reduced_plastic

Description

The reduced plastic behavior is an alternate formulation of the gen_evp behavior which provides a much more efficient implicit integration. The behavior reduces the integration variables to a single tensor and a scalar per deformation potential. Because the integration must assume certain forms for the potentials and hardening variables, this behavior uses a sub-set of the gen_evp options. In particular, there is no possibility for state interactions, and the number of potentials implemented is reduced. Domain modifying options such as damage or localization is nor currently implemented in this framework either.

Thermal deformations, variable coefficients, all the elasticity models, all the flow laws, and the majority of kinematic hardening models are implemented. There is no limitation on the number or mixing of kinematic models which are entered per potential, as long as they support the reduced integration. Note that certain laws break distinctly the reduced integration and are not implemented (i.e. Ziegler).

There is currently a limitation that the isotropic hardening be a function of the cumulated multiplier. This means that the internal variable versions of isotropic model are not supported. Note that non-macro potential models such as the mono-crystals are not implemented.

Syntax

***behavior reduced_plastic [ modifier ] \(~\,\) **elasticity <ELASTICITY> [ **thermal_strain <THERMAL_STRAIN> ] [ **potential <POTENTIAL> [name] ] \(~\,~\,~\,~\,\) ...

Stored Variables

The stored variables for this model are the following:

prefix	size	description	default
eto	T-2	total (small deformation) strain	yes
sig	T-2	Cauchy stress	yes
eel	T-2	elastic strain	no
ein	T-2	total inelastic strain tensor	yes

The variable ein is only stored in the event of multiple potentials. The separate inelastic strain tensors for each potential, and their hardening variable names will be given for each separate potential type.

This behavior must be used with a \(\theta\)-method of type A.

Example

An example the input for which can be found in /test/Kinematic/MAT/.. is given below.

***behavior reduced_plastic
 **elasticity isotropic
       young 185000.
       poisson 0.3
 **potential gen_evp ev
   *store_all
   *flow norton
       K  .05
       n  2.0
   *kinematic nonlinear_with_crit
       C     600000.
       D     1000.
       omega 0.50
       m1    1.
       m2    1.
       eta   1.e-12
   *isotropic constant
       R0 400.
***return