The characterization of vibration-fatigue strength is one of the key parts of mechanical design. It is closely related to structural dynamics, which is generally studied in the frequency domain, particularly when working with vibratory loads. A fatigue-life estimation in the frequency domain can therefore prove advantageous with respect to a time-domain estimation, especially when taking into consideration the significant performance gains it offers, regarding numerical computations. Several frequency-domain methods for a vibration-fatigue-life estimation have been developed based on numerically simulated signals. This research focuses on a comparison of different frequency-domain methods with respect to real experiments that are typical in structural dynamics and the automotive industry. The methods researched are: Wirsching-Light, the empirical alpha method, Gao-Moan, Dirlik, Zhao-Baker, Tovo-Benasciutti and Petrucci-Zuccarello. The experimental comparison researches the resistance to close-modes, to increased background noise, to the influence of spectral width, and multi-vibration-mode influences. Additionally, typical vibration profiles in the automotive industry are also researched. For the experiment an electro-dynamic shaker with a vibration controller was used. The reference-life estimation is the rainflow-counting method with the Palmgren-Miner summation rule.It was found that the Tovo-Benasciutti method gives the best estimate for the majority of experiments, the only exception being the typical automotive spectra, for which the enhanced Zhao-Baker method is best suited. This research shows that besides the Dirlik approach, the Tovo-Benasciutti and Zhao-Baker methods should be considered as the preferred methods for fatigue analysis in the frequency domain.
See also related paper: [Uninterrupted and accelerated vibrational fatigue testing with simultaneous monitoring of the natural frequency and damping],
Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
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