/FAIL/FLD

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/FAIL/FLD/`mat_ID`/`unit_ID`
`fct_ID`	`I`_{fail_sh}		`fct_ID`_adv	`R`_ani		`D`_adv		`I`_strain	`Ixfem`

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)
`fct_ID`	Function identifier (FLD diagram) (Integer)
`I`_{fail_sh}	Shell failure flag = 1 Shell is deleted or cracked, if there is one layer in the failure zone. = 2 The layer stress tensor is set to zero, if this layer is in the failure zone, and the shell is deleted or cracked, only if all layers are in the failure zone. = 3 Shell is deleted only when membrane strain reaches criterion. = 4 Criterion is calculated but element is not deleted. (Integer) If `Ixfem` =0: failure - element deleted If `Ixfem` =1: failure - element cracked 2
`fct_ID`_adv	Failure advancement diagram function identifier Only active, if `Ixfem`=1 3 (Integer)
`I`_strain	Engineering / True input strain flag = 0 (Default) FLD curve defined in terms of true strain = 1 FLD curve defined in terms of engineering strain (Integer)
`R`_ani	Average anisotropy factor Default = 1.0 (Real, positive)
`D`_adv	Criterion for crack advancement Only active, if `Ixfem`=1 3 (Real, between 0 and 1) Default = 0.5, if `fct_ID`_adv is not defined (for backward compatibility) Default = 1.0, if `fct_ID`_adv is defined
`Ixfem`	XFEM flag (for /PROP/SHELL, /PROP/SH_SANDW, and /PROP/TYPE51 properties only) = 1 XFEM formulation 2 = 0 (Default) Without XFEM (Integer)
`fail_ID`	Failure criteria identifier 4 (Integer, maximum 10 digits)

Example (element deleted)

#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/4/1
metal
#              RHO_I
              2.8E-9                   0
#                  E                  Nu
               60000                  .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/FLD/4/1
#  Func_id  Ifail_sh          Fct_ID_adv               R_ani                Dadv   Istrain     Ixfem
      1012         1                   0                   0                   0         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1012
FLD diagram
#                  X                   Y
                -0.7                0.90                                                            
                -0.4                0.60                                                           
                -0.3                0.50                                                            
                -0.2                0.40                                                            
               -0.15                0.35
                -0.1                0.30                                                            
               -0.05                0.29                                                           
               -0.03                0.28                                                            
                 0.0                0.28
                0.05                0.33
                 0.1                0.36
                 0.2                0.39
                 0.3                0.42				 
                 0.4                0.45				 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Example (element cracked)

#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/4/1
metal
#              RHO_I
              2.8E-9                   0
#                  E                  Nu
               60000                  .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/FLD/4/1
#  Func_id  Ifail_sh          Fct_ID_adv               R_ani                Dadv   Istrain     Ixfem
      1012         1                1013                   0                 0.6         0         1
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1012
FLD diagram - Initiation
#                  X                   Y
                -0.7                0.90                                                            
                -0.4                0.60                                                           
                -0.3                0.50                                                            
                -0.2                0.40                                                            
               -0.15                0.35
                -0.1                0.30                                                            
               -0.05                0.29                                                           
               -0.03                0.28                                                            
                 0.0                0.28
                0.05                0.33
                 0.1                0.36
                 0.2                0.39
                 0.3                0.42				 
                 0.4                0.45				 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1013
failure advancement diagram 
#                  X                   Y
                -0.7                0.90                                                            
                -0.4                0.60                                                           
                -0.3                0.50                                                            
                -0.2                0.40                                                            
               -0.15                0.35
                -0.1                0.30                                                            
               -0.05                0.29                                                           
               -0.03                0.28                                                            
                 0.0                0.28
                0.05                0.33
                 0.1                0.36
                 0.2                0.39
                 0.3                0.42				 
                 0.4                0.45				 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

This failure model is available for Shell only.
XFEM formulation (I_xfem=1) is only compatible with Belytchko (I_shell=1 or 2), I_shell=3 or 4 and QEPH (I_shell=24) shell elements. If XFEM flag is activated (I_xfem=1), the failure criteria will lead to element cracking instead of element or layer deletion.
Two XFEM options are available: mono-layer and multi-layer. The XFEM option depends on the property type associated to the failure criterion applied to the material identifier:
1. If /PROP/SHELL (TYPE1) is used, then mono-layer XFEM will be applied.
  In this case, the whole element thickness is considered as a single layer. The failure criterion is calculated in each integration point, but only one crack can appear in this element. This approach is compatible with all values of the shell flag (I_{fail_sh}=1 or 2). The crack direction is determined by the principal constraints in the last failed integration point.
2. If /PROP/SH_SANDW (TYPE11) is used, then multi-layer XFEM will be applied.
  In this case, each integration point over thickness is considered as a distinct layer. The failure criterion is calculated separately and the crack direction may be different in each layer. Crack direction in each layer will independently propagate from one element to another. Multi-layer XFEM is not compatible with I_{fail_sh}=1. Its value will be automatically set to I_{fail_sh}=2 in this case.
3. If /PROP/TYPE51 is used, then multi-layer XFEM will be applied and the separate cracks may appear in each layer and propagate independently from one element to another. Thus, crack directions and patterns will be different in each layer. The failure criterion is calculated separately in each integration point and crack will propagate when all the integration points fail within a layer. Multi-layer XFEM is not compatible with I_{fail_sh}=1. Its value will be automatically set to I_{fail_sh}=2.
  Warning: Mono-layer and multi-layer XFEM formulations cannot be mixed in the same model, yet. The choice between them must be made for the whole model.
  
  Figure 1.
When the Ixfem option is used, a supplementary criterion is available for crack advancement, which may be different from the one used for the failure initialization. It will be used for elements with an existing crack tip at their border. If fct_ID_adv is defined, D_adv is used as a scale factor for this function to obtain the advancement failure value. If fct_ID_adv is not defined, the original FLD diagram (fct_ID) is used with the D_adv scale factor to obtain this value.
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).
The R_ani is only used for animation output /ANIM/SHELL/FLDZ to define FLD index compression zone with the slope.(1)
$α = \arctan (- \frac{R_{a n i}}{1 + R_{a n i}})$

If default $R_{a n i} = 1.0$ is used, then $- \frac{R_{a n i}}{1 + R_{a n i}} = - \frac{1}{2}$ and the bound of failure zone 2 and failure zone 3 is by $\frac{ε_{m i n o r}}{ε_{m a j o r}} = - 2$

Figure 2.