Re: [Yade-users] [Question #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Solved Alexander Eulitz [Eugen] confirmed that the question is solved: Thanks a lot Klaus. But isn't this change already part of daily build? -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Anton Gladky posted a new comment: Daily-builds are currently broken because of failing PFV-test. Anton 2013/9/8 Alexander Eulitz [Eugen] question225...@answers.launchpad.net: Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Solved Alexander Eulitz [Eugen] confirmed that the question is solved: Thanks a lot Klaus. But isn't this change already part of daily build? -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Open = Answered Klaus Thoeni proposed the following answer: Hi Alex it's implemented now [1]. Just update your source files an re-compile the code and you will be able to use it. Klaus [1] https://github.com/yade/trunk/commit/bd698e9a7aa9e05dfc7ead6293e3dd35a8f960d9 On Friday 06 September 2013 10:11:40 Alexander Eulitz [Eugen] wrote: Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Open Alexander Eulitz [Eugen] is still having a problem: Thank you Klaus, for your advice. Right now I'm using a diffrent IP2 functor: Ip2_FrictMat_FrictMat_MindlinPhys() according to [1] it does not have a frictAngle Attribute. My Law2 is Law2_ScGeom_MindlinPhys_Mindlin() How can I nake use of a match maker for friction angle in this case? thanks, Alex -- 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 -- Dr. Klaus Thoeni - Centre for Geotechnical and Materials Modelling Civil, Surveying and Environmental Engineering - Engineering Building EA The University of Newcastle, Callaghan, NSW 2308, Australia web: http://www.newcastle.edu.au/research-centre/cgmm phone: +61 (0)2 4921 5735 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Open Alexander Eulitz [Eugen] is still having a problem: Thank you Klaus, for your advice. Right now I'm using a diffrent IP2 functor: Ip2_FrictMat_FrictMat_MindlinPhys() according to [1] it does not have a frictAngle Attribute. My Law2 is Law2_ScGeom_MindlinPhys_Mindlin() How can I nake use of a match maker for friction angle in this case? thanks, Alex -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Open Alexander Eulitz [Eugen] is still having a problem: I'd like to reopen this thread. I'm trying to implement a matchmaker for the friction angle. How can I do so? Is the match maker kind of a further engine in the simulation? Thanks, Alex -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 wasabi posted a new comment: hi Eugen, I agree with Jan that the friction can be considered as static. Since the simulation (both static and dynamic) is computed each timestep, and system at each step = static. @Hien Nguyen: not as what you said. The friction determined by Mohr- Coulomb theory is INTERNAL friction for macro behavior of material. It includes friction and interlocking, does not mean friction between 2 objects or 2 particles. -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Bruno Chareyre proposed the following answer: I don't see why computing at each step is static, nor why the contact laws would define only static friction. The shear force at a sliding contact defines dynamic friction, right? In the current contact laws the maximum fs before sliding (static) and the fs during sliding (dynamic) are computed with the same angle. It simply means the assumption static friction = dynamic friction. So FrictPhys::friction, is not static OR dynamic, it is static AND dynamic. -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Bruno Chareyre proposed the following answer: Eugen, The three bodies problem you refer to is the classical caveat of computing contact parameters from bodies properties. I had the same problem years ago with PFC. But matchmakers gives you all freedom to solve this problem, as suggested by Jan. Note that your three bodies problem has in fact an easy solution without matchMakers. If you want friction f12 between b1 and plane 2, and friction f13 between b1 and plane 3, then why would you assign the minimum friction paramater to b1? You are not looking for troubles are you? ;) Since b1's friction is a meaningless parameter with the only purpose of defining contacts friction, you will give it any value (say 6e66), then you will assign f12 to plane 2 and f13 to plane 3. Of course, if we must have at the same time friction f23 between planes 2 and 3, we are toasted already, then goto: matchmakers. -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Open Eugen Kubowsky is still having a problem: Thanks again for all your help so far! let me start with Jan: @Jan frictionAngle - internalFrictionAngle - contact law: it is similar case as young or poisson parameters - each contact law may consider this parameter in different way. The friction angle itself is related to internal friction angle of a material [1] I'm using Law2_ScGeom_FrictPhys_CundallStrack and Law2_ScGeom_MindlinPhys_Mindlin right now. For a better impression what I'm using Yade for see this screenshot. http://s7.directupload.net/images/130404/9x582i65.png As you see there are several spheres inside a (green) facet cylinder. The grey facet cylinder is rotating around the z-axis on a circular path inside the green cylinder. All the spheres in my application are bodies made of the same material (ceramic), I don't use clumps. The cylinders are made of a different material. In some scenarios the cylinders are made of the same material (namely steel) - in other scenarios the grey cylinder is made of steel and the green cylinder is made of polyurethane [1] coated steel. So I have three diffrent materials and need to specify material properties young, poisson and frictionAngle for each. ...and (in case of FrictPhys_CundallStrack) is used for Mohr-Coulumb plasticity condition shearStress = normalStress * tan(frictionAngle) So what happens if Mohr-Coulumb plasticity condition is hurt? Particles wont break, will they? Is it possible to apply a force on a single particle in a simulation? This way I could check what happens when Mohr-Coulumb plasticity condition is hurt. But in general (maybe not all contact laws) Yade uses static friction angle between two individual particles. Do you mean static friction angle between two particles (e.g. spheres) made of the same material? (at least if I use these 2 mentioned contact laws) Because this would give a hint of how to determine the static friction angle exactly: follow method 2 or 3 from [2] with plane and box being made of identical material. It depends on the simulation setup and what you really call friction angle (like young parameter, it is parameter of one bond, but real Young's modulus of particle assembly is different). If you have a cube made from spherical particles placed on rough plane made of spherical particles, it would probably be possilbe (I am not sure) to get different values forexperiment static and dynamic friction angle between such cube and plane (although using only one parameter of contact law). As mentioned above I dont use clumps, so I'm interested in assigning right material parameters to my (independent) spheres and my facet models. Following this frictionAngle of the material of the spheres means frictionAngle of a single sphere. Acoording to your link to MatchMaker, you can define what law will be used for averaging (min, max, average..) Yes, I read about that. But I don't know of any appropriate mechanical theory that justifies choosing any of these laws. Considering the CundallStrack contactLaw (as you mentioned) this frictionAngle will be used for Mohr-coulomb plasticity condition only, right? So it is plausible to chose the minmal angle, because this material will fail first. But what about MindlinPhys_Mindlin? As I mentioned earlier - in my eyes frictionAngle cant be defined for a single material but for a pair of two materials. it can be defined for two bodies (possible with the same material) and if the material is composed of many bodies, it has some its own angle of repose [1], which is related to (internal) friction ange of such material. But how Yade uses frictionAngle is depending on contact law, right? According to Bruno - no contact law distinguishes between static and dynamic friction(angle). So again the question: is there any further use of frictionAngle than checking plasticity condition when using MindlinPhys_Mindlin? @Bruno: When body1 and body2 have different values of friction, the minimum is used for the contact by default. More sophisticated combinations are possible with matchMakers (do you have something precise in mind?) As I said before, I dont know the reason why the minimal value of friction is used. It would make sense if the value of friction (frictionAngle) is used for checking plasticity condition only in Yade. @wasabi: I agree that there is a difference between frictionAngle between two materials as shown in [2] and angle of internalFriction as mentioned in [3]. So if the frictionAngle was merely used for Mohr-Coulomb condition than it could be interpreted as angle of internal friction. @Bruno: The three bodies problem you refer to is the classical caveat of computing contact parameters from bodies properties. I had the same problem years ago with PFC. Could you please give a brief summary of your
Re: [Yade-users] [Question #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Open = Answered Bruno Chareyre proposed the following answer: As I said before, I dont know the reason why the minimal value of friction is used. The hardness of the contact between talc and diamond is the hardness of talc. The logic is the same in our case for friction. Would you suggest a better default behavior? Since it is only a default it is not really important anyway. The good question is what physics you want to simulate, and this really depends on your materials, not on Yade. We can't decide for you. It would make sense if the value of friction (frictionAngle) is used for checking plasticity condition only in Yade. I don't understand this statement. Could you please give a brief summary of your PFC problem and your solution? 2 groups of spheres (say A and B), 3 values of contact stiffness to be defined independently for A-A, A-B, and B-B. Not possible if stiffness is assigned to materials A and B (3 equations, 2 unknowns...), which is the case in PFC and in YADE. For PFC, there was simply no solution at that time. For Yade, there is now the matchmakers. They were introduced by Vaclav in response to a question very similar to yours. I don't know if they have been really used by somebody yet. Yes, this can be a great solution, providing that the dummy friction of b1 is used for that purpose only. I'm not sure about that You can be sure. I wrote CundallStrack, and I know Hertz is using the same logic. What about this idea: Are you speaking of experiments setup or simulation? If this is a simulation, this would be a sort of debugging, and I can tell you that you will find the expected result: fmax = weigth*tan(min(f1,f2)). -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Anton Gladky proposed the following answer: Hi, my 2cts. You can have a look in the source code, where friction angle is calculated and implemented [1], especially lines 67, 72, 231 and 383. They will give you an exact information about friction angle in this constitutive law in Yade. Actually, in other DEM-codes AFAIK the implementation is almost the same. I do not think, that the friction angle is the parameter, which will sufficiently influence on the macro-results of your simulation. You will, probably, get a noticeable difference, say, between mu=0 and mu=0.2, but you will unlikely see a big difference between mu=0.2 and