/FAIL/XFEM_JOHNS (Obsolete)

Block Format Keyword Describes a XFEM (eXtended Finite Element Method) failure model.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/FAIL/XFEM_JOHNS/mat_ID/unit_ID
D1 D2 D3 D4 D5
ε ˙ 0 Ifail_sh              

Optional Line

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
fail_ID          

Definitions

Field Contents SI Unit Example
mat_ID Material identifier

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
D1 1st parameter

(Real)

 
D2 2nd parameter

(Real)

 
D3 3rd parameter

(Real)

 
D4 4th parameter

(Real)

 
D5 5th parameter

(Real)

 
ε ˙ 0 Reference strain rate

(Real)

[ 1 s ]
Ifail_sh Shell failure flag
= 1
Shell is cracked (not deleted), if D = Δ ε p ε f 1 for one integration point or layer.
= 2
For each integration point, the stress tensor is set to zero, if D = Δ ε p ε f 1 ; and shell is cracked (not deleted), for all integration points or layers.

(Integer)

 
fail_ID (Optional) Failure criteria identifier 4

(Integer, maximum 10 digits)

 

Example (Steel)

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
#              MUNIT               LUNIT               TUNIT
Mg                  mm                   s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  1. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/PLAS_JOHNS/1/1
Steel
#              RHO_I
              7.8E-9
#                  E                  Nu
              210000                  .3
#                  a                   b                   n           EPS_p_max            SIG_max0
                 270                 450                  .6                   0                   0
#                  c           EPS_DOT_0       ICC   Fsmooth               F_cut               Chard
                   0                   0         0         0                   0                   0
#                  m              T_melt              rhoC_p                 T_r
                   0                   0                   0                   0
/FAIL/JOHNSON/1/1
#                 D1                  D2                  D3                  D4                  D5
                0.11                0.08                -1.5                   0                   0
#              EPS_0  Ifail_sh  Ifail_so                                    Dadv               Ixfem
                   1         1         1                                     0.5                   1
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

  1. This failure model is available for Shell only.
  2. The parameters are used in the stress-strain relationship:
    (1)
    ε f = [ D 1 + D 2 exp ( D 3 σ * ) ] [ 1 + D 4 In ( ε ˙ * ) ] [ 1 + D 5 T * ]

    Where,

    σ * = σ m σ V M ; ε ˙ * = ε ˙ ε ˙ 0

    T* is computed in the material law, if this one is thermo plastic, like /MAT/LAW4 (HYD_JCOOK).

  3. Current known limitations are:
    • /PARITH/ON does not ensure results repeatability, if SPMD > 1; it works in SMP parallel mode only.
    • XFEM is currently NOT compatible with either /ANIM/VECT or with /PARITH/OFF.
  4. The fail_ID is used with /STATE/BRICK/FAIL and /INIBRI/FAIL. There is no default value. If the line is blank, no value will be output for failure model variables in the /INIBRI/FAIL (written in .sta file with /STATE/BRICK/FAIL option).