<POROUS_CRITERION> elliptic#
Description#
The elliptic criterion is a simple ellipse in P-q plane, and allows a great deal of flexibility in adjusting the pressure sensitivity of plasticity. This model can be used for general densification of problems, such as powder compaction and foam plasticity.
where \(C\) and \(F\) are the coefficients named C and
F.
Because the ratio between the deviatoric and pressure sensitivity is determined by the \(C\) and \(F\) coefficients, we can get great flexibility by making these coefficients depend on the porosity state variable \(f\). A typical limiting case is that the material should behave in a fully deviatoric way at the fully dense condition (when \(f=0\) then C=1 and D=0), and similarly when the material is fully void there should only be pressure dependence( when \(f=1\) then C=0 and D=1).
Syntax#
*porous_criterion elliptic
\(~\,\) coefficients
\(~\,\) …
Example#
A simple example from a test case is given below
*porous_criterion elliptic
F f
0. 0.
5. 1.
C f
1. 0.
11. 1.