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An airbag inflates below a rigid cylinder, causing the cylinder to fly into the air.

Introduction

*AIRBAG_SIMPLE_AIRBAG_MODEL
Airbag Deploys into Cylinder
LS-DYNA Manual Section: *AIRBAG_SIMPLE_AIRBAG_MODEL

Additional Sections:
*CONTACT_NODES_TO_SURFACE
*RIGIDWALL_PLANAR

Example: Airbag Deploys into Cylinder

Filename: airbag.deploy.k

Description:
An airbag inflates below a rigid cylinder, causing the cylinder to fly
into the air.

Model:
The volume pressure relationships is defined by the Simple Airbag Model
for control volumes.
The bag inflates through the flow of mass into the bag.

Input:
The control volume defines the thermodynamic relationship for the gas in
terms of parameters such as heat capacity, gas temperature, incoming mass,
and out going mass (*AIRBAG_SIMPLE_AIRBAG_MODEL). A rigidwall is used below
the airbag to act as ground (*RIGIDWALL_PLANAR). A ground is displayed using
rigid shell elements, but is used only for visualization purposes. The contact
between the airbag and the cylinder is automatically generated by part id
(*CONTACT_NODES_TO_SURFACE).

Results:
The plots show the bag expanding. The ASCII file abstat contains information
on the computed pressure, volume, mass flow and internal energy of the control
volume (*DATABASE_ABSTAT).

Keywords

*AIRBAG_SIMPLE_AIRBAG_MODEL
*CONTACT_NODES_TO_SURFACE
*CONTROL_ENERGY
*CONTROL_OUTPUT
*CONTROL_TERMINATION
*DATABASE_ABSTAT
*DATABASE_BINARY_D3PLOT
*DATABASE_BINARY_D3THDT
*DATABASE_EXTENT_BINARY
*DATABASE_GLSTAT
*DATABASE_MATSUM
*DATABASE_RBDOUT
*DATABASE_RCFORC
*DATABASE_RWFORC
*DEFINE_CURVE
*ELEMENT_SHELL
*END
*KEYWORD
*MAT_FABRIC
*MAT_RIGID
*NODE
*PART
*RIGIDWALL_PLANAR
*SECTION_SHELL
*SET_PART_LIST
*TITLE

Reduced Input

  *KEYWORD
  *TITLE
  Airbag and Structure
  $
  $  LSTC Example
  $
  $  Last Modified: August 29, 1997
  $
  $  Airbag with a cylinder on top, deploys and pushes the cylinder into the air.
  $
  $  Airbag is approximately 19 x 25 inches, with 0.015 in thickness
  $
  $
  $   Units: lbf-s^2/in, in, s, lbf, psi, lbf-in
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Control Ouput
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
  $
  *CONTROL_TERMINATION
  $   endtim    endcyc     dtmin    endneg    endmas
   3.000E-02
  $
  *CONTROL_ENERGY
  $     hgen      rwen    slnten     rylen
           2         2         2
  $
  *CONTROL_OUTPUT
  $    npopt    neecho    nrefup    iaccop     opifs    ipnint    ikedit
           1         3
  $
  *DATABASE_BINARY_D3PLOT
  $       dt      lcdt
   5.000E-04
  $
  *DATABASE_EXTENT_BINARY
  $    neiph     neips    maxint    strflg    sigflg    epsflg    rltflg    engflg
  
  $   cmpflg    ieverp    beamip
                     1
  $
  *DATABASE_BINARY_D3THDT
  $       dt       lcdt
      999999
  $
  $
  *DATABASE_ABSTAT
  $       dt
   2.000E-04
  $
  *DATABASE_GLSTAT
  $       dt
   2.000E-04
  $
  $
  *DATABASE_MATSUM
  $       dt
   2.000E-04
  $
  *DATABASE_RCFORC
  $       dt
   2.000E-04
  $
  *DATABASE_RBDOUT
  $       dt
   2.000E-04
  $
  *DATABASE_RWFORC
  $       dt
   2.000E-04
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Airbag
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
  $
  *AIRBAG_SIMPLE_AIRBAG_MODEL
  $      sid    sidtyp      rbid      vsca      psca      vini       mwd      spsf
           1         1
  $
  $       cv        cp         t      lcid        mu         a        pe        ro
   1.736E+03 2.430E+03 1.200E+03         1 7.000E-01 0.000E+00 1.470E+01 3.821E-06
  $
  $      lou
  
