Hi Francois, thanks for pointing that out. This formulation is in Yade for several years [1] already. I am not sure, whether it is correct and we need to check this out. I just keep it "as it was" not to break a lot of things.
[1] https://github.com/yade/trunk/blob/0.60/pkg/dem/ViscoelasticPM.cpp#L24 Anton 2014-04-09 11:57 GMT+02:00 François <[email protected]>: > Hi Anton, > > I checked the Pournin's implementation you made, and I may have found a > little error. According to the formula (10) in the paper, the four formulas > (22) are the resulting stiffness/viscosity_coefs of a contact, and you > rightly transcript them. But in your algorithm, you set > kn1 = kn2 = *formula_in_(22)* > and then : > *kn = contactParameterCalculation(kn1,kn2) *which is the same as :* kn = > **contactParameterCalculation(kn1,kn1) = (kn1) / 2* > Which finally gives : > *kn = * > *formula_in_(22) / 2 * > Do you agree with this ? > > François > > > 2014-04-03 15:11 GMT+02:00 François <[email protected]>: > > Hi, >> >> One last thing : in the 3rd case (young modulus >> case >> ), it would be useful to determine >> cn from E1,E2,massR and en. I know the formula for normal cn, but not for >> cs. Do you have an idea ? >> >> Thanks, >> >> François. >> >> >> 2014-04-03 10:15 GMT+02:00 François <[email protected]>: >> >> 2014-04-03 10:00 GMT+02:00 Anton Gladky <[email protected]>: >>> >>> 2014-04-03 9:51 GMT+02:00 François <[email protected]>: >>>> > It will for sure break my scripts, as I used massMultiply=0. But your >>>> > implementation is part of my "todo list", which I can remove now :-) >>>> > You have made huge changes at once, so I need a little bit of time to >>>> check >>>> > everything. What I can see now is that you use "isnormal(r)" function >>>> into >>>> > the Ip2, which returns false if r==0. It will be a problem, for >>>> example if >>>> > we want to set cn, but cs=0 (same matter for en and et). >>>> >>>> I just wanted to check, that it is not(isnan). Thank for notice, will >>>> change to >>>> not(isnan). >>>> >>> Yes that's what I supposed. >>> >>> >>>> >>>> I think you can just remove massmultiply from your scripts and it >>>> should work >>>> fine. >>>> >>> I will re-check everything and see whether I am consistent with the >>> current implementation. You can delete the "massmultiply" argument in the >>> "contactParameterCalculation" function, as it's not used any more. >>> >>>> Anton >>>> >>> >>> François >>> >>> >> >
_______________________________________________ Mailing list: https://launchpad.net/~yade-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-dev More help : https://help.launchpad.net/ListHelp
