Re: [Yade-users] [Question #691610]: Magnitude of contact normal force
Question #691610 on Yade changed: https://answers.launchpad.net/yade/+question/691610 Status: Answered => Open Leonard is still having a problem: Hi Jan, Thanks for your reply. 1. The maximum force is IMO not a very good indicator. >> Yes, I use maximum force here to say that I really got a small magnitude of >> ForceN. 2. You can easily check confinement, number of interactions and average forces. Could you please explain more about how to relate these 3 values? For my case, the size of sample is 0.07*0.07*0.14 (m), the size of particle is around 6 mm (from 2 to 9 mm), the number of spheres is 7000, the number of contacts is 13219 (at this moment), the average ForceN is around 5 N, the deviatoric stress q at this moment is around 160 kPa, the confinement is 100 kPa. Thanks! Leonard -- You received this question notification because your team yade-users 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 #691584]: About periodic simple shear
Question #691584 on Yade changed: https://answers.launchpad.net/yade/+question/691584 Status: Answered => Solved Lei Hang confirmed that the question is solved: Thanks Jan Stránský, that solved my question. -- You received this question notification because your team yade-users 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 #691610]: Magnitude of contact normal force
Question #691610 on Yade changed: https://answers.launchpad.net/yade/+question/691610 Status: Open => Answered Jan Stránský proposed the following answer: Hello, you cannot directly just compare young, confinement and force, they have different units. Size of particles plays important role. E.g. if you have half particle size, there are 4 times more particles on the same area to transmit the pressure, so the inter-particle forces will be 4 times smaller. Also the maximum force is IMO not a very good indicator, there could be one "crazy" particle or interaction with much higher force then the rest of simulation (it is dynamic simulation after all), some average or mean or median or some distribution characteristics would IMO make more sense than plain maximum value. You can easily check confinement, number of interactions and (average?) forces if the values roughly makes sense (and that you e.g. did not make mistake in physical units interpretation). cheers Jan -- You received this question notification because your team yade-users 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 #691584]: About periodic simple shear
Question #691584 on Yade changed: https://answers.launchpad.net/yade/+question/691584 Status: Open => Answered Jan Stránský proposed the following answer: Hello, > O.cell [1] > hSize [2] > "Base cell vectors (columns of the matrix)" [2]. > O.cell [1] > hSize [3] > components of velocity gradient [4] > trsf is deformation gradient [5] > stress here is matrix form of Cauchy stress tensor [6]. This is the standard approach on this forum to "cite" references summarized at the end of the message (or at the end of a previous message in the thread) Full links in the text looks messy and also this way you can easily reference one link at multiple places (like O.cell here) > Does "hsize" mean the size of cell? no, see [2] :-), where it states that hSize is "Base cell vectors (columns of the matrix)". I.e. vectors of the edges of the cell. > Does "diagonal terms" mean the size of cell? In case of diagonal matrix, the diagonal terms represent size. In general case not. > O.cell.velGrad=Matrix3(0,0,.1, 0,0,0, 0,0,0) > Here, how to determine it shears in xz? > Why is it in the xz plane rather than in other planes? because the only non-zero term is at index (0,2), corresponding to xz (0=x,2=z) shear component, which is shear in xz plane. > Why is it shearing rather than rotating? just because it is.. see e.g. [7], section "2D Transformations" (or google "2x2 matrix mapping scale skew rotation"). It is for 2D, which easier to understand and does not differ from 3D much. velGrad is "roughly" (in "small strain sense") time derivative of deformation gradient (see [4] for full definition and relation). cheers Jan [7] https://www.cs.brandeis.edu/~cs155/Lecture_06.pdf -- You received this question notification because your team yade-users 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 #691610]: Magnitude of contact normal force
New question #691610 on Yade: https://answers.launchpad.net/yade/+question/691610 Hi, I am working on a triaxial compression test using rigid walls under 100 kPa confining pressure, and I am interesting to see the contact normal force distribution. I use i.phys.normalForce.norm() to get ForceN of each sphere-sphere contact. Here I got the following questions: 1. The maximum normal contact force I got is about 40 N (under 100 kPa confining pressure), while the data I found in other papers usually could be several kN (such as 8 kN). Why there is such a big difference? 2. I guess one possible reason might be the young's module (E) of the material. But I use E = 2e8 Pa which is at the same magnitude of the E used in the papers I refer to, it should not lead to such a difference. Do you have any ideas of why the forceN I get is so low? Or the result is just like this? Many thanks! Leonard -- You received this question notification because your team yade-users 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 #691584]: About periodic simple shear
Question #691584 on Yade changed: https://answers.launchpad.net/yade/+question/691584 Status: Answered => Open Lei Hang is still having a problem: Thank you for your answer! I have some other questions. 1. What is the meaning of the numbers(2,3,4,5) in "hsize[2]","hsize[3]","velocity gradient [4]","deformation gradient [5]"? Are they the order of attributes in this script? Does "hsize" mean the size of cell? Does "diagonal terms" mean the size of cell? 2. "> In the "Checkstress()" part, it changes to "O.cell.velGrad=Matrix3(0,0,.1, 0,0,0, 0,0,0)" now it is changed to shear: diagonal terms are zero = no change of size non-diagonal terms are non-zero = some shear or rotation (in this case only one, xz, non-diagonal term is non-zero = shear in xz plane)." Here, how to determine it shears in xz? Why is it shearing rather than rotating? Why is it in the xz plane rather than in other planes? -- You received this question notification because your team yade-users 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 #691560]: contact normal is not spherical
Question #691560 on Yade changed: https://answers.launchpad.net/yade/+question/691560 Status: Open => Needs information Jan Stránský requested more information: > some codes are listed here: instant replay: please read [1] and provide a MWE* illustrating result and how you measured "contact normal". To not-just-guess (out of mny possible reasons), we need your code. cheers Jan *M = minimal *W = working (complete is a necessary condition) [1] https://www.yade-dem.org/wiki/Howtoask -- You received this question notification because your team yade-users 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 #691584]: About periodic simple shear
Question #691584 on Yade changed: https://answers.launchpad.net/yade/+question/691584 Status: Open => Answered Jan Stránský proposed the following answer: Hello, first of all, I am not sure if periodic simulations are a good very first starting point to learn Yade.. The previous scripts are OK? > 1.What is the meaning of "O.cell.hSize=Matrix3(2,0,0, 0,2,0, 0,0,2)"? it assign Matrix3(2,0,0, 0,2,0, 0,0,2) object to O.cell [1] as its hSize [2] attribute > What is the meaning of the numbers in the Matrix? "Base cell vectors (columns of the matrix)" [2]. In this case, diagonal terms are "normal size" (i.e. 2x2x2), zero non-diagonal terms means no skew and no rotation (non-diagonal terms control skew and/or rotation) > 2."pack.regularHexa(pack.inAlignedBox((0,0,0),(2,2,2)),radius=.1,gap=0,color=(0,0,1))". > What is the meaning of the "color=(0,0,1)"? In some other scripts I also see > "color=(1,1,1)" color of resulting particles (in ideal case, the documentation should tell that **kw are keywords passed to utils.sphere function. You are welcome to improve the documentation! :-) > 3.What is the meaning of "O.cell.velGrad=Matrix3(-.1,0,0, 0,-.1,0, 0,0,-.1)"? you assign Matrix3(-.1,0,0, 0,-.1,0, 0,0,-.1) object to O.cell [1] as its hSize [3] attribute. The components are components of velocity gradient (in matrix form). In this case, only diagonal negative terms it is isotropic compaction. > What is the meaning of the numbers in the Matrix? components of velocity gradient [4] The indexing of the components is very similar to those of deformation gradient (O.cell.trsf), see below. > In the "Checkstress()" part, it changes to "O.cell.velGrad=Matrix3(0,0,.1, > 0,0,0, 0,0,0)" now it is changed to shear: diagonal terms are zero = no change of size non-diagonal terms are non-zero = some shear or rotation (in this case only one, xz, non-diagonal term is non-zero = shear in xz plane). > 4.What is the meaning of "O.cell.trsf[0,2]" in the "checkDistorsion" part? > What do the numbers in the "trsf" mean? trsf is deformation gradient [5] of the cell trsf[0,2] means its xz shear part (see below) > stress=sum(normalShearStressTensors(),Matrix3.Zero) > 5.In > "plot.addData(exz=O.cell.trsf[0,2],szz=stress[2,2],sxz=stress[0,2],tanPhi=(stress[0,2]/stress[2,2]) > if stress[2,2]!=0 else 0,i=O.iter)" part,What is the meaning of the number > in the "streess[]"? For example, "stress[2,2]" or "stess[0,2]" stress here is matrix form of Cauchy stress tensor [6]. Indices are 0=x, 1=y, 2=z stress[2,2] means stress_zz, i.e. normal z component stress[0,2] means stress_xz, i.e. shear xz component The indices corresponds to those of hSize, velGrad and trsf (where it is related to strain/strain-rate counterpart) cheers Jan [1] https://yade-dem.org/doc/yade.wrapper.html#cell [2] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Cell.hSize [3] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Cell.velGrad [4] https://www.continuummechanics.org/velocitygradient.html [5] https://en.wikipedia.org/wiki/Finite_strain_theory#Deformation_gradient_tensor [6] https://en.wikipedia.org/wiki/Cauchy_stress_tensor -- You received this question notification because your team yade-users 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 #691593]: avoid this message : "The constructor with a shareWidget is deprecated, use the regular contructor instead."
Question #691593 on Yade changed:
https://answers.launchpad.net/yade/+question/691593
Status: Open => Solved
Luc OGER confirmed that the question is solved:
Dear Jérôme
thanks for the hint where to find the 'solution': it is effectively
inside the libQGLviewer 2.7.0 to 2.7.2 library, especially inside the
qglviewer.cpp:
#ifndef DOXYGEN
/*! These contructors are deprecated since version 2.7.0, since they are not
* supported by QOpenGlWidget */
/*! Constructor. See \c QGLWidget documentation for details.
All viewer parameters (display flags, scene parameters, associated objects...)
are set to their default values. See the associated documentation.
If the \p shareWidget parameter points to a valid \c QGLWidget, the QGLViewer
will share the OpenGL context with \p shareWidget (see isSharing()). */
QGLViewer::QGLViewer(QWidget *parent, const QGLWidget *shareWidget,
Qt::WindowFlags flags)
: QOpenGLWidget(parent, flags) {
Q_UNUSED(shareWidget)
qWarning("The constructor with a shareWidget is deprecated, use the regular "
"contructor instead.");
defaultConstructor();
}
now I will try to find a solution
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