A basic study on reliability of axles for high-speed railway

(1)提出了一种将超声掠入射SH波检测系统与波形形成方法相结合的超声新技术。应用该技术，可以检测新干线列车轮对车轴的微动疲劳裂纹。(2)对混合表面改进后的车轴进行了疲劳试验和超声波检测。结果表明，由于残余压应力的存在，车轴的疲劳极限提高，但裂纹的检测变得更加困难。(3)对一种轴承用高碳铬钢JISSUJ2进行了等幅和变幅平台序列下的旋转弯曲高周疲劳试验。在重复的两步着陆的情况下，疲劳裂纹起源的网站从试样表面的变化，由于负载的变化，以次表面。讨论了线性损伤累积律在变幅载荷序列下的适用性。(4)通过结合渗碳和WPC工艺，可以在近表面附近产生高的压缩残余应力，保持由渗碳形成的深层压缩残余应力。与仅渗碳改性的那些相比，通过组合改性的缺口试样显示出显著更高的疲劳强度。

(1) A new ultrasonic technique in combination of ultrasonic grazing SH wave inspection system and a wave forming method were proposed. Applying this technique, it became possible to detect the fretting fatigue cracks in wheel set axle of shinkansen train.(2) Fatigue test and ultrasonic test were performed for the hybrid surface improved axles. The results show that the fatigue limit of the axle increases but the detection of cracks becomes more difficult because of large compressive residual stresses.(3) Rotating bending, high-cycle fatigue tests under constant amplitude and variable amplitude land sequences were carried out on a high carbon chromium steel for bearings, JIS SUJ2. In the case of repeated two-step landing, fatigue crack origin sites change from the specimen surface to the subsurface due to the load variation. The usefulness of linear damage accumulation law under variable amplitude load sequences was discussed.(4) By combining the carburizing and the WPC process, it is possible to generate a high compressive residual stress near the near the surface, maintaining a deep layer of compressive residual stress formed by the carburizing The notched specimens modified by combined show a significantly higher fatigue strength compared to those modified by only carburizing.