[Getdp] Permanent magnet in GetDP
gilles quemener
quemener at lpccaen.in2p3.fr
Wed Aug 9 16:45:38 CEST 2017
Hi Jasper,
Thanks for your answer. This is a good news ! However, at lunch time I thought about it a bit more and figured out that one has to take into account the fact that a permanent magnet is anisotropic and therefore we should use a permeability tensor instead of a scalar constant ... this will make the formulation much more complicated !
Cheers,
Gilles
> De: "Jasper" <funkybob at gmail.com>
> À: "Gilles Quéméner" <quemener at lpccaen.in2p3.fr>
> Cc: "getdp" <getdp at onelab.info>
> Envoyé: Mercredi 9 Août 2017 16:37:12
> Objet: Re: [Getdp] Permanent magnet in GetDP
> Hi Gilles,
> Your suggestion is typically the way I've done it in the past, specify by HcB
> and mu_r. From my understanding, in a NdFeB magnet at low temperatures this
> linear relation should be valid and the results have appear plausible so far
> :-)
> Keep in mind that once the relatively small difference between e.g. N40 and N42
> starts to matter in your simulation you should really consult your magnet
> supplier as the magnets typically have tolerances and are also not completely
> homogenous etc...
> Best regards,
> Jasper
> On Wed, Aug 9, 2017 at 11:55 AM, gilles quemener < [
> mailto:quemener at lpccaen.in2p3.fr | quemener at lpccaen.in2p3.fr ] > wrote:
>> Hi,
>> Following my previous message, I digged more into the .pro files of GetDP demos
>> magnet.xxx
>> and it seems that one could perhaps use both Hc and µ_r to distinguish between
>> NdFeB magnets grades.
>> In GetDP demos, the permanent magnets material could be defined as in
>> MaterialDatabase.pro w/
>> the following lines :
>> // NdFeB magnet N45
>> Materials() += Str[ "NdFeB_Grade_N45" ];
>> NdFeB_mur = 1.172; // Br = 1370 mT, Hcb = 930000 A/m and µ_r = Br / Hcb / µ_o
>> NdFeB_sigma = 2e5;
>> NdFeB_hc = 930000;
>> where µ_r and Hcb values have been taken from the ttypical table below.
>> Could anyone confirm or infirm this approach ?
>> Remanence
>> coercivity
>> coercivity
>> product
>> Br
>> Hcb
>> Hcj
>> B H max
>> µ = Br / Hcb µ_r= µ / µo
>> mT
>> kA/m
>> kA/m
>> kJ/m3
>> T/A/m
>> min typ min typ min min typ °C
>> N-35 1170 1120 870 920 955 263 279 80 1.217391E-06 0.969
>> N-38 1220 1260 870 920 955 279 303 80 1.369565E-06 1.090
>> N-40 1260 1300 870 920 955 303 318 80 1.413043E-06 1.124
>> N-42 1300 1330 870 920 955 318 334 80 1.445652E-06 1.150
>> N-45 1330 1370 900 930 955 334 358 80 1.473118E-06 1.172
>> N-48 1370 1410 900 930 875 358 382 80 1.516129E-06 1.206
>> N-50 1410 1440 830 850 875 382 398 80 1.694118E-06 1.348
>> N-52 1430 1480 820 840 875 398 422 80 1.761905E-06 1.402
>> N-33M 1140 1170 830 859 1114 239 263 100 1.362049E-06 1.084
>> N-35M 1170 1220 870 891 1114 263 279 100 1.369248E-06 1.090
>> N-38M 1220 1260 900 915 1114 279 303 100 1.377049E-06 1.096
>> N-40M 1260 1300 930 915 1114 303 318 100 1.420765E-06 1.131
>> N-42M 1300 1330 950 915 1114 318 334 100 1.453552E-06 1.157
>> N-45M 1330 1370 980 915 1114 334 358 100 1.497268E-06 1.191
>> N-48M 1370 1410 1010 980 1114 358 382 90 1.438776E-06 1.145
>> N-50M 1410 1440 1030 980 1114 382 398 90 1.469388E-06 1.169
>> N-30H 1080 1140 810 810 1353 223 239 120 1.407407E-06 1.120
>> N-33H 1140 1170 830 830 1353 239 263 120 1.409639E-06 1.122
>> N-35H 1170 1220 870 870 1353 263 279 120 1.402299E-06 1.116
>> N-38H 1220 1260 900 900 1353 279 303 120 1.400000E-06 1.114
>> N-40H 1260 1300 930 930 1353 303 318 120 1.397849E-06 1.112
