What you just said sounds right, but what you've actually got looks to me like the torque per unit volume. I think you need to integrate that over a volume to get the actual torque acting on that volume.
OTOH if that value is nonzero then your object is spinning up -- it's not just sitting there. If you're looking at something like a steel shaft which is under torsion but stationary then T12 = T21 and you need to look at something more complicated to figure out what the torque on the shaft is -- maybe the gradient of the stress tensor? David Jonsson wrote: > On Wed, May 13, 2009 at 9:36 PM, David Jonsson > <[email protected] <mailto:[email protected]>> wrote: > > Hi > > Can someone explain to me how to calculate the torque from the > stress tensor? > > > It seems to be this simple > > Torque = T12 - T21 > > For a two dimensional tensor > > T= T11 T12 > Â Â Â Â T21 T22 > > Right? > > Now I will do some nice calculations, but first I would like to have > this confirmed. > > David > >
