Question #253045 on Yade changed: https://answers.launchpad.net/yade/+question/253045
Status: Answered => Open Dominik Boemer is still having a problem: Hey Anton, sorry for my late answer. There seem to be three errors, one in the paper and two in the code: 1. The forth equation of (22)[Pournin2001] should be the following: ct = - 2 / (tc * (1/meff + R1^2/I1 + R2^2/I2)) * ln(et) Why? First, the differential equations in (21)[Pournin2001] is similar (i.e. it has the same form) to the second one and the initial conditions of both equations are also similar. Thus, the results should be similar. Why is the second equation of (22)[Pournin2001] correct? Because this equation is the same than the one in [2], which seems to be correct. [2] Nagurka & Huang_A, Mass-Spring-Damper Model of a Bouncing Ball_19_Ijee1697 2. Taking into account the previous correction, the equations of [Pournin2001] are correct. This is the reason why cs1 = cs2 = -2.0/7.0 /Tc * log(Et)*massR; [3] should be replaced by cs1 = cs2 = -4.0/7.0 /Tc * log(Et)*massR; [3] https://github.com/yade/trunk/blob/master/pkg/dem/ViscoelasticPM.cpp#L194 3. As the equations of [Pournin2001] are correct (with the correction), const Real massR = 2*mass1*mass2/(mass1+mass2); [4] should be replaced by const Real massR = mass1*mass2/(mass1+mass2); according to [Pournin2001, just below equation (19)]. [4] https://github.com/yade/trunk/blob/master/pkg/dem/ViscoelasticPM.cpp#L173 Alright? I hope I am not missing anything. Regards, Dominik -- 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