2010/3/25 Bruno Chareyre <[email protected]> > > BTW, Bruno do you know if this method to get the timestep that varies with >> the global stiffness can be well applied also when we have a non linear >> relationship between forces and displacements at contact? As in the >> Hertz-Mindlin formulation, for instance. Do you think that in such a case >> the critical time step should change or should be taken differently than >> having a linear relationship? >> >> > If you assume small variations per step (i.e. no 2-steps bouncings with > Hert-Mindlin), you can compute dt exactly the same way. All you need is to > define dt with tangent stiffness : dfn/dun and dfs/dus for the current state > of the contact. >
I don't remember, did you write your law with tangent or secant stiffness (I > hope french maths translate well...)? > Actually I defined the normal stiffness as secant and the shear one as tangent. This because I was following PFC manual. But I see it is better to get both stiffnesses as tangent (I will modify it). So once I do that I can just pass those values to the GST, right? > > If you use tangent stifness, you have stritcly nothing to do to get > Hert-Mindlin handled by GSTimestepper. > > If you use secant stiffness, you can still exploit the old useless > intitialKn/Ks that remains in interactionPhysics, and which is currently > redundant with kn. Let kn be the tangent and be used by timestepper, and use > intialKn in you law (and rename initialKn to say what it is in your law, no > engine is using that anyway). > > How is HM working for you a.t.m.? > > Bruno > > _______________________________________________ > Mailing list: > https://launchpad.net/~yade-dev<https://launchpad.net/%7Eyade-dev> > Post to : [email protected] > Unsubscribe : > https://launchpad.net/~yade-dev<https://launchpad.net/%7Eyade-dev> > More help : https://help.launchpad.net/ListHelp > >
_______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
