/FAIL/ORTHSTRAIN

Block Format Keyword An orthotropic strain failure criteria with size effects, strain rate effects, and damage. Available for solid and shell elements.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/FAIL/ORTHSTRAIN/`mat_ID`/`unit_ID`

Card 1

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
		`P_thick`_fail							`Strdef`

Card 2 - Global strain rate dependency parameters

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
${\dot{ε}}_{0}$		`F`_cut

Card 3 - Element size scale function

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
`fct_ID`_el	`Fscale`_el		`El_ref`

Card 4 - Direction 11

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{11 d_t}$		$ε_{11 f_t}$		`fct_ID`_11t	$ε_{11 d_c}$		$ε_{11 f_c}$		`fct_ID`_11c

Card 5 – Direction 22

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{22 d_t}$		$ε_{22 f_t}$		`fct_ID`_22t	$ε_{22 d_c}$		$ε_{22 f_c}$		`fct_ID`_22c

Card 6 - Direction 33 (solids only, leave blank for shells)

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{33 d_t}$		$ε_{33 f_t}$		`fct_ID`_33t	$ε_{33 d_c}$		$ε_{33 f_c}$		`fct_ID`_33c

Card 7 - Direction 12

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{12 d_t}$		$ε_{12 f_t}$		`fct_ID`_12t	$ε_{12 d_c}$		$ε_{12 f_c}$		`fct_ID`_12c

Card 8 - Direction 23 (solids only, leave blank for shells)

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{23 d_t}$		$ε_{23 f_t}$		`fct_ID`_23t	$ε_{23 d_c}$		$ε_{23 f_c}$		`fct_ID`_23c

Card 9 - Direction 31 (solids only, leave blank for shells)

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ε_{31 d_t}$		$ε_{31 f_t}$		`fct_ID`_31t	$ε_{31 d_c}$		$ε_{31 f_c}$		`fct_ID`_31c

Card 10 – Failure model ID (optional line)

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

Definition

Field	Contents	SI Unit Example
`mat_ID`	Material identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit Identifier. (Integer, maximum 10 digits)
`P_thick`_fail	Ratio of through thickness integration points that must fail before the element is deleted (shells only). Default = 1.0 (Real)
`Strdef`	Strain measure definition used in failure criterion. = 1 (Default) Strain defined by `I`_smstr flag in property. = 2 Engineering strain. = 3 True strain. (Integer)
${\dot{ε}}_{0}$	Reference strain rate. If $\dot{ε} \leq {\dot{ε}}_{0}$ , no strain rate effect. (Real)	$[\frac{1}{s}]$
`F`_cut	Cutoff frequency for strain rate smoothing. Default = 10³⁰ (Real)	$[Hz]$
`fct_ID`_el	Element size factor function identifier. (Integer)
`Fscale`_el	Element size function scale factor. Default = 1.0 (Real)
`El_ref`	Reference element size. Default = 1.0 (Real)	$[m]$
$ε_{11 d_t}$	Tensile strain when damage begins in direction 11.
$ε_{11 f_t}$	Tensile strain when the material fails in direction 11.
`fct_ID`_11t	Strain rate factor function in tension, direction 11.
$ε_{11 d_c}$	Compression strain when damage begins in direction 11.
$ε_{11 f_c}$	Compression strain when the material fails in direction 11.
`fct_ID`_11c	Strain rate factor function in compression direction 11.
$ε_{22 d_t}$	Tensile strain when damage begins in direction 22.
$ε_{22 f_t}$	Tensile strain when the material fails in direction 22.
`fct_ID`_22t	Strain rate factor function in tension direction 22.
$ε_{22 d_c}$	Compression strain when damage begins in direction 22.
$ε_{22 f_c}$	Compression strain when the material fails in direction 22.
`fct_ID`_22c	Strain rate factor function in compression direction 22.
$ε_{33 d_t}$	Tensile strain when damage begins in direction 33.
$ε_{33 f_t}$	Tensile strain when the material fails in direction 33.
`fct_ID`_33t	Strain rate function in tension direction 33.
$ε_{33 d_c}$	Compression strain when damage begins in direction 33.
$ε_{33 f_c}$	Compression strain when the material fails in direction 33.
`fct_ID`_33c	Strain rate factor function in compression direction 33.
$ε_{12 d_t}$	Tensile strain when damage begins in direction 12.
$ε_{12 f_t}$	Tensile strain when the material fails in direction 12.
`fct_ID`_12t	Strain rate factor function in tension direction 12.
$ε_{12 d_c}$	Compression strain when damage begins in direction 12.
$ε_{12 f_c}$	Compression strain when the material fails in direction 12.
`fct_ID`_12c	Strain rate factor function in compression direction 12.
$ε_{23 d_t}$	Tensile strain when damage begins in direction 23.
$ε_{23 f_t}$	Tensile strain when the material fails in direction 23.
`fct_ID`_23t	Strain rate factor function in tension direction 23.
$ε_{23 d_c}$	Compression strain when damage begins in direction 23.
$ε_{23 f_c}$	Compression strain when the material fails in direction 23.
`fct_ID`_23c	Strain rate factor function in compression direction 23.
$ε_{31 d_t}$	Tensile strain when damage begins in direction 31.
$ε_{31 f_t}$	Tensile strain when the material fails in direction 31.
`fct_ID`_31t	Strain rate factor function in tension direction 31.
$ε_{31 d_c}$	Compression strain when damage begins in direction 31.
$ε_{31 f_c}$	Compression strain when the material fails in direction 31.
`fct_ID`_31c	Strain rate factor function in compression direction 31.
`fail_ID`	(Optional) Failure model identifier. (Integer, maximum 10 digits)

