[Yade-users] [Question #239900]: equivalent damping calculation in ViscElPhys
New question #239900 on Yade: https://answers.launchpad.net/yade/+question/239900 Hi all, I have a question about the formulation of the equivalent damping in ViscElphys. For now, it is made such as : cn = ((1/cn1) + (1/cn2))^(-1) which is equivalent to cn = cn1cn2/(cn1+cn2) However, in the case where cn2 = 0 for example, the formulation in the code is not equivalent to the expression above. In the code, it is written that in case of cn2 = 0, 1/cn2 = 0, which gives : cn = ((1/cn1) + 0)^(-1) This is not equivalent to the formulation cn = cn1cn2/(cn1+cn2), because then cn would be 0. (The problem is the same if cn1 = 0) It seems to me that the formulation of the code is false : if one damping parameter of the contact is zero, then as the two dashpot are considered in series, the equivalent damping should be zero. However I am not completely sure it is that simple, so I would like to have your opinion on that. I hope my question is clear. Thanks Raphael -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
[Yade-users] [Question #239901]: Sphere + facet collision problem
New question #239901 on Yade:
https://answers.launchpad.net/yade/+question/239901
Hi,
if I run the simulation, the spheres seem to cross the cauldron or they're
jumping very fast away. I if I change the material to ViscElMat and change the
appropriate Law, the spheres don't cross the cauldron's surface. I would like
to know, how to stop this behaviour regarding the material "FrictMat". Am I
using the wrong laws or is the matter with importing a .stl- file?
Here's my Code:
from yade import pack, plot, qt
from yade import ymport
facetMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
sphereMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
fctIds=O.bodies.append(ymport.stl('cauldron',color=(1,1,1),wire=True,fixed=True))
sphereRadius = .02
nbSpheres = (2,2,2)
for i in xrange(nbSpheres[0]):
for j in xrange(nbSpheres[1]):
for k in xrange(nbSpheres[2]):
x = (i*2 - nbSpheres[0])*sphereRadius*1.15
y = (j*2 - nbSpheres[1])*sphereRadius*1.15
z = (k*2 - nbSpheres[2])*sphereRadius*1.15
s=sphere([x,y,z+.2],sphereRadius,color=[1,1,6])
O.bodies.append(s)
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
# handle sphere+sphere and facet+sphere collisions
[Ig2_Sphere_Sphere_L3Geom(),Ig2_Facet_Sphere_L3Geom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_L3Geom_FrictPhys_ElPerfPl()]
),
GravityEngine(gravity=(0,0,-9.81)),
NewtonIntegrator(damping=0.5),
qt.SnapshotEngine(fileBase='3d-',iterPeriod=5,label='snapshot'),
PyRunner(command='finish()',iterPeriod=2)
]
O.dt=.9*utils.PWaveTimeStep()
qt.View()
def finish():
utils.makeVideo(snapshot.snapshots, 'simple_steel_collision.mpeg',
fps=25, bps=1)
O.pause()
rr=yade.qr.Renderer()
rr.shape=False
rr.IntrPhys=True
Best regards!
Thanks
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Re: [Yade-users] [Question #239901]: Sphere + facet collision problem
Question #239901 on Yade changed:
https://answers.launchpad.net/yade/+question/239901
Description changed to:
Hi,
if I run the simulation, the spheres seem to cross the cauldron and disappear
or they're jumping very fast away. I if I change the material to ViscElMat and
change the appropriate Law, the spheres don't cross the cauldron's surface
(https://github.com/yade/trunk/blob/master/examples/baraban/baraban.py). I
would like to know, how to stop this behaviour regarding the material
"FrictMat". Am I using wrong laws or is the matter with importing .stl- files?
Here's my Code:
from yade import pack, plot, qt
from yade import ymport
facetMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
sphereMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
fctIds=O.bodies.append(ymport.stl('cauldron',color=(1,1,1),wire=True,fixed=True))
sphereRadius = .02
nbSpheres = (2,2,2)
for i in xrange(nbSpheres[0]):
for j in xrange(nbSpheres[1]):
for k in xrange(nbSpheres[2]):
x = (i*2 - nbSpheres[0])*sphereRadius*1.15
y = (j*2 - nbSpheres[1])*sphereRadius*1.15
z = (k*2 - nbSpheres[2])*sphereRadius*1.15
s=sphere([x,y,z+.2],sphereRadius,color=[1,1,6])
O.bodies.append(s)
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
# handle sphere+sphere and facet+sphere collisions
[Ig2_Sphere_Sphere_L3Geom(),Ig2_Facet_Sphere_L3Geom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_L3Geom_FrictPhys_ElPerfPl()]
),
GravityEngine(gravity=(0,0,-9.81)),
NewtonIntegrator(damping=0.5),
qt.SnapshotEngine(fileBase='3d-',iterPeriod=5,label='snapshot'),
PyRunner(command='finish()',iterPeriod=2)
]
O.dt=.9*utils.PWaveTimeStep()
qt.View()
def finish():
utils.makeVideo(snapshot.snapshots, 'simple_steel_collision.mpeg',
fps=25, bps=1)
O.pause()
rr=yade.qr.Renderer()
rr.shape=False
rr.IntrPhys=True
Best regards!
