NUMERICAL SIMULATION OF THE X-RAY STRESS ANALYSIS TECHNIQUE IN POLYCRYSTALLINE MATERIALS WITH HEXAGONAL CRYSTAL SYMMETRY, H. Wern, T. Maas, N. Koch, pp. 122-127

In this paper, the correlation between the local strain distributions and the average strains obtained by an x-ray measurement are studied through numerical modeling. The finite element method (FEM) is used to simulate the local strain distributions within a three-dimensional random aggregate of isotropic and orthotropic single crystals with hexagonal symmetry under uniaxial elastic tension. Calculations are performed for polycrystalline Titanium and Zinc slabs. The strain/stress values in the crystallites that satis@ the difhaction condition are then used to simulate the x-ray data that would be obtained if the difI?action peaks horn such aggregates were measured. The correlation between the applied far-field stress, the local stresses and the average stresses as determined through x-ray analysis are presented. Because of the elastic anisotropy, stresses, in general, cannot be determined better than 10% or 20% irrespective of the model which is used to calculate the x-ray elastic constants (Voigt, Reuss, Kroner). However, horn the calculation of the lull compliance tensor, e.g. in the Reuss model, in some cases, isotropic behavior and, thus, reliable stresses can be concluded. The corresponding results are presented.