Snap-Back under Displacement Control

The implicit arc length method is used to solve the snap-back of the system. Differences between truss (elform 3) and discrete beam/cable (elform 6) can be studied. Example 5 from Introductory Manual for LS-DYNA Users by James M. Kennedy.

*BOUNDARY_SPC_NODE
*CONTROL_IMPLICIT_AUTO
*CONTROL_IMPLICIT_GENERAL
*CONTROL_IMPLICIT_SOLUTION
*CONTROL_TERMINATION
*DATABASE_BINARY_D3PLOT
*DATABASE_ELOUT
*DATABASE_GLSTAT
*DATABASE_HISTORY_BEAM
*DATABASE_HISTORY_NODE
*DATABASE_MATSUM
*DATABASE_NODAL_FORCE_GROUP
*DATABASE_NODFOR
*DATABASE_NODOUT
*DATABASE_SPCFORC
*DEFINE_CURVE
*ELEMENT_BEAM
*END
*KEYWORD
*LOAD_NODE_POINT
*MAT_ELASTIC
*MAT_ELASTIC_SPRING_DISCRETE_BEAM
*NODE
*PART
*SECTION_BEAM
*SET_NODE_LIST
*TITLE

*KEYWORD
*TITLE
Snap-Back Under Displacement Control
*CONTROL_IMPLICIT_AUTO
         1        20         5 1.000e-09   0.00100
*CONTROL_IMPLICIT_GENERAL
         1   0.00100         2         1         2         1
*CONTROL_IMPLICIT_SOLUTION
         6        40        15    0.0010    0.0100    0.0100  0.900000  1.000000
         2         1         1         2
         0         1       0.0         1         2
*CONTROL_TERMINATION
  1.000000         0       0.0       0.0       0.0
*DATABASE_ELOUT
1.0000e-04         1
*DATABASE_GLSTAT
1.0000e-04         1
*DATABASE_MATSUM
1.0000e-04         1
*DATABASE_NODFOR
1.0000e-04         1
*DATABASE_NODOUT
1.0000e-04         1
*DATABASE_SPCFORC
1.0000e-04         1
*DATABASE_BINARY_D3PLOT
  0.010000
*DATABASE_NODAL_FORCE_GROUP
         1
*DATABASE_HISTORY_BEAM
         1         2         3         4
*DATABASE_HISTORY_NODE
         1         2         3         4         5
*DEFINE_CURVE
         1         0       0.0       0.0       0.0       0.0
                 0.0                 0.0
          1.00000000         4000.000000
*ELEMENT_BEAM
*NODE
*BOUNDARY_SPC_NODE
*PART
         1         1         1
*SECTION_BEAM
         1         6  1.000000         0         0       0.0
  1.000000  1.000000         0       0.0       0.0       0.0       0.0       0.0
*MAT_ELASTIC_SPRING_DISCRETE_BEAM
         1  1.000000  1.500000       0.0       0.0       0.0       0.0
         0         0       0.0       0.0  1.000000
*PART
         2         2         2
*SECTION_BEAM
         2         3       0.0         0         0       0.0
  1.000000  1.000000  1.000000  1.000000  1.000000
*MAT_ELASTIC
         2  1.0000005.0000e+07       0.0       0.0       0.0       0.0
*PART
         3         1         3
*MAT_ELASTIC_SPRING_DISCRETE_BEAM
         3  1.000000  0.250000       0.0       0.0       0.0       0.0
         0         0       0.0       0.0  1.000000
*PART
         4         1         4
*MAT_ELASTIC_SPRING_DISCRETE_BEAM
         4  1.000000  1.000000       0.0       0.0       0.0       0.0
         0         0       0.0       0.0  1.000000
*LOAD_NODE_POINT
         1         1         1  1.000000
*SET_NODE_LIST
         1       0.0       0.0       0.0       0.0
         1         2         3         4         5
*END