Thanks
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Re: [Yade-users] [Question #239901]: Sphere + facet collision problem
Question #239901 on Yade changed:
https://answers.launchpad.net/yade/+question/239901
Description changed to:
Hi,
if I run the simulation, the spheres seem to cross the cauldron or they're
jumping very fast away. I if I change the material to ViscElMat and change the
appropriate Law, the spheres don't cross the cauldron's surface. I would like
to know, how to stop this behaviour regarding the material "FrictMat". Am I
using wrong laws or is the matter with importing a .stl- file?
Here's my Code:
from yade import pack, plot, qt
from yade import ymport
facetMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
sphereMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
fctIds=O.bodies.append(ymport.stl('cauldron',color=(1,1,1),wire=True,fixed=True))
sphereRadius = .02
nbSpheres = (2,2,2)
for i in xrange(nbSpheres[0]):
for j in xrange(nbSpheres[1]):
for k in xrange(nbSpheres[2]):
x = (i*2 - nbSpheres[0])*sphereRadius*1.15
y = (j*2 - nbSpheres[1])*sphereRadius*1.15
z = (k*2 - nbSpheres[2])*sphereRadius*1.15
s=sphere([x,y,z+.2],sphereRadius,color=[1,1,6])
O.bodies.append(s)
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
InteractionLoop(
# handle sphere+sphere and facet+sphere collisions
[Ig2_Sphere_Sphere_L3Geom(),Ig2_Facet_Sphere_L3Geom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_L3Geom_FrictPhys_ElPerfPl()]
),
GravityEngine(gravity=(0,0,-9.81)),
NewtonIntegrator(damping=0.5),
qt.SnapshotEngine(fileBase='3d-',iterPeriod=5,label='snapshot'),
PyRunner(command='finish()',iterPeriod=2)
]
O.dt=.9*utils.PWaveTimeStep()
qt.View()
def finish():
utils.makeVideo(snapshot.snapshots, 'simple_steel_collision.mpeg',
fps=25, bps=1)
O.pause()
rr=yade.qr.Renderer()
rr.shape=False
rr.IntrPhys=True
Best regards!
Thanks
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Re: [Yade-users] [Question #239901]: Sphere + facet collision problem
Question #239901 on Yade changed:
https://answers.launchpad.net/yade/+question/239901
Status: Open => Answered
Jan Stránský proposed the following answer:
Hi Martin,
try to decrease the time step and let us know if it helped or not. If not,
we will find better solution :-)
cheers
Jan
2013/11/27 Martin Nie
> New question #239901 on Yade:
> https://answers.launchpad.net/yade/+question/239901
>
> Hi,
> if I run the simulation, the spheres seem to cross the cauldron or they're
> jumping very fast away. I if I change the material to ViscElMat and change
> the appropriate Law, the spheres don't cross the cauldron's surface. I
> would like to know, how to stop this behaviour regarding the material
> "FrictMat". Am I using the wrong laws or is the matter with importing a
> .stl- file?
> Here's my Code:
>
> from yade import pack, plot, qt
> from yade import ymport
>
> facetMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
>
> sphereMat=O.materials.append(FrictMat(density=7850,young=210e9,poisson=.25))
>
> fctIds=O.bodies.append(ymport.stl('cauldron',color=(1,1,1),wire=True,fixed=True))
>
> sphereRadius = .02
> nbSpheres = (2,2,2)
> for i in xrange(nbSpheres[0]):
> for j in xrange(nbSpheres[1]):
> for k in xrange(nbSpheres[2]):
> x = (i*2 - nbSpheres[0])*sphereRadius*1.15
> y = (j*2 - nbSpheres[1])*sphereRadius*1.15
> z = (k*2 - nbSpheres[2])*sphereRadius*1.15
> s=sphere([x,y,z+.2],sphereRadius,color=[1,1,6])
> O.bodies.append(s)
>
>
> O.engines=[
>ForceResetter(),
>InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
>InteractionLoop(
> # handle sphere+sphere and facet+sphere collisions
> [Ig2_Sphere_Sphere_L3Geom(),Ig2_Facet_Sphere_L3Geom()],
> [Ip2_FrictMat_FrictMat_FrictPhys()],
> [Law2_L3Geom_FrictPhys_ElPerfPl()]
>
>
>),
>GravityEngine(gravity=(0,0,-9.81)),
>NewtonIntegrator(damping=0.5),
>
>qt.SnapshotEngine(fileBase='3d-',iterPeriod=5,label='snapshot'),
>PyRunner(command='finish()',iterPeriod=2)
>
> ]
> O.dt=.9*utils.PWaveTimeStep()
>
> qt.View()
>
> def finish():
> utils.makeVideo(snapshot.snapshots, 'simple_steel_collision.mpeg',
> fps=25, bps=1)
> O.pause()
>
>
> rr=yade.qr.Renderer()
> rr.shape=False
> rr.IntrPhys=True
>
> Best regards!
