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Re: [femm] Re: Force calculation on an axisymmetric model
Thanks for all the suggestions.
Indeed the main problem was that I hadn't set the relative permeability in
the axial direction (the current density was correct). About the
discrepancy between experimental and simulation results, I must say that I
read the value on the "wrong column": it was 1.1 N instead of 1.35 N, but
it still's a lot far away from the 0.5685 or 0.5456 N that Dave (David
Meeker) calculated. Probably, as Israel Kehaty sugested, it is due to the
side friction force (I'm not very shure of the accuracy of the mesurament
device also).
Two more questions if you don't mind:
1. If I compute the same device (as a time harmonic problem at) 50 Hz, I
get the following results:
-----------------
DC Force:
z-direction = -2.762e-001 N
100.000000 Hz Force:
z-direction = -2.762e-001 + j 1.524e-002 N
-----------------
Shouldn't the DC force be equal to 0.5685 N as if it was calculated at 0
Hz? And, if I'm performing a computation at 50 Hz, why does it give me the
value at 100 Hz?
2. If I want the mesh to have smaller elements near the iron (or some other
place), what is the best way of performing this? To define two or three
blocks of air one inside the other's with different mesh size (and
choosing in the "Segment property" to "Hide segment in postprocessor")?
Perhaps it would be better with semi-circles than with rectangles (as I
have done)...
And finally a thing that is a little bit confusing to me: when I make some
alteration to a model in Femm editor (without saving and reprocessing), and
I clik on the "glasses symbol" it shows me the FE solution of a previous
version of that model, without giving me any warning that the model as
changed or that the solution presented is not for the model that its being
changed. It can get confusing also because I can do the following: I have
my model, I process, and see the solution. If I'm not satisfied, I can go
to the Femm editor, change the model, save, reprocess and call the new
solution. If I hadn't close the previous solution on the Femm View, I will
have two solutions open, with the same name (or three as it just happened
to me with "ECS10C_50Hz" model). I don't know if anyone else experiments
this problem but for me it's confusing. Perhaps the program should not
allow to open two solutions with the same name, or put some version number
on the windows, maybe with the date and time.
Well these are some sugestions for 3.0 Beta version.
Thanks a lot.
(sorry, I'm sending the two model files, just in case someane wants to
check).
[Format] = 3.0
[Frequency] = 50.000000
[LengthUnits] = centimeters
[ProblemType] = axisymmetric
[Coordinates] = cartesian
[Comment] = "Problema PADE: Lab. electromagnetismo.\nElectroiman cilíndrico, calculo de forças, etc.\n50 Hz"
[PointProps] = 0
[BdryProps] = 1
<BeginBdry>
<BdryName> = "New Boundary"
<BdryType> = 0
<A_0> = 0.000000
<A_1> = 0.000000
<A_2> = 0.000000
<Phi> = 0.000000
<c0> = 0.000000
<c1> = 0.000000
<Mu_ssd> = 0.000000
<Sigma_ssd> = 0.000000
<EndBdry>
[BlockProps] = 3
<BeginBlock>
<BlockName> = "Air"
<Mu_x> = 1.000000
<Mu_y> = 1.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 0.000000
<J_im> = 0.000000
<Sigma> = 0.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
<BeginBlock>
<BlockName> = "Copper1"
<Mu_x> = 1.000000
<Mu_y> = 1.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 1.539235
<J_im> = 0.000000
<Sigma> = 0.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
<BeginBlock>
<BlockName> = "Steel with reluct 575 m/H"
<Mu_x> = 1384.000000
<Mu_y> = 1384.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 0.000000
<J_im> = 0.000000
<Sigma> = 2.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
[CircuitProps] = 0
[NumPoints] = 20
0.000000 -1.000000 0 0
0.000000 10.500000 0 0
1.400000 0.000000 0 0
3.500000 0.000000 0 0
1.400000 -7.100000 0 0
3.500000 -7.100000 0 0
0.500000 -1.000000 0 0
0.500000 10.500000 0 0
0.000000 100.000000 0 0
0.000000 -100.000000 0 0
100.000000 100.000000 0 0
100.000000 -100.000000 0 0
15.000000 15.000000 0 0
0.000000 15.000000 0 0
0.000000 -15.000000 0 0
15.000000 -15.000000 0 0
0.000000 12.000000 0 0
1.000000 12.000000 0 0
0.000000 -3.000000 0 0
1.000000 -3.000000 0 0
[NumSegments] = 23
1 0 -1 1 0 0
6 0 -1 0 0 0
6 7 -1 0 0 0
1 7 -1 0 0 0
2 3 -1 0 0 0
3 5 -1 0 0 0
5 4 -1 0 0 0
4 2 -1 0 0 0
8 10 -1 1 0 0
10 11 -1 1 0 0
11 9 -1 1 0 0
9 14 -1 1 0 0
14 18 -1 1 0 0
8 13 -1 1 0 0
12 13 -1 0 1 0
12 15 -1 0 1 0
15 14 -1 0 1 0
1 16 -1 0 0 0
16 13 -1 1 0 0
18 0 -1 0 0 0
16 17 -1 0 1 0
17 19 -1 0 1 0
19 18 -1 0 1 0
[NumArcSegments] = 0
[NumHoles] = 0
[NumBlockLabels] = 5
0.300000 3.900000 3 2.000000e-001 0 0.000000 0
2.400000 -3.700000 2 5.000000e-001 0 0.000000 0
38.000000 27.000000 1 5.000000e+000 0 0.000000 0
11.000000 -4.000000 1 5.000000e-001 0 0.000000 0
0.300000 -2.200000 1 3.500000e-001 0 0.000000 0
[Format] = 3.0
[Frequency] = 0.000000
[LengthUnits] = centimeters
[ProblemType] = axisymmetric
[Coordinates] = cartesian
[Comment] = "Problema PADE: Lab. electromagnetismo.\nElectroiman cilíndrico, calculo de forças, etc."
