Study On Fatigue Life In Frequency Domain For Bogie Frame Of High-Speed Trains

As a key component of railway vehicle, the fatigue strength of the bogie frame directly affects the safe operation of trains. Traditional frame design follows the relevant standards for fatigue load test using fatigue strength checking methods (such as the use of Goodman curve). This method often leads to excessive fatigue strength of the overall frame and lack of structural fatigue in local areas. And the amplitude loads used in the test are inconsistent with random excitation suffered on the frame in the actual operation. Therefore, vibration fatigue analysis of structures under random excitation on frame design is of important guiding significance.This paper uses the inverse Fourier transform and trigonometric series method for numerical simulation of random processes, and verifies the correctness and the feasibility of building load history through comparative analysis. With numerical simulation of track irregularity based on cubic-spline interpolation, corresponding velocity and acceleration time history are obtained. Compared with the theoretical formula, the results show the incentive conversion method has a good feasibility.In this paper, a cantilever beam modal has been built. In order to clarify the differences between frequency-domain method and time-domain, and provide theoretical basis for frame frequency-domain calculation of fatigue, the cantilever beam's vibration fatigue life was been predicted by using time-domain and frequency-domain method respectively. Meanwhile the damping in the analysis of fatigue life prediction in frequency-domain and the time step in transient response analysis has also been investigated.The finite element of bogie frame has been established in this paper by using simulation software Nastran to obtain the stress response power spectrum under muilti-excitation of bogie frame. According to weld S-N curve and the fatigue life modal in frequency-domain, we have obtained the weld fatigue life distribution of the bogie for 95% survival under random vibration by using fatigue software nSoft. The results of frame life prediction based on different welding standards show that the standard of Institute of International welding are somewhat safe.The result shows that the fatigue life calculation of the frequency-domain can be good used to predict the vibration fatigue, and provide a effective method for anti-fatigue design of frame..