MATX62

Bulk Data Entry Defines additional material properties for Hyper-visco-elastic material for geometric nonlinear analysis. This material is used to model rubber, polymers, and elastomers. This material is compatible with solid and shell elements.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
MATX62	`MID`	`MUMAX`
	`LAW`	`MU1`	`ALFA1`	`MU2`	`ALFA2`	`MU3`	`ALFA3`
		`MU4`	`ALFA4`	`MU5`	`ALFA5`	etc

Optional continuation lines for Maxwell value:

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
	`MAXWELL`	`GAM1`	`T1`	`GAM2`	`T2`	`GAM3`	`T3`
		`GAM4`	`T4`	`GAM5`	`T5`	etc

Example

(1)	(2)	(3)	(4)	(5)	(6)
MAT1	102	10.0		0.495	6.0E-10
MATX62	102
	`LAW`	0.10	2.0	-0.010	-2.0

Definitions

Field	Contents	SI Unit Example
`MID`	Material ID of the associated MAT1. 1 No default (Integer > 0)
`MUMAX`	Maximum viscosity. Default = 10³⁰ (Real)
`LAW`	Indicates that material parameters `MUi` and `ALFAi` follow.
`MUi`	Parameter $μ$ _i. (Real)
`ALFAi`	Parameter α_i. (Real)
`MAXWELL`	Indicates that `MAXWELL` model parameter pairs `GAMi` and `Ti` follow.
`GAMi`	Stiffness ratio $γ_{i}$ . (Real)
`Ti`	Time relaxation $τ_{i}$ . (Real)

Comments

The material identification number must be that of an existing MAT1 Bulk Data Entry. Only one MATXi material extension can be associated with a particular MAT1.
MATX62 is only applied in geometric nonlinear analysis subcases which are defined by ANALYSIS = EXPDYN. It is ignored for all other subcases.
NU is defined on the corresponding MAT1.
If no pair GAM1, T1 is given the law is hyper-elastic.
The strain energy density W is computed using the following equation:
(1)
$W (λ_{1}, λ_{2} λ_{3}) = \sum_{i = 1}^{N} \frac{2 μ}{α_{i}^{2}} (λ_{1}^{α_{i}} + λ_{2}^{α_{i}} + λ_{3}^{α_{i}} - 3 + \frac{1}{β} (J^{- α i β} - 1))$

with $λ_{i}$ being the i^th principal stretch, J = $λ$ ₁ * $λ$ ₂ * $λ$ ₃ being the relative volume and $β = \frac{v}{(1 - 2 v)}$ . O < NU < 0.5

The ground shear modulus is:(2)
$G = \sum_{1}^{N} μ_{i}$
This card is represented as a material in HyperMesh.