Generation of vibration load spectrum for fatigue analysis of equipment mounted on bogie frame of railway vehicle based on fatigue damage spectrum

The equipment mounted on the bogie frame of railway vehicles is subjected to non-stationary vibrations from the bogie frame. Currently, the vibration load spectrum for fatigue analysis of equipment is expressed with the power spectral density, which is generally obtained with the power values of measured vibrations or stationary Gaussian vibrations collected at the specific operating conditions. However, this does not have the equivalent damage potential as the non-stationary vibrations. Thus, a generation method of the vibration load spectrum is proposed based on the fatigue damage spectrum (FDS) to obtain the equivalent damage potential as the one from the non-stationary vibrations in this paper. That is, the FDS of non-stationary vibration is calculated with the time domain method, and the vibration load spectrum is generated in the frequency domain with this FDS. Then the method is verified by the measured vibration and dynamic strain of equipment. Finally, the vibration load spectrum of equipment mounted on the bogie frame is generated with the measured vibrations in a maintenance cycle and the fatigue analysis is performed. The results show that the generated vibration load spectrum can validly contain the high power in non-stationary vibrations and express the distribution of power over frequency, which gives much better estimates of the fatigue damage of equipment than other load spectra. The generated vibration load spectrum is suitable for quantifying the actual non-stationary vibrations and can be used for the anti-fatigue design of equipment.