Janek Kozicki said: (by the date of Sun, 4 Jul 2010 20:47:40 +0200) > I'm not sure if I worded myself clearly.... I hope that you can > understand what I mean?
to rephrase in even different words: in plastic regime the Fs remains constant at the limiting value. While the sphere slipping distance sᵢ-sᵢ₋₁ can be actually bigger, that what has been contributed into the value of Fs, and is 's'. hmm, I see that ElasticContactLaw.cpp lines 96-104 are actually implementing a simlar thing to what I'm saying, by actually calculating the difference between s and sᵢ-sᵢ₋₁. So apparently there is just a bug inside here. Is maxFs correct? is trialForce the right value? Is the formula really similar? Let's rewrite this: plasticDissipation += ((1/currentContactPhysics->ks)*(trialForce-shearForce))//plastic disp. .dot(shearForce);//active force into: Ep += (Fs-Fsmax)⋅Fsmax/ks And compare this with: Es+=(Fs²⁄ks)⁄2 hmmm is there a "⁄2" missing? I mean: Ep += ((Fs-Fsmax)⋅Fsmax/ks)⁄2 I'm not sure in fact :) Next I am trying to check this again: Es+=(Fs²⁄ks)⁄2 where in fact: Fs²⁄ks = (ks*s)²/ks = ks*s² And compare again with this: Ep += ((Fs-Fsmax)⋅Fsmax/ks)⁄2 and try to rewrite it: (Fs-Fsmax)⋅Fsmax/ks = Fs⋅Fsmax/ks-Fsmax²/ks = = (ks*s)*(ks*∑(sᵢ-sᵢ₋₁))/ks - (ks*∑(sᵢ-sᵢ₋₁)²/ks = = s*ks*∑(sᵢ-sᵢ₋₁) - ks*∑(sᵢ-sᵢ₋₁)² but I must leave now. You could start derivation from this place where I stopped, and try to continue verifying if Ep is correct or not. Also I wanted to check how Ep could be expressed if using the same terms as in (or in terms of) Ws =∑ (Fsᵢ+Fsᵢ₋₁)*(sᵢ-sᵢ₋₁)⁄2 but unfortunately not today, I must go. But maybe you will be able to figure this out? best regards -- Janek Kozicki http://janek.kozicki.pl/ | _______________________________________________ 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