/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 | |||||||||
ρi | ρ0 | ||||||||
E | ν | ||||||||
a | b | n | εmaxp | σmax | |||||
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) |
|
ρi | Initial
density. (Real) |
[kgm3] |
ρ0 | Reference density
used in E.O.S (equation of state). Default = ρ0=ρi (Real) |
[kgm3] |
E | Young's
modulus. (Real) |
[Pa] |
ν | Poisson's
ratio. (Real) |
|
a | Plastic yield
stress. (Real) |
[Pa] |
b | Plastic hardening
parameter. (Real) |
[Pa] |
n | Plastic hardening
exponent. (Real) |
|
εmaxp | Failure plastic
strain. Default = 1030 (Real) |
|
σmax | Maximum
stress. Default = 1030 (Real) |
[Pa] |
Pmin | Cutoff minimum
pressure ( < 0 ). Default = -1030 (Real) |
[Pa] |
▸Example (Aluminum)
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: σ=(a+bε np)
Where, ˉεp 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:P=Kμ
Where, K=E3(1−2ν) is the bulk modulus and μ=ρρ0−1 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 ˉεp attains (or exceeds) the value of εmaxp (for tension, compression or shear), in one integration point, the solid element are deleted.