A pulsed neutron imaging technique is used to reconstruct the residual strain within a polycrystalline material from Bragg edge strain images. This technique offers the possibility of a nondestructive analysis of strain fields with a high spatial resolution. A finite element approach is used to reconstruct the strain using the least square method constrained by the conditions of equilibrium. The procedure is developed and verified by validating for a cantilevered beam problem. It is subsequently demonstrated by reconstructing the strain from experimental data for a ring-and-plug sample, measured at the spallation neutron source RADEN at J-PARC in Japan. The reconstruction is validated by comparison with conventional constant wavelength strain measurements on the KOWARI diffractometer at ANSTO in Australia. It is also shown that the addition of a simple Tikhonov regularization can improve the reconstruction.

中文翻译：

---

使用有限元方法进行应变重建的能量分辨中子成像

脉冲中子成像技术用于从布拉格边缘应变图像重建多晶材料内的残余应变。该技术提供了以高空间分辨率对应变场进行无损分析的可能性。有限元方法用于使用受平衡条件约束的最小二乘法重建应变。该程序是通过验证悬臂梁问题来开发和验证的。随后通过从日本 J-PARC 的散裂中子源 RADEN 测量的环塞样品的实验数据重建应变来证明。通过与澳大利亚 ANSTO 的 KOWARI 衍射仪上的常规恒定波长应变测量进行比较，对重建进行了验证。