Periodic RVE-type Simulation

Note

Read first: Simple Simulation

A periodic polycrystal containing 40 grains, generated and meshed by Neper, is used:

../../_images/mesh1.png

The domain is a unit cube. Length units are assumed to be mm, thus, all pressure units assumed to be MPa for the simulation (including input parameters). An FCC material with Anisotropic Elasticity and the Base Model for plasticity is considered, with the following material parameters:

Single crystal elastic constants and plasticity parameters.

\(C_{11}\) [MPa]

\(C_{12}\) [MPa]

\(C_{44}\) [MPa]

\(m\) [-]

\(\dot{\gamma_0}\) [1/s]

\(h_0\) [MPa]

\(g_0\) [MPa]

\(g_s\) [MPa]

\(245.0 \times 10^3\)

\(155.0 \times 10^3\)

\(62.5 \times 10^3\)

0.05

1.0

200.0

210.0

330.0

As the domain is a periodic “(representative) volume element”, the loading is defined in terms of strain rate, target strain and maximal strain increment. Minimal changes (compared to Simple Simulation and Periodic RVE-type Simulation) is made to the Configuration File (simulation.cfg) file, as described (and highlighted) below. However, in the current implementation, all components of the strain rate must be specified. Rigid-body motions are fixed automatically.

The example below shows plane tension-compression of the polycrystal.

  • simulation.msh

  • simulation.cfg

    ### FEPX Configuration File
    
    ## Material Parameters
    
        number_of_phases 1
    
        phase 1
        
          crystal_type BCC
    
          c11 236.9e3
          c12 140.6e3
          c44 116.0e3
    
          m 0.020d0
          gammadot_0 1.0d0
    
          hard_type isotropic
          h_0 391.90d0
          g_0 200.0d0
          g_s0 335.0d0
          n 1.0d0
    
    ## Boundary Conditions
    
        set_bc strainrate 11 1e-2 periodic
        set_bc strainrate 22 0 periodic
        set_bc strainrate 33 -1e-2 periodic
        set_bc strainrate 12 0 periodic
        set_bc strainrate 13 0 periodic
        set_bc strainrate 23 0 periodic  
    
    ## Deformation History
    
        number_of_steps 1
        target_strain11 0.01
        dstrain 0.001
        
    ## Printing Results
    
        print coo
        
        print disp
        print forces
        
        print strain
        print strain-eq
        print strain-el
        print strain-el-eq
        print strain-pl
        print strain-pl-eq
        
        print stress
        print stress-eq
        
        print work
        print work-pl
    
        print ori
        
        print slip
        print sliprate
        print crss
    
../../_images/pbc_strain11.png

Slove \(y\)-view of the strain field (\(\epsilon_{11}\)) at 1% strain (displacement field is exaggerated 10x for illustrative purposes). The lattice structure represents the underformed state.

../../_images/pbc_strain11_slice.png

View of the strain field (\(\epsilon_{11}\)) in the slice \(y=0.5\) at 1% strain (displacement field is exaggerated 10x for illustrative purposes). The lattice structure represents the underformed state.