Yade

Changing properties of spheres causing problems.

Asked by Emon Mitra

In the gravity deposition followed by uniaxial compression example if I change the physical properties of the sphere using the following code:

idAlumina=O.materials.append(FrictMat(density=3.95e3,young=30e9,poisson=.3,frictionAngle=.5236))

The gravity deposition and uniaxial compression both get really slow. If I use default values, the compression typically starts in 8000 iterations or less but with these properties the compression doesn't start till at least 80000 iterations have passed. Does anybody have any idea why this is happening and how to solve it?

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Jan Stránský
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Best Jan Stránský (honzik) said : 		#1

Hi Emon,
check time step (O.dt) in both cases ;-) time step depends on material
stiffness and since stiffness ratio in your cases (default and proposed by
you) is 300, your time steps should be in ratio approx. 17
(sqrt(stiffness)) resulting in what you see..
cheers
Jan

2014-05-02 4:47 GMT+02:00 Emon Mitra <email address hidden>:

> New question #248023 on Yade:
> https://answers.launchpad.net/yade/+question/248023
>
> In the gravity deposition followed by uniaxial compression example if I
> change the physical properties of the sphere using the following code:
>
>
> idAlumina=O.materials.append(FrictMat(density=3.95e3,young=30e9,poisson=.3,frictionAngle=.5236))
>
> The gravity deposition and uniaxial compression both get really slow. If I
> use default values, the compression typically starts in 8000 iterations or
> less but with these properties the compression doesn't start till at least
> 80000 iterations have passed. Does anybody have any idea why this is
> happening and how to solve it?
>
> --
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Revision history for this message
Emon Mitra (emon-mitra) said : 		#2

Thanks Jan Stránský, that solved my question.