CRASURV Formulation

Block Format Keyword

/MAT/LAW25 - Orthotropic Shell and Solid Material – CRASURV Formulation (Iform = 1)

Description

This law describes the composite shell and solid material using the CRASURV formulation. This material is assumed to be orthotropic-elastic before the Tsai-Wu criterion is reached. The material becomes nonlinear afterwards. For solid elements, the material is assumed to be linearly elastic in the transverse direction. The Tsai-Wu criterion can be set dependent on the plastic work and strain rate in each of the orthotropic directions and in shear to model material hardening. Strain and plastic energy criterion for brittle damage and failure is available. A simplified delamination criterion based on out-of-plane shear angle can be used.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW25/mat_ID/unit_ID or /MAT/COMPSH/mat_ID/unit_ID
mat_title

E11		E22				Iform		E33
G12		G23		G31		f1		f2
t1		m1		t2		m2		dmax

Composite Plasticity Hardening

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

Global Composite Plasticity Parameters

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

Composite Plasticity in Tension Directions 1 and 2

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

Composite Plasticity in Compression Directions 1 and 2

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

Composite Plasticity in Shear

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

Delamination

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
				d3max

Strain Rate Filtering

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

Field	Contents	SI Unit Example
mat_ID	Material identifier (Integer, maximum 10 digits)
unit_ID	Optional unit identifier (Integer, maximum 10 digits)
mat_title	Material title (Character, maximum 100 characters)
	Initial density (Real)
E11	Young‘s modulus in direction 1 (Real)
E22	Young’s modulus in direction 2 (Real)
	Poisson’s ratio (Real)
Iform	Formulation flag (Comment 1) (Integer) = 1: CRASURV formulation
E33	Young’s modulus in direction 33 (Comment 4) (Real)
G12	Shear modulus in direction 12 (Real)
G23	Shear modulus in direction 23 (Real)
G31	Shear modulus in direction 31 (Real)
f1	Maximum tensile strain for element deletion in material direction 1 Default = 1.2 x 1030 (Real)
f2	Maximum tensile strain for element deletion in material direction 2 Default = 1.2 x 1030 (Real)
t1	Tensile failure strain in the material direction 1 at which stress starts to reduce (Comment 6) Default = 1.0 x 1030 (Real)
m1	Maximum tensile strain in material direction 1 at which the stress in the element is set to a value dependent on dmax (Comment 6) Default = 1.1 x 1030 (Real)
t2	Tensile failure strain in the material direction 2 at which stress starts to reduce Default = 1.0 x 1030 (Real)
m2	Maximum tensile strain in material direction 2 at which the stress in the element is set to a value dependent on dmax. Default = 1.1 x 1030 (Real)
dmax	Maximum damage factor (dmax < 1) (Comment 6) Default = 0.999 (Real)
	Maximum plastic work per unit shell volume Default = 1030 (Real)
	Reference plastic work per unit shell volume (Comment 17) Default = 1.0 (in local unit system) (Real)
Ioff	Flag that controls shell and thick shell element deletion depending on failure modes in the element layers. (Integer) = 0: shell is deleted if for one element : shell is deleted if for one element layer. = 1: shell is deleted if for all element layers. = 2: shell is deleted if for each element layer, = 3: shell is deleted if for each element layer, = 4: shell is deleted if for each element layer, condition 1 and condition 2 are satisfied. = 5: shell is deleted if all element layers, condition 1 or condition 2 is satisfied. = 6: shell is deleted if for each element layer condition 1 or condition 2 is satisfied.
ratio	Ratio parameter which controls the deletion of shell elements based on the number of failed layers (Comment 9) Default = 1.0 (Real) < 0.0: the element will be deleted if all layers but one failed (that is, the number of layers that did not fail is equation to 1). > 0.0: the element will be deleted if
c	Global strain rate coefficient for plastic work criteria (Real) = 0.0: there is no strain rate dependency
	Reference strain rate If , no strain rate effect (Real)
	Reduction factor for F12 coefficient calculation in Tsai-Wu criterion Default set to 1.0 (Real)
