/MAT/LAW35 (FOAM

Block Format Keyword

/MAT/LAW35 - Visco-Elastic Foam Material

Description

This law describes a visco-elastic foam material using Generalized Maxwell-Kelvin-Voigt model where viscosity is based on Navier equations. This law is applicable only for shell and solid elements and can be used for open cell foams, polymers, elastomers, seat cushions and dummy paddings.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW35/mat_ID/unit_ID or /MAT/FOAM_VISC/mat_ID/unit_ID
mat_title

E				E1		E2		n
C1		C2		C3			IFlag	Pmin
fct_IDf		Fscaleprs
Et
P0

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)
E1	Coefficient for Young’s modulus update (Real)
E2	Coefficient for Young’s modulus update (Real)
n	Exponent on relative volume (Real)
C1	Coefficient for pressure calculation (Real)
C2	Coefficient for pressure calculation (Real)
C3	Coefficient for pressure calculation (Real)
IFlag	Open cell foam flag (Integer) = 0: input is a pressure vs. compression curve (as in /MAT/LAW21 (DPRAG)). = 1: input is a function defining an “equivalent air pressure” that is removed from the system vs. compression. This corresponds to an open cell foam formulation.
Pmin	Minimum pressure (Real)
fct_IDf	Curve identifier for pressure as function of volumetric strain volumetric strain is (Integer)
Fscaleprs	Pressure function scale factor Default = 1.0 (Real)
Et	Tangent modulus (Real)
	Tangent Poisson’s ratio (Real)
	Viscosity coefficient in pure shear (Navier’s constant) (Real)
	Navier’s constant (Real)
P0	Initial air pressure (Real)
	Ratio of foam to polymer density (Real)
	Initial volumetric strain (Real)

#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/FOAM_VISC/1/1

Foam

# RHO_I

4.3E-11

# E NU E1 E2 n

.2 0 0 0 0

# C1 C2 C3 I_flag P_min

1 1 1 0 0

# fct_IDf Fscale_prs

1076 0

# E_t NU_t ETA_0 Lamda

.25 0 10000 0

# P0 Phi gamma_0

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/1076

Pressure versus compression

# X Y

-100000 -1000

-10 -1000

0 0

3000 7.633

209000 7.633

210000 18.5

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

#ENDDATA

/END

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

1.	In all cases, for shear and bulk modulus calculation, the following value of the Young’s modulus will be used:

2.	If fct_IDf = 0,

where,

3.	If fct_IDf ≠ 0, the pressure is read from curve.

4.	For closed cell polyurethane foam, the skeletal spherical stresses may be augmented by:

/MAT/LAW35 (FOAM_VISC)

/MAT/LAW35 (FOAM_VISC)

/MAT/LAW35 (FOAM_VISC)

Description

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