> Thanks
>
>
> --
> 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 : yade-users@lists.launchpad.net
> Unsubscribe : https://launchpad.net/~yade-users
> More help : https://help.launchpad.net/ListHelp
>
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Re: [Yade-users] [Question #239901]: Sphere + facet collision problem
Question #239901 on Yade changed: https://answers.launchpad.net/yade/+question/239901 Martin Nie posted a new comment: hi Jan, many thanks for your quick response. I tried to decrease the time step, but it doesn't work. (The Timestep is decreased to 1*e-11) -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239824]: u
Question #239824 on Yade changed: https://answers.launchpad.net/yade/+question/239824 Status: Open => Answered Bruno Chareyre proposed the following answer: Do you know how the explicit integration in DEM works? Because it seems you are looking for something that does not exist: we have no functional representation of the displacements. Or maybe I don't understand your question. Besides, could you please edit the title of your question and make it something with some sense? -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239900]: equivalent damping calculation in ViscElPhys
Question #239900 on Yade changed:
https://answers.launchpad.net/yade/+question/239900
Status: Open => Answered
Bruno Chareyre proposed the following answer:
>if one damping parameter of the contact is zero, then as the two
dashpot are considered in series, the equivalent damping should be zero.
I tend to fully agree if you speak of single dashpots in series.
However, if you say each particle's surface is deformable in a visco-
elastic manner and the deformations of the two sufaces are cumulative
(reason behind the harmonic average of stiffness) then it could make
more sense to say that you have two parallel spring-dashpots systems in
series, like model B in [1] except that Mt=0.
Then the question becomes: what is the equivalent viscosity (if possible
to define one, it may not be the case[*]) of such system? I don't think
it is cn = cn1cn2/(cn1+cn2). It should not be zero either when one of
the particles is purely elastic (cn=0), since the second one is still
viscous.
[1] http://www.sccs.swarthmore.edu/users/06/dluong1/e12/Lab4/diagrams/models.gif
[*] The more I think to it the less I see it feasible to have a unique
equivalent viscosity. For instance, if the force is constant then each surface
deformation is taking place following an exponential trend. Since the sum of
two exponential functions does not give an exponential function, it seems you
can't reduce the 2x{spring+dashpot} system to a {spring+dashpot} with
equivalent properties.
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[Yade-users] [Question #239918]: how to add a new field in controller GUI in order to pass a parameter to a specific law
New question #239918 on Yade: https://answers.launchpad.net/yade/+question/239918 Hi There, I just started using Yade. Presently I use those commands to launch the controller view (GUI) 1- I run the command yade then Ipress F12 I would like to add a new field (Real value) in Generate Panel, especially when choosing "CohesiveTriaxialTest" in order to pass this new value to cohesiveFrictionalRelationships of type Ip2_CohFrictMat_CohFrictMat_CohFrictPhys in class CohesiveTriaxialTest when creating actors. Could please help me to resolve this problem? Kind regards, Mansour -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
[Yade-users] [Question #239919]: Is getStress documentation ok ?
New question #239919 on Yade: https://answers.launchpad.net/yade/+question/239919 Hi, >From the code of getStress() function >(https://github.com/yade/trunk/blob/master/pkg/dem/Shop_02.cpp#L382 I guess) >it seems to me that sigma_ij ~ f_i * l_j While the doc says sigma_ij ~ l_i * f_j Not sure since I could not check how the operator * here works, but could someone confirm ? -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239918]: how to add a new field in controller GUI in order to pass a parameter to a specific law
Question #239918 on Yade changed: https://answers.launchpad.net/yade/+question/239918 Status: Open => Answered Bruno Chareyre proposed the following answer: Hi Mansour, What you ask is not difficult to do, however I'm not sure it is a good thing for you to follow this line. Nowadays the preprocessors are only usefull for showing yade to someone in less than 5 seconds. Other than that they really lack the flexibility of python scripts (and they force you to recompile the code each time you change the simulation setup). I suggest you check example scripts (namely examples/triax-tutorial), where similar things are achieved without the graphical interface. Bruno -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239919]: Is getStress documentation ok ?