>> N-42H 1300 1330 950 950 1353 318 334 120 1.400000E-06 1.114
>> N-44H 1330 1360 970 970 1353 334 350 120 1.402062E-06 1.116
>> N-46H 1360 1380 980 980 1353 350 366 120 1.408163E-06 1.121
>> N-48H 1380 1410 1010 1060 1353 366 382 120 1.330189E-06 1.059
>> N-30SH 1080 1140 810 860 1592 223 239 150 1.325581E-06 1.055
>> N-33SH 1140 1170 830 880 1592 239 263 150 1.329545E-06 1.058
>> N-35SH 1170 1220 870 920 1592 263 279 150 1.326087E-06 1.055
>> N-38SH 1220 1260 900 950 1592 279 303 150 1.326316E-06 1.055
>> N-40SH 1260 1300 930 980 1592 303 318 150 1.326531E-06 1.056
>> N-42SH 1300 1330 950 1000 1592 318 334 150 1.330000E-06 1.058
>> N-44SH 1330 1360 970 1020 1592 334 350 150 1.333333E-06 1.061
>> N-28UH 1040 1080 770 810 1989 199 223 180 1.333333E-06 1.061
>> N-30UH 1080 1140 810 860 1989 223 239 180 1.325581E-06 1.055
>> N-33UH 1140 1170 830 880 1989 239 263 180 1.329545E-06 1.058
>> N-35UH 1170 1220 870 920 1989 263 279 180 1.326087E-06 1.055
>> N-38UH 1220 1260 900 950 1989 279 303 180 1.326316E-06 1.055
>> N-40UH 1250 1280 900 950 1989 302 326 180 1.347368E-06 1.072
>> N-28EH 1040 1080 770 810 2387 199 223 200 1.333333E-06 1.061
>> N-30EH 1080 1140 810 860 2387 223 239 200 1.325581E-06 1.055
>> N-33EH 1140 1170 830 880 2387 239 263 200 1.329545E-06 1.058
>> N-35EH 1170 1220 870 920 2387 263 279 200 1.326087E-06 1.055
>> N-38EH 1220 1260 900 950 2387 279 303 200 1.326316E-06 1.055
>> N-25AH 970 1020 730 770 2787 180 200 220 1.324675E-06 1.054
>> N-28AH 1040 1080 770 810 2787 203 218 220 1.333333E-06 1.061
>> N-30AH 1080 1140 810 860 2787 220 250 220 1.325581E-06 1.055
>> N-25BH 950 1000 710 750 3000 170 190 230 1.333333E-06 1.061
>> Data upto temperature column from :
>> [
>> http://www.goudsmitmagnets.com/magnets-assemblies/permanent-magnets/neodymium-magnets-ndfeb/neodymium-magnets-ndfeb
>> |
>> http://www.goudsmitmagnets.com/magnets-assemblies/permanent-magnets/neodymium-magnets-ndfeb/neodymium-magnets-ndfeb
>> ]
>> Cheers,
>> Gilles
>>> De: "Gilles Quéméner" < [ mailto:quemener at lpccaen.in2p3.fr |
>>> quemener at lpccaen.in2p3.fr ] >
>>> À: "getdp" < [ mailto:getdp at onelab.info | getdp at onelab.info ] >
>>> Envoyé: Mercredi 9 Août 2017 10:21:31
>>> Objet: Permanent magnet in GetDP
>>> Hi,
>>> When simulating permanent NdFeB magnets in a homemade BEM program, I use a
>>> permeability of 1.05 and a remanent magnetization/field
>>> depending on the magnet grade as given for instance in the following table :
>>> Minimum Values
>>> Grade Br Hc (Hcb) Hci (Hcj) BHmax
>>> (T) (kA/m) (kA/m) (kJ/m³)
>>> N27 1.030 796 955 199
>>> N30 1.080 796 955 223
>>> N33 1.130 836 955 247
>>> N35 1.170 867 955 263
>>> N38 1.210 899 955 287
>>> N40 1.240 923 955 302
>>> N42 1.280 923 955 318
>>> N45 1.320 875 955 342
>>> N48 1.380 836 875 366
>>> N50 1.400 796 875 382
>>> N52 1.430 796 875 398
>>> Looking closer to the magnet.xxx files in the GetDP demos folder, I cannot
>>> figure out how the
>>> remanent magnetization is taken into account as only Hc seems to be used in the
>>> material definition.
>>> I would think that both Hc and Br should be used.
>>> How would one distinguish between N40 and N42 grades which have the same Hc
>>> values ? How the fact
>>> that an N50 magnet has a larger remanent field than an N40 one is accounted for
>>> in GetDP when
>>> Hc(N50) is smaller than Hc(N40) and equal to Hc(N27) ?
>>> Thanks a lot for any hints,
>>> Gilles
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