Tomographic reconstruction of residual strain in axisymmetric systems from Bragg-edge neutron imaging

In this paper, we address the tomographic reconstruction of elastic strain fields from Bragg-edge measurements. The non-trivial null space of the Longitudinal Ray Transform lies at the heart of this problem, precluding direction inversion from measured data. We have approached this problem by considering the physical constraints of equilibrium through the minimisation of strain energy. Through this approach, a method is developed for axisymmetric systems that is capable of reconstructing residual strain fields. This algorithm has been demonstrated for two such fields, and is capable of rejecting simulated Gaussian measurement noise of the magnitude expected in experimental data. In contrast to previous algorithms for this class of system, a clear path to general application (i.e. arbitrary geometry) exists.