Question #206415 on Yade changed: https://answers.launchpad.net/yade/+question/206415
Jan Stránský proposed the following answer: Hello Ning, this equality is of course always valid :-) I had in my mind different aspect: the derivation of the stress of one (I will call it "investigated") particle is based on the equation [1] stress = sum ( x_i * f_i ) where x_i is the contact point (with respect to the center of particle), where some external force "f" is applied (external in the sense with respect to the investigated particle). Here we do not care about the opposite particles at all. For the special case of spheres, this "x" equals half of the branch vector between investigated particle and the formula can be accordingly simplified with real branch vectors. But for the clump case, if you use some point on the line connecting clumps' centers (which in general differs from real "x"), you are in fact using different formula. It is the same case as if you have force acting on rigid body. You can shift the force to any point, but you have to add some moment to preserve the equality of these two situations. @Chiara: Exactly, "the contact point does not need to be located in line with the branch vector", but at the same time you can't place it to the line with the branch vector (what is done by the approach proposed by Ning) if it is located in different place. Or of course you can, but then the result would be different.. Jan [1] https://yade- dem.org/doc/yade.utils.html#yade._utils.bodyStressTensors 2012/12/18 Chiara Modenese <question206...@answers.launchpad.net> > Question #206415 on Yade changed: > https://answers.launchpad.net/yade/+question/206415 > > Chiara Modenese proposed the following answer: > Hi Jan, > > I agree with Ning, the contact point does not need to be located in line > with the branch vector for the derivation to be valid. See Bagis' paper > (or similar references). > > Chiara > > -- > 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 > -- 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