ICCglobal	Global strain rate effect flag (Comment 11) (Integer) = 0: default set to 1 = 1: strain rate effect on , , , , is taken into account, but there is no strain rate effect on = 2: there is no strain rate effect on , , , , and = 3: there is strain rate effect on , , , , and = 4: strain rate effect on is taken into account, but there is no strain rate effect on , , , , and
	Yield stress in tension in direction 1 Default = 0.0 (Real)
	Plastic hardening parameter in tension in direction 1 Default = 0.0 (Real)
	Plastic hardening exponent in tension in direction 1 Default = 1.0 (Real)
	Maximum stress in tension in direction 1 Default = 1030 (Real)
	Strain rate coefficient in tension in direction 1 Default = c (Real) = 0: no strain rate dependency
	Initial softening strain in tension in the material direction 1 Default = 1.0 x 1030 (Real)
	Maximum softening strain in tension in the material direction 1 Default = 1.2 * (Real)
	Residual stress in tension in direction 1 Default = 10-3 * (Real)
	Maximum plastic work per unit shell volume in tension in direction 1 Default = 1030 (Real)
	Yield stress in tension in direction 2 Default = 0.0 (Real)
	Plastic hardening parameter in tension in direction 2 Default = 0.0 (Real)
	Plastic hardening exponent in tension in direction 2 Default = 1.0 (Real)
	Maximum stress in tension in direction 2 Default = 1030 (Real)
	Strain rate coefficient in tension in direction 2 Default = c (Real) = 0: no strain rate dependency
	Initial softening strain in tension in the material direction 2 Default = 1.0 x 1030 (Real)
	Maximum softening strain in tension in direction 2 Default = 1.2 * (Real)
	Residual stress in tension in direction 2 Default = 10-3 * (Real)
	Maximum plastic work per unit shell volume in tension in direction 2 Default = 1030 (Real)
	Yield stress in compression in direction 1 Default = 0.0 (Real)
	Plastic hardening parameter in compression in direction 1 Default = (Real)
	Plastic hardening exponent in compression in direction 1 Default = (Real)
	Maximum stress in compression in direction 1 Default = 1030 (Real)
	Strain rate coefficient in compression in direction 1 Default = c (Real) = 0: no strain rate dependency
	Initial softening strain in compression in the material direction 1 Default = 1.0 x 1030 (Real)
	Maximum softening strain in compression in the material direction 1 Default = 1.2 * (Real)
	Residual stress in compression in direction 1 Default = 10-3 * (Real)
	Maximum plastic work per unit shell volume in compression in direction 1 Default = 1030 (Real)
	Yield stress in compression in direction 2 Default =0.0 (Real)
	Plastic hardening parameter in compression in direction 2 Default = (Real)
	Plastic hardening exponent in compression in direction 2 Default = (Real)
	Maximum stress in compression in direction 2 Default = 1030 (Real)
	Strain rate coefficient in compression in direction 2 Default = c (Real) = 0: no strain rate dependency
	Initial softening strain in compression in the material direction 2 Default = 1.0 x 1030 (Real)
	Maximum softening strain in compression in the material direction 2 Default = 1.2 * (Real)
	Residual stress in compression in direction 2 Default = 10-3 * (Real)
	Maximum plastic work per unit shell volume in compression in direction 2 Default = 1030 (Real)
	Yield stress in direction 12 (in 45 degree of fiber direction) Default = 0.0 (Real)
	Plastic hardening parameter in direction 12 Default = (Real)
	Plastic hardening exponent in direction 12 Default = (Real)
	Maximum stress in direction 12 Default = 1030 (Real)
	Strain rate coefficient in direction 12 Default = c (Real) = 0: no strain rate dependency
	Initial softening strain in the material direction 12 Default = 1.0 x 1030 (Real)
	Maximum softening strain in the material direction 12 Default = 1.2 * (Real)
	Residual stress in direction 12 Default = 10-3 * (Real)
	Maximum plastic work per unit shell volume in direction 12 Default = 1030 (Real)
	Out of plane shear strain when delamination begins (Comment 12) Default = 1030 (Real)
	Out of plane shear strain when delamination ends and the element is deleted (Comment 12) Default = 1.1 * 1030 (Real)
d3max	Maximum delamination damage factor (d3max < 1) (Comment 14) Default = 1.0 (Real)
Fsmooth	Strain rate smoothing flag (Integer) = 0: strain rate smoothing is inactive (default) = 1: strain rate smoothing is active
Fcut	Cutoff frequency for strain rate smoothing Default = 1030 (Real)

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/UNIT/1

unit for mat

g 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/COMPSH/1/1

carbon based tissue

# RHO_I

.0015

# E11 E22 NU12 Iform E33

56275 54868 .042 1 0

# G12 G23 G31 EPS_f1 EPS_f2

4212 4212 4212 0 0

# EPS_t1 EPS_m1 EPS_t2 EPS_m2 d_max

.016305 .02 .014131 .016 0

# Wpmax Wpref Ioff ratio

15 0 6 .5

# c EPS_rate_0 alpha ICC_global

0 0 0 0

# sig_1yt b_1t n_1t sig_1maxt c_1t

917.59 0 1 919 0

# EPS_1t1 EPS_2t1 SIGMA_rst1 Wpmax_t1

0 0 0 0

# sig_2yt b_2t n_2t sig_2maxt c_2t

775.38 0 1 777 0

# EPS_1t2 EPS_2t2 sig_rst2 Wpmax_t2

0 0 0 0

# sig_1yc b_1c n_1c sig_1maxc c_1c

355 .17 .84 708.87 0

# EPS_1c1 EPS_2c1 sig_rsc1 Wpmax_c1

.0226 .025 0 0

# sig_2yc b_2c n_2c sig_2maxc c_2c

355 .17 .84 702.97 0

# EPS_1c2 EPS_2c2 sig_rsc2 Wpmax_c2

.0226 .025 0 0

# sig_12y b_12 n_12 sig_12max c_12

30 2.872290896763 .3 132.57 0

# EPS_1_12 EPS_2_12 sig_rs_12 Wpmax_12

0 0 0 0

# GAMMA_ini GAMMA_max d3_max

0 0 0

# Fsmooth Fcut

0 0

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#ENDDATA

/END

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/UNIT/1

unit for mat

Mg mm s

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 2. MATERIALS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/COMPSH/1/1

KEVLAR

# RHO_I

1.4E-9

# E11 E22 NU12 Iform E33

87000 87000 .3 1 0

# G12 G23 G31 EPS_f1 EPS_f2

2200 2200 2200 0 0

# EPS_t1 EPS_m1 EPS_t2 EPS_m2 d_max

.015 .017 .015 .017 0

# Wpmax Wpref Ioff ratio

0 0 6 .5

# c EPS_rate_0 alpha ICC_global

0 0 0 0

# sig_1yt b_1t n_1t sig_1maxt c_1t

650 0 1 0 0

# EPS_1t1 EPS_2t1 SIGMA_rst1 Wpmax_t1

0 0 0 0

# sig_2yt b_2t n_2t sig_2maxt c_2t

650 0 1 0 0

# EPS_1t2 EPS_2t2 sig_rst2 Wpmax_t2

0 0 0 0

# sig_1yc b_1c n_1c sig_1maxc c_1c

335 0 1 650 0

# EPS_1c1 EPS_2c1 sig_rsc1 Wpmax_c1

.02 0 0 0

# sig_2yc b_2c n_2c sig_2maxc c_2c

160 0 0 650 0

# EPS_1c2 EPS_2c2 sig_rsc2 Wpmax_c2

.03 0 0 0

# sig_12y b_12 n_12 sig_12max c_12

50 0 0 100 0

# EPS_1_12 EPS_2_12 sig_rs_12 Wpmax_12

0 0 0 0

# GAMMA_ini GAMMA_max d3_max

0 0 0

# Fsmooth Fcut

0 0

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#ENDDATA

/END

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

1.	The formulation flag Iform should be set to 1, for the CRASURV (crash survivability) formulation.

This material requires orthotropic shell properties (/PROP/SH_ORTH, /PROP/SH_COMP or /PROP/SH_SANDW). These properties specify the orthotropic direction, therefore, it is not compatible with the isotropic shell property (/PROP/TYPE1). Property /PROP/SH_ORTH is not compatible with the CRASURV formulation.

3.	This material is available with under-integrated Q4 and fully integrated BATOZ shell formulations.

This material is compatible with orthotropic solid property (/PROP/SOL_ORTH), the orthotropic thick shell property (/PROP/TSH_ORTH) and the composite thick shell property (/PROP/TSH_COMP). These properties specify the orthotropic directions. It is assumed that, for solids and thick shells, the material is elastic and the E33 value must be set in such cases.

5.	The material is assumed to be elastic until the Tsai-Wu criterion is fulfilled:

Where, , and are the stresses in the material coordinate system.

The variable coefficients (functions of plastic work) of the Tsai-Wu criterion are determined as follows:

Where, i=1 or 2.

