Re: [Yade-users] [Question #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Answered Raphaël Maurin proposed the following answer: No idea of that, maybe someone else can answer ? Raphaël -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Answered => Open frankie is still having a problem: OK thanks, Raphael, one last question: How can I know when it is published on yade daily exactly? cheers, Frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Answered Raphaël Maurin proposed the following answer: This probably means that you don't have the latest version of yade compiled from source. This is very recent change (2 days ago), so that it is for now only published in the source code. If you want to use it, you should either compile yade from the current source code, or wait some time (1 week?) for it to be published in yade daily. Raphaël -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Answered => Open frankie is still having a problem: Raphael, . If I use your new version from the doc., I got a message error: no such attribute en: O.materials.append(ViscElMat(young = wYoung, poisson = wPoisson, en=0.8,et=1, density = wDensity,frictionAngle=35, label='wall') ? Frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Answered Raphaël Maurin proposed the following answer: Look at the documentation, this is now possible with the latest version (from source code), I submitted it two days ago. This imply however that the tangential restitution coefficient is 1 (no tangential viscous damping). Raphaël -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Needs information => Open frankie gave more information on the question: Hi Raphael, I want as input parameters if possible: young, poisson and restitution coefficient. This would be easiest to get from experiments than damping parameters then whose numerical values to choose are unknown for me. regards, Frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Needs information Raphaël Maurin requested more information: Hi Frankie, I do not understand completely your last question: what are the original mechanical parameters of your material? Isn't it given in term of restitution coefficient ? What do you want to model ? The documentation of the law have been published now (https://yade-dem.org/doc/yade.wrapper.html?highlight=law2_scgeom_viscelphys_basic#yade.wrapper.Law2_ScGeom_ViscElPhys_Basic), but I am not sure it will help you. Raphaël -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 frankie posted a new comment: ... The problem for me is giving a dimension and numbers to the parameters cn and cs with respect to the original mechanical parameters of the material. the stability of my simulation is very parameter sensitive. Probably, your documentation could help ? best regards Frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Answered => Open frankie is still having a problem: ... The problem for me is giving a dimension and numbers to the parameters cn and cs with respect to the original mechanical parameters of the material. the stability of my simulation is very parameter sensitive. Probably, your documentation could help ? best regards Frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Anton Gladky proposed the following answer: 2015-06-02 16:56 GMT+02:00 Raphaël Maurin : > PS : I am making the documentation for the law right now, so maybe it > will be more clear with it. I will be commiting it soon. That would be fine Raphaël! We do really need that. Thanks 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
Re: [Yade-users] [Question #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Answered Raphaël Maurin proposed the following answer: Hi, The law recognizes directly the input depending on the material precisions. For example, if you want to use it with young modulus, Poisson's ratio, and damping parameters, you define your material: O.material.append(ViscElMat(young = a1, poisson = a2, cn = a3, cs = a4,density = a5,frictionAngle = a6, label = 'Mat')), with ax the parameters of your problem, and associate this material with the spheres you are creating. The law will directly recognize that you use these parameters and will compute the equivalent stiffnesses and damping constant accordingly. If you are trying to precise two parameters which does not use the law the same way, e.g. en, tc, young and poisson, it will throw an error. Raphaël PS : I am making the documentation for the law right now, so maybe it will be more clear with it. I will be commiting it soon. -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Answered => Open frankie is still having a problem: Thank you for your answers Raphael and Bruno, The Visco-elastic contact law supports by official definition explicit parameter input (Kn, Ks, Cn and Es). I would like Young modulus, poisson ratio and damping parameter as preferable inputs as Raphael suggested. How does the visco-elastic law recognize the correct different inputs I want (propositions of Raphael) from the definition of the material parameters ? best regards, frankie -- 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Bruno Chareyre posted a new comment: Thank you Raphaël for the great answer. Shouldn't this go to the documentation? There should be at least the two main governing equations to (normal and shear). 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Bruno Chareyre proposed the following answer: Hi, I would use the word "classical" very carefuly when it comes to contact laws. I think the version we have in Yade is some of the most consistent around. It does not mean - of course - that it uses the only valid constitutive assumptions. The one you mention is inconsistent: equation 5 is not objective. Your question raises the fact that documentation is badly missing for Law2_ScGeom_ViscElPhys_Basic. The information can only be found through the mailing list... I'm opening a bug. 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 #267566]: linear spring dashpot law?
Question #267566 on Yade changed: https://answers.launchpad.net/yade/+question/267566 Status: Open => Answered Raphaël Maurin proposed the following answer: Hi, The spring-dashpot law is a contact law with an equivalent spring-viscous damper system (+ tangential friction) and is called in yade Law2_ScGeom_ViscElPhys_Basic. The possible differences with what you call the spring-dashpot law stand in the way you are evaluating the equivalent spring-viscous damper constants. In a way, it is then up to you to know how you want to compute these equivalent constant. In Yade, there is different possibilities depending on what you precise in the material you define: - If you precise the contact time (tc) and the normal and tangential restitution coefficient (en and es), it is computing the equivalent stiffnesses and viscous damping from the formulation of Pournin 2001 (see in yade ref). This is not what is usually called spring-dashpot law. - If you precise the normal and tangential stiffnesses (kn, ks) and damping constant (cn,cs) of each particle, it is computing the equivalent stiffnesses and damping constant of each contact made of two particles 1 and 2 according to kn = 2*kn1*kn2/(kn1+kn2), and the same for ks, cn and cs. This is probably the nearest from spring-dashpot law except that you do not precise directly kn and the restitution coefficient. - Another alternative (more practical when dealing with polydisperse sample) is to precise the young modulus (E) and poisson's ratio(v), and the damping constants of each particle. The equivalent damping constant of the contacts are calculated as the previous case, and computing the spring constant is evaluated considering kn1 = E1*R1 and kn2 = E2*R2 (R: radius), while ks1 = v1*kn1 and ks2 = v2*kn2. -With Francois Kneib, we developed another alternative (which is not commited for now) where you can precise directly the young modulus, poisson's ratio, and restitution coefficient. If necessary, this can be commited quickly. Here are more or less the details about this contact law, for more precisions, look at the source code (https://github.com/yade/trunk/blob/master/pkg/dem/ViscoelasticPM.cpp). Concerning your question, to resume my answer would then be that the contact law you are looking for is Law2_ScGeom_ViscElPhys_Basic, and that depending on how you want to evaluate the equivalent constants of the contact, you can use the different inputs for the material, or develop another way in the contact law. I hope it is clear, don't hesitate to ask question if it is not the case. Raphaël -- 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
