Re: [femm] FE magnetics commercial ware

[David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>]

Well, my first run-in with Amperes was back in about 1996, where a guy that I
worked with was running an old beta version of Amperes that some friend at IES
had given him. It was slow, hard to use, and gave some pretty whacky results.
However, the program has come along quite a bit in the last 5 or 6 years. At
work, we have a copy of it, and I use it on occasion, mostly for "open core"
problems where a 3-D program is really necessary.

Anyhow, I've checked it in the past by modeling some relatively complicated
axisymmetric geometries as 3D problems in Amperes, and then comparing to the
results from femm. I have generally been satisfied by the level of accuracy in
the recent versions of Amperes, although it's certainly not _impossible_ to give
it a pathological geometry. The user interface is sort of unusual, but not too
hard to use--it took me about a day of messing around with it to comfortably say
that I knew how to run the program. On the down side, it can take a _long_ time
run, and it can requires a really high-end machine to run it effectively. It is
normal for it to make require multiple gigabytes free as swap space for
relatively dense meshes. It can also take a long time to do the numerical
integrations that are required to evaluate forces. And, of course, the program
is licenses for on the order of $10K US per year (which seems like a lot, but
it's not out of line for low sales volume scientific software).

We also have multiple seats Ansoft's Flux 2D and Flux 3D. The program seems
accurate enough, but the user interface looks like something from the early
1980's. I've done a few sample problems on it, but it was such a drag to use
that I didn't re-install it when I changed computers about 8 months ago.
However, the version that I have is about 3 years old, so things might have
improved since then.

Some people that I work pretty closely with use Opera (Vector Fields) and Magnet
(Infolytica). I've generally been pleased with the results of these two
programs. Recently, I've been involved in designing some machines that really
test the envelope of Infolytica's 3D abilities. We ran into some snags, but the
Infolytica people have been particularly responsive in helping us out, for which
they should be commended.

Also, I've compiled a list of links to all of the commercial low-frequency
magnetics codes that I could find, some 24 different sites. It's been hiding on
the femm website for a while at: http://members.aol.com/GMagnetics/links.htm
If I've missed any, let me know.

"Steven Stretz" <stretzsj@xxxxxxxxxx> wrote:
> Dave, I don't know if you get enough praise and thanks for your work.
> It would be, is, great to have an open source finite element program
available.
> It would also be nice if it were to develop like a "Netscape" and the
magnetics
> community could improve and expand it. But alas that is not an easy task. I
> only wish I could contribute more but my expertise in the theory and math is
> limited. Anyway thanks for your time, work, and creativity. Best of luck in
2001.

I've sort of been hoping to entice someone to help extend the program's
capabilites in future versions. I've been getting bogged down with other stuff
lately, and I haven't been able to devote lots of time to working on femm. The
program's capabilities are roughly equal to that of a "low-end" commercial
solver, but it still lacks a lot of the useful features of the "high-end"
programs. Who knows--it might even be fun to take a stab at a 3D program....

Dave.

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