Permeance (B/H) Variation vs. Magnet Grade?

["shanteserve" <shanteserve@xxxxxxxxx>]

Hello. I am relatively new to magnetics and have a question about 
circuit permeance in permanent magnet designs.

As I understand it, the circuit permeance(Bd/Hd) is mainly a function 
of the model geometry. I seem to get significantly different 
results, however, depending on what magnet grade I choose in my FEMM 
models (I obtain these values by using "point properties" and 
selecting a specific, pre-determined point inside the magnet). I get 
similar results if I model something as simple as a bar magnet, even 
though published charts indicate that B/H is only a function of 
geometry and the effective spacing of the magnet poles.

The FEMM results suggest that the slope of the load line is very 
dependent on the B-H curve of the magnet material. This is contrary 
to all of the published theory that I have reviewed....

Any insight into what is causing this phenomenon? Any guidance would 
be appreciated.

Thanks,
Scott