*MAT_068 (NONLINEAR_PLASTIC_DISCRETE_BEAM)

LS-DYNA Input Interface KeywordDefines a nonlinear elasto-plastic discrete beam material with 6 decoupled DOFs with an optional preload.

Format

(1) (2) (3) (4) (5) (6) (7) (8)
*MAT_068 or *MAT_NONLINEAR_PLASTIC_DISCRETE_BEAM
mat_ID ρ i TK_r TK_s TK_t RK_r RK_s RK_t
TD_r TD_s TD_t RD_r RD_s RD_t    
LCPD_r LSPD_s LCPD_t LCPM_r LCPM_s LCPM_t    
FFAIL_r FFAIL_s FFAIL_t MFAIL_r MFAIL_s MFAIL_t    
UFAIL_r UFAIL_s UFAIL_t TFAIL_r TFAIL_s TFAIL_t    
FO_r FO_s FO_t MO_r MO_s MO_t    

Definition

Field Contents SI Unit Example
mat_ID Material identifier.

(Integer)

ρ i Initial density.

(Real)

[ kg m 3 ]
TK_r, TK_s, TK_t Stiffness in directions r, s, t.

(Real)

[ N m ]
RK_r, RK_s, RK_t Rotational stiffness for axis r, s, t.

(Real)

[ N m rad ]
TD_r, TD_s, TD_t Damping in directions r, s, t.

(Real)

[ N • s m ]
RD_r, RD_s, RD_t Rotational damping in directions r, s, t.

(Real)

[ Nms rad ]
LCPD_r, LCPD_s, LCPD_t Force versus plastic displacement curve identifier in directions r, s, t. 44

(Real)

[ N ]
LCPM_r, LCPM_s, LCPM_t Moment versus plastic rotations curve identifier in directions r, s, t. 44

(Real)

[ Nm ]
FO_r, FO_s, FO_t Force preload in directions r, s, t. [ N ]
MO_r, MO_s, MO_t Moment preload in directions r, s, t. [ Nm ]
FFAIL_r, FFAIL_s, FFAIL_t Failure forces in directions r, s, t. [ N ]
MFAIL_r, MFAIL_s, MFAIL_t Failure moments in directions r, s, t. [ Nm ]
UFAIL_r, UFAIL_s, UFAIL_t Failure elongations in directions r, s, t. [ m ]
TFAIL_r, TFAIL_s, TFAIL_t Failure rotation angles in directions r, s, t. [ rad ]

Comments

  1. This keyword maps to /MAT/LAW108 (SPR_GENE).
  2. The material is only used with *SECTION_BEAM, ELFORM = 6 discrete beam elements.
  3. Beams with zero initial length are recommended.
  4. Force versus displacement and moment versus angle curves can be specified in the 1st (and optionally 3rd ) quadrants . The 1st quadrant (+ve) values are used for Tensile (or clockwise) behavior and the 3rd quadrant (-ve) values for Compressive (or anti-clockwise) behavior. If only the 1st quadrant data (starting at 0,0) is defined, the curve will be mirrored for the 3rd quadrant such that spring behavior is the same/symmetrical.
  5. If for a DOF both force-based and displacement-based failure is defined, then only force failure will be used.
  6. The option “_TITLE” can be added to the end of this keyword. When “_TITLE” is included, an extra 80 characters long line is added after the keyword input line which allows an entity title to be defined.