Development of high precision evaluation system of fatigue damage by time-of-flight neutron method

(1)根据绕射强度确定了几种结构材料由应变计算应力的绕射弹性常数。对碳化硅颗粒增强铝合金光滑试件在单调轴向载荷作用下的应力进行了测量。在复合材料中，测量了组成相中的相应力。在此基础上确定了用于应力测量的衍射面和衍射光强。疲劳损伤可以通过轮廓展宽的变化来判断。(3)对奥氏体不锈钢SUS316 NG进行了轴向拉伸压缩疲劳试验。测量了疲劳过程中轮廓展宽的变化。当机械加工产生较大的残余压应力时，在较高的应力幅值下，残余压应力在早期减小。另一方面，对于较低的应力幅值，残余应力变化较小。(4)对于焊接构件的应力测量，第二类应力是决定宏观应力的重要因素。在这种情况下，使用小块作为无应力晶格间距的参考是有效的。ECAP法制备的超细晶铜的线宽随着塑性应变的增大而增大。然而，在卸载过程中，该值下降到初始值。疲劳载荷下的谱线展宽变化不大。(6)对径向准直器限制LMM量规体积的性能进行了评估。测得的轮廓线与模拟结果一致。可以足够精确地测量应力。

(1) The diffraction elastic constants for calculating the stress from the strain were determined for several structural materials on the basis of the diffraction intensity. The accuracy of the stress measurement was clarified.(2) Stress measurement in the smooth specimens of aluminum alloy reinforced with SiC particles under monotonic axial loading was carried out. In the composites, the phase stress in the constituent phase was measured. The diffraction plane and diffraction intensity for stress measurement were determined on the basis of the confident limit. Fatigue damage could be determined from the change of the profile broadening.(3) Fatigue tests of an austenitic stainless steel SUS316NG were conducted under axial tension compression. The change of the profile broadening was measured during fatigue process. When the large compressive residual stress was induced by the machining, the compressive residual stress decreased in the early stage at the higher applied stress amplitude. On the other hand, for the lower stress amplitude, the change of the residual stress is small.(4) For the stress measurement of the welded components, the second kind of stress is important to determine the macro stress. In that case, the use of the small piece as a reference of the stress free lattice spacing is effective. The residual stress in the butt welded joint could be determined.(5) The line broadening in the ultrafine-grained Cu fabricated by ECAP method increased with the plastic strain. The value, however, decreased to the initial value during unloading. The change of the line broadening under fatigue loading is not so large.(6) Performance evaluation of the radial collimator to limit the gage volume of lmm was conducted. The measured profile was identical to the result of the simulation. The stress can be measured with enough accuracy.