Method Study on Fatigue Life Prediction of Welds Based on Harmonic Response Analysis

Facing the challenge that the weld fatigue life prediction results are not accurate because the quasi-static method does not consider the natural frequency of the structure, the paper, upon the correction of time-domain loading based on the harmonic response analysis, proposed a new method for fatigue life prediction of welds within a new time-domain. The history of time domain loading at the air springs was obtained by the Mechanical Simulation, while the history of frequency domain loading was obtained upon the Fourier transformation. The harmonic response analysis was carried out on a car body to obtain the frequency response coefficient at key nodes of the car body, then the time-load history was corrected, and finally the fatigue life of key welds was obtained by the quasi-static method and the structure stress method. The result shows that, the fatigue life of the car body is 1.65e5 km obtained by the correction method, which is more conservative and takes full consideration of the impact of the structure's natural frequency, providing a new concept for future researches of life prediction.