Magnets snapping — Welcome to LS-DYNA Examples

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Two magnets covered by a layer of insulator material (stiff plastic) are coming into contact with each other (snapping) due to electromagnetic forces. This example shows how magnets can be simulated using the EM solver and how dynamic motion due to magnetic forces can be simulated. It uses the FEM-BEM monolithic magnetostatics solver (used for zero-conductivity ferromagnetic materials) and a AMS preconditionner.

Description

Two magnets covered by a layer of insulator material (stiff plastic) are coming into contact with each other (snapping) due to electromagnetic forces. This example shows how magnets can be simulated using the EM solver and how dynamic motion due to magnetic forces can be simulated. It uses the FEM-BEM monolithic magnetostatics solver (used for zero-conductivity ferromagnetic materials) and a AMS preconditionner.

Animated Result

EM surface magnetic forces :

https://www.youtube.com/watch?v=HLkAk02zijg

Keywords

*CONTROL_TERMINATION
*CONTROL_TIMESTEP
*DATABASE_BINARY_D3PLOT
*DEFINE_CURVE_TITLE
*EM_CIRCUIT
*EM_CONTROL
*EM_CONTROL_COUPLING
*EM_CONTROL_TIMESTEP
*EM_MAT_001
*EM_MAT_002
*EM_OUTPUT
*EM_PERMANENT_MAGNET
*EM_SOLVER_BEM
*EM_SOLVER_BEMMAT
*EM_SOLVER_FEM
*EM_SOLVER_FEMBEM_MONOLITHIC
*END
*KEYWORD
*MAT_RIGID
*PARAMETER
*PART
*SECTION_SOLID
*TITLE

Reduced Input

*keyword
$ ****************************************************************************
$ electromagnetism
$ ****************************************************************************
*EM_CONTROL
$--------1---------2---------3---------4---------5---------6---------7---------8
$    emsol     numls        dt
         1               &emdt                              &em_femmtx&em_bemmtx
*EM_CONTROL_COUPLING
,2
*EM_SOLVER_FEM
$--------1---------2---------3---------4---------5---------6---------7---------8
$   reltol   maxiter     stype    precon   uselast  ncyclfem msglvlFem
     1.e-4     10000         1         1         1                   0
*EM_SOLVER_BEM
$--------1---------2---------3---------4---------5---------6---------7---------8
$   reltol   maxiter solvetype    precon   uselast  ncyclbem 
     &btol     10000         2         2         1         
$*EM_SOLVER_FEMBEM
$$--------1---------2---------3---------4---------5---------6---------7---------8
$$   reltol   maxiter    forcon
$     1.e-6        50                             3
*EM_SOLVER_BEMMAT
$--------1---------2---------3---------4---------5---------6---------7---------8
$    matId                                                                relTol
         1                                                                 &ptol
*EM_SOLVER_BEMMAT
$--------1---------2---------3---------4---------5---------6---------7---------8
$    matId                                                                relTol
         2                                                                 &qtol
*EM_SOLVER_BEMMAT
$--------1---------2---------3---------4---------5---------6---------7---------8
$    matId                                                                relTol
         3                                                                 &wtol
*EM_PERMANENT_MAGNET
$--------1---------2---------3---------4---------5---------6---------7---------8
$       ID   Part ID         -     North     South         M=0.38/mu0
         1         1                   1         2      9.e5
*DEFINE_CURVE
100,
0,9.e5
5e-3,9.e5
1.,9.e5
*EM_PERMANENT_MAGNET
$--------1---------2---------3---------4---------5---------6---------7---------8
$       ID   Part ID         -     North     South         M=0.38/mu0
         3         3                   3         4      9.e5
*EM_MAT_002
$ Magnetic material 1
$      mid     mtype     sigma     eosid     murel     eosmu
         1         4        0.         0   &murel1
$         1         4   &sigma1         0   &murel1
*EM_MAT_002
$ Magnetic material 2
$--------1---------2---------3---------4---------5---------6---------7---------8
$      mid     mtype     sigma     eosid     murel     eosmu
         3         4        0.         0   &murel3
$         3         4   &sigma3         0   &murel3
*EM_MAT_001
$ Dummy coil material
$--------1---------2---------3---------4---------5---------6---------7---------8
$      mid     mtype     sigma     eosid          
         2         1    
*EM_MAT_001
$ Dummy coil material
$--------1---------2---------3---------4---------5---------6---------7---------8
$      mid     mtype     sigma     eosid          
         4         1               
*EM_OUTPUT
$--------1---------2---------3---------4---------5---------6---------7---------8
$     matS      matF      solS      solF      mesh    memory    timing d3plotAsc
         2         2         2         2         0         0         0         
$      mf2       gmv d3plotFor  timeHist
         0         1         0
*EM_SOLVER_FEMBEM_MONOLITHIC
$--------1---------2---------3---------4---------5---------6---------7---------8
$ COUPLING KSP_TYPE   KSP_ATOL  KSP_RTOL KSP_MAXIT GMRES_RST    FEM_PC     DEBUG
         0               1.e-9     1.e-5    100000                   1
$--------1---------2---------3---------4---------5---------6---------7---------8
$    FORCE NEWT_STOL NEWT_ATOL NEWT_RTOL NEWT_MAXI                        
               1.e-9     1.e-9     1.e-5
$--------1---------2---------3---------4---------5---------6---------7---------8
$    LS_ON   LS_FTOL   LS_GTOL   LS_RTOL  LS_SAMPL LS_NUM_SP LS_MAXFUN
         1     1.e-9      0.01     1.e-5                         30000
$--------1---------2---------3---------4---------5---------6---------7---------8
$$USE_ENERG  STOP_ERR WIDTH_ERR    XTRAPF
$         
*EM_EOS_PERMEABILITY
$ eostype=1 --> B = B(H), eostype=2 --> H = H(B)
$--------1---------2---------3---------4---------5---------6---------7---------8
$    eosid   eostype      lcid
       101         2       102
*DEFINE_CURVE
$ Dummy current
$     LCID      SIDR       SFA       SFO      OFFA      OFFO    DATTYP
$--------1---------2---------3---------4---------5---------6---------7
       999                           0.0
0.000,0.00
9.000,0.00
$
*define_curve
$B=B(H)
101
0.0,0.00000
1757.0,0.01287
3515.0,0.14758
4173.0,0.15738
5894.0,0.16830
8640.0,0.18008
12348.0,0.19246
16935.0,0.20516
22297.0,0.21789
28313.0,0.23036
34847.0,0.24230
41751.0,0.25343
48870.0,0.26350
138035.0,0.38115
227200.0,0.49880
316364.0,0.61645
405529.0,0.73410
494694.0,0.85175
583859.0,0.96940
673024.0,1.08705
762188.0,1.20470
851353.2,1.32235
940518.0,1.43999
$
*define_curve
$ H=H(B)
102
0.0,0.00000
0.01287,1757.0
0.14758,3515.0
0.15738,4173.0
0.16830,5894.0
0.18008,8640.0
0.19246,12348.0
0.20516,16935.0
0.21789,22297.0
0.23036,28313.0
0.24230,34847.0
0.25343,41751.0
0.26350,48870.0
0.38115,138035.0
0.49880,227200.0
0.61645,316364.0
0.73410,405529.0
0.85175,494694.0
0.96940,583859.0
1.08705,673024.0
1.20470,762188.0
1.32235,851353.2
1.43999,940518.0
$
*DEFINE_CURVE
333
0.,1.
0.04,1.
0.04001,-1.
1.,-1.
*end

Figures

 

magnetsnap.png

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