Re: Force calculation

["David Meeker" <dmeeker@xxxxxxxx>]

--- In femm@xxxxxxxxxxxxxxx, faridun naim <poyet16@xxxx> wrote:
> 
> I'm now at the stage to find the force, voltage and flux value. 
> I've tried the line integral to find the force at the interface
> between the moving translator and the stator but the results 
> are not as desired. I'm not quite sure on what type of integration
> to be used. At the moment I've tried a line integral of type no.3
> to find force, but the results show the values of zero at each 
> position. I don't think the results should be like that. Therefore
> I would like to ask for your kindness, to spend your very precious
> time to go through my program attached below and correct any errors
> or give any suggestion for the improvement of my program. In order
> to obtain the flux value and voltage for linear generator could
> you please suggest me the appropriate method? 

First off, the line integral(3) returns multiple results, as described
in section 5.3.1 of the manual. Most of these end up being zero for
the DC axisymmetric case. 

In your script, you use:
> force=lineintegral(3)

You actually want to pick off the third result, which is DC
z-direction force. To do that, you'd use:

c0,c1,force=lineintegral(3)

where c0 and c1 are just placeholders.

You also haven't defined a good contour--it looks like it just
encloses air. Check out "Section 4.11.3--Maxwell Stress Tensor Line
Integral" in the manual for some pointers. Alternatively, you could
use the "weighted stress tensor" block integral, which often provides
better results.

Dave.
--
http://femm.berlios.de/dmeeker