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  • The relevance of non-stationarities and non-Gaussianities in vibration fatigue [Elektronski vir]
    Česnik, Martin, strojnik ...
    In classical fatigue of materials, the frequency contents of dynamic loading are well below the natural frequencies of the observed structure or test specimen. However, when dealing with vibration ... fatigue the frequency contents of dynamic loading and structure's dynamic response overlap, resulting in amplified stress loads of the s tructure. For such cases, frequency counting methods are especially convenient. 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. Since it is common in real environments for the structure to be excited with non - Gaussian and non-stationary loads , this study addresses the effects of s uch dynamic excitation to experimental time -to -failure of a structure. Initially , the influence of non-Gaussian stationary excitation is experimentally studied via excitation signals with equal power density spectrum and different values of kurtosis. Since no relevant changes of structure's time -to -failure were observed, the study focused on 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 -fail ure 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. T o 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-station ary excitation. The non -stationarity index is used to determine if the frequency - domain methods can safely be applied for time -to -failure calculation.
    Source: MATEC web of conferences [Elektronski vir]. - ISSN 2261-236X (Vol. 165, 2018, f. 1-9)
    Type of material - conference contribution
    Publish date - 2018
    Language - slovenian
    COBISS.SI-ID - 16101915

    Link(s):

    https://www.matec-conferences.org/articles/matecconf/pdf/2018/24/matecconf_fatigue2018_10011.pdf
    DOI

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