宽带随机载荷下船舶结构的两种疲劳直接计算方法

针对船舶疲劳计算将外载荷以及波浪引起的船舶交变应力响应过程当窄带模型处理，而现实海况模型更接近宽带模型这一问题，考虑从应力范围分布为切入点，以实船结构为研究对象，采用两种直接计算法——HCSR直接计算方法和谱分析方法解决宽带随机载荷下的疲劳计算问题.谱分析法以Rice分布为基础，建立宽带载荷下等效应力范围的近似计算模型进行疲劳求解；而HCSR直接计算方法则用连续型模型Weibull分布来表示宽带