Abstract
In vibration fatigue the frequency contents of dynamic loading and structure’s dynamic response overlap, resulting in amplified stress loads of the structure. Time domain fatigue approach does not give a good insight into the underlying mechanics of failure and therefore recently vibration fatigue in frequency domain is getting a lot of scientific attention. Gaussianity and stationarity assumptions are applied in frequency-domain methods for obtaining dynamic structure’s response and frequency-domain methods for calculating damage accumulation rate. However, in application, the structures are excited with non-Gaussian and non-stationary loads and this study addresses the effects of such dynamic excitation to experimental time-to-failure of a structure.
The influence of non-Gaussian, but stationary excitation, is experimentally studied via excitation signals with equal power density spectrum and different values of kurtosis. The non-Gaussianity was found not to significantly change the structure’s time-to-failure and therefore, the study focuses on the non-stationary excitation signals that are also inherently non-Gaussian. The non-stationarity of excitation was achieved by amplitude modulation and significantly shorter times-to-failure were observed when compared to experiments with stationary non-Gaussian excitation.
Additionally, the structure’s time-to-failure varied with the rate of the amplitude modulation. To oversee this phenomenon the presented study proposes a non-stationarity index which can be obtained from the excitation time history. The non-stationarity index was experimentally confirmed as a reliable estimator for severity of non-stationary excitation. The non-stationarity index is used to determine if the frequency-domain methods can safely be applied for time-to-failure calculation.
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Slavič, J., Česnik, M., Capponi, L., Palmieri, M., Cianetti, F., Boltežar, M. (2020). Non-stationarity and non-Gaussianity in Vibration Fatigue. In: Walber, C., Walter, P., Seidlitz, S. (eds) Sensors and Instrumentation, Aircraft/Aerospace, Energy Harvesting & Dynamic Environments Testing, Volume 7. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-030-12676-6_7
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DOI: https://doi.org/10.1007/978-3-030-12676-6_7
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