中子基应变测量技术中关于$d_0$的研究：基于平衡的非破坏性$d_0$估算方法
An essay on $d_0$ in neutron-based strain measurement techniques: equilibrium-based methods for non-destructive $d_0$ estimation
AI总结：
该论文针对中子基应变测量中无应力参考晶格间距$d_0$的确定难题，开发了一系列基于力学平衡的非破坏性估算方法，通过实际样品验证了其适用性。
AI中文摘要：
无应力参考晶格间距$d_0$的确定是衍射基应变测量中一项核心且常被低估的难题。尽管通常将$d_0$视为材料常数，但由于亚体尺度下的成分、相、织构和残余应力，$d_0$常随位置和测量方向变化。虽然从试样直接测量$d_0$通常更可取，但有时不切实际甚至不可能。本文综述了$d_0$问题的总体情况，并开发了一系列基于力学平衡的非破坏性替代方法，涵盖从已有的基于力平衡的技术，到边界条件的应用，最后到通过本征应变分析实现的样品内逐点平衡方法。所有方法均提供了实际样品的实例，包括增材制造的Inconel合金立方体、古罗马青铜医用探针以及一件据称源自波斯的古代青铜匕首。后两个实例表明，当破坏性参考测量完全不合适时，平衡可作为估算$d_0$的实用物理约束。
英文摘要：
Determination of the stress-free reference lattice spacing, $d_0$, is a central and often underestimated difficulty in diffraction-based strain measurement. Although commonly treated as a material constant, $d_0$ often varies with position and measurement direction as a result of composition, phase, texture and residual stress at the sub-bulk scale. While direct measurement of $d_0$ from coupons is usually preferable, this is sometimes impractical or even impossible. This paper reviews the $d_0$ problem in general and develops a hierarchy of non-destructive alternatives based on mechanical equilibrium. This ranges from established techniques based on force-balance, to the application of boundary conditions and finally an approach based on point-wise equilibrium within a sample, implemented through eigenstrain analysis. In all cases, examples are provided in the form of real samples including an additively manufactured Inconel cube, ancient Roman bronze medical probes and an ancient bronze dagger of purported Persian origin. These latter examples demonstrate that equilibrium can provide a practical physical constraint for estimating $d_0$ when destructive reference measurements are entirely inappropriate.
