Special mathematical transformation-based fatigue damage estimation under narrowband non-Gaussian random loadings

The frequency-domain method for estimating fatigue damage is important and efficient for engineering applications. However, when dealing with non-Gaussian loadings, the widely used method based on Hermite polynomials model (HPM) has some limitations. To overcome this problem, this paper proposes a new frequency-domain method based on a special mathematical transformation model which was proposed by Johnson (JTM) for narrowband non-Gaussian cases. Numerical simulations are used to validate the new method. Considering different types of spectra and different combinations of kurtosis and skewness, Gaussian and non-Gaussian stress time series are generated for fatigue analysis. The fatigue damage estimates from the time-domain method based on rainflow counting and the frequency-domain methods based on HPM and JTM are compared. The results demonstrate that frequency-domain fatigue damage estimation is effective, but has some errors, which are discussed in this paper. The main finding is that JTM performs as well as HPM when non-Gaussianity is not strong. Therefore, JTM can be used as an alternative to HPM for estimating fatigue damage in the frequency domain under narrowband non-Gaussian conditions.