Material Assignment for Microstructures — Lesson 4

Material assignment for crystal plasticity is handled automatically by the preprocessing Python script provided in Lesson 3. When starting from a .vtk file using the structured hexahedral mesh option, run the preprocessing script with:

A file named MatAssign_vtk.dat is generated. When using the unstructured tetrahedral mesh generated in Lesson 3, run the script with:

A file named MatAssign_cdb.dat is generated. The .dat file contains the necessary material assignment information needed by the Mechanical APDL solver to conduct a crystal plasticity analysis.

The crystal plasticity material model requires many material parameters. The detailed documentation for those parameters can be accessed in the documentation 4.9. Crystal Plasticity. The material parameters can be edited in the Python script:

The properties used in this course were calibrated from tensile experiments of Aluminum 2024 T3. Ansys Inc. also provides calibrated crystal plasticity material parameters for copper.

Download the Copper crystal plasticity parameters here.

Note that the default material assignment option assigns a constant and uniform initial slip resistance field to all grains regardless of their shapes and sizes. As such, it is unable to capture the Hall-Petch effect, where the yield stress of the material increases with decreasing average grain size. To learn how to incorporate the Hall-Petch effect into crystal plasticity in Ansys Mechanical, please refer to the following Chapter 67: Crystal Plasticity with Hall-Petch Effect.