2023.1

2023.1

*MAT_181 (SIMPLIFIED_RUBBER/FOAM)

LS-DYNA Input Interface KeywordDefines a rubber and foam material with uniaxial tensile/compression test results as input curve. This material can be used with solid elements only.

Format

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MAT_181 or MAT_SIMPLIFIED_RUBBER/FOAM
`mat_ID`	$ρ_{i}$	`K`	`Mu`	`G`
`Length`	`Width`	`Thick`	`Table_ID`	`Tension`

Optional card 1: unloading behavior

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`Fct_unl`	`Hys`	`Shape`

Definition

Field	Contents	SI Unit Example
`mat_ID`	Material identifier. (Integer)
$ρ_{i}$	Poisson's ratio. (Real)	$[\frac{kg}{m^{3}}]$
`K`	Bulk modulus. (Real)	$[Pa]$
`Mu`	Numerical Navier Stokes viscosity. Default = 0.1 (Real)
`G`	Shear modulus. (Real)	$[Pa]$
`Length`	Specimen gauge length. (Real)	$[m]$
`Width`	Specimen gauge width. (Real)	$[m]$
`Thick`	Specimen gauge thickness. (Real)	$[m]$
`Table_ID`	Curve or table identifier defining the force versus gauge length and for the different strain rate value defined in the table. (Integer)
`Tension`	Unloading rate effects option flag. = -1 Unloading in tension follows the quasi static unloading curve; Unloading in compression follow the loading strain rate dependent curves. = 0 (Default) Unloading follows the quasi-static unloading curve. = 1 Unloading follows the loading strain rate dependent curves and the unloading curve is not used. (Integer)
`Fct_unl`	Unloading curve identifier. (Integer)
`Hys`	Hysteresis unloading factor. Ignore if, unloading function is used. 0.0 ≤ `Hys` ≤ 1.0 Default = 0 (Real)
`Shape`	Shape factor. Ignored if, unloading function is used. Default = 1.0 (Real)

Comments

This keyword maps to /MAT/LAW70 (FOAM_TAB) for foam, and /MAT/LAW88 for the hyperelastic materials.
The option “_TITLE” can be added to the end of this keyword. When “_TITLE” is included, an extra 80 characters long line is added after the keyword input line which allows an entity title to be defined.