/MAT/LAW60 (PLAS

Block Format Keyword

/MAT/LAW60 - Elastic Plastic Piecewise Nonlinear Material

Description

This law models an isotropic elasto-plastic material using user-defined functions for the work-hardening portion of the stress-strain curve (i.e. plastic strain vs. stress) for different strain rates. It is similar to Law 36, except yield stress is a nonlinear interpolation from the functions.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW60/mat_ID/unit_ID or /MAT/PLAS_T3/mat_ID/unit_ID
mat_title

E
Nfunct	Fsmooth	Chard		Fcut
fct_IDp	Fscale		fct_IDE	Einf		CE
fct_ID1	fct_ID2	fct_ID3	fct_ID4	fct_ID5

Read only if 6 < Nfunct < 10

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
fct_ID6	fct_ID7	fct_ID8	fct_ID9	fct_ID10

Always Read

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
Fscale1		Fscale2		Fscale3		Fscale4		Fscale5

Read only if 6 < Nfunct < 10

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
Fscale6		Fscale7		Fscale8		Fscale9		Fscale10

Always Read

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

Read only if 6 < Nfunct < 10

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

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)
	Failure plastic strain Default = 1.0 x 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)
Nfunct	Number of functions. It should be 4 < Nfunct < 10 Default < 10 (Integer)
Fsmooth	Smooth strain rate option flag Default = 0 (Integer) = 0: no strain rate smoothing = 1: strain rate smoothing active
Chard	Hardening coefficient (Real) = 0: the hardening is a full isotropic model = 1: the hardening uses the kinematic Prager-Ziegler model = value between 0 and 1: the hardening is interpolated between the two models
Fcut	Cutoff frequency for strain rate filtering (Comment 7) Default = 1.0 x 1030 (Real)
	Maximum tensile failure strain Default = 3.0 x 1030 (Real)
fct_IDp	Pressure vs. yield factor function (Comment 9) Default = 0 (Integer)
Fscale	Scale factor for yield factor in fct_IDp Default = 1.0 (Real)
fct_IDE	Function identifier for the scale factor of Young modulus, when Young modulus is function of the plastic strain (Comment 6): 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)
fct_ID1	Yield stress function identifier 1 corresponding to strain rate (Integer)
fct_ID2	Yield stress function identifier 2 corresponding to strain rate (Integer)
fct_ID3	Yield stress function identifier 3 corresponding to strain rate (Integer)
fct_ID4	Yield stress function identifier 4 corresponding to strain rate (Integer)
fct_ID5	Yield stress function identifier 5 corresponding to strain rate (Integer)
fct_ID6	Yield stress function identifier 6 corresponding to strain rate (Integer)
fct_ID7	Yield stress function identifier 7 corresponding to strain rate (Integer)
fct_ID8	Yield stress function identifier 8 corresponding to strain rate (Integer)
fct_ID9	Yield stress function identifier 9 corresponding to strain rate (Integer)
fct_ID10	Yield stress function identifier 10 corresponding to strain rate (Integer)
Fscale1	Scale factor for ordinate (stress) in fct_ID1 Default = 1.0 (Real)
Fscale2	Scale factor for ordinate (stress) in fct_ID2 Default = 1.0 (Real)
Fscale3	Scale factor for ordinate (stress) in fct_ID3 Default = 1.0 (Real)
Fscale4	Scale factor for ordinate (stress) in fct_ID4 Default = 1.0 (Real)
Fscale5	Scale factor for ordinate (stress) in fct_ID5 Default = 1.0 (Real)
Fscale6	Scale factor for ordinate (stress) in fct_ID6 Default = 1.0 (Real)
Fscale7	Scale factor for ordinate (stress) in fct_ID7 Default = 1.0 (Real)
Fscale8	Scale factor for ordinate (stress) in fct_ID8 Default = 1.0 (Real)
Fscale9	Scale factor for ordinate (stress) in fct_ID9 Default = 1.0 (Real)
Fscale10	Scale factor for ordinate (stress) in fct_ID10 Default = 1.0 (Real)
	Strain rate 1 (Real)
	Strain rate 2 (Real)
	Strain rate 3 (Real)
	Strain rate 4 (Real)
	Strain rate 5 (Real)
	Strain rate 6 (Real)
	Strain rate 7 (Real)
	Strain rate 8 (Real)
	Strain rate 9 (Real)
	Strain rate 10 (Real)

(Aluminum)

#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/LAW60/1/1

Aluminum_example

# RHO_I

.0027

# E NU Eps_p_max Eps_t Eps_m

60400 .33 0 0 0

# N_funct F_smooth C_hard F_cut Eps_f

4 0 0 0 0

# fct_IDp Fscale fct_IDE EInf CE

0 0 0 0 0

# Funtions

1 2 3 4

# Scale factors Fscale_5

1 1.2 1.4 1.6

# Strain rates Eps_dot_5

0 20 30 40

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

#- 3. FUNCTIONS:

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

/FUNCT/1

function_36

# X Y

0 90

2.5E-4 100

.001 104

.009 121

.017 136

.021 143

.036 156

.045 162

.055 165

.072 170

.075 170

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

/FUNCT/2

function_36

# X Y

0 90

2.5E-4 100

.001 104

.009 121

.017 136

.021 143

.036 156

.045 162

.055 165

.072 170

.075 170

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

/FUNCT/3

function_36

# X Y

0 90

2.5E-4 100

.001 104

.009 121

.017 136

.021 143

.036 156

.045 162

.055 165

.072 170

.075 170

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

/FUNCT/4

function_36

# X Y

0 90

2.5E-4 100

.001 104

.009 121

.017 136

.021 143

.036 156

.045 162

.055 165

.072 170

.075 170

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

#ENDDATA

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

1.	The first point of yield stress functions (plastic strain vs stress) should have a plastic strain value of zero. If the last point of the first (static) function equals 0 in stress, default value of is set to the corresponding value of .

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

3.	If (largest principal strain) , stress is reduced using the following relation:

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

5.	The kinematic hardening model is not available in global formulation (hardening is fully isotropic).

6.	For kinematic hardening and strain rate dependency, yield stress depends on the strain rate.

7.	Strain rate filtering input (Fcut) is only available for shell and solid elements.

8.	Strain rate filtering is used to smooth strain rates.

fct_IDp is used to distinguish the behavior in tension and compression for certain materials (i.e. pressure dependent yield). This is available for solid elements only. The effective yield stress is then obtained by multiplying the nominal yield stress by the yield factor corresponding to the actual pressure.

clip0079

10.	If , yield stress is a cubic interpolation between functions fn-1, fn, fn+1 and fn+2

11.	If , yield stress is interpolated between functions f1, f2 and f3.

12.	If , yield is extrapolated between functions fNfunc-3, fNfunc-2, fNfunc-1 and fNfunc

13.	If , yield is extrapolated between functions fNfunc-2, fNfunc-1 and fNfunc

mat_law60_yield

14.	Functions describing strain dependence must be defined for different strain rates values.

15.	Strain rate values must be given in strictly ascending order.

16.	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, and is the accumulated equivalent plastic strain.

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

/MAT/LAW60 (PLAS_T3)

/MAT/LAW60 (PLAS_T3)

/MAT/LAW60 (PLAS_T3)