/MAT/LAW74

Block Format Keyword

/MAT/LAW74 - Thermal Hill Orthotropic 3D Material

Description

This law describes the Thermal Hill orthotropic 3D material and is applicable only to solid elements. The yield stress may depend on strain rate, or on both strain rate and temperature.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW74/mat_ID/unit_ID
mat_title

E
fct_IDE		Einf		CE
	Fsmooth	Chard		Fcut


Tab_ID
Ti

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	Initial Young’s modulus (Real)
	Poisson’s ratio (Real)
fct_IDE	Function identifier for the scale factor of Young modulus, when Young modulus is function of the plastic strain. Default = 0: in this case the evolution of Young depends on Einf and CE. (Integer)
Einf	Saturated Young’s modulus for infinitive plastic strain (Real)
CE	Parameter for Young’s modulus evolution (Real)
	Failure plastic strain Default = 1030 (Real)
	Tensile failure strain at which stress starts to reduce Default = 1.0 x 1030 (Real)
	Maximum tensile failure strain at which the stress in element is set to zero Default = 2.0 x 1030 (Real)
Fsmooth	Smooth strain rate option flag Default = 0 (Integer) = 0: no strain rate smoothing = 1: strain rate smoothing active
Chard	Hardening coefficient (Real) = 0: hardening is full isotropic model = 1: hardening uses the kinematic Prager-Ziegler model = between 0 and 1: hardening is interpolated between the two models
Fcut	Cutoff frequency for strain rate filtering Default = 1.0 x 1030 (Real)
	Yield in direction 1 (Real)
	Yield in direction 2 (Real)
	Yield in direction 3 (Real)
	Yield in shear direction 12 (Real)
	Yield in shear direction 23 (Real)
	Yield in shear direction 31 (Real)
Tab_ID	Table identifier for yield stress definition (Comment 6) (Integer)
	Yield stress scale factor Default set to 1.0 (Real)
	Strain rate scale factor Default set to 1.0 (Real)
Ti	Initial temperature Default set to 293 K (Real)
	Specific heat per volume unit (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/LAW74/1/1

Aluminum

# RHO_I

.0027

# E NU EPSILON_P_MAX EPSILON_T EPSILON_M

60400 .33 0 0 0

# fct_ID EINF CE

0 0 0

# FSMOOTH C_HARD FCUT

1 0 10

# SIGMA11Y SIGMA22Y SIGMA33Y

1 1 1

# SIGMA12Y SIGMA23Y SIGMA31Y

1 1 1

# TABLE SIGMA_SCALE EPSPT_SCALE

10 0 0

# TI RHO0_CP

0 0

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

#- 3. FUNCTIONS:

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

/TABLE/1/10

table

#DIMENSION

# fct_ID X Z

38 0 293

38 10 293

39 11 293

40 20 293

38 0 400

38 10 400

39 11 400

40 20 400

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

/FUNCT/38

function_38

# X Y

0 90

2.5E-4 100

.001 104.5

.009 121

.01 136

.02 143.5

.04 163

.07 169.5

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

/FUNCT/39

function_39

# X Y

0 108

2.5E-4 120

.001 125.4

.009 145.2

.01 163.2

.02 172.2

.04 195.6

.07 203.4

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

/FUNCT/40

function_40

# X Y

0 126

2.5E-4 140

.001 146.3

.009 169.4

.01 190.4

.02 200.9

.04 228.2

.07 237.3

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

#ENDDATA

/END

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

1.	This material law must be used with property set /PROP/TYPE6 (SOL_ORTH), /PROP/TYPE14 (SOLID), /PROP/TYPE20 (TSHELL) or /PROP/TYPE21 (TSH_ORTH).

2.	The yield stress is defined by a user function and the yield stress is compared to equivalent stress:

Where,

Where, and represent the stress components either in the orthotropic frame if an orthotropic property is used, or in the orthogonalized isoparametric frame.

3.	If (plastic strain) reaches , in one integration point, the solid element is deleted.

4.	If largest principal strain , stress is reduced using the following relation:

5.	If , the stress is reduced to 0 (but the element is not deleted).

6.	The table for yield stress definition can be 2-dimensional or 3-dimensional.

•	If the table is 2-dimensional, its parameters are assumed to represent respectively plastic strain and strain rate . Then if and yield is linearly interpolated between the four values of the table corresponding to .

•	If the table is 3-dimensional, its parameters are assumed to represent respectively plastic strain, strain rate, and temperature . Then if and and yield is linearly interpolated between the eight values of the table corresponding to .

If or falls out of the range of the table, yield stress is obtained by linear extrapolation. Thus it is necessary to input into the table the static curves corresponding to zero strain rate (entry should belong to the table definition).

Values of the table are yield stress values.

7.	If yield stress also depends on temperature, the table is 3-dimensional:

If the /HEAT/MAT option is not associated to the material identifier, adiabatic conditions are assumed and temperature is computed as:

where, Eint is the internal energy computed by RADIOSS, and Volume are the current density and volume, Cp is the heat capacity per mass unit.

Otherwise, the finite element formulation for heat transfer must be asked for (Iform =1 in option /HEAT/MAT); initial temperature and specific heat input in the option /HEAT/MAT will then be used.

8.	The evolution of Young’s modulus:

•	If fct_IDE > 0, the curve defines a scale factor for Young modulus evolution with equivalent plastic strain, which means the Young Modulus is scaled by the function :

The initial value of the scale factor should be equal to 1 and it decreases.

•	If fct_IDE = 0, the Young modulus is calculated as:

Where, E and Einf are respectively the initial and asymptotic value of Young’s modulus, accumulated equivalent plastic strain.

Note: If fct_IDE = 0 and CE = 0, Young modulus E is kept constant.