[deprecated list] question about clump?

Discussion:

Václav Šmilauer

2009-06-05 20:02:48 UTC

What's the problem there? The new clump collides with the other clump
getting some rotational motion, then different spheres hit the ground at
different points which makes its trajectory bend towards the side of
contact, as there is shear. Did I miss something?

Vaclav

Hello, everyone, sorry to bother you again!
First thank Vaclav for the reply about box interaction. Vaclav
suggested me "replacing box by a few clumped spheres would be good
enough for your purposes."
These days I try to learn how to use clump as the example in
yade(ClumpTestGen), but i noticed there seems exist some unreasonable
movement in the shear direction when I generated more some clumps in the
example(ClumpTestGen). is it because of the interaction between clumps?
shared_ptr<Body>
ground=Shop::box(Vector3r(0,0,-1),Vector3r(10,10,.2));
// three-sphere clump
clumpPos=Vector3r(0.5,2.5,2);
relPos.push_back(Vector3r(0,-.5,.5)); radii.push_back(.5);
relPos.push_back(Vector3r(0,.5,0)); radii.push_back(.5);
relPos.push_back(Vector3r(.5,0,0)); radii.push_back(.5);
createOneClump(rootBody,clumpPos,relPos,radii);
relPos.clear(); radii.clear();
// four-sphere clump (this one seems have abnormal movement,
horizontal translation in a curve (not a line) on the plane after
interaction)
clumpPos=Vector3r(0.5,-2.5,2);
relPos.push_back(Vector3r(0,0,0)); radii.push_back(.5);
relPos.push_back(Vector3r(.5,0,0)); radii.push_back(.5);
relPos.push_back(Vector3r(0,.5,0)); radii.push_back(.5);
relPos.push_back(Vector3r(0,0,.5)); radii.push_back(.5);
createOneClump(rootBody,clumpPos,relPos,radii);
relPos.clear(); radii.clear();
setDefault("param_damping",.8); //(made changes in shop)
I set up time step=10e-5 on control panel.
thank you very much!

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Václav Šmilauer

2009-06-07 18:07:54 UTC

Permalink

at the begining the clumps have both rotational and translational
motion, but later the rotational motion finish and just have
translational motion. at this time I found the clump slip on the plane
in a curve. I think its trajectory should slip in a line, because
there is no rotational motion and just have translational motion.

At the beginning they have no motion at all. Gravity, since it is
uniform, gives translational motion. At impact, it causes rotation of
the clump. There is nothing wrong with that, it is just sum of kinetic
energy that should be preserved and one can transform in another.

If you take a stick and let it fall, then if one of the ends touches
ground the first, the still will get rotational motion. I just tried
with a pen on table and it is true ;-)

V

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Jingsong Chen

2009-06-05 15:33:02 UTC

Permalink

Hello, everyone, sorry to bother you again!
First thank Vaclav for the reply about box interaction. Vaclav
suggested me "replacing box by a few clumped spheres would be good
enough for your purposes."
These days I try to learn how to use clump as the example in
yade(ClumpTestGen), but i noticed there seems exist some unreasonable
movement in the shear direction when I generated more some clumps in the
example(ClumpTestGen). is it because of the interaction between clumps?

I just make the plane bigger and add two more clumps as follow:

shared_ptr<Body>
ground=Shop::box(Vector3r(0,0,-1),Vector3r(10,10,.2));

// three-sphere clump
clumpPos=Vector3r(0.5,2.5,2);
relPos.push_back(Vector3r(0,-.5,.5)); radii.push_back(.5);
relPos.push_back(Vector3r(0,.5,0)); radii.push_back(.5);
relPos.push_back(Vector3r(.5,0,0)); radii.push_back(.5);
createOneClump(rootBody,clumpPos,relPos,radii);
relPos.clear(); radii.clear();

// four-sphere clump (this one seems have abnormal movement,
horizontal translation in a curve (not a line) on the plane after
interaction)
clumpPos=Vector3r(0.5,-2.5,2);
relPos.push_back(Vector3r(0,0,0)); radii.push_back(.5);
relPos.push_back(Vector3r(.5,0,0)); radii.push_back(.5);
relPos.push_back(Vector3r(0,.5,0)); radii.push_back(.5);
relPos.push_back(Vector3r(0,0,.5)); radii.push_back(.5);
createOneClump(rootBody,clumpPos,relPos,radii);
relPos.clear(); radii.clear();

setDefault("param_damping",.8); //(made changes in shop)

I set up time step=10e-5 on control panel.

thank you very much!
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陈敬松

2009-06-07 05:20:53 UTC

Permalink

thank you for the reply!

at the begining the clumps have both rotational and translational motion, but later the rotational motion finish and just have translational motion. at this time I found the clump slip on the plane in a curve. I think its trajectory should slip in a line, because there is no rotational motion and just have translational motion.

Jingsong

Date: Fri, 5 Jun 2009 22:02:48 +0200
Subject: Re: [Yade-users] question about clump?
What's the problem there? The new clump collides with the other clump
getting some rotational motion, then different spheres hit the ground at
different points which makes its trajectory bend towards the side of
contact, as there is shear. Did I miss something?
Vaclav

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Mailing list: https://launchpad.net/~yade-users
Unsubscribe : https://launchpad.net/~yade-users
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