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# Re: [femm] creating new non-linear BH curves

- To: femm@egroups.com
- Subject: Re: [femm] creating new non-linear BH curves
- From: David Meeker <dmeeker@foster-miller.com>
- Date: Tue, 01 Aug 2000 13:16:40 -0400
- Organization: Foster-Miller, Inc.
- References: <8m6r7s+nt3f@eGroups.com>

    ***************************************** (on mail)

    The file example.zip was checked and NO virus was found
    The file dmeeker.vcf was checked and NO virus was found
    *********************************************************

    Turbo-Jon wrote:

    > when I try to read in a .dat file - created by exporting a curve from
    > MAXWELL - it appears that all the negative Hc values are converted to
    > positive values.
    >
    > or to be more precise the shape of the curve is OK, but it is shifted
    > from where it originally crosses B=0, (at Hc) up to H=0. REulting in
    > the entire curve being in the first quadrant.
    >
    > is this a problem whith FEMMPLOT or the way it reads in the values

    This is just how the program models permanent magnets. It thinks of
    permanent magnets as basically chunks of ferromagnetic material with very
    thin coils wrapped around them. When you load a B-H curve from a text file,
    the program shifts the data to the right so that it is in the first quadrant
    like a "normal" ferromagnetic material. Then, you assign the Hc parameter
    in the materials dialog, which denotes how far the data needed to be shifted
    to the right to bring it into the 1st quadrant. For more information,
    Appendex A1 in the manual talks about modeling of permanent magnets in femm.

    Because it is very short, I have attached an example .fem file that
    implements your material and models a bar magnet made out of it.

    Dave.

Attachment: `zip00002.zip`
Description: Zip compressed data

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    n:Meeker;David
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    x-mozilla-html:TRUE
    url:http://members.aol.com/dcm3c
    org:Foster-Miller, Inc.;Electrical and Electronic Systems Group
    version:2.1
    email;internet:dmeeker@foster-miller.com
    title:Senior Engineer
    adr;quoted-printable:;;350 Second Avenue=0D=0A;Waltham;MA;02451-1196;USA
    fn:David Meeker, Ph.D.
    end:vcard

- References:
  - creating new non-linear BH curves
    - From: "Turbo-Jon " <jon.crawley@turbosound.com>

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