*MAT_024 (PIECEWISE_LINEAR_PLASTICITY)

LS-DYNA Input Interface KeywordDefines an isotropic elasto-plastic material using tabulated stress versus plastic strain input for different strain rates.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
MAT_024_{OPTION} or MAT_PIECEWISE_LINEAR_PLASTICITY_{OPTION}
`mat_ID`	$ρ_{i}$	`E`	$υ$	`SIGY`	`ETAN`	`FAIL`
`C`	`P`	`LCSS`	`LCSR`	`VP`
`EPS1`	`EPS2`	`EPS3`	`EPS4`	`EPS5`	`EPS6`	`EPS7`	`EPS8`
`ES1`	`ES2`	`ES3`	`ES4`	`ES5`	`ES6`	`ES7`	`ES8`

Definition

Field	Contents	SI Unit Example
`OPTION`	<BLANK> (Default) Linear strain rate interpolation between stress-strain curves. LOG_INTERPOLATION Logarithmic strain rate interpolation between stress-strain curves.
`mat_ID`	Material identifier. (Integer)
$ρ_{i}$	Initial density. (Real)	$[\frac{kg}{m^{3}}]$
`E`	Young’s modulus. (Real)	$[Pa]$
$υ$	Poisson’s ratio. Default = 0 (Real)
`SIGY`	Yield stress, ignored if `LCSS` > 0 or stress-strain values `EPS1`-`EPS8`, `ES1`-`ES8` specified. (Real)	$[Pa]$
`ETAN`	Plastic hardening modulus, not used if `LCSS` > 0. (Real)	$[Pa]$
`FAIL`	Plastic strain to failure. (Real)
`C`	Strain rate coefficient. (Real)	$[\frac{1}{s}]$
`P`	Strain rate exponent. (Real)
`LCSS`	Stress versus plastic strain curve or table identifier. (Integer)	$[Pa]$
`LCSR`	Curve identifier defining the scaling coefficient for the stress-strain curve for a corresponding strain rate. (Integer)
`VP`	Strain rate type flag: 0 Total strain rate. 1 Plastic strain rate. (Integer)
`EPS1`-`EPS8`	Plastic strain data points. (Real)
`ES1`-`ES8`	Yield stress data points. (Real)	$[Pa]$

Comments

This keyword maps to /MAT/LAW36 (PLAS_TAB) when stress-strain curves are specified using LCSS or EPS and ES. If SIGY, ETAN, C, and P are used, then it maps to /MAT/LAW44 (COWPER).
This material is only compatible with truss elements only when plasticity is specified through SIGY and ETAN.
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.