/MAT/LAW28 (HONEYCOMB)

Block Format Keyword

/MAT/LAW28 - Three dimensional Orthotropic Nonlinear Elasto-plastic fully Compressible Material

Description

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

E11		E22		E33
G12		G23		G31
fct_ID11	fct_ID22	fct_ID33	Iflag1	Fscale11		Fscale22		Fscale33
max11		max22		max33
fct_ID12	fct_ID23	fct_ID31	Iflag2	Fscale12		Fscale23		Fscale31
max12		max23		max31

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 material density (Real)
E11	Young’s modulus in orthotropic dimension 1 (Real)
E22	Young’s modulus in orthotropic dimension 2 (Real)
E33	Young’s modulus in orthotropic dimension 3 (Real)
G12	Shear modulus in direction 12 (Re
G23	Shear modulus in direction 23 (Real)
G31	Shear modulus in direction 31 (Real)
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 (Comment 6) Default = 0 (Integer) = 0: yield stress is a function of (volumetric strains) =1: yield stress is a function of (strains) = -1: yield stress is a function of - .
Fscale11	Scale factor for yield stress function 11 Default = 1.0 (Real)
Fscale22	Scale factor for yield stress function 22 Default = 1.0 (Real)
Fscale33	Scale factor for yield stress function 33 Default = 1.0 (Real)
max11	Failure strain in tension in direction 11 (Real)
max22	Failure strain in tension in direction 22 (Real)
max33	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 Default = 0 (Integer) = 0: yield stress is a function of (volumetric strains) =1: yield stress is a function of (strains) = -1: yield stress is a function of - .
Fscale12	Scale factor for shear yield function 12 Default = 1.0 (Real)
Fscale23	Scale factor for shear yield function 23 Default = 1.0 (Real)
Fscale31	Scale factor for shear yield function 31 Default = 1.0 (Real)
max12	Failure strain in shear direction 12 (Real)
max23	Failure strain in shear direction 23 (Real)
max31	Failure strain in shear direction 31 (Real)

#RADIOSS STARTER

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

/UNIT/1

unit for mat

Mg mm s

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#- 2. MATERIALS:

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/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:

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/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----|

1.	This material law requires solid orthotropic property /PROP/TYPE6. 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

3.	All element degrees of freedom are fully uncoupled:

Elastic case example:

law28_comment

4.	For each tension/compression and shear direction, the true stress as function of a true volumetric strain "mu", or a true strain "eps" can be specified.

Sign conventions for strain are:

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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):

For small strains (Isolid = 1):

Where, l0 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.

/MAT/LAW28 (HONEYCOMB)

/MAT/LAW28 (HONEYCOMB)

/MAT/LAW28 (HONEYCOMB)

Format

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