Neutron diffraction strain tomography: 2D axisymmetric sample geometry

Abstract: We consider a method for neutron residual strain/stress analysis combining features of transmission strain tomography (e.g. through Braggs edge imaging) and neutron diffraction techniques. Analogous to transmission strain tomography, our approach observes integrals of strain along the path of a beam, however, rather than transmitted beams, we observe a diffracted beam. The practical feasibility of neutron diffraction tomography is demonstrated in case of a 2D axisymmetric sample where the reconstruction of the stress field is determined from the measurement of a strain profile. The reconstruction is compared to a set of measurements made using a traditional neutron stress scanning technique in order to validate the new method. Similar strain accuracy was achieved by the new technique within a reasonable measurement time. The practical and theoretical challenges regarding the technique are also discussed.