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Block Format Keyword

/FAIL/FLD - Forming Limit Diagram

Description

Describes the forming limit.

Format

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/FAIL/FLD/mat_ID/unit_ID

fct_ID

Ifail_sh

 

fct_ID adv

 

 

Dadv

 

Ixfem

Optional line:

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(2)

(3)

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(5)

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fail_ID

 

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier

(Integer, maximum 10 digits)

 

unit_ID

Optional unit identifier

(Integer, maximum 10 digits)

 

fct_ID

Function identifier (FLD diagram)

(Integer)

 

Ifail_sh

Shell failure flag

(Integer)

If Ixfem =0: failure – element deleted

If Ixfem =1: failure – element cracked (Comment 2)

= 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.

 

fct_IDadv

Failure advancement diagram function identifier

Only active, if Ixfem=1 (Comment 3)

(Integer)

 

Dadv

Criterion for crack advancement

Only active, if Ixfem=1 (Comment 3)

(Real, between 0 and 1)

Default = 0.5, if fct_IDadv is not defined (for backward compatibility)

Default = 1.0, if fct_IDadv is defined

 

Ixfem

XFEM flag (for /PROP/SHELL, /PROP/SH_SANDW, and /PROP/TYPE51 properties only)

Default = 0 (Integer)

= 1: XFEM formulation (Comment 2)

= 0: Without XFEM

 

fail_ID

(Optional) Failure criteria identifier (Comment 4)

(Integer, maximum 10 digits)

 
hmtoggle_plus1Example (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

#                  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

#   fct_ID  Ifail_sh          fct_ID_adv                                    Dadv               Ixfem

      1012         1                   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----|
hmtoggle_plus1Example (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

#                  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

#   fct_ID  Ifail_sh          fct_ID_adv                                    Dadv               Ixfem

      1012         1                1013                                     0.6                   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----|
hmtoggle_plus1Comments
1.This failure model is available for Shell only.
2.XFEM formulation (Ixfem=1) is only compatible with Belytchko (Ishell=1 or 2), Ishell=3 or 4 and QEPH (Ishell=24) shell elements. If XFEM flag is activated (Ixfem=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:

a)  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 (Ifail_sh=1 or 2). The crack direction is determined by the principal constraints in the last failed integration point.

b)  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 Ifail_sh=1. Its value will be automatically set to Ifail_sh=2 in this case.

c) 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 Ifail_sh=1. Its value will be automatically set to Ifail_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.

fail_fld

3.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_IDadv is defined, Dadv is used as a scale factor for this function to obtain the advancement failure value. If fct_IDadv is not defined, the original FLD diagram (fct_ID) is used with the Dadv scale factor to obtain this value.
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).

See Also

Failure to Element/Material Compatibility

Example 26 - Ruptured Plate