▸Example

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  2. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/PLAS_TAB/1/1
DP600 from SSAB Homepage
#        Init. dens.          Ref. dens.
              7.8E-6                   0
#                  E                  Nu           Eps_p_max              Eps_t1              Eps_t2
                 210                  .3                   0                   0                   0
#    Nfunc   Fsmooth               Chard                Fcut               Eps_f
         4         1                   0                  10                   0
#    Ipfun             Fpscale
         0                   0
# Funtions
        14        14        14        14
# Scale factors
                   1                 1.0                 1.2                 1.2
# Strain rates
                1e-6                1e-5                 0.1                 1.0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FAIL/ORTHSTRAIN/1/1
#                            Pthick_fail                                                      Strdef
                                     0.8
#           Epsp_ref                Fcut        
                 0.0                 0.0
#   fct_el           Fscale_el              El_ref     
         0                   0                   0
#           eps11d_t            eps11f_t   fct_11t            eps11d_c            eps11f_c   fct_11c
                0.01                0.05      1000                 0.1                 0.2      2000        
#           eps22d_t            eps22f_t   fct_22t            eps22d_c            eps22f_c   fct_22c
                0.01                0.05      1001                 0.1                 0.2      2001        
#           eps33d_t            eps33f_t   fct_33t            eps33d_c            eps33f_c   fct_33c
                0.01                0.05      1001                 0.1                 0.2      2001        
#           eps12d_t            eps12f_t   fct_12t            eps12d_c            eps12f_c   fct_12c
                0.01                0.05      1001                 0.1                 0.2      2001        
#           eps23d_t            eps23f_t   fct_23t            eps23d_c            eps23f_c   fct_23c
                0.01                0.05      1001                 0.1                 0.2      2001        
#           eps31d_t            eps31f_t   fct_31t            eps31d_c            eps31f_c   fct_31c
                0.01                0.05      1001                 0.1                 0.2      2001        
#  Fail_ID 
     