[PointProps] = 0
[BdryProps] = 1
<BeginBdry>
<BdryName> = "New Boundary"
<BdryType> = 0
<A_0> = 0.000000
<A_1> = 0.000000
<A_2> = 0.000000
<Phi> = 0.000000
<c0> = 0.000000
<c1> = 0.000000
<Mu_ssd> = 0.000000
<Sigma_ssd> = 0.000000
<EndBdry>
[BlockProps] = 3
<BeginBlock>
<BlockName> = "Air"
<Mu_x> = 1.000000
<Mu_y> = 1.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 0.000000
<J_im> = 0.000000
<Sigma> = 0.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
<BeginBlock>
<BlockName> = "Copper1"
<Mu_x> = 1.000000
<Mu_y> = 1.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 1.539235
<J_im> = 0.000000
<Sigma> = 0.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
<BeginBlock>
<BlockName> = "Steel with reluct 575 m/H"
<Mu_x> = 1384.000000
<Mu_y> = 1384.000000
<H_c> = 0.000000
<H_cAngle> = 0.000000
<J_re> = 0.000000
<J_im> = 0.000000
<Sigma> = 0.000000
<d_lam> = 0.000000
<Phi_h> = 0.000000
<LamType> = 0
<LamFill> = 1.000000
<BHPoints> = 0
<EndBlock>
[CircuitProps] = 0
[NumPoints] = 20
0.000000 -1.000000 0 0
0.000000 10.500000 0 0
1.400000 0.000000 0 0
3.500000 0.000000 0 0
1.400000 -7.100000 0 0
3.500000 -7.100000 0 0
0.500000 -1.000000 0 0
0.500000 10.500000 0 0
0.000000 100.000000 0 0
0.000000 -100.000000 0 0
100.000000 100.000000 0 0
100.000000 -100.000000 0 0
15.000000 15.000000 0 0
0.000000 15.000000 0 0
0.000000 -15.000000 0 0
15.000000 -15.000000 0 0
0.000000 12.000000 0 0
1.000000 12.000000 0 0
0.000000 -3.000000 0 0
1.000000 -3.000000 0 0
[NumSegments] = 23
1 0 -1 1 0 0
6 0 -1 0 0 0
6 7 -1 0 0 0
1 7 -1 0 0 0
2 3 -1 0 0 0
3 5 -1 0 0 0
5 4 -1 0 0 0
4 2 -1 0 0 0
8 10 -1 1 0 0
10 11 -1 1 0 0
11 9 -1 1 0 0
9 14 -1 1 0 0
14 18 -1 1 0 0
8 13 -1 1 0 0
12 13 -1 0 0 0
12 15 -1 0 0 0
15 14 -1 0 0 0
1 16 -1 1 0 0
16 13 -1 1 0 0
18 0 -1 1 0 0
16 17 -1 0 0 0
17 19 -1 0 0 0
19 18 -1 0 0 0
[NumArcSegments] = 0
[NumHoles] = 0
[NumBlockLabels] = 5
0.300000 3.900000 3 2.000000e-001 0 0.000000 0
2.400000 -3.700000 2 5.000000e-001 0 0.000000 0
38.000000 27.000000 1 5.000000e+000 0 0.000000 0
11.000000 -4.000000 1 5.000000e-001 0 0.000000 0
0.300000 -2.200000 1 3.500000e-001 0 0.000000 0
Paulo Pereirinha
------------------------------------------------
Paulo José Gameiro Pereirinha
Departamento de Engenharia Electrotécnica
Instituto Superior de Engenharia de Coimbra
Quinta da Nora -Apartado 10057
3030-601 Coimbra, Portugal
Tel. Gabinete: +351-239 790242
Telefonista: +351-239 790200
Fax: +351-239 790270