Several recent methods for tomographic reconstruction of stress and strain fields from Bragg-edge neutron strain images have been proposed in the literature. This paper presents an extension of a previously demonstrated approach based on Gaussian Process regression which enforces equilibrium in the method. This extension incorporates knowledge of boundary conditions, primarily boundary tractions, into the reconstruction process. This is shown to increase the rate of convergence and is more tolerant of systematic errors that may be present in experimental measurements. An exact expression for a central calculation in this method is also provided which avoids the need for the approximation scheme that was previously used. Convergence of this method for simulated data is compared to existing approaches and a reconstruction from experimental data is provided. Validation of the results to conventional constant wavelength strain measurements and comparison to prior methods shows a significant improvement.

中文翻译：

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布拉格边缘中子透射应变断层扫描中牵引约束的实现

文献中提出了几种最近的基于布拉格边缘中子应变图像的应力和应变场的断层扫描重建方法。本文介绍了之前演示的基于高斯过程回归的方法的扩展，该方法在该方法中强制实现平衡。此扩展将边界条件的知识（主要是边界牵引）纳入重建过程。这被证明可以提高收敛速度，并且更能容忍实验测量中可能存在的系统误差。还提供了该方法中中心计算的精确表达式，从而避免了对先前使用的近似方案的需要。将这种方法对模拟数据的收敛性与现有方法进行了比较，并提供了从实验数据进行的重建。对传统恒定波长应变测量结果的验证以及与先前方法的比较显示出显着的改进。