/MAT/LAW62 (VISC

Block Format Keyword

/MAT/LAW62 - Hyper Visco-Elastic Material

Description

This law describes the hyper visco-elastic material. This law is compatible with solid and shell elements. In general it is used to model polymers and elastomers.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW62/mat_ID/unit_ID or /MAT/VISC_HYP/mat_ID/unit_ID
mat_title

		N	M

Define N parameters (5 per Line)

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

Define M parameters (5 per Line)

(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)
	Poisson’s ratio (Real)
N	Law order - must be positive (Integer)
M	Maxwell model order (Integer) = 0: the law is hyper elastic
	Maximum viscosity Default = 1030 (Real)
	ith parameter of the ground shear modulus (Real)
	ith material parameter (Real)
	ith stiffness ratio (Real)
	ith time relaxation (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/LAW62/1/1

LAW62 RUBBER

# RHO_I

1E-9

# Nu N M mu_max

.495 2 0 1000

# mu_i

2 1

# alpha_i

2 -2

# gamma_i

# tetha_i

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

#ENDDATA

/END

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

1.	Strain energy W is computed using the following equation:

With

are eigenvalue of F (F is deformation gradient matrix),

J is Jacobian determinant, with ,

N is the order of law,

and are the material parameters:

and

is the Poisson’s ratio.

2.	Coefficients () are used to describe rate effects through the Maxwell model:

law82_maxwell_model

The initial shear modulus is:

The sum of should be greater than 0.

The stiffness ratio is:

With,

and is the ground shear modulus

The relative time, must be positive:

3.	Rate effects are modeled using a convolution integral using Prony series. This is an extension of small strain theory to large strain. Strain rate effect applies only to the deviatoric stress. The full expression of the deviatoric viscous stress can be found in the RADIOSS Theory Manual.

4.	There are several differences between /MAT/LAW42 and /MAT/LAW62. Special care should be taken that the ground shear modulus expression depending on input values is not the same. Also it corresponds to the long-term shear modulus in one case, whereas to the initial shear modulus in another case.

/MAT/LAW62 (VISC_HYP)

/MAT/LAW62 (VISC_HYP)

/MAT/LAW62 (VISC_HYP)