/MAT/LAW28 (HONEYCOMB)

Block Format Keyword This law describes a three dimensional nonlinear elasto-plastic material, usually used to model honeycomb or foam material.

Nonlinear elasto-plastic behavior can be specified for each othrotropic direction and shear as function of strain or volumetric strain. All degrees of freedom are uncoupled and the material is fully compressible. Tension and shear strain based failure criteria can be specified.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/MAT/LAW28/mat_ID/unit_ID or /MAT/HONEYCOMB/mat_ID/unit_ID
mat_title
ρ i                
E11 E22 E33        
G12 G23 G31        
Failure plastic strain and yield stress in normal direction 11, 22, 33:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
fct_ID11 fct_ID22 fct_ID33 Iflag1 Fscale11 Fscale22 Fscale33
ε max11 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIZaaabeaaaaa@3C17@ ε max22 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIZaaabeaaaaa@3C17@ ε max33 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIZaaabeaaaaa@3C17@        
Shear failure plastic strain and shear yield stress in direction 12, 23, 31:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
fct_ID12 fct_ID23 fct_ID31 Iflag2 Fscale12 Fscale23 Fscale31
ε max12 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaigdacaaIYaaabeaaaaa@3C14@ ε max23 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaikdacaaIZaaabeaaaaa@3C16@ ε max31 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@        

Definitions

Field Contents SI Unit Example
mat_ID Material identifier

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
mat_title Material title

(Character, maximum 100 characters)

 
ρ i Initial material density

(Real)

[ kg m 3 ]
E11 Young's modulus in orthotropic dimension 1

(Real)

[ Pa ]
E22 Young's modulus in orthotropic dimension 2

(Real)

[ Pa ]
E33 Young's modulus in orthotropic dimension 3

(Real)

[ Pa ]
G12 Shear modulus in direction 12

(Real)

[ Pa ]
G23 Shear modulus in direction 23

(Real)

[ Pa ]
G31 Shear modulus in direction 31

(Real)

[ Pa ]
fct_ID11 Yield stress function identifier in direction 11

(Integer)

 
fct_ID22 Yield stress function identifier in direction 22

(Integer)

 
fct_ID33 Yield stress function identifier in direction 33

(Integer)

 
Iflag1 Strain formulation for yield functions 11, 22, and 33 6

(Integer)

= 0 (Default)
Yield stress is a function of μ (volumetric strains)
= 1
Yield stress is a function of ε (strains)
= -1
Yield stress is a function of - ε .
 
Fscale11 Scale factor for yield stress function in direction 11

Default = 1.0 (Real)

[ Pa ]
Fscale22 Scale factor for yield stress function in direction 22

Default = 1.0 (Real)

[ Pa ]
Fscale33 Scale factor for yield stress function in direction 33

Default = 1.0 (Real)

[ Pa ]
ε max 11 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in tension in direction 11

(Real)

 
ε max 22 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in tension in direction 22

(Real)

 
ε max 33 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in tension in direction 33

(Real)

 
fct_ID12 Shear yield stress function identifier in direction 12

(Integer)

 
fct_ID23 Shear yield stress function identifier in direction 23

(Integer)

 
fct_ID31 Shear yield stress function identifier in direction 31

(Integer)

 
Iflag2 Strain formulation for shear yield functions 12, 23, and 31

(Integer)

= 0 (Default)
Yield stress is a function of μ (volumetric strains)
= 1
Yield stress is a function of ε ˙ (strains)
= -1
Yield stress is a function of - ε ˙ .
 
Fscale12 Scale factor for shear yield function 12

Default = 1.0 (Real)

[ Pa ]
Fscale23 Scale factor for shear yield function 23

Default = 1.0 (Real)

[ Pa ]
Fscale31 Scale factor for shear yield function 31

Default = 1.0 (Real)

[ Pa ]
ε max 12 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in shear direction 12

(Real)

 
ε max 23 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in shear direction 23

(Real)

 
ε max 31 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqyTdu2aaS baaSqaaiGac2gacaGGHbGaaiiEaiaaiodacaaIXaaabeaaaaa@3C15@ Failure strain in shear direction 31

(Real)

 

Example (Steel)

#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/HONEYCOMB/1/1
Steel
#              RHO_I
              7.8E-9
#               E_11                E_22                E_33
              200000              200000              200000
#               G_12                G_23                G_31
              100000              100000              100000
# fct_ID11  fct_ID22  fct_ID33    Iflag1            Fscale11            Fscale22            Fscale33
         1         1         1         0                   0                   0                   0
#          Eps_max11           Eps_max22           Eps_max33
                   0                   0                   0
# fct_ID12  fct_ID23  fct_ID31    Iflag2            Fscale12            Fscale23            Fscale31
         2         2         2         0                   0                   0                   0
#          Eps_max12           Eps_max23           Eps_max31
                   0                   0                   0
#---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: 1
#                  X                   Y
                   0                 200 
                  .5                 200 
                 1.5              200000 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/2
FUNCTION: 2
#                  X                   Y
                   0                 100 
                  .5                 100 
                 1.5              100000 
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
/END
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

  1. This material law requires solid orthotropic property /PROP/TYPE6 (SOL_ORTH). Material is compatible with hexa and tetra elements, including 10-node tetrahedron elements. Refer to Material Compatibility for more compatibility information.
  2. Material orthotropic coordinate system for each element (directions 1, 2, and 3) are specified in the property card /PROP/TYPE6 either through a given skew system or related to element coordinate system.

    law28
    Figure 1.
  3. All element degrees of freedom are fully uncoupled.

    Elastic case example:

    σ 11 = E 11 ε 11

    σ 12 = G 12 ε 12

    σ 22 = E 22 ε 22

    σ 23 = G 23 ε 23

    σ 33 = E 33 ε 33

    σ 31 = G 31 ε 31

  4. For each tension/compression and shear direction, the true stress as function of a true volumetric strain μ , or a true strain ε can be specified.
    Sign conventions for strain are:

    clip066
    Figure 2.
    The stress values should always be positive. The following sign conventions for strain are used:
    Strain Definition Compression Tension
    Volumetric strain (Iflag1 =0) + -
    Strain (Iflag1 =1) - +
    Strain (Iflag1 =-1) + -
  5. For large strain formulations (Isolid> 1):(1)
    μ = ( ρ ρ 0 1 ) = ( V 0 V 1 )         ε = ln l l 0
    For small strains (Isolid = 1):(2)
    μ = ( ε 1 + ε 2 + ε 3 )         ε i = l i l i 0 l i 0

    Where, l 0 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiBamaaBa aaleaacaaIWaaabeaaaaa@37CE@ is the initial length.

  6. When switching from a volumetric strain formulation to a strain formulation, Iflag1 = -1 or Iflag2 = -1 allows the same function definition to be retained.
  7. If one of the tension strain or shear strain failures is reached, the element is deleted.