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A railgun consists of two parallel metal rails connected to an electric power supply. The projectile completes the circuit. The current flowing through the rails and projectile generates a magnetic field which in turn generates a Lorentz force propelling the projectile out of the barrel at a very high speed.

Description

A railgun consists of two parallel metal rails connected to an electric power supply. The projectile completes the circuit. The current flowing through the rails and projectile generates a magnetic field which in turn generates a Lorentz force propelling the projectile out of the barrel at a very high speed. This problem serves as an example to illustrate the EM contact. Current is allowed to flow through conductors by ‘stitching the BEM meshes of the various parts together. As such, it is highly recommended to re-compute the BEM matrix often to ensure stability.

Animated Result

Current Density fringes

ezgif.comvideotogif.gif

Keywords

                                                            
*CONTROL_TERMINATION
*CONTROL_TIMESTEP
*DATABASE_BINARY_D3PLOT
*DEFINE_CURVE_FUNCTION
*DEFINE_CURVE_TITLE
*EM_DATABASE_GLOBALENERGY
*EM_CIRCUIT
*EM_CIRCUIT_ROGO
*EM_CONTROL
*EM_CONTROL_CONTACT
*EM_MAT_001
*EM_OUTPUT
*EM_SOLVER_FEM
*EM_SOLVER_BEM
*EM_SOLVER_BEMMAT
*END
*KEYWORD
*MAT_ELASTIC
*MAT_RIGID
*PARAMETER
*PART
*SECTION_SOLID
*TITLE

Reduced Input

$-----------------------------------------------------------------------------
$
$ Example provided by Iñaki (LSTC)
$
$ E-Mail: info@dynamore.de
$ Web: http://www.dynamore.de
$
$ Copyright, 2015 DYNAmore GmbH
$ Copying for non-commercial usage allowed if
$ copy bears this notice completely.
$
$X------------------------------------------------------------------------------
$X
$X 1. Run file as is.
$X    Requires LS-DYNA MPP R8.0.0 (or higher) with double precision 
$X
$X------------------------------------------------------------------------------
$# UNITS: (g/mm/s) 
$X------------------------------------------------------------------------------
$X
*KEYWORD
*TITLE
EM Railgun example
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             EM CONTROL                                       $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*EM_CONTROL
$--------1---------2---------3---------4---------5---------6---------7---------8
$    emsol    
         1        
*EM_CONTROL_CONTACT
$--------1---------2---------3---------4---------5---------6---------7---------8
$   EMcont
         1
*EM_CONTROL_TIMESTEP
$#  tstype    dtcons      lcid                            
         1    &em_dt
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             EM CIRCUIT                                       $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*EM_CIRCUIT
$--------1---------2---------3---------4---------5---------6---------7---------8
$   circid  circtype      lcid      
         1         1         4
$ ssidCurr ssidVltin ssidVltOt    partID
         4         1         2
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             EM MAT and EOS                                   $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*EM_MAT_001
$   em_mid     mtype     sigma     eosId skinDepth           
         1         2  &em_cond
*EM_MAT_001    
         2         2  &em_cond
*EM_MAT_001   
         3         2  &em_cond 
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             EM SOLVER                                        $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*EM_SOLVER_BEMMAT
$#   matid                                                                reltol
         1                                                                  1e-6 
*EM_SOLVER_BEMMAT
$#   matid                                                                reltol
         2                                                                  1e-6      
*EM_SOLVER_BEM
$#  reltol     maxit     stype    precon    uselas  ncyclbem
      1e-6      1000         2         2         1&em_bemmtx
*EM_SOLVER_FEM
$#  reltol     maxit     stype    precon    uselas  ncyclbem
      1e-3      1000         1         1         1&em_femmtx
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$                                                                              $
$                             EM OUTPUT                                        $
$                                                                              $
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8 
*EM_OUTPUT
$     matS      matF      solS      solF      mesh
         2         2         2         2         0  
*EM_DATABASE_GLOBALENERGY
$#   outlv
         1
*END

Figures

Cylinder Flow

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