I am needing design method - book, articles, papers etc for calculating torque values with PM torque couplers. These could be cylindrically placed magnets or parallel flat magnets. Can any one help ?
if you wanna design the thing, try to source magnets with proper data sheets and invent your own maths - that's always fun!
Try http://www.rare-earth-magnets.com/. Don't know if they are any good but they've got pretty extensive data sheets and enough magnetic literature too put you on variety of wrong tangents for a fun filled afternoon!