I am trying to use Elmer to calculate demagnetisation behaviour of a magnet, in order to do so I need to input a demagnetisation curve (where its knee point is at B>0 and H are negative values). I changed the PM material section according to this post :https://www.elmerfem.org/forum/viewtopic.php?t=7042
Specifically these few lines:
Code: Select all
Material 2
Name = "N52"
Relative Permeability = 1.05
Magnetization 1 = 956180
Electric Conductivity = 0.667
H-B Curve = Variable "nonlin"
include HB_N52
End
End
Code: Select all
Material 4
Name = "PM"
Relative Permeability = 1.05
Electric Conductivity = 0
Magnetization 1 = 0
Magnetization 2 =519435
H-B Curve = Variable "nonlin"
Real Monotone Cubic
0.000843 -519435
0.056154 -516384
0.092699 -515317
0.131122 -512802
0.169682 -511050
0.201866 -508916
0.233615 -506782
0.26288 -504542
0.293817 -501448
0.33042 -498247
0.362566 -493980
0.392992 -489179
0.421125 -483312
0.450756 -475310
0.478149 -465175
0.5016 -453973
0.521266 -442238
0.538269 -430503
0.554577 -418767
0.571002 -407032
0.58731 -395297
0.60304 -383561
0.618886 -371826
0.633342 -360091
0.649535 -348355
0.665265 -336620
0.680763 -324885
0.694873 -313149
0.710834 -301414
0.727258 -289679
0.742525 -277943
0.757445 -266208
0.773753 -254473
0.78902 -242737
0.804287 -231002
0.818744 -219267
0.834705 -207531
0.84974 -195796
0.865818 -184061
0.881663 -172326
0.89774 -160590
0.912313 -148855
0.928968 -137120
0.944814 -125384
0.960312 -113649
0.974653 -101914
0.989689 -90178.3
1.00484 -78442.9
1.021727 -66707.6
1.035605 -54972.3
1.051219 -43237
1.066717 -31501.6
1.081405 -19766.3
1.097019 -8030.99
1.108842 -557.999
End
End
By changing the PM material code in the .sif file I also find that:
1. Elmer simulation doesn't want to converge when my input of Magnetization is Smaller than the Hc of the BH data (For example Magnetization 2 = 700000 and this Hc = -519435 ).
2. Changing the Relative Permeability value doesn't impact the result. Even if I delete the complete line of Relative Permeability.
3. Both of changing magnitude of BH curve and Magnetization 1 or 2 can vary the simulation result.
So my question is , what is the correct input when I have a non-linear demagnetisation curve for magnet material?
Kind regards,
Eric