/MAT/LAW3 (HYDPLA)
Block Format Keyword 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 |
Definition
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material
identifier. (Integer, maximum 10 digits) |
|
unit_ID | 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) |
Example (Aluminum)
#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----|
Comments
- 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:
(1) Where, is the plastic strain.
- The plastic yield stress should always be greater than zero. To model pure elastic behavior, the plastic yield stress will be set to 1030.
- By default, the
hydrostatic pressure is linearly proportional to volumetric
strain:
(2) Where, is the bulk modulus and is the volumetic strain.
An additional Equation of State (Equation of State) 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.
- When attains (or exceeds) the value of (for tension, compression or shear), in one integration point, the solid element are deleted.