[Getdp] Permanent magnet in GetDP

Wed Aug 9 11:55:06 CEST 2017

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 	

Cheers, 

Gilles 

> De: "Gilles Quéméner" <quemener at lpccaen.in2p3.fr>
> À: "getdp" <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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