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A square cross section of a crush tube uses adaptivity to re-fine the mesh as needed to improve accuracy.

Introduction

```CONTROL_ADAPTIVE

*CONTROL_SUBCYCLE

Example: Square Crush Tube with Adaptivity

Description:
A square cross section of a crush tube uses adaptivity to re-fine the mesh as
needed to improve accuracy.

Model:
Only 1/4 of the tube is modeled because of symmetry. The nodes on top of the
crush tube are assigned extra mass with *EL EMENT_MASS and given an initial
velocity in the y direction of -5,646 mm/s. The nodes on the bottom of the
tube are fixed in y-translation. Automatic single surface contact is defined
to prevent penetration when the folds of the crush tube start to form.
The model has sub-cycling defined.

Results:
The mesh at the fold location in the crush tube is automatically re-fined as
the crush progresses.```

Keywords

```*CONSTRAINED_NODE_SET
*CONTACT_AUTOMATIC_SINGLE_SURFACE
*CONTROL_ENERGY
*CONTROL_OUTPUT
*CONTROL_SUBCYCLE
*CONTROL_TERMINATION
*DATABASE_BINARY_D3PLOT
*DATABASE_GLSTAT
*DATABASE_MATSUM
*ELEMENT_MASS
*ELEMENT_SHELL
*END
*INITIAL_VELOCITY_NODE
*KEYWORD
*MAT_PLASTIC_KINEMATIC
*NODE
*PART
*SECTION_SHELL
*SET_NODE
*SET_PART
*TITLE```

Reduced Input

```  *KEYWORD
*TITLE
square cross section for single surface contact and adaptivity test
\$
\$  LSTC Example
\$
\$
\$  Units: ton, mm, s, N, MPa, N-mm
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Control Ouput
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
*CONTROL_TERMINATION
\$   endtim    endcyc     dtmin    endneg    endmas
3.000E-03
\$
*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
0.999e-4
\$
*DATABASE_GLSTAT
\$       dt
0.00002
\$
*DATABASE_MATSUM
\$       dt
0.00002
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
1.0e-4       5.0         2         2       0.0       0.0         0
\$
\$
*CONTROL_SUBCYCLE
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Initial Conditions
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
*INITIAL_VELOCITY_NODE
\$      nid        vx        vy        vz       vxr       vyr       vzr
650.0000E+00-0.5646E+40.0000E+00
660.0000E+00-0.5646E+40.0000E+00
990.0000E+00-0.5646E+40.0000E+00
1320.0000E+00-0.5646E+40.0000E+00
1650.0000E+00-0.5646E+40.0000E+00
1980.0000E+00-0.5646E+40.0000E+00
4230.0000E+00-0.5646E+40.0000E+00
4560.0000E+00-0.5646E+40.0000E+00
4890.0000E+00-0.5646E+40.0000E+00
5220.0000E+00-0.5646E+40.0000E+00
5550.0000E+00-0.5646E+40.0000E+00
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Constraints
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
*CONSTRAINED_NODE_SET
\$     nsid       dof
11         2
\$
*SET_NODE
\$      sid       da1
11        11
\$     nid1      nid2      nid3      nid4      nid5      nid6      nid7      nid8
65        66        99       132       165       198       423       456
489       522       555
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Define Contacts - sliding interface definitions
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
*CONTACT_AUTOMATIC_SINGLE_SURFACE
\$     ssid      msid     sstyp     mstyp    sboxid    mboxid       spr       mpr
1         0         2         0
\$       fs        fd        dc        vc       vdc    penchk        bt        dt

\$      sfs       sfm       sst       mst      sfst      sfmt       fsf       vsf

\$
\$
*SET_PART
\$      sid       da1
1         1
\$      pid
1
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Define Parts and Materials
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
*PART
\$      pid       sid       mid     eosid      hgid      grav    adpopt
square-tube
1         1         1         0         0         0         1
\$
\$
*MAT_PLASTIC_KINEMATIC
\$      mid        ro         e        pr      sigy      etan      beta
1 7.850E-09 1.994E+05 3.000E-01 3.366E+02 1.000E+00 1.000E+00 0.000E+00
\$      src       srp        fs

\$
\$
*SECTION_SHELL
\$      sid    elform      shrf       nip     propt   qr/irid     icomp
1         2        1.        3.        0.        0.         0
\$       t1        t2        t3        t4      nloc
1.2       1.2       1.2       1.2
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$\$\$\$  Define Nodes and Elements
\$
\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
\$
\$...>....1....>....2....>....3....>....4....>....5....>....6....>....7....>....8
\$
\$\$\$\$\$  Elements - Discrete Masses
\$
*ELEMENT_MASS
\$    eid     nid            mass
65      65       1.000E-02
66      66       1.000E-02
99      99       1.000E-02
132     132       1.000E-02
165     165       1.000E-02
198     198       5.000E-03
423     423       1.000E-02
456     456       1.000E-02
489     489       1.000E-02
522     522       1.000E-02
555     555       5.000E-03
\$
*END```