The values of the limiting stresses when the material becomes nonlinear in directions 1, 2 or 12 (shear) are modified based on the values of plastic work and strain rate, as shown below:

In tension:

In compression:

In shear:

The superscripts c and t represent compression and tension, respectively and i =1 or 2.

For the definitions of other parameters, refer to the card descriptions above.

This criterion represents a second order closed three-dimensional Tsai-Wu surface in , and space. This surface is scaled, moved and rotated due to the variation of plastic work and true strain rate.

For shear, the parameters determining nonlinear behavior are the same in tension and compression.

6.	Global tensile strain damage between and is controlled by the damage factor di, which is given by the following equation:

in directions, i = 1, 2

Stress is reduced according to damage parameter . Damage is reversible between and . When , damage is set to dmax and it is not updated further. Element deletion is controlled by the Ioff flag.

Strain damage is available for each direction in tension, compression and shear. It is controlled by and in tension, and in compression and and in shear. It works similar to global strain damage; however, the element is not deleted.

mat_law27_tensile

7.	For the plastic work failure criterion, and are defined as follows:

and

When , the stress is set to zero in the layer. Element deletion is controlled by the Ioff flag.

8.	The plastic work failure criterion is accounted for in each direction separately.

The element is deleted if the plastic work in corresponding directions are as follows:

and in tension

and in compression

and in shear

This Ratio field can be used to provide stability to composite shell components. For example, it allows you to delete unstable elements wherein all layers but one have failed. This last layer may cause instability during simulation due to a low stiffness value. This option is available for strain and plastic energy based brittle failure.

10.	Tensile strain and energy failure criterion of LAW25 is not available for orthotropic shells with /PROP/TYPE9.

11.	The ICC flag defines the effect of strain rate on the maximum plastic work and on the Tsai-Wu criterion limit. For ICC = 2, 3 and 4, the plastic work failure criterion is:

12.

The simple delamination criterion is based on the evaluation of out-of-plane shear strains (

and

). Element stresses

and

are gradually reduced when the resultant out-of-plane shear

lies within

. The element is completely removed (fails) if the value of

becomes greater than the value of d3max (specified on this material card) in one of the shell layers.

13.	Failure criterion in LAW25 is not applicable to solid elements. To determine failure for solid elements, the /FAIL card should be used.

14.

For shell and thick shell composite parts, with /PROP/SH_COMP, /PROP/SH_SANDW, /PROP/TSH_ORTH or /PROP/TSH_COMP, material is defined directly in the property card. The failure criteria defined within this material (for example, LAW25) are accounted for. Material referred to in the corresponding /PART card is not used.

15.	For post-processing of this material in the animation file, the following engine cards should be used:

/ANIM/SHELL/EPSP - for plastic work output
/ANIM/SHELL/TENS/STRAIN – for strain tensor output in the elemental coordinate system
/ANIM/ SHELL/TENS/STRESS – for stress tensor output in the elemental coordinate system
/ANIM/PHI – angle between elemental and first material direction
/ANIM/SHELL/FAIL – number of failed layers.

16.	For post-processing of this material in the time-history file, the following definitions in /TH/SHEL or /TH/SH3N card should be used:

PLAS (or EMIN and EMAX) for minimum and maximum plastic work in the shell

WPLAYJJ (JJ=0 to 99) for plastic work in a corresponding layer

17.

The unit of

is an energy per unit of volume. If the default value (0) is encountered, the default value is 1 unit of the model (example:

). For proper conversion of this value if changing units in pre- and post-, it is advised to replace the default value by the true value (1), so that the value of

will be automatically converted. Leaving the

field to (0) may result in errors in case of automatic conversion.

Note that a local unit system can be created for the material to avoid conversion.

18.	The 01.out file displays some information when the failure criteria is met:

•	Failure 1 and 2 means tensile failure direction 1 or 2, respectively

•	Failure -P means global plastic work failure

•	P-T1 / P-T2 means plastic work failure in tension direction 1 or 2, respectively

•	P-C1 / P-C2 means plastic work failure in compression direction 1 or 2, respectively

•	P-T12 means plastic work failure in shear

The failure message also indicates which element and which layer is affected. It is output when the failure criteria is met for an integration point. As Batoz elements have 4 integrations points for each layer, this message may be output up to 4 times per layer and elements in this case.

CRASURV Formulation (Iform = 1)
CRASURV Formulation (Iform = 1)

CRASURV Formulation (Iform = 1)

CRASURV Formulation (Iform = 1)

CRASURV Formulation (Iform = 1)

Format

See Also: