2010/4/25 Václav Šmilauer <[email protected]> > > > both TranslationEngine and JumpChangeSe3 work if bodies are dynamic. > > Now I tried a simple sphere-sphere interaction test using the basic > > Law2_ScGeom_FrictPhys_Basic() law. One ball is fixed, the other one is > > moved by using JumpChangeSe3 (setting setVelocities to true). The only > > thing I notice is that although no damping is present, the moving ball > > gets the rest at equilibrium (just run the attached script and press > > F8 to see what I mean, you will see the contact normal force getting a > > constant value). > > If I try the same test but using ForceEngine (now it is commented in > > the attached file but you can try to use it while commenting out > > JumpChangeSe3) I get the expected result, the moving ball is bouncing > > around the equilibrium (again just run the script and press F8). > > > > Nothing wrong, I just wuold like to understand (and maybe you can help > > me) why in displacement control I do not any bouncing around the > > equilibrium. Is not the same as applying a body force according to the > > code? > > I think the result it right. ForceEngine will apply force, which will > end up in sum with repulsive/attractive force between particles. The > equilibrium position will be moved by ForceEngine, but you will still > observe oscillation as if without ForceEngine. > > For JumpChangeSe3, particle is displaced by delta at every step. The > equilibrium ("constant" position) will come at the moment when > displacement by JumpChangeSe3 will be exactly compensated by > displacement by NewtonIntegrator later in the same step. That's how I > would explain the "equilibrium". >
Hi Vaclav, I am not entirely happy with this. I think the result is correct, the code does what we say to do. However, dose this mean that if you apply an initial velocity to the body, instead of a force, the coefficient of restitution would be zero? Sorry if I guess, thanks for comments. Chiara > > Let me know it it makes sense, I will have a look a little bit more > otherwise -- no problem. > > Cheers, v. > > > > > > _______________________________________________ > Mailing list: > https://launchpad.net/~yade-users<https://launchpad.net/%7Eyade-users> > Post to : [email protected] > Unsubscribe : > https://launchpad.net/~yade-users<https://launchpad.net/%7Eyade-users> > More help : https://help.launchpad.net/ListHelp >
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