Development of nondestructive evaluation system of fatigue damage by neutron diffraction

1.基于EShelby夹杂力学和自洽模型，提出了一种估算工程材料绕射弹性常数的方法。残余应力分析仪(RESA)是在日本原子能研究所(JAERI)JRR-3M反应堆T2-1导流管上研制的。为了确定残馀应力的分布，新研制了自动定位装置和弯曲晶体聚焦系统。碳化硅颗粒增强铝的应力分配与细观力学预测结果吻合较好。氧化铝中加入氧化锆和碳化硅后的残余热应力测量值与微观力学热膨胀系数失配的预测值相吻合。研制的中子应力测量系统已成功应用于热核聚变堆芯铝套、ITER超导线圈护套材料和焊接管道中残余应力分布的测量。用中子衍射法检测了缺口碳钢棒材疲劳裂纹萌生时残余应力的变化。用中子衍射法检测了不锈钢管道焊接接头附近因裂纹扩展而产生的残余应力的重新分布。提出了一种中子应力测量标准化的方法。

1. A method to estimate the diffraction elastic constants of engineering materials was proposed on the basis of Eshelby's inclusion mechanics combined with the self-consistent model.2. The residual stress analyzer (RESA) was developed at the guide tube of T2-1 of the reactor, JRR-3M, at Japan Atomic Energy Research Institute (JAERI). To determine the distribution of the residual stress, an automatic devise for positioning and a bent crystal system for focusing were newly developed.3. The stress partioning of aluminum reinforced by SiC particles agrees very well with the prediction by micromechanics. The measured values of thermal residual stresses in alumina mixed with zirconia or with silicon carbide agreed with the prediction from the mismatch of the thermal expansion coefficient by micromechanics.4. The developed system for neutron stress measurements was successfully applied to measure the residual stress distribution in aluminum shrink fit, jacket material for ITER superconducting coil, and welded pipes.5. The change of the residual stress was detected by neutron diffraction at the time of crack initiation in fatigue of notched carbon steel bars. The redistribution of the residual stress due to crack propagation was detected by neutron diffraction near the weld joint of stainless pipes.6. A method was proposed toward standardization of neutron stress measurements.