  $
  *SET_PART_LIST
  $      sid       da1       da2       da3       da4
           1
  $
  $     pid1      pid2      pid3      pid4      pid5      pid6      pid7      pid8
           3
  $
  *DEFINE_CURVE
  $     lcid      sidr      scla      sclo      offa      offo
           1
  $
  $           abscissa            ordinate
             0.000E+00           0.000E+00
             3.200E-02           2.600E+01
             4.500E-02           6.000E-01
             8.000E-02           1.000E-01
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Rigid Walls
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Ground
  $
  *RIGIDWALL_PLANAR
  $...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
  $     nsid    nsidex     boxid
           0         0         0
  $       xt        yt        zt        xh        yh        zh      fric
         0.0       0.0       0.0       0.0       1.0       0.0       0.5
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Define Contacts - Sliding Interfaces
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
  $
  $$$$  Contact between the airbag and the cylinder.
  $
  *CONTACT_NODES_TO_SURFACE
  $
  $     ssid      msid     sstyp     mstyp    sboxid    mboxid       spr       mpr
           3         2         3         3                             1         1
  $
  $       fs        fd        dc        vc       vdc    penchk        bt        dt
         0.5       0.5
  $
  $      sfs       sfm       sst       mst      sfst      sfmt       fsf       vsf
      1.0000   0.06667
  $
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Define Parts and Materials
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  *PART
   Plate - Rigid - Fixed (for viewing)
  $      pid       sid       mid     eosid      hgid    adpopt
           1         1         1         0         0         0
  $
  *PART
   Cylinder - Rigid          
  $      pid       sid       mid     eosid      hgid    adpopt
           2         1         2         0         0         0
  $
  *PART
   Airbag - Fabric           
  $      pid       sid       mid     eosid      hgid    adpopt
           3         2         3         0         0         0
  $
  $
  $$$$$$  Materials
  $
  $
  *MAT_RIGID
  $      mid        ro         e        pr         n    couple         m     alias
           1   7.84e-4  30.00e+6      0.30
  $
  $      cmo      con1      con2
           1         7         7
  $
  $   lco/a1        a2        a3        v1        v2        v3
  
  $
  $
  *MAT_RIGID
  $      mid        ro         e        pr         n    couple         m     alias
           2   1.96e-4  30.00e+6      0.30
  $
  $      cmo      con1      con2
  
  $
  $   lco/a1        a2        a3        v1        v2        v3
  
  $
  $
  *MAT_FABRIC
  $      mid        ro        ea        eb        ec      prba      prca      prcb
           3   1.00e-4   2.00e+6   2.00e+6   2.00e+6      0.35      0.35      0.35
  $
  $      gab       gbc       gca       gse        el       prl    lratio      damp
     1.53e+6   1.53e+6   1.53e+6
  $
  $     aopt
  
  $
  $       xp        yp        zp        a1        a2        a3
  
  $
  $       v1        v2        v3        d1        d2        d3
  
  $
  $$$$$$  Sections
  $
  *SECTION_SHELL
  $      sid    elform      shrf       nip     propt   qr/irid     icomp
           1         0
  $
  $       t1        t2        t3        t4      nloc
       0.500     0.500     0.500     0.500
  $
  $
  *SECTION_SHELL
  $      sid    elform      shrf       nip     propt   qr/irid     icomp
           2         9                   4                             1
  $
  $       t1        t2        t3        t4      nloc
       0.015     0.015     0.015     0.015
  $
  $       b1        b2        b3        b4        b5        b6        b7        b8
  
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $$$$  Define Nodes and Elements
  $
  $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
  $
  $...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
  $    nid               x               y               z      tc      rc
  $
  *END

Figures

image01.gif

image02.gif

Animated Result

Result

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