一种新的高斯多模态随机疲劳损伤频域分析方法

A new frequency-domain method for analysis of Gaussian multi-modal random fatigue damage

摘要:

为准确地在频域内对高斯双模态和三模态过程的随机疲劳损伤进行评估,提出了一种模态耦合分析方法.不同于传统概率方法,该方法从分割功率谱的角度出发,将功率谱分割成很多份极窄的频带,每个频带所造成的疲劳损伤可以利用传统窄带假设单独计算,而任意2个频率模态间的耦合影响效应则通过引入耦合因子ξ进行表达.最后,通过本文提出的公式,对这些极窄频带造成的疲劳损伤和模态耦合造成的疲劳损伤进行合理组合,得到总的疲劳损伤.通过大量数值试验,以时域的雨流计数法结果作为参照,并对比现有的多个主要频域疲劳分析方法,验证了新提出的模态耦合法的精确性和鲁棒性.

Abstract:

To accurately assess the random fatigue damage of bimodal and trimodal Gaussian process in frequency domain, a cross-mode coupling analysis method is proposed in this paper. Different from the conventional probabilistic method, the proposed method was developed based on spectral discretization method. The response spectrum was discretized into a large number of infinitesimal frequency bands, and the fatigue damage with respective to each band could be computed individually, while a coupling coefficient ξ was introduced to account for the cross-mode coupling between any two frequency components. By using the combination rule developed in this paper, the fatigue damages caused by the infinitesimal frequency bands and their couplings were assembled to obtain the total fatigue damage. Through comprehensive case studies, by taking the results of rainflow counting (RFC) method as reference and comparing with several main frequency-domain methods, it was proved that the proposed cross-mode coupling method is more accurate and robust.