Research on the Dynamic Stress Tracking Test Period of the Bogie Frame for Metro Vehicle

Dynamic stress is one of the key indicators reflecting the fatigue characteristics of metro bogie frames. Considering the test costs, operation safety, and other factors, it is impossible to record all the dynamic stress data for the whole service period in the tracking test. Therefore, the overall stress spectrum is statistically deduced based on limited dynamic stress data samples, which can not only provide a basis for the fatigue reliability research of the bogie frame, but also save costs. In this paper, the typical fatigue control points in different areas of the frame with large equivalent stress are selected for research. The daily measured stress spectrum samples are obtained through the rainflow counting method, and the statistical stress spectrum is then compiled. Weibull distribution fitting of the stress spectrum is carried out to obtain the scale and shape parameter samples for different fatigue control parts. After sampling of the obtained parameter samples and conducting variance homogeneity tests as well as t-tests, the minimum sample size representing the overall distribution of the interval is obtained. Therefore, the shortest tracking test period reflecting the overall stress distribution of typical fatigue control parts can be obtained.