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
