Microstructural studies using X-ray diffraction http://merkel.texture.rocks/>RDX/ |

Texture - Individual orientations from Beartex
- Individual orientations from MAUD
- Plot individual orientations in MTex
- Polycrystal velocities in MTex
In works Memo |
Multifit /
## Stress Optimizations## WarningStress optimizations are not reliable. It is not a software issue with Polydefix, but issues with the equations behind stress optimizations. They are based on elastic strain theories and have been shown to give inconsistent results. Refer to the strain fitting options section for more details and publications about those problems. In theory, stress should be adjusted by comparing results of models like Elasto-Plastic Self Consistent calculations to the strain measured experimentally. Elastic solutions should be used with caution. ## Elastic calculation of stressesPolydefix can use the lattice strain parameters A. K. Singh, C. Balasingh, H. K. Mao, R. J. Hemley and J. Shu, Analysis of lattice strains measured under non-hydrostatic pressure, J. Appl. Phys., 1998, 83, 7567-7575 , doi: 10.1063/1.367872
## Isotropic stress modelIf you selected the isotropic model when setting up your material properties, you were asked to enter parameters G, and _{1}G. They are used to calculate an average shear modulus according to
_{2}G = G where t = 6 * G * Q(hkl) where ## Anisotropic stress modelFor cubic and hexagonal crystal symmetries, you can also use an anisotropic stress model based on the Reuss bound in the paper of Singh et al 1998. In this case, when setting up your material properties, you were asked to enter elastic moduli and pressure derivatives. We use the hydrostatic pressure calculated in pressure and unit cell optimizations and, for each elastic modulus, calculate C For cubic materials, elastic moduli are used to calculate an effective average shear moduli for the 1/[2 G(hkl)] = S Γ(hkl) = (h where the S For hexagonal materials, elastic moduli are used to calculate an effective average shear moduli for the 1/[2 G(hkl)] = (2S + l l M where the S For each measured diffraction line, we then calculate a corresponding differential stress t = 6 * G(hkl) * Q(hkl) where |

Page last modified on January 27, 2010, at 07:31 AM