Question #239919 on Yade changed: https://answers.launchpad.net/yade/+question/239919 Status: Open => Answered Bruno Chareyre proposed the following answer: The stress tensor is supposed to be symmetric, so it doesn't really matter (in static cases at least, in dynamic cases both are wrong anyway). Yet, for consistency it would be better to have fi*lj in the doc. Feel free to fix it. -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239918]: how to add a new field in controller GUI in order to pass a parameter to a specific law
Question #239918 on Yade changed: https://answers.launchpad.net/yade/+question/239918 Status: Answered => Open mansour talhaoui is still having a problem: Hi Bruno, Thank you very much. much appreciated. I have checked your example but really it is not clear enough because I don't know how to use python. I totally agree with you that changing c++ code will always lead to recompile the code for each modification but it is not a big deal for me (at least in this step of prove of concept) as I would like to do a tweak modification ( adding a constant to formula of calculation of normal adhesion) in C++ code and I think there is no impact or regression that's why I prefer to follow this line to avoid having a wrong results. I already tried to adapt the scripts to meet my requirements but it does not work. honestly it is so difficult for me to use python. cheers! -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239918]: how to add a new field in controller GUI in order to pass a parameter to a specific law
Question #239918 on Yade changed: https://answers.launchpad.net/yade/+question/239918 Status: Open => Answered Anton Gladky proposed the following answer: Hi, 2013/11/27 mansour talhaoui : > I already tried to adapt the scripts to meet my requirements but it does > not work. honestly it is so difficult for me to use python. you do not need to know "the whole" Python to write simulation scripts for Yade. Just basic commands. Anton -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
[Yade-users] [Question #239945]: displacement
New question #239945 on Yade: https://answers.launchpad.net/yade/+question/239945 Hi I would like to use the manifold cover concept of the numerical manifold method in YADE, So I want to know the particle displacement function source code. It is that displacement function is the function used to represent the particle movement. Which is the source of displacement function of particle motion in yade? What information do I need to learn？ -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239945]: displacement
Question #239945 on Yade changed: https://answers.launchpad.net/yade/+question/239945 Status: Open => Answered Anton Gladky proposed the following answer: Hi, I am not sure, that my answer will be useful. Please, have a look at newtonintegrator [1]. Maybe it will give you some ideas. [1] https://github.com/yade/trunk/blob/master/pkg/dem/NewtonIntegrator.cpp#L227 Anton 2013/11/28 pingyang.1...@163.com : >I would like to use the manifold cover concept of the numerical > manifold method in YADE, So I want to know the particle displacement > function source code. It is that displacement function is the function used > to represent the particle movement. Which is the source of displacement > function of particle motion in yade? What information do I need to learn？ -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239945]: displacement
Question #239945 on Yade changed: https://answers.launchpad.net/yade/+question/239945 Status: Answered => Open pingyang.1...@163.com is still having a problem: thank you At 2013-11-28 14:46:16,"Anton Gladky" wrote: >Question #239945 on Yade changed: >https://answers.launchpad.net/yade/+question/239945 > >Status: Open => Answered > >Anton Gladky proposed the following answer: >Hi, > >I am not sure, that my answer will be useful. Please, have a look at >newtonintegrator [1]. Maybe it will give you some ideas. > >[1] >https://github.com/yade/trunk/blob/master/pkg/dem/NewtonIntegrator.cpp#L227 > >Anton > > >2013/11/28 pingyang.1...@163.com : >>I would like to use the manifold cover concept of the numerical >> manifold method in YADE, So I want to know the particle displacement >> function source code. It is that displacement function is the function used >> to represent the particle movement. Which is the source of displacement >> function of particle motion in yade? What information do I need to learn？ > >-- >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 : yade-users@lists.launchpad.net >Unsubscribe : https://launchpad.net/~yade-users >More help : https://help.launchpad.net/ListHelp -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #239918]: how to add a new field in controller GUI in order to pass a parameter to a specific law
Question #239918 on Yade changed: https://answers.launchpad.net/yade/+question/239918 Christian Jakob posted a new comment: > honestly it is so difficult for me to use python. It is not difficult! Change the script, like bruno suggested and run it in your console, like: yade scriptname.py -- 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 : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
