Yade

How to use dem-fem coupling program to analyze soil-tire contact

Asked by Ryota Nakanishi

Hi all,
I am trying to analyze contact problems between soil and off-road tire by dem-fem coupling program developed by Jan Stránský (Ref[1]). However, I have some problems with constructing the simulation especially because I am not familiar with OOFEM.

The tire is represented by FEM and I am trying to apply DeadWeight on the tire to apply gravity force.
I tried the code below based on the example ‘surf1_oofem.py’, which is included in the coupling program, but the error occurs.
And I am also not sure that the argument of DeadWeight is correct.
Is it possible to use DeadWeight with the coupling program?

ltf = liboofem.loadTimeFunction("constantFunction",1,f_t=0)
bc = liboofem.boundaryCondition(1, domain, loadTimeFunction=1, prescribedValue=0.0)
dw = liboofem.deadWeight(2, domain, components=[3,0.0,0.0,-9.81], loadTimeFunction=1)

AttributeError: 'module' object has no attribute 'deadweight'

And is it possible to apply constant pressure on the surface of the tire to represent the internal air pressure of tire?
I think ConstantSurfaceLoad is suitable for this purpose but using ConstantSurfaceLoad causes the same error as the DeadWeight above.

I am also trying to apply force or torque to rotate the tire at constant rotational velocity. Then is it possible to apply additional force on the tire made by FEM mesh by Yade’s module like O.forces.addF()?

Thanks,
Ryota

Ref:
[1] https://github.com/stranskyjan/dem-fem-coupling

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Jan Stránský (honzik) said : 		#1

Hello,

> I am trying to apply DeadWeight on the tire to apply gravity force.

I will have a look. Is the tire loaded by a car? Then I think the dead weight does not make much sense and an external load to its center should do the job..

> And is it possible to apply constant pressure on the surface of the tire to represent the internal air pressure of tire? I think ConstantSurfaceLoad is suitable for this purpose but using ConstantSurfaceLoad causes the same error as the DeadWeight above.

> I am also trying to apply force or torque to rotate the tire at constant rotational velocity. Then is it possible to apply additional force on the tire made by FEM mesh by Yade’s module like O.forces.addF()?

not sure, I am a afraid that not.. maybe the torque can be applied in Yade and according to the rotation a boundary condition of some nodes may be updated.. will have a look, too

Concerning AttributeError, the problem is that I implemented only loads which I used for the examples, I will add more of them..

Please describe here or send me email describing more in detail what you want to simulate, I will try to add a basic version of it

cheers
Jan

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Ryota Nakanishi (matr7) said : 		#2

Hi Jan,

Thank you for your reply!

Actually, I tried to apply force with Yade's O.forces.addF().
However, no force was applied to tire made by FEM mesh.

I think it is because the dem-fem coupling program get forces from DEM with O.interactions[id1,id2].phys.normalForce+O.interactions[id1,id2].phys.shearForce (, which is in OofemYadeMeshSurfaceMap::getForcesFromDem() of demfemcoupling.py).

O.forces.addF() does not affect O.interactions[id1,id2].phys.normalForce or shearForce, so I am trying to modify getForcesFromDem().

Then I apply additional force to rotate tire and represent external load and airpressure.
I am trying to run the program but controlling the additional force to rotate the tire with constant angular velocity is difficult.
I also tried to apply forced displacement on the wheel of the tire, but I was unable to do.

> I will have a look. Is the tire loaded by a car? Then I think the dead weight does not make much sense and an external load to its center should do the job.

Exactly.
I think that concerning the dead weight of tire will make the analysis more accurate, but the tire is loaded by an external load and the dead weight is not indispensable.

> Please describe here or send me email describing more in detail what you want to simulate, I will try to add a basic version of it

Thank you for your proposal!
I will send you email to describe the simulation more in detail.

Thanks a lot,
Ryota

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.