Polycrystal plasticity – trial problems and first steps August 2007 monthly meeting

Polycrystal Plasticity UMAT Refs Kysar implements the Bassani & Wu hardening model: Huang – Single Crystal Plasticity UMAT RPI implements both the Voce-Kocks and RPI hardening model: Voce-Kocks – FCC Strain Hardening Maniatty – Elasto-viscoplastic Model

1-Grain, 27-Element Test Problem Single Grain Model - 5% applied compressive strain z 1 3 2 8 7 9 5 6 4 12 10 11 y x

1-Grain, 27-Element Test Problem x y z Kysar UMAT 1 2 3

1-Grain, 27-Element Test Problem z RPI UMAT 2 1 3 y x

Kysar-RPI comparison Although the hardening models are not the same, many of the material input parameters are the same (e.g. RPI updates the saturation stress, where it is constant in Kysar). We took Antoinette’s material parameters and put them into Kysar’s .inp so we could observe differences in the material models.

Kysar-RPI comparison

Next Steps: - “Validation” models - Realization models Automation of model generation using Python/ABAQUS Demo zip file