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The force and torque between two permanent magnets?

  1. Dec 16, 2015 #1
    Hi all =)

    I am interested to find the forces and torques between two (diametrically magnetized) cylindrical permanent magnets (PMs) placed within a vicinity, as shown below:
    The NdFeB PMs placed beside one another with a distance, d. Both are rotated by independent external sources (I have solenoids to independently drive the PMs). This will affect each PM in terms of the torque and force.

    So I am just wondering if I could use the same force/torque equations (e.g. for the force as shown below) between two axially magnetized PMs for the diametrically magnetized ones as well:
    I do not have a software for this, thus I would need to model it mathematically.. (i have spent weeks trying to find a way to do it but I ran out of idea)

    I see that most cases are calculated for axially magnetized PMs so I am not sure if the generally available equations for the axially magnetized PMs can be used in my case. I got pretty confused as to how I should compute the dynamics (force and torque of one PM (primary) when another is closely present).. as well as how far should the PMs be apart so I could ignore the effect of the other PM onto the primary PM.

    Looking forward to hearing from anyone with ideas and advice =) Thank you very much!
  2. jcsd
  3. Dec 16, 2015 #2
  4. Dec 20, 2015 #3
    Thanks, Dr Courtney. Seems like FEM is the best way to approach problems like this?
  5. Dec 21, 2015 #4
    Experiment is the best way. FEM can be tricky, and results must be validated to be reliable.
  6. Dec 21, 2015 #5
    I have some hall effect sensors which could help get the magnetic field at a certain location..I could use that for force or torque verification through my equations. Do you have any suggestions on what sensors or equipment I could use in experiments as such? Thanks again~! =)
  7. Dec 22, 2015 #6
    If your FEM or equation predicts force, you should measure force. The same is true with torque. There are a lot of ways to measure force: displacements of pendula, electronic sensors, etc. Measuring torque is harder.
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