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1000
eps11t
#                  X                   Y
                  0.                   1
                  1.                   1
                 1.2                   1                                                            
              1.0e20                   1                                                            
/FUNCT/2000
eps11c
#                  X                   Y
                  0.                   1
                 .05                   1
                 .06                   1                                                            
              1.0e20                   1                                                            
/FUNCT/1001
bidont
#                  X                   Y
                  0.                   1
              1.0e20                   1                                                            
/FUNCT/2001
bidonc
#                  X                   Y
                  0.                   1
              1.0e20                   1                                                            
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/14
Mat_Curev Quasi-static DOCOL DP 600 (Material from SSAB Homepage 2010)
#                  X                   Y
                   0                .306                                                            
              .00112                .415                                                            
              .00218                .445                                                            
                .003                .461                                                            
              .00404                .474                                                            
              .00517                .489                                                            
              .00613                .498                                                            
               .0071                .505                                                            
              .00806                .512                                                            
              .00901                .522                                                            
               .0102                 .53                                                            
               .0121                .543                                                            
                .013                 .55                                                            
                .014                .555                                                            
                .015                .561                                                            
               .0159                .567                                                            
               .0171                .572                                                            
               .0181                .577                                                            
               .0204                .592                                                            
               .0303                .632                                                            
               .0405                .663                                                            
               .0502                .687                                                            
                 .06                .706                                                            
               .0702                .722                                                            
               .0807                .737                                                            
                 .09                .749                                                            
               .0997                .758                                                            
                .101                .759                                                            
                 .11                .768                                                            
           .15000001                .805                                                            
                  .2                 .84                                                            
           .30000001                  .9                                                            
                  .5                   1                                                            
                   1                1.21                                                            
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

A damage factor is the maximum over time and is calculated for each direction and stress state via:(1)
$d_{i j l} = (\frac{ε_{i j f_l}}{ε_{i j l}}) (\frac{ε_{i j l} - α \cdot ε_{i j d_l}}{ε_{i j f_l} - ε_{i j d_l}})$

Where, the direction is indicated by using the common ij notation and loading state is either compression (l=c) or tension (l=t).

Where, $α = f a c t o r_{e l} \cdot f a c t o r_{r a t e}$ .

The element size correction factor is:(2)
$f a c t o r_{e l} = F s c a l e_{e l} \cdot f_{e l} (\frac{S i z e_{e l}}{E l_r e f})$

Where,

$f_{e l}$

Element size correction factor function defined via $f c t_I D_{e l}$

$S i z e_{e l}$

Characteristic element size.

The strain rate factor is:(3)
$f a c t o r_{r a t e} = f_{i j l} (\frac{{\dot{ε}}_{i j l}}{{\dot{ε}}_{0}})$

Where,

$f_{i j l}$

Strain rate factor function defined via $f c t_I D_{i j l}$ .

${\dot{ε}}_{i j l}$

Current (filtered) strain rate in direction ij and load case l.

${\dot{ε}}_{0}$

Entered reference strain rate.
Material damage and stress softening are calculated as:
$D_{\max} = \max (d_{i j l})$ and $σ = (1 - D_{\max}) σ$
- If $0 < D_{\max} < 1$ , the stress tensor is reduced.
- If $D_{\max} \geq 1$ ,the material has failed and the integration point stress tensor is set to zero.
- $D_{\max}$ can be output using options in /ANIM/Eltype/DAMA or /H3D/Eltype/DAMA.
Solid elements are deleted when all integration points reach the failure criterion. Shells are deleted when the sum of thickness of failed layers /integration points in the normal direction is greater than prescribed P_thick_fail value.(4)
$\frac{\sum_{l a y e r s} t h i c k n e s s_{f a i l}}{\sum_{l a y e r s} I P} > P_t h i c k_{f a i l}$
When the failure model is applied to a material in STACK property, P_thick_fail defines a relative thickness of failed integration points, necessary to switch off the corresponding layer. The global element suppression criterion must be defined at the property level.
/FAIL/ORTHSTRAIN should be only associated to materials compatible with orthotropic shell properties. LAW25 is compatible only if it’s used within shell property TYPE51.