (jduriez) said : 		#1

Hi,

For such question, the answer will always be "in the ::go() function of the Law2_... class you are using" (or in a subfunction called by this go function).

The name of the file where this function is depends on the habits of the guy who commited. Either there are directly (hpp & cpp) files named Law2..., or this Law2::go function is included with other related stuff (like Ip2_...) in MyModel*PM* files. With search functions (of kdevelop for instance), it should be easy to locate such things.

If you are using e.g. Law2_ScGeom_FrictViscoPhys_CundallStrackVisco, you will find what you search in https://github.com/yade/trunk/blob/master/pkg/dem/FrictViscoPM.cpp. (finally, there seems to be no shear viscosity there, but maybe it is however helpful !)

Jérôme

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Best Anton Gladky (gladky-anton) said : 		#2

Hi,

shear force is calculated here [1] and here [2]:

shearForce += phys.ks*dt*shearVelocity;
...
shearForceVisc = phys.cs*shearVelocity;

[1] https://github.com/yade/trunk/blob/master/pkg/dem/ViscoelasticPM.cpp#L97
[2] https://github.com/yade/trunk/blob/master/pkg/dem/ViscoelasticPM.cpp#L135

Regards

Anton

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Andy Torres (torand2000) said : 		#3

Thanks Anton Gladky, that solved my question.

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Bruno Chareyre (bruno-chareyre) said : 		#4

Dear Andy,
Could you give a pointer to Pourin 2001? I can't find any author with this name in PRE.
Just curious.

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Anton Gladky (gladky-anton) said : 		#5

[Pournin2001] in references.

Anton

2014-04-25 10:11 GMT+02:00 Bruno Chareyre
<email address hidden>:
> Question #247576 on Yade changed:
> https://answers.launchpad.net/yade/+question/247576
>
> Bruno Chareyre posted a new comment:
> Dear Andy,
> Could you give a pointer to Pourin 2001? I can't find any author with this name in PRE.
> Just curious.
>
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Andy Torres (torand2000) said : 		#6

Sorry Bruno, i just saw your message! Just in case:
L. Pournin, Th. M. Liebling, A. Mocellin (2001),
Molecular-dynamics force models for better control of energy dissipation in numerical simulations of dense granular media.
Phys. Rev. E (65), pages 011302. DOI 10.1103/PhysRevE.65.011302