INTERACTION#

Description#

This option allows addition of various variable interactions in the gen_evp behavior object.

Syntax#

The syntax of the interaction types depends on the type of interaction. Generally there will be a specification of the type of interaction and two identifying tokens which define the variables which interact. This structure is summarized below:

**interaction [ type ] item1 item2 \(~\,~\,\)

where type may be from the following types:

CODE

DESCRIPTION

iso

Crystalline isotropic hardening interaction.

default

In the absence of type the default “state” interaction will be implemented as described by [M20]. This interaction calculates associated forces including terms of other internal variables. The coupling will be stated by using the (user supplied) name of a potential and the (user supplied) name of hardening mechanisms.

**interaction P1::H  P2::H <COEFFICIENT>

iso

This interaction will link the isotropic variables of one class of slip systems with another (latent strain coupling) between two mono-crystal potentials. The coupling is written:

(426)#\[R_i = R_{o_i} + Q_i \sum_{j=1}^{n}(1-e^{-bv_j})h_{ij}\]

syntax for this type of coupling takes the names of the two potentials, and a coefficient definition named h:

**interaction iso name1  name2 \(~\,~\,\) h <COEFFICIENT>

Note

for interactions between slip systems within one potential one should use the SLIP_INTERACTION class.

Example#

This is an example of the state-law default coupling to link two kinematic variables in a time-dependent viscoplastic potential and a time-independent plasticity potential.

(427)#\[\begin{split}\begin{aligned} &\ten X_{X1} = \frac{2}{3}C_{X1}\ten \alpha_{X1} + \frac{2}{3}C_{int}\ten \alpha_{X2} \\ &\ten X_{X2} = \frac{2}{3}C_{X2}\ten \alpha_{X2} + \frac{2}{3}C_{int}\ten \alpha_{X1} \\ \end{aligned}\end{split}\]

The example material definition for this type of interaction is as follows:

  ***behavior gen_evp
   **elasticity isotropic
     young 170000.0
     poisson 0.30
   **potential gen_evp ev
     *flow norton
         n  1.0
         K  20300.
     *kinematic nonlinear X1
         C  2000.0
         D  50.0
     *isotropic constant
         R0 20.0
   **potential gen_evp ep
     *kinematic nonlinear X2
         C  25000.0
         D  10.0
      *isotropic constant
         R0 850.0
   **interaction ev::X1 ep::X2 25000.0
***return

The names X1 and X2 were given in order to have readable names for the kinematic variables. In this syntax it is important to notice that a specification ev::X1 is different than ev::X1 because the kinematic names are localized within each potential.