Attractive force between 2 disc magnets

[kevinhogg33]

This is my first attempt at using this web-site, hopefully you guys have the infinate wisdom that I hope you have (and that i clearly dont )...

My question is, as the title suggests, to do with calculating the attractive forces between 2 identical disc magnets.

More specifically I am looking for a "magic equation" that allows me to simply plug in numbers such as the dimensions of the discs, separation of the disks and permeability of magnetic discs and at the end, an attractive force will pop out!

I've found a web-site with a calculator on it which seems to solve this question but I kinda want to see the equation itself to prove to myself that the numbers are not being picked out of the ether...

Any help you guys can give would be much appreciated,

cheers,

Kev.

 

[UKpete]

Kevin, I think it will be difficult. As you can appreciate, with magnetic fields spilling out and following long air paths, and the forces between two poles being proportional to separation squared (amongst other factors), it is a highly non-linear problem. This means that it can't be solved analytically with any reasonable accuracy so any equation must be derived empirically. So the data must be obtained by experiment, or preferably using finite element analysis, for different geometries then fitting the data to an equation with appropriate factors within.

I would imagine that the website you saw has done just this (using the finite element approach). But I could be wrong!