中文摘要：

为了在频域内解决双峰应力谱密度下的结构疲劳寿命估算问题,提出了双峰应力谱的雨流幅值分布模型,并给出了参数估算方法。假设雨流幅值分布为两个双参数Weibull分布的组合,权重系数反映了两个谱密度峰值对雨流幅值分布的贡献;雨流幅值分布模型中的参数均是随机过程谱参数的函数。数值模拟结果表明：两个Weibull分布的组合能够很好地描述双峰应力谱的雨流幅值分布,模型中的参数能够根据双峰应力谱密度的谱参数计算得出。

英文摘要：

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 Weibult 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-modat stress power spectral density very well and the model parameters can be obtained using the spectral parameters.