Re: BH data

["mikejhutch" <mhutchings@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Keith

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.

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

Mike

--- In femm@xxxx, Keith Gregory <k.gregory@xxxx> 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