Nonlinear Hardening 1
In this nonlinear hardening law, the yield stress is given by
[math]\displaystyle{ \sigma_y = \sigma_{Y0}(1+K\alpha)^n }[/math]
where [math]\displaystyle{ \sigma_{Y0} }[/math] is initial yield stress, α is cumulative equivalent plastic strain, and K and n are dimensionless hardening law coefficients.
An alternate nonlinear hardening law is also available.
Hardening Law Properties
The material parameters in this hardening law are defined with the following properties:
| Property | Description |
|---|---|
| yield | The initial yield stress (enter in units of MPa). This stress corresponds to the axial stress at yield during uniaxial, 3D loading. |
| Khard | The dimensionless parameter K for nonlinear hardening. |
| nhard | The dimensionless exponent parameter (n) in the nonlinear hardening law. If n=1, it is more efficient to use linear hardening instead. |
History Data
This hardening law defines one history variable, which is stored as history variable #1. It stores the the cumulative equivalent plastic strain (absolute) defined as
[math]\displaystyle{ \alpha = \sum \sqrt{2\over3}\ ||d\varepsilon_p|| }[/math]
where dεp is the incremental plastic strain tensor in one time step.