  The spatial variability of stress fields resulting from polycrystalline
aggregate calculations involving random grain geometry and crystal orientations
is investigated. A periodogram-based method is proposed to identify the
properties of homogeneous Gaussian random fields (power spectral density and
related covariance structure). Based on a set of finite element polycrystalline
aggregate calculations the properties of the maximal principal stress field are
identified. Two cases are considered, using either a fixed or random grain
geometry. The stability of the method w.r.t the number of samples and the load
level (up to 3.5 % macroscopic deformation) is investigated.
