Thank you.
I started learning to use the program and I
started collecting as many as examples with PM as possible. In case someonein
this list wants to share one (or more) examples with PM, please send
this to eric.vogels@xxxxxxxxx Thanksin
advance.
Eric Vogels
----- Original Message -----
Sent: Monday, November 18, 2002 7:28
AM
Subject: Re: [femm] New FEMM user
eavogels wrote:
Dear Mr.
Meeker. My name is Eric Vogels and I will try to learn FEMM. I followed
this group almost half a year and I must admit that the level where
everyone is discussing models is too high for me to understand.
Unfortunately I have not the right education but since many years
I'm experimenting with magnets. Now I want to learn FEMM in order to
be able to build my models in the program first, before building in
real live. Do you think there is a change that I can use FEMM by
only reading the manual and looking at examples or is fysics
education neccesary. Please advice me. I only use permanent magnets,
mounted on wheels. I wonder is examples with permanent magnets are
available. I'm good in cutting and pasting other peoples work. In
case you want to see where I work with in my spare time look at: <http://fdp.hemsida.net> Thanks (and
thank you for the nice program). Eric
Vogels.
Configurations of permanent magnets can be
modeled by femm, but they must be configurations that can well-approximated by
a 2D planar geometry or configurations that are rotationally symmetric (e.g.
like a typical speaker design).
I know of many users who have
been able to set up and analyze programs and get OK results without much of a
formal background in magnetism. For example, I've seen some pretty good
simulations that have been created by high school students who where
interested in modeling coil guns. However, as has been pointed out in several
messages in the "FEMM Vs. commercial code" thread,
without a fairly good understanding of the physics behind the program, itis
possible to make models that aren't reasonable. Since the finite element
is only an approximate method of solving the differential equations that are
usually employed to model magnetic phenomena, it is possible to create
geometries or meshes that give bad results if you don't have some
understanding the numerical methods behind the program (and their
shortcomings). Most importantly, it can be especially difficult to
understand the results of the program without a good theoretical understanding
of what the program is supposed to be doing. In some sense, the program
is really just like any calculator--it crunches the numbers, but doesn't have
any intrinsic understanding of the problem that it's solving--that's the
user's job.
Anyhow, I guess that I have been sort of remiss in putting
up permanent magnet examples on the website. As an example, a fun PM
configuration to look at is a Halbach array, which is an array of permanent
magnets that tends to concentrate the PM flux on one side of the array.
Since it's only about 1K, I've attached a sample of a wavelength's worth
of such an array. It's a good example in the sense that it shows how
permanent magnets can be been defined and oriented in the program. There have
also been some pretty good threads that had to do with specific PM machine
modeling problems on the mailing list. (e.g. the collection of messages that
was spawned by http://groups.yahoo.com/group/femm/message/1229
having to do with small brushless DC motors).
Dave. --
David Meeker
dmeeker@xxxxxxxx
http://femm.berlios.de/dmeeker Your
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