The crystal plasticity analysis uses the following material properties:[1][2]
| Crystal Plasticity Material Properties | |
|---|---|
 [MPa] | 106700 |
 [MPa] | 60400 |
 [MPa] | 28300 |
| Coefficient of thermal expansion [1/K] | 4.473 x 10-5 |
| Crystal type [/] | FCC |
| Initial hardness per slip family [MPa] | 201 |
| Hardness modulus per slip family [MPa] | 1750 |
| Saturation hardness per slip family [MPa] | 381 |
| Total hardness change [MPa] | 50 |
| Power dependence of saturation hardness [/] | 0.0 |
| Cross hardness parameter [/] | 1.4 |
| Slip pre-exponential [1/s] | 1.732 x 106 |
| Slip power dependence 1 [/] | 0.131 |
| Slip power dependence 2 [/] | 1 |
| Initial ratio of thermal to athermal hardness [/] | 0.7 |
| Activation energy [J] | 2.5 x 10-19 |
| Lattice C by A ratio [/] | 1.0 |
Each material ID can be associated with only one hardness value. If using a nonuniform initial hardness distribution, create a new material for each hardness value even if all other properties remain identical.
Because creating material assignments manually is a labor-intensive task, especially for a large polycrystal, a Python script is available for writing the material-assignment commands. Two options are available within the script to write the nonuniform initial hardness:
Create one material ID per element:
This option is suitable for small models only, as many material data must be read, leading to a significant overhead.
Group hardness values by bins:
This option is suitable for larger models. For each grain, all voxels within it are grouped into bins based on their hardness values. One material ID is created for each bin in the grain, and the average hardness value of the bin is used. You can specify the number of bins in the grouping.
Material properties can be entered into the Python script, which uses .vtk files (described in Problem Description) for input and writes a writes a .inp file to define the meshed geometry and a .dat file containing all material assignments. The .dat file can then be included in the solution (overwriting any existing material assignments) to perform a crystal plasticity analysis.