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Yes, exactly the same thing, provided deltaV_2 is the disp. of the material point at contact (not just the disp of the body's center - that explains the rotational term with cross product).v_rel = deltaV_2 - deltaV_1 Question: is that what we do in this line:Vector3r relativeVelocity = (de2->vel + de2->angVel.Cross(_c2x_)) - (de1->vel + de1->angVel.Cross(_c1x_));?I know what that line means, but it is to say the same thing as I expressed above?
I discover this long discussion on sign/sense convention now after few days of network problem... Just one remark : the initial convention (ScGeom) has never been explicitely linked to the sign of compression/traction in my brain (as opposed to what was suggested by remarks on geomechanical sign conventions).
"My" explanation of the convention was : if the normal is defined as b1->b2 (i.e. "from b1 to b2"), it is more intuitive to define the force as well as "applied by b1 on b2". The fact that it will give a positive product (normal*force) for compressive interactions is a consequence, not an objective of the convention.
I hope it creates even more trouble... ;) Bruno
**************************One more observation about the relative velocity. I am quite confident to repeat that we cannot predict the sense of this vector. This is a result of the motion, and the shear increment that we get can give a positive contribution or a deduction to the total shear force according to that. Now (perhaps) it does not make too much different to sayrel_vel = body1_vel - body2_vel OR rel_vel = body2_vel - body1_vel Therefore it should be fine both saying shearForce -= rel_vel * dt * ks OR shearForce += rel_vel * dt * kssince is the sense of the force increment that at each time step will give the right contribution. Please, correct me if I am wrong (I have a lot of doubts on this side).Thanks, Chiara ------------------------------------------------------------------------ _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@xxxxxxxxxxxxxxxxxxx Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
-- _______________ Bruno Chareyre Associate Professor Grenoble INP Lab. 3SR BP 53 - 38041, Grenoble cedex 9 - France Tél : 33 4 56 52 86 21 Fax : 33 4 76 82 70 43 ________________
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