/MAT/LAW27 (PLAS

Block Format Keyword

/MAT/LAW27 - Elasto-plastic Material with Brittle Failure

Description

This law combines an isotropic elasto-plastic Johnson-Cook material model with an orthotropic brittle failure model. Material damage is accounted for prior to failure. Failure and damage occur only in tension. This law is applicable only for shells.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW27/mat_ID/unit_ID or /MAT/PLAS_BRIT/mat_ID/unit_ID
mat_title

E
a		b		n
c				ICC
				dmax1
				dmax2

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)
E	Young’s modulus (Real)
	Poisson’s ratio (Real)
a	Plasticity yield stress (Real)
b	Plasticity hardening parameter (Real)
n	Plasticity hardening exponent (Real)
	Plasticity maximum stress Default = 1030 (Real)
c	Strain rate coefficient Default = 0.00 (Real) = 0: no strain rate effect
	Reference strain rate If , no strain rate effect (Real)
ICC	Strain rate computation flag (Comment 4) (Integer) = 0: default set to 1 = 1: strain rate effect on = 2: no strain rate effect on
	Tensile failure strain at which stress starts to reduce in the principal strain direction 1 (Comment 5) Default = 1.0 x 1030 (Real)
	Maximum tensile failure strain in principal strain direction 1 at which the stress in the element is set to a value dependent on dmax1 (Comment 5) Default = 1.1 x 1030 (Real)
dmax1	Maximum damage factor in principal strain direction 1 (Comment 5) Default = 0.999 (Real)
	Maximum tensile strain for element deletion in principal strain direction 1 (Comment 5) Default = 1.2 x 1030 (Real)
	Tensile failure strain at which stress starts to reduce in the principal strain direction 2 Default = 1.0 x 1030 (Real)
	Maximum tensile strain in principal strain direction 2 at which the stress in the element is set to a value dependent on dmax2 Default = 1.1 x 1030 (Real)
dmax2	Maximum damage factor in principal strain direction 2 (Comment 5) Default = 0.999 (Real)
	Maximum tensile strain for element deletion in principal strain direction 2 Default = 1.2 x 1030 (Real)

#RADIOSS STARTER

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/UNIT/1

unit for mat

Mg mm ms

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#- 2. MATERIALS:

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/MAT/PLAS_BRIT/1/1

Aluminum

# RHO_I

.0027

# E NU

60400 .33

# a b n SIG_max0

90.266 223.14 .375 177

# c EPS_DOT_0 ICC

0 0 0

# EPS_t1 EPS_m1 d_max1 EPS_f1

.16 .72 .999 1

# EPS_t2 EPS_m2 d_max2 EPS_f2

0 0 0 0

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#ENDDATA

/END

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1.	In this model, the material behaves as a linear-elastic material when the equivalent stress is lower than the plastic yield stress. For higher stress values, the material behavior is plastic and the stress is calculated as shown.

Where, is the plastic strain and is the strain rate.

The plasticity hardening exponent, n must be less than 1.

2.	This law allows the modeling of material damage and brittle failure in two principal directions (1 and 2).

3.	This law is only applicable to shell elements. It is compatible with Shell Property (/PROP/TYPE1) and Sandwich Shell Property (/PROP/TYPE11).

4.	The ICC flag defines the effect of strain rate on the maximum material stress . The figure below shows the value of for the corresponding ICC flag.

mat_law27

5.	When principal strain becomes higher than , then 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 and it is not updated further.

mat_law27_tensile .

/MAT/LAW27 (PLAS_BRIT)

/MAT/LAW27 (PLAS_BRIT)

/MAT/LAW27 (PLAS_BRIT)

See Also: