Question #673130 on Yade changed: https://answers.launchpad.net/yade/+question/673130
Status: Open => Answered Jan Stránský proposed the following answer: > using the 'ForceRecorder' function > are these forces related to the center of gravity of the surface or to other > point? > how is it calculated? is it the sum of all the forces acting on the single > facet which built the surface? Yes, ForceRecorder just sums forces acting on individual bodies [1]. Forces are considered to act on b.state.pos (not necessarily center of gravity), but in the case of forces themselves it is not that important (however, it is important for torques). > I tryied to compare the recorder engine results with the lybrary : > O.forces.f() (plot on graph). What i obtained is that the force acting on the > 'clumped body' is always zero. > why is this difference present? (even if i write from terminal > O.forces.f(NumberOfOneClumpedFacet), it returns (0,0,0), or > O.forces.f(clumpID).norm(), it still returns (0,0,0)) You have different cases here, therefore this difference :-) I guess if you put [clumpId] to ForceRecorder, you would get zero, too. It is just implementation choice, the force acting on clump itself is computed when needed from clump members [2,3], but is not stored.. cheers Jan [1] https://github.com/yade/trunk/blob/master/pkg/dem/ForceTorqueRecorder.cpp#L6 [2] https://github.com/yade/trunk/blob/master/pkg/dem/NewtonIntegrator.cpp#L134 [3] https://github.com/yade/trunk/blob/master/pkg/dem/Shop_01.cpp#L134 -- You received this question notification because your team yade-users 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