mu=0.5. You should check and decide, whether you really need set the friction angle so accurately. Cheers, [1] https://github.com/yade/trunk/blob/master/pkg/dem/HertzMindlin.cpp#L67 -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Jan Stránský proposed the following answer: Hi Eugen, Eugen Kubowsky is still having a problem: Thanks again for all your help so far! let me start with Jan: @Jan frictionAngle - internalFrictionAngle - contact law: it is similar case as young or poisson parameters - each contact law may consider this parameter in different way. The friction angle itself is related to internal friction angle of a material [1] I'm using Law2_ScGeom_FrictPhys_CundallStrack and Law2_ScGeom_MindlinPhys_Mindlin right now. For a better impression what I'm using Yade for see this screenshot. http://s7.directupload.net/images/130404/9x582i65.png As you see there are several spheres inside a (green) facet cylinder. The grey facet cylinder is rotating around the z-axis on a circular path inside the green cylinder. All the spheres in my application are bodies made of the same material (ceramic), I don't use clumps. The cylinders are made of a different material. In some scenarios the cylinders are made of the same material (namely steel) - in other scenarios the grey cylinder is made of steel and the green cylinder is made of polyurethane [1] coated steel. So I have three diffrent materials and need to specify material properties young, poisson and frictionAngle for each. In my opinion, the MatchMaker is perfect solution for such scenario (see below). ...and (in case of FrictPhys_CundallStrack) is used for Mohr-Coulumb plasticity condition shearStress = normalStress * tan(frictionAngle) So what happens if Mohr-Coulumb plasticity condition is hurt? Particles wont break, will they? Is it possible to apply a force on a single particle in a simulation? This way I could check what happens when Mohr-Coulumb plasticity condition is hurt. This law takes place in interactions, i.e. between two particles. If two particles overlap, they generate some normal force (Fn=normalStiffness*normalDisplacement). If they further slide or rotate, this mutual transverse displacement causes shear force (Fs=shearStiffness*shearDisplacement). In continuum plasticity, this would be trial stress. Now the plasticity condition is checked Fs.norm() = normalForce*tan(frictionAngle). If it is satisfied, nothing happens. If it is not, then the force (while preserving its direction) is reduced such that its magnitude satisfied condition Fs.norm() = normalForce*tan(frictionAngle). In continuum plasticity, this would be stress return. But in general (maybe not all contact laws) Yade uses static friction angle between two individual particles. Do you mean static friction angle between two particles (e.g. spheres) made of the same material? (at least if I use these 2 mentioned contact laws) Because this would give a hint of how to determine the static friction angle exactly: follow method 2 or 3 from [2] with plane and box being made of identical material. Yes (also according to Bruno's answer), these contact laws does not differentiate between static and dynamic, simply uses plastic condition mentioned above. It depends on the simulation setup and what you really call friction angle (like young parameter, it is parameter of one bond, but real Young's modulus of particle assembly is different). If you have a cube made from spherical particles placed on rough plane made of spherical particles, it would probably be possilbe (I am not sure) to get different values forexperiment static and dynamic friction angle between such cube and plane (although using only one parameter of contact law). As mentioned above I dont use clumps, so I'm interested in assigning right material parameters to my (independent) spheres and my facet models. Following this frictionAngle of the material of the spheres means frictionAngle of a single sphere. This my note probably does not fit to your scenario, sorry, just ignore it :-) Acoording to your link to MatchMaker, you can define what law will be used for averaging (min, max, average..) Yes, I read about that. But I don't know of any appropriate mechanical theory that justifies choosing any of these laws. Considering the CundallStrack contactLaw (as you mentioned) this frictionAngle will be used for Mohr-coulomb plasticity condition only, right? So it is plausible to chose the minmal angle, because this material will fail first. But what about MindlinPhys_Mindlin? Just an example (I have no idea what the parameters should be in reality): for the materials of particles, you know frictionAngle = 45 deg, particles-steel = 20 deg and particles-coated steel=10 deg. So you simply define frictionAngle: particles: 45 deg steel: 20 deg coated steel: 10 deg and use MatchMaker to use minimal value. If the values are oposite, use maximum, Therefore interpaticle interactions will use their own friction angle and interactions between particles and other material will
Re: [Yade-users] [Question #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Open = Answered Nguyen Hien proposed the following answer: Hi, I'm modelling triaxial test and I play a lot with this parameter, in soil mechanics, angle of friction is about the behavior of the soil: The friction angle is a shear strength parameter of soils. Its definition is derived from the Mohr-Coulomb failure criterion and it is used to describe the friction shear resistance of soils together with the normal effective stress. In the stress plane of Shear stress-effective normal stress, the soil friction angle is the angle of inclination with respect to the horizontal axis of the Mohr-Coulomb shear resistance line (1). And I think that's what YADE is using. I give you a demonstration of the definition of this term, I think it's clear for you. http://i.imgur.com/QZ0Cr6m.png (2) (1) - http://www.geotechdata.info/parameter/angle-of-friction (2) - Soil Mechanic p.62 - Lambe -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Answered = Open Eugen Kubowsky is still having a problem: Thanks Nguyen. if you look at [1] there is one thing I dont understand. I give you an example: in [1] you see a box which is placed on a plane. Mass of the box causes force N on the plane. Now I push the box with an increasing force T. using the maximal possible T for which the box wont start sliding gives me a frictionAngle. (static friction) If we assume that the box is already moving (with constant speed) there is an T for which acceleration will be zero - so velocity stays constant. This T gives an dynamic frictionAngle. This leads to my second question from above: Does yade use static or dynamic frictionAngle Concerning my first question - let us enhance this little example. may the box be made of material1 and the plane of material2. If you determine the frictionAngle it is valid for this pair of materials only. Think of a different plane made of material3. The experiment from above will give you a diffrent frictionAngle. But when you simulate this box on a plane in Yade both materials must be given a frictionAngle, from which the matchmaker [2] will use the lowest for calculation of interactions[3]. This leads to a problem: if frictionAngle of material1 is lower than material2 and material3 than the matchmaker will use its frictionAngle whatever plane it will be placed on. Hence force T would be equal for both planes. This does not go in hand with real experiments. As I mentioned earlier - in my eyes frictionAngle cant be defined for a single material but for a pair of two materials. --- [1] http://www.geotechdata.info/parameter/angle-of-friction [2] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.MatchMaker [3] https://yade-dem.org/doc/yade.wrapper.html#yade.wrapper.Ip2_FrictMat_FrictMat_FrictPhys -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Status: Open = Answered Jan Stránský proposed the following answer: Hello Eugen, if you look at [1] there is one thing I dont understand. I give you an example: in [1] you see a box which is placed on a plane. Mass of the box causes force N on the plane. Now I push the box with an increasing force T. using the maximal possible T for which the box wont start sliding gives me a frictionAngle. (static friction) If we assume that the box is already moving (with constant speed) there is an T for which acceleration will be zero - so velocity stays constant. This T gives an dynamic frictionAngle. This leads to my second question from above: Does yade use static or dynamic frictionAngle it is similar case as young or poisson parameters - each contact law may consider this parameter in different way. The friction angle itself is related to internal friction angle of a material [1] and (in case of FrictPhys_CundallStrack) is used for Mohr-Coulumb plasticity condition shearStress = normalStress * tan(frictionAngle) But in general (maybe not all contact laws) Yade uses static friction angle between two individual particles. It depends on the simulation setup and what you really call friction angle (like young parameter, it is parameter of one bond, but real Young's modulus of particle assembly is different). If you have a cube made from spherical particles placed on rough plane made of spherical particles, it would probably be possilbe (I am not sure) to get different values for static and dynamic friction angle between such cube and plane (although using only one parameter of contact law). But you are rihgt, that these parameters could be documented better :-) Concerning my first question - let us enhance this little example. may the box be made of material1 and the plane of material2. If you determine the frictionAngle it is valid for this pair of materials only. Think of a different plane made of material3. The experiment from above will give you a diffrent frictionAngle. But when you simulate this box on a plane in Yade both materials must be given a frictionAngle, from which the matchmaker [2] will use the lowest for calculation of interactions[3]. Acoording to your link to MatchMaker, you can define what law will be used for averaging (min, max, average..) This leads to a problem: if frictionAngle of material1 is lower than material2 and material3 than the matchmaker will use its frictionAngle whatever plane it will be placed on. Hence force T would be equal for both planes. This does not go in hand with real experiments. see above. As I mentioned earlier - in my eyes frictionAngle cant be defined for a single material but for a pair of two materials. it can be defined for two bodies (possible with the same material) and if the material is composed of many bodies, it has some its own angle of repose [1], which is related to (internal) friction ange of such material. HTH Jan [1] http://en.wikipedia.org/wiki/Angle_of_repose -- 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 #225776]: Definition of Yade's frictionAngle for a single material
Question #225776 on Yade changed: https://answers.launchpad.net/yade/+question/225776 Bruno Chareyre proposed the following answer: Hi Eugen, All the current contact laws assume static=dynamic, because nobody really needed something else yet. Writing a different laws with different friction in static vs. dynamic would not be difficult. You are right, of course, friction gets meaningful only with a contact pair, but Yade's logic is to define the properties in materials first. Not really a problem when you are used to it. When body1 and body2 have different values of friction, the minimum is used for the contact by default. More sophisticated combinations are possible with matchMakers (do you have something precise in mind?) 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
