ForceRecorder Unit

Hi Luis,

yes, if your input young is supposed to be in [Pa] and dimensions in [m],
than resulting force is in [N] (forces) or [Nm] (torques).

Could you please describe a bit some more details about your experiment and
simulations? We can then have clearer idea about the differences and the
source of this "mistake".

cheers
Jan

2014-11-29 15:26 GMT+01:00 Luis Barbosa <
<email address hidden>>:

> New question #258401 on Yade:
> https://answers.launchpad.net/yade/+question/258401
>
> Hello colleagues,
>
> I'm in doubt in relation to unit of the results, which I got from
> ForceRecorder.
> All input units in simulation are:
> friction angle #radians
> young #Pa
> density #kg/m3
> bodies and spheres dimensions are in meters
>
> The results are in order of 25000000 (max value), but from the experiments
> (I've made) the results are close to 250 N (max value).
> Is this result in N and my simulation completely wrong, or is there some
> mistake in unit?
>
> Thanks!
>
>
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Hi Jan,
Thanks for while,
Let me describe a little bit my experiment:

I've constructed:
A small "soil bin": width:0.2m length:0.2m hight:0.3m
3 types of tip to a penetrometer: 1- cone with 90 degrees; 2- cone with 30 degrees and 3- flat tip
4 types of granular material: micro spheres of glass, polystyrene, steel and sand.
The soil bin was filled each time with a different material;

Using an Instron (universal testing machine), I've done the penetration test for each tip, at 0,005 m/s in all materials.
The main aim is get the energy x depth as done by [1].
My first idea was use ForceRecorder to make a direct comparison with results from Instron.

Simulations:

I've imported to yade, all penetrometers and soil bin as .stl;
Created a cloud of spheres with initial porosity; (There is an open question mine, about voxelporosity)
After the gravity deposition the penetrometer starts to travel and the results are acquired.
I'm using PWaveTimeStep instead of GlobalStiffnessTimeStepper.

Best regards.
Luis

[1] Asaf.Z, Rubinstein D., Shmulevich I. Determination of discrete element model parameters required for soil tillage. Soil and tillage Research, 2007.

Hi Luis,
could you give the script + .stl files somewhere on the internet such that
we can download them and examine your example?
Thanks
Jan

2014-11-29 20:01 GMT+01:00 Luis Barbosa <
<email address hidden>>:

> Question #258401 on Yade changed:
> https://answers.launchpad.net/yade/+question/258401
>
> Status: Answered => Open
>
> Luis Barbosa is still having a problem:
> Hi Jan,
> Thanks for while,
> Let me describe a little bit my experiment:
>
> I've constructed:
> A small "soil bin": width:0.2m length:0.2m hight:0.3m
> 3 types of tip to a penetrometer: 1- cone with 90 degrees; 2- cone with 30
> degrees and 3- flat tip
> 4 types of granular material: micro spheres of glass, polystyrene, steel
> and sand.
> The soil bin was filled each time with a different material;
>
> Using an Instron (universal testing machine), I've done the penetration
> test for each tip, at 0,005 m/s in all materials.
> The main aim is get the energy x depth as done by [1].
> My first idea was use ForceRecorder to make a direct comparison with
> results from Instron.
>
> Simulations:
>
> I've imported to yade, all penetrometers and soil bin as .stl;
> Created a cloud of spheres with initial porosity; (There is an open
> question mine, about voxelporosity)
> After the gravity deposition the penetrometer starts to travel and the
> results are acquired.
> I'm using PWaveTimeStep instead of GlobalStiffnessTimeStepper.
>
> Best regards.
> Luis
>
>
> [1] Asaf.Z, Rubinstein D., Shmulevich I. Determination of discrete element
> model parameters required for soil tillage. Soil and tillage Research, 2007.
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
>
> _______________________________________________
> Mailing list: https://launchpad.net/~yade-users
> Post to : <email address hidden>
> Unsubscribe : https://launchpad.net/~yade-users
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Hi Jan,
Let me know if you can access it:

https://drive.google.com/file/d/0B9LhrwAf_vasME03NXpkYzN2aW8/view?usp=sharing
https://drive.google.com/file/d/0B9LhrwAf_vasemduZzhKbHVnWlk/view?usp=sharing
https://drive.google.com/file/d/0B9LhrwAf_vascExRdTJhSDE3cDQ/view?usp=sharing

Thanks
Luis

Hi Luis, I cna acces it, thanks. Unfortunatelly, currently I have no time
to give answer, I will do it in a week or two..
cheers
Jan

2014-12-02 1:02 GMT+01:00 Luis Barbosa <<email address hidden>
>:

> Question #258401 on Yade changed:
> https://answers.launchpad.net/yade/+question/258401
>
> Luis Barbosa posted a new comment:
> Hi Jan,
> Let me know if you can access it:
>
>
> https://drive.google.com/file/d/0B9LhrwAf_vasME03NXpkYzN2aW8/view?usp=sharing
>
> https://drive.google.com/file/d/0B9LhrwAf_vasemduZzhKbHVnWlk/view?usp=sharing
>
> https://drive.google.com/file/d/0B9LhrwAf_vascExRdTJhSDE3cDQ/view?usp=sharing
>
> Thanks
> Luis
>
> --
> You received this question notification because you are a member of
> yade-users, which is an answer contact for Yade.
>
> _______________________________________________
> Mailing list: https://launchpad.net/~yade-users
> Post to : <email address hidden>
> Unsubscribe : https://launchpad.net/~yade-users
> More help : https://help.launchpad.net/ListHelp
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Hi Luis,
Tip penetration should occure in a granular layer wich is initially at static equilibrium, no?
I don't see anything in your script for generating such initial configuration. Did you check what happens in a 3D view?
If you are lucky the travel time of the tip is enough to let particles equilibrate before ppenetration starts, else most likely the force you get results from colissions of bouncing spheres with the tip, clearly not the experimental situation.

Hi Jan, thanks and no problem!!!

Hi Bruno,
Is your suggestion use utils.unbalancedForce()<.05? For example!
In paraview 3d, every thing seems to be ok.
The total time of simulation is aproximately 16 hours. 1 hour for particle deposition and 15 hours to tip travel. The speed of the tip is very low.
When the tip touch the spheres, probably, not sure, the particles are equilibrated at this point.

I've tried to use utils.unbalancedForce and voxelPorosity, to reach a desired porosity after the static equilibrium, but nothing happened, even errors didn't appears. The results were the same without unbalancedForce.

Thanks!
Luis

Hi, are there any news?

Thanks Bruno Chareyre, that solved my question.