On 27 April 2010 17:13, Bruno Chareyre wrote:
>
> I was only testing a contact law forcing displacements, but now I realize
>> that the best way to check that is actually applying a force (constant or
>> variable in time) or an initial velocity (in the way you suggest).
>>
> Ok. For this proble
I was only testing a contact law forcing displacements, but now I
realize that the best way to check that is actually applying a force
(constant or variable in time) or an initial velocity (in the way you
suggest).
Ok. For this problem, I would simply block DOF's and assign constant
velocit
On 27 April 2010 12:53, Bruno Chareyre wrote:
>
> Would not just be simply an initial velocity you assign, which might
>> change once your body hits another one, isn't it?
>>
> In that case, you just assign an initial velocity (body.vel=.., no engine,
> no blocked DOF). This is not what I call a
Would not just be simply an initial velocity you assign, which might
change once your body hits another one, isn't it?
In that case, you just assign an initial velocity (body.vel=.., no
engine, no blocked DOF). This is not what I call a
"prescribed-something" body, just the usual dynamic body
On 26 April 2010 11:49, Bruno Chareyre wrote:
>
>> Prescribing displacement (even by fixing position of
>> support) means that energy might disappear from the system...
>>
> This is what I was trying to find out, I mean, _why_ that happens..
>
>>
>>
>
> By definition, you impose displacement on
Prescribing displacement (even by fixing position of
support) means that energy might disappear from the system...
By definition, you impose displacement on a non-equilibrated body. So
that if you impose a displacement "du" on body "i", you provide energy
du*force[i] to the system, which
> I am not entirely happy with this. I think the result is correct, the
> code does what we say to do. However, dose this mean that if you apply
> an initial velocity to the body, instead of a force, the coefficient
> of restitution would be zero? Sorry if I guess, thanks for comments.
Applying d
2010/4/25 Václav Šmilauer
>
> > both TranslationEngine and JumpChangeSe3 work if bodies are dynamic.
> > Now I tried a simple sphere-sphere interaction test using the basic
> > Law2_ScGeom_FrictPhys_Basic() law. One ball is fixed, the other one is
> > moved by using JumpChangeSe3 (setting setVelo
2010/4/25 Václav Šmilauer
>
> > both TranslationEngine and JumpChangeSe3 work if bodies are dynamic.
> > Now I tried a simple sphere-sphere interaction test using the basic
> > Law2_ScGeom_FrictPhys_Basic() law. One ball is fixed, the other one is
> > moved by using JumpChangeSe3 (setting setVelo
> both TranslationEngine and JumpChangeSe3 work if bodies are dynamic.
> Now I tried a simple sphere-sphere interaction test using the basic
> Law2_ScGeom_FrictPhys_Basic() law. One ball is fixed, the other one is
> moved by using JumpChangeSe3 (setting setVelocities to true). The only
> thing I n
2010/4/23 Václav Šmilauer
>
> >
> > Using ScGeom, being the bodies Dynamic and using JumpChangeSe3 should
> > work?
> > Well let's try again.. I will let you know..
>
> Make sure you set
>
> https://www.yade-dem.org/sphinx/yade.wrapper.html#yade.wrapper.JumpChangeSe3.setVelocitiesto
> true (it i
Yes Bruno, this would be lovely (and perhaps simple to do). Can we
(you) do that? Do we already have a sort of DOFs for velocities
exactly as for generalized displacements?
Apparently, it is already implemented that way. NewtonIntegrator.cpp:182 :
blockTranslateDOFs(state->blockedDOFs, st
On 23 April 2010 14:06, Bruno Chareyre wrote:
> A logic I found very efficient for this problem (perhaps already possible
> in Yade?) is the one of PFC :
> You can declare some DOF's fixed for velocities/spins (say, Vx is declared
> fixed).
> After that, if you set Vx=0, the body doesn't move. If
A logic I found very efficient for this problem (perhaps already
possible in Yade?) is the one of PFC :
You can declare some DOF's fixed for velocities/spins (say, Vx is
declared fixed).
After that, if you set Vx=0, the body doesn't move. If you set
Vx=something, it will move at constant Vx.
If
> Ok, thanks a lot. But how is it that with TranslationEngine doesn't
> work? I mean it doesn't because we account for the displacement twice?
> I am looking at the code right now but I cannot find out why..
TranslationEngine will work for dynamic bodies, as it only sets
velocity, nothing else. I
2010/4/23 Václav Šmilauer
>
> >
> > Using ScGeom, being the bodies Dynamic and using JumpChangeSe3 should
> > work?
> > Well let's try again.. I will let you know..
>
> Make sure you set
>
> https://www.yade-dem.org/sphinx/yade.wrapper.html#yade.wrapper.JumpChangeSe3.setVelocitiesto
> true (it i
>
> Using ScGeom, being the bodies Dynamic and using JumpChangeSe3 should
> work?
> Well let's try again.. I will let you know..
Make sure you set
https://www.yade-dem.org/sphinx/yade.wrapper.html#yade.wrapper.JumpChangeSe3.setVelocities
to true (it is false by default), then it will work. See
2010/4/23 Václav Šmilauer
>
> > Reading JumpChangeSe3 (wouldn't it be better to call it
> > StepChangeSe3,
> > or rather StepChange... something else?) code, positions are
> > updated "by
> > hand"
> >
> > if(!setVelocities || (setVelocities && !b-
> Reading JumpChangeSe3 (wouldn't it be better to call it
> StepChangeSe3,
> or rather StepChange... something else?) code, positions are
> updated "by
> hand"
>
> if(!setVelocities || (setVelocities && !b->isDynamic))
>
>
2010/4/19 Václav Šmilauer
>
> >
> > Yes, I confirm (by myself :-) ) that doing so we account for the
> > applied displacement twice. Actually this fact is already documented
> > and avoid in JumpChangeSe3 class. Maybe we can add a comment also in
> > TranslationEngine so that if one wants to use
>
> Yes, I confirm (by myself :-) ) that doing so we account for the
> applied displacement twice. Actually this fact is already documented
> and avoid in JumpChangeSe3 class. Maybe we can add a comment also in
> TranslationEngine so that if one wants to use it on dynamic bodies, it
> knows that
I then tried to see what happens if I use TranslationEngine. In such case I
> can still run the simulation havin non dynamic bodies (and I get the same
> result as above). My question is: in this second case, if I set the body I
> am forcing to move as dynamic, am I considering twice the applied
>
Hi Vaclav,
I am doing a comparison between TranslationEngine and JumpChangeSe3.
I see that using JumpChangeSe3, setting velocities (as I am using ScGeom),
and setting the displacement it works fine. What I note is that in this way
I am not using NewtonIntegrator at all as bodies are non dynamic,
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