关键词: 随机振动, 雨流计数法, 幅值分布, 振动疲劳, 数值模拟, 双峰谱密度

Abstract: To solve the fatigue life prediction problem of structures under bi-modal stress power spectral density in the frequency domain, this article presents a model of rainflow amplitude distribution of bi-modal stress power spectral density and provides a method to estimate its parameters. The rainflow amplitude distribution is assumed to be the combination of two two-parameter Weibull distributions with their weight coefficient reflecting the different contributions of each Weibull distribution. Parameters of the rainflow amplitude distribution are functions of the spectral parameters of a random process. The results of numerical simulation show that the combination of two Weibull distributions can describe the rainflow amplitude distribution of bi-modal stress power spectral density very well and the model parameters can be obtained using the spectral parameters.

Key words: random vibration, rainflow counting method, amplitude distribution, vibration fatigue, numerical simulation, bi-modal spectral density