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/MAT/LAW52 (GURSON)

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/MAT/LAW52 - Gurson Material

Description

This law is based on the Gurson constitutive law, which is used to model visco-elastic-plastic strain rate dependent porous metals.

Format

(1)

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(10)

/MAT/LAW52/mat_ID/unit_ID or /MAT/GURSON/mat_ID/unit_ID

mat_title

 

 

 

 

 

 

 

 

E

Iflag

Fsmooth

Fcut

Iyield

 

A

B

N

c

p

SN

fI

fN

fc

fF

 

 

 

If Iyield > 0:

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

Tab_ID

XFAC

YFAC

 

 

 

 
hmtoggle_plus1Flag Definition

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)

 

Iflag

Viscoplastic flow flag (Comment 1)

(Integer)

= 0: von Mises criteria

= 1: von Mises criteria

= 2: 1 + void nucleation set to zero in compression

= 3: 0 + void nucleation set to zero in compression

 

Fsmooth

Smooth strain rate are computed

(Integer)

= 0: no strain rate smoothing (default value)

= 1: strain rate smoothing is active

 

Fcut

Cutoff frequency for strain rate filtering

Default = 1030  (Real)

Iyield

Flag for computing the Yield stress using Yield stress table (Yield stress vs plastic strain) (Comment 3).

(Integer)

 

A

Yield stress

(Real)

B

Hardening parameter

(Real)

N

Hardening exponent

(Real)

 

c

Strain rate coefficient in Cowper-Symond's law

(Real)

 

p

Strain rate exponent in Cowper-Symond's law

(Real)

 

Damage material parameters

(Real)

 

SN

Gaussian standard deviation

(Real)

Nucleated effective plastic strain

(Real)

 

fI

Initial void volume fraction

(Real)

 

fN

Nucleated void volume fraction

(Real)

 

fc

Critical void volume fraction at coalescence

(Real)

 

fF

Critical void volume fraction at ductile fracture

(Real)

 

Tab_ID

Yield stress table identifier (stress-strain functions with correspond strain rate).

(Integer)

 

XFAC

Scale factor for the first entry (plastic strain) in function which used for Tab_ID.

Default = 1.0  (Real)

 

YFAC

Scale factor for ordinate (Yield stress) in function which used for Tab_ID.

Default = 1.0  (Real)

 
hmtoggle_plus1Example (Steel)

#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/LAW52/1/1

Steel

#              RHO_I

               .0078

#                  E               NU_12     Iflag   Fsmooth                Fcut    Iyield

              200000                  .3         0         0                   0         1

#                  A                   B                   N                   c                   p

                 200                 533                   1                 802               3.585

#            alpha_1             alpha_2             alpha_3                  SN                EpsN

                1.25                   1                2.25                  .1                  .2

#                 Fi                  FN                  Fc                  FF

                 .01                 .04                 .12                  .2

#   Tab_ID                XFAC                YFAC

      1000                   0                   0

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

/TABLE/1/1000

curve_list with strain rates

        2

# function                    stain rate

     10010                        1.0e-4

     10020                           1.0

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

/FUNCT/10010

plastic strain vs yield stress funct dt=1.0e-4

#     plastic strain       yield stress  

              0.0000                200.

              1.0000                733.

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

/FUNCT/10020

plastic strain vs yield stress funct dt=1.0

#     plastic strain       yield stress

              0.0000                250.

              1.0000                783.

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

#ENDDATA

/END

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
hmtoggle_plus1Comments
1.The von Mises criteria for viscoplastic flow:

If Iflag = 0:

If Iflag = 1:

if

if

Where, is the admissible stress,  is the trace[] (hydrostatic stress), is the von Mises stress, , , and are the material parameter for Gurson Law and , symbolm, and is the specific coalescence function.

if

if

with

corresponding to the coalescence function

3.If one integration point reaches f * > f F , the element is deleted.
4.This law is available for shell and solid elements.
5.In plot files (/TH/SHEL, /TH/SH3N and /TH/BRICK) or animation files (/ANIM), the following variables are available:
•USR1: plastic strain
•USR2:
•USR3: admissible stress
•USR4: f
•USR5:

See Also:

Material Compatibility

Law Compatibility with Failure Model

/MAT/LAW52 in Theory Manual