Re: [Yade-users] [Question #264174]: how is shear force related to poisson ratio?
Question #264174 on Yade changed: https://answers.launchpad.net/yade/+question/264174 Hongyang Alex Cheng proposed the following answer: Hi, Shenyang Like Bruno said. you should take a look at the functors you use. The contact springs are defined by the law2 and the Ip2 functors. The meaning of Young's modulus and poisson ratio varies from different set of law2 and lp2 functors in use (see linear contact and mindlin contact for instance). If you use the linear contact law changing poisson ratio will only affect the shear stiffness. Note that adjusting material constants doesn't have effect on existing contacts. Alex On Fri, Mar 27, 2015 at 10:41 AM, Shenyang Cai < question264...@answers.launchpad.net> wrote: > Question #264174 on Yade changed: > https://answers.launchpad.net/yade/+question/264174 > > Shenyang Cai posted a new comment: > Hi Bruno, > > I'm still confused. When two spheres are in contact, I suppose there > must be a normal stifness and a shear stiffness(though it may equal > zero) between them, regardless of the IPhys and Law functors. > > My idea is to change some parameters in the material class to enlarge > the shear stiffness between the spheres. And I thought "poisson" is a > factor. If changing "poisson" does not lead to the change of shear > stiffness, then what paremeters should I focus on to achieve my goal? > > > Thanks! > Shenyang > > -- > 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 #264174]: how is shear force related to poisson ratio?
Question #264174 on Yade changed: https://answers.launchpad.net/yade/+question/264174 Shenyang Cai posted a new comment: Hi Bruno, I'm still confused. When two spheres are in contact, I suppose there must be a normal stifness and a shear stiffness(though it may equal zero) between them, regardless of the IPhys and Law functors. My idea is to change some parameters in the material class to enlarge the shear stiffness between the spheres. And I thought "poisson" is a factor. If changing "poisson" does not lead to the change of shear stiffness, then what paremeters should I focus on to achieve my goal? Thanks! Shenyang -- 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 #264142]: Law Functor
Question #264142 on Yade changed: https://answers.launchpad.net/yade/+question/264142 Felipe posted a new comment: Hello Jerome, Thank you for answering my question.. I'll read both tutorial. I also liked the link about others examples. For the moment, you solved my questions. Cheeres, Felipe -- 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 #264142]: Law Functor
Question #264142 on Yade changed: https://answers.launchpad.net/yade/+question/264142 Status: Answered => Solved Felipe confirmed that the question is solved: Hello Jan, Thank you again. For sure, the next time I will try more specific in my questions. For the moment, you solved my questions. Thank you so much. Cheeres, Felipe -- 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 #264142]: Law Functor
Question #264142 on Yade changed: https://answers.launchpad.net/yade/+question/264142 Felipe confirmed that the question is solved: Thanks Jan Stránský, that solved my question. -- 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 #263739]: isotropic compression at controled pressure
Question #263739 on Yade changed: https://answers.launchpad.net/yade/+question/263739 Status: Open => Answered Bruno Chareyre proposed the following answer: >coupled with a small max_vel No need I think. For very smooth evolutions select a large N (10e4 or so), in which case "number" can be 1 (the number of iterations between each change of the applied pressure). Depends how close to equilibrium you want to be (it will need a bit of trial-error probably). In my experience there is an overhead when writing: for k in range(100): O.run(1,1) which makes things slower compared to (for instance) for k in range(10): O.run(10,1) That would be the only reason to use larger stress steps with more iterations between them. -- 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 #264191]: Ig2_Facet_Sphere_ScGeom contact calculation
New question #264191 on Yade: https://answers.launchpad.net/yade/+question/264191 Hello everyone, I am wondering how the contact between spheres and facets is handled (overlap calculation), if the normal projection of the sphere's center onto the facet is not located on this facet (edge/vertex contact; regularization)? If you know how works this algorithm, I would appreciate to get a simple explanation before decrypting the code [1] during hours. Thank you, Dominik [1] https://github.com/yade/trunk/blob/master/pkg/dem/Ig2_Facet_Sphere_ScGeom.cpp -- 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 #263739]: isotropic compression at controled pressure
Question #263739 on Yade changed: https://answers.launchpad.net/yade/+question/263739 Status: Answered => Open Luc OGER is still having a problem: thanks for the fast reply. I don't want to reach quickly the isotropic goal as some local reorganisaiton for the contacts between spheres is part of my studies, indeed the particles are frictionless which allow rotations and sliding during the slow compression process. so I guess that this solution (copy from your answer) will be the good one coupled with a small max_vel if the change of the triaxgoal loop only occurs when it is reached ?: Number effect is unclear for me in this example : "If what you want is to increase the isotropic confinement progressively: for k in range(N): triax.goal1=triax.goal2=triax.goal3=isoP*float(k)/float(N) O.run(number,True)" -- 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 #263739]: isotropic compression at controled pressure
Question #263739 on Yade changed: https://answers.launchpad.net/yade/+question/263739 Status: Open => Answered Bruno Chareyre proposed the following answer: Hello, I don't understand exactly in which sense it is not what you expect. I suggest to forget max_vel, assign a very large value to it so that it does not interfere. Trying to summarize what to do in your case (assuming TriaxialStressCOntroller is labeled "triax"): #stress control in all directions and for all boundaries independently triax.stressMask = 7 triax.internalCompaction=False # if there is gravity, imposing the same stress at the top and bottom boundaries would lead to free fall... block the bottom wall: triax.wall_bottom_activated=False #define the target stresses to be applied, if it must be isotropic: triax.goal1=triax.goal2=triax.goal3=isoP #then run O.run() This will reach the target isoP very quickly (a few iterations), in fact it could well result in a dynamic compaction at constant applied pressure (exception is if you impose a small max_vel). If what you want is to increase the isotropic confinement progressively: for k in range(N): triax.goal1=triax.goal2=triax.goal3=isoP*float(k)/float(N) O.run(number,True) The problem is the initial stress under gravity is not isotropic, for superimposing an isotropic stress to the intitial anisotropic one, better something like this: #initialize with current stress triax.goal1=triax.stress(0)[0] triax.goal2=-triax.stress(3)[1] triax.goal3=triax.stress(4)[2] #and increase progressively for k in range(N): triax.goal1+= isoP/float(N) triax.goal2+= isoP/float(N) triax.goal3+= isoP/float(N) O.run(number,True) 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 #264057]: Simulating time-dependent behavior of geo-material in Yade
Question #264057 on Yade changed: https://answers.launchpad.net/yade/+question/264057 Status: Answered => Solved Fu zuoguang confirmed that the question is solved: Dear Prof. Chareyre， Thanks all the same. -- 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 #263739]: isotropic compression at controled pressure
Question #263739 on Yade changed: https://answers.launchpad.net/yade/+question/263739 Status: Answered => Open Luc OGER is still having a problem: I made several tests to see if putting some max_vel solved my problem, it seems that it is not what I was expected. but to understand more my queston, I have to described what I was looking for : I want to look at the consequence at the anisotropy linked to the gravity deposition process. So my first step is doing a packing from spheres distributed randmoly inside big vertical box , letting them settling down, (in order to get a quasi cubic dense packing) putting the top wall at the upper point of the packing and then doing an isotropic compression by pressure control on all the walls but one by one. Indeed, the top wall starts with zero pressure and has to move alone to reach some pressure similar to the mean values of the others before moving the other walls. Otherwise I will reorganise too much the structure before compressing. i hope my description is clear enough for the understanding. -- 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 #264174]: how is shear force related to poisson ratio?
Question #264174 on Yade changed: https://answers.launchpad.net/yade/+question/264174 Status: Open => Answered Chareyre proposed the following answer: Hi, The parameters in Material classes cannot be "studied" because they are only numbers with names, not well defined physical parameters (suprising maybe). Better start thinking the other way around: look what kind of contact parameters the law functors are using, then how this contact parameters are defined based on material parameters. You will see that different functors lead to different interpretations of what Material::poisson is. For Ip2_FrictMat_FrictMat_FrictPhys+ Law2_ScGeom_FrictPhys_CundallStrack the normal force is independent of Poisson, yes. It is the expected behavior. I hope it helps. 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 #264142]: Law Functor
Question #264142 on Yade changed: https://answers.launchpad.net/yade/+question/264142 Jan Stránský proposed the following answer: Hi Felipe, brief summary contact laws are at [1]. There is brief description, publications and also names of example scripts you can look at. You can also browse documentation [2], where are listed parameters you can use. There are some derived from base classes which are not usually used (bases, dict, updateAttrs) and some you can set/modify, specifically for Law2_ScGeom_FrictPhys_CundallStrack [3]: neverErase, sphericalBodies. Furthermore you can use some methods defined on this law, on the example: elasticEnergy(), initPlasticDissipation(), plasticDissipation(). See examples for more details. if you are new to Yade, I really recommend to read the introduction, tutorial and user's manual, as cnatact law iteslf depends not only on law functor, but also on used particle shapes, materials, igeom functors and iphys functors.. cheers Jan PS: I am really not sure what "how you construct in ".py"" exactly means, next time please be more specific to get answer earlier :-) [1] https://yade-dem.org/wiki/ConstitutiveLaws#Constitutive_laws [2] https://yade-dem.org/doc/yade.wrapper.html#constitutive-laws [3] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Law2_ScGeom_FrictPhys_CundallStrack 2015-03-25 23:51 GMT+01:00 Felipe : > Question #264142 on Yade changed: > https://answers.launchpad.net/yade/+question/264142 > > Status: Answered => Open > > Felipe is still having a problem: > Hey Jan, > > Thank you for answering my question. > > I'm really appreciate that. > > However, I would like to learn more specific about contact laws. > > If you have examples about it, could you send me to learn and also > seeing how you construct in ".py"? > > Cheers, > > Felipe > > -- > 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 #264057]: Simulating time-dependent behavior of geo-material in Yade
Question #264057 on Yade changed: https://answers.launchpad.net/yade/+question/264057 Status: Open => Answered Chareyre proposed the following answer: Dear Fu Zuogang, The paper is still "in preparation" unfortunately, it should be removed from the web page. The contact law itslef is functional though. 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
