Re: What is the best way to model Horseshoe magnets

["David Meeker" <dcm3c@xxxxxxx>]

--- In femm@xxxx, "Peter Ceelen" <peter.ceelen@xxxx> wrote:
> What is the best way to model a horseshoe (U shaped) magnet with the
> poles on the top faces? The particular magnets I am trying to model
> are a rectangular U in shape. I have modelled them as a single
> body, as three bodies that meet at a 45 degree angle, and with
> increasing numbers of wedge shaped bodies in the corners that
> meet at correspondingly smaller angles as the number of bodies
> increases. These all give different results and I am wondering
> which of these ways is the most accurate. I have included simple
> models as examples. [...]

Hmmm--this is sort of an interesting question. The method with lots 
of wedges does act diferent because there's these little loops of flux 
that circulate by the interior corners, sort of constricting the flux 
path. Alternatively, the method with "three bodies that meet at a 45 
degree angle" makes flux lines that practically turn a 90 degree 
corner at the joints, using the entire cross-section of the magnet.

I'd guess that the most "accurate" way to model it would depend upon 
how you'd build the thing. I could imagine physically constructing it 
out of three pieces and actually building the "three bodies that meet 
at a 45 degree angle" configuration. But what I'm guessing that you 
are thinking of is building the U and magnetizing as one piece. You 
might have to do something subtle like try to model the U in the 
magnetizing fixture to see how it orients the magnetization.

Anyhow, I know that there are a few list members who work at companies 
that design and manufacture permanent magnets. Any suggestions?

Dave Meeker
http://members.aol.com/_ht_a/dcm3c