[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# Re: [femm] Force calculation on an axisymmetric model

- To: femm@egroups.com
- Subject: Re: [femm] Force calculation on an axisymmetric model
- From: "Israel Kehaty" <tsiporak@hotmail.com>
- Date: Sat, 30 Sep 2000 14:18:32 GMT

`sometimes the arrangment for measuring the solenoid force is measuring the friction between the plunger
and the solenoid housing too. For example if the plunger is connected to a moveable force measuring device and the housing is fixed, and the cylindrical plunger is lying inside the solenoid body a side force is created
because the plunger is not realy concentic to the solenois housing. The result is a friction force which the
force measuring device reads added to the actual solenoid force.`

>     From: David Meeker <dmeeker@foster-miller.com>
>     Reply-To: femm@egroups.com
>     To: femm@egroups.com
>     Subject: Re: [femm] Force calculation on an axisymmetric model
>     Date: Fri, 29 Sep 2000 16:24:31 -0400

> ``
> `Paulo José Gameiro Pereirinha wrote:`
> `> Hello!
> >
> > I'm in Portugal and trying to compute the atraction magnetic force on an
> > plunger electromagnet with axisymmetric geometrie. I'm using the Femm 3.0.
> > To compute the force exerced on the iron can I just define a contour in the
> > air around the iron (which means that one side of the contour will be on
> > the line of coordinate z=0) and integrate the Maxwell Stress Tensor? (i.e.
> > is this command valid for axisymmetric models?). If I do so, I obtain
> > -2.783e-3 N, but the experimental result is about 1.35 N. I'm sending the
> > model in attachement.
> >
> > Thanks in advance.`
> `Well, I looked at your data file, and I think that the problem is the material
> property definition for your Steel material. The relative permeability in the
> radial direction is defined as 1384, but the relative permeability in the axial
> direction is defined as 1. I'd guess that you would want to define the
> permeability to be 1384 in both directions.`
> `Anyhow, stress tensor is valid in axisymmetric problems as well. When I run
> the problem with the above change in permeability in the z-direction and
> integrate force along the box you have defined around your iron part through
> the air, I get a force of 0.5685 N. As a sanity check, I ran the same geometry
> on the IES Amperes 3-D boundary element solver, which I happen to have laying
> around the office. The force result from Amperes was 0.5456 N. The
> implication is that the femm force result seems reasonable. I can't say what
> the discrepancy is that causes the difference with the experimental result of
> 1.35 N.`
> `Dave.`
> `<< dmeeker.vcf >>`

    _________________________________________________________________________
    Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

`Share information about yourself, create your own public profile at http://profiles.msn.com.`

- Prev by Date: Re: [femm] Force calculation on an axisymmetric model
- Next by Date: Re: Force calculation on an axisymmetric model
- Previous by thread: Re: [femm] Force calculation on an axisymmetric model
- Next by thread: Can any one post a begineer's guide on FEM plz.
- Index(es):
  - Date
  - Thread