/MAT/LAW3 (HYDPLA)

Block Format Keyword

/MAT/LAW3 - Elasto-plastic Hydrodynamic Material

Description

This law represents an isotropic elasto-plastic material using the Johnson-Cook material model. This model expresses material stress as a function of strain and may account for the nonlinear dependence between pressure and volumetric strain when corresponding equation of state is specified. A built-in failure criterion based on the maximum plastic strain is available. This material law is compatible with solid elements only.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/MAT/LAW3/mat_ID/unit_ID or /MAT/HYDPLA/mat_ID/unit_ID
mat_title

E
a		b		n
Pmin

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)
	Reference density used in E.O.S (equation of state) Default = (Real)
E	Young’s modulus (Real)
	Poisson’s ratio (Real)
a	Plastic yield stress (Real)
b	Plastic hardening parameter (Real)
n	Plastic hardening exponent (Real)
	Failure plastic strain Default = 1030 (Real)
	Maximum stress Default = 1030 (Real)
Pmin	Cutoff minimum pressure ( < 0 ) Default = -1030 (Real)

#RADIOSS STARTER

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

/UNIT/1

unit for mat

g cm mus

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

#- 2. MATERIALS:

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

/MAT/HYDPLA/1/1

Aluminum

# RHO_I RHO_0

2.8 0

# E nu

.72352 .33

# a b n eps_max sigma_max

.0024 .0042 .8 9 .0068

# Pmin Psh

-.005

/EOS/TILLOTSON/1/1

Aluminum

# C1 C2 A B

.752 .65 .5 1.63

# ER ES VS E0 RHO_0

.135 .081 1.1 0 0

# ALPHA BETA

5 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 this model, the material behaves as a linear-elastic material when the equivalent stress is lower than the plastic yield stress. For higher stress values, the material behavior is plastic and the stress is calculated as shown:

Where, is the plastic strain.

2.	The plastic yield stress should always be greater than zero. To model pure elastic behavior, the plastic yield stress will be set to 1030.

3.	By default, the hydrostatic pressure is linearly proportional to volumetric strain:

Where, is the bulk modulus and is the volumetic strain.

An additional Equation of State (/EOS) card can refer to this material in order to incorporate a nonlinear dependency between hydrostatic pressure and volumetric strain. The yield stress should be strictly positive.

4.	When attains (or exceeds) the value of (for tension, compression or shear), in one integration point, the solid element are deleted.