--- In femm@xxxx, Keith Gregory <k.gregory@xxxx> wrote: > 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.
A basic model LVDT model using mumetal core at even 100 Hz shows pronouned skin effect. At 5kHz there is a danger of saturation near the material surface at normal drive levels.
> > >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?
I hope to use LF ac to cycle the jumps and give larger noise output. Literature suggests that Barkhausen noise can indicate heat treatment and internal stresses, inter alia; as properties of cores are affected by handling stresses I believe BN can provide an insightful tool into known quality issues.
> In addition, if my memory serves aren't there several different Radiomental > alloys differentiated by a number such as Radiometal 36?
Yes. The 36 refers to % nickel in the alloy. Varoius types give different permeability / resistivity / cost materials for different applications.