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# Re: [femm] Re: BH data

- To: femm@yahoogroups.com
- Subject: Re: [femm] Re: BH data
- From: Keith Gregory <k.gregory@lboro.ac.uk>
- Date: Wed, 23 Oct 2002 13:29:15 +0100
- In-reply-to: <ap5m6k+4rj6@eGroups.com>
- References: <5.1.0.14.0.20021023080512.00abc6a0@staff-mailin.lboro.ac.uk>

`Mike,`
`I think you would find that static finite elements models with single valued magnetization characteristics would give pretty good approximations of field distribution and winding inductances in the 50-60Hz types of applications where the materials are laminated. Although calculating inductances in saturated conditions is complicated. Loss calculations even at 50 or 60 Hz are not as straightforward. Operating in Khz I really have no idea how good results would be.`
`Manufacturers' mag curves are, I think, measured under DC conditions (if anyone wants to contradict me here please do, it would be useful to know).`

>     The d.c. hysteresis loops cited are from manufacturers data (Telcon
>     Metals, Crawley, long since defunct). Presumably these would be
>     compiled from slow changes at a few Hz max; if not then a.c. effects
>     may come into play.

`
Manufacturers' mag curves are, I think, measured under DC conditions (if anyone wants to contradict me here please do, it would be useful to know).`

>     I am currently interested in trying to observe Barkhausen noise for
>     NiFe materials. I expect to use up to about 100 Hz field for this, and
>     believe that the spectrum of the noise will contain much information,
>     if it can be unravelled; early days yet. Comments are very welcome

`
The classic demonstration of Barkhausen jumps is done with "DC" magnetization, usually with a permanent magnet. I have a vague memory of a paper describing a different way which can produce noise displays on an oscilloscope. I'm not sure what information it would contain though, what had you got in mind?`
`In addition, if my memory serves aren't there several different Radiomental alloys differentiated by a number such as Radiometal 36?`
`Keith.`

>     In femm@y..., Keith Gregory <k.gregory@l...> wrote:
>     > Michael,
>     >
>     > Could I ask what you mean by low frequency?
>     >
>     > Keith.
>     >
>     > At 15:30 21/10/2002 +0100, you wrote:
>     >
>     > >Hi David (Meeker) and others,
>     > >
>     > >I am trying to include Radiometal in the materials library. I have
>     the
>     > >manufacturers data for d.c. induction but it is in the form of an
>     initial
>     > >magnetisation curve. This is unlike the mumetal and supermalloy
>     materials
>     > >in the femm library, which show a high initial slope /
>     permeability,
>     > >declining steadily as saturation is approached. These plots ignore
>     hysteresis.
>     > >
>     > >I am tempted to input data from the radiometal d.c. hysteresis
>     loops which
>     > >I also have, shifted to pass through the origin. At least then the
>     plot
>     > >shape is correct. Is this likely to give acceptable results for
>     modelling
>     > >of low frequency fields and inductances?
>     > >
>     > >Perhaps the included BH curves are similarly derived. I feel it
>     will be
>     > >better to do this than use a description with an initially
>     increasing
>     > >permeability with H.
>     > >
>     > >BTW thank you for an excellent free tool, and all the inputs to an
>     > >interesting discussion group.
>     > >
>     > >Michael J Hutchings

> ``
> ``
> ``
> `Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/`

``

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- References:
  - Re: [femm] BH data
    - From: Keith Gregory <k.gregory@lboro.ac.uk>
  - Re: BH data
    - From: "mikejhutch" <mhutchings@solartronmetrology.com>

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