离心轮内部疲劳裂纹扩展及其无损定量表征

为研究某离心轮内部疲劳裂纹扩展及其无损定量表征,开展了高速低循环旋转疲劳试验以及多种无损检测定量表征、断口分析、疲劳裂纹扩展仿真对比研究.研究结果表明:疲劳裂纹到达表面后,疲劳裂纹处于非稳定扩展阶段;20000～21700循环间,区间疲劳裂纹扩展速率仿真值与无损表征值接近;21700～21789循环间,区间疲劳裂纹扩展...

Fatigue Crack Growth and Nondestructive Quantitative Characterizationin Centrifugal Wheels

In order to study the internal fatigue crack growth and the nondestructive quantitative characterization of the centrifugal wheels, the high-speed and low cycle rotating fatigue tests were carried out, and a variety of nondestructive quantitative characterization, fracture analysis and fatigue crack growth simulation were compared. The results show that after the fatigue cracks reach to the surfaces, the fatigue cracks are in the unstable growth stage. During 20 000~21 700 cycles, the simulation values of the interval fatigue crack growth rate are close to the non-destructive characterization values. During 21 700~21 789 cycles, the non-destructive characterization values of the interval fatigue crack growth rate are about 2.5 times larger than that of the simulation values. When the fatigue cracks propagate inside the centrifugal wheel and outside the inclusion areas, the fatigue cracks are in a stable growth stage. Total focusing method(TFM) ultrasonic testing and time of flight diffraction(TOFD) ultrasonic testing may identify the inclusion / fatigue crack internal growth of the centrifugal wheels. At 0 and 6000 cycles, the fatigue cracks are in the inclusion area, the nondestructive characterization values remain unchanged. After 9000 cycles, the TFM ultrasonic nondestructive characterization values of cracks height H and radial length LR increase significantly, the change is similar to the fracture values, but the increased amplitude is smaller.