Sgamma Michele, Palmieri Massimiliano, Barsanti Michele, Bucchi Francesco, Cianetti Filippo, Frendo Francesco
Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy.
Industrial Engineering Department, University of Perugia, Perugia, Italy.
Heliyon. 2024 May 14;10(10):e30832. doi: 10.1016/j.heliyon.2024.e30832. eCollection 2024 May 30.
Fatigue assessment of components subjected to random loads is a challenging task both due to the variability in amplitude and frequency of the loads and for the computational times required to perform classical time domain fatigue analysis. The frequency domain approach to fatigue life assessment offers a solution by utilizing the power spectral density of the random load, requiring minimal computational effort. However, frequency domain methods are limited to stationary Gaussian signals, while real-world loads often exhibit non-Gaussian characteristics. Previous research proposed formulas to extend frequency domain methods to non-Gaussian cases, but they require knowledge of the parameters related to non-Gaussianity of the component's stress (skewness and kurtosis), which would require a time domain analysis of the stress history on the component and a strong reduction of the computational advantages. This paper aims to address this gap by conducting an extensive campaign of numerical simulations to evaluate the influence of various parameters on the degree of non-Gaussianity of the response of a system. A single-dof mass-spring-damper system was subjected to non-Gaussian random loads of different natures, and the response is analyzed to determine the values of skewness and kurtosis. The study investigated the influence on non-normality indexes of the system's output of several input parameters, which include both the characteristics of the input load and the properties of the dynamic system. The findings contribute to a better understanding of non-Gaussianity in dynamic systems and pave the way for conducting efficient fatigue analyses in the frequency domain. Future work will extend the study to non-stationary random loads, further advancing the understanding of non-Gaussianity and non-stationarity in dynamic systems.
对承受随机载荷的部件进行疲劳评估是一项具有挑战性的任务，这既是由于载荷幅值和频率的变化性，也是因为进行经典时域疲劳分析所需的计算时间。频域疲劳寿命评估方法通过利用随机载荷的功率谱密度提供了一种解决方案，所需计算量最小。然而，频域方法仅限于平稳高斯信号，而实际载荷往往呈现非高斯特性。先前的研究提出了将频域方法扩展到非高斯情况的公式，但这些公式需要了解与部件应力的非高斯性相关的参数（偏度和峰度），这需要对部件上的应力历史进行时域分析，从而大大降低了计算优势。本文旨在通过开展广泛的数值模拟活动来填补这一空白，以评估各种参数对系统响应非高斯程度的影响。一个单自由度质量 - 弹簧 - 阻尼系统承受了不同性质的非高斯随机载荷，并对响应进行分析以确定偏度和峰度的值。该研究调查了几个输入参数对系统输出的非正态性指标的影响，这些参数包括输入载荷的特性和动态系统的属性。研究结果有助于更好地理解动态系统中的非高斯性，并为在频域中进行高效疲劳分析铺平道路。未来的工作将把研究扩展到非平稳随机载荷，进一步加深对动态系统中非高斯性和非平稳性的理解。
