Re: [femm] Permanent Magnet Data

[David Meeker <dmeeker@xxxxxxxx>]

tano1938 wrote:

> Are the BH curve data and the coercivity values for permanent magnet
> materials given in the materials library intrinsic values or do they
> include the free space permeability as well? I'm having some problem
> relating this data to published data from the manufacturer. Also, is
> the data for Alnico series for cast Alnico? I'm assuming that I can
> shift this data by the coercivity value to obtain second quadrant
> demagnetization curves.
>
> Thanks for the help
The information in the femm B-H curve for a permanent magnet is the 
"normal" demagnetization curve (as opposed to the the "intrinsic" 
demagnetization curve, see http://www.magnetweb.com/Sect1C.htm for an 
explanation) shifted to the right by Hc. You can recover the second 
quadrant normal demagnetization curve by subtracting Hc from the H 
values listed in the tables.

The Alnico 8 curve was obtained by digitizing figure 4-2(a), "Unit 
property curves for anisotropic cast Alnico," from:
R. J. Parker and R. J. Studders, "Permanent magnets and their 
application," John Wiley and Sons, Inc., New York, 1962
The Alnico 5 and 6 curves were cribbed from the "Standard handbook for 
electrical engineers." Although it is not noted whether or not these 
are cast alnicos, the demagnetization curves don't differ drastically 
from the curves for Alnico 5 and 6 from the Parker and Studders book.

Dave.
--
David Meeker
email: dmeeker@xxxxxxxx
www: http://femm.berlios.de/dmeeker