Re: Lua sample of line integral

[jim271@xxxxxxxxxxx]

There is a sample script file that's distributed with FEMM 3.1 
showing how to do this very thing using the Lorentz force on the 
coil. I've found this to be much easier than drawing a contour to use 
for the stress tensor. Just highlight the object used for the coil 
and then calculate the Lorentz force. The force on the coil is equal 
and opposite (opposite sign) to the force on the plunger.

I've included a script file that I use, which also shows some 
additional formating I've incorporated. One thing I found helpful is 
to restore the original fem file after running the script. When first 
learning to use lua, I often made edit changes to the "temp" file 
left in the display after running a script. Of course, this doesn't 
work, so I started reloading the original file automatically. You 
have to "save" the file in order to change the file name that appears 
in the upper left corner of the screen. 


**** Primary script : *********

open_femm_file("coil_1inch.fem")
save_femm_file("temp.fem")

handle=openfile("lua_data.txt","a");

write(handle,"\n","======= ",date("%c")," 
=================================================","\n")

closefile(handle)

seteditmode("group")
for n=0,15 do
analyse()
runpost("lua_post.lua")
if (n<16) then
selectgroup(1)
move_translate(0,0.1) -- move plunger upward.
end

end
open_femm_file("coil_1inch.fem") -- Restore original fem file
save_femm_file("coil_1inch.fem")

******* End of primary lua file 
**********************************************

*** lua_post.lua *** Post processing script:

handle=openfile("lua_data.txt","a");
groupselectblock(2) -- select the coil
fzr=blockintegral(12) -- Lorentz force

write(handle,format("LForce= %8.2f \n",fzr)) 

closefile(handle)
exitpost()

************* End of post processing 
**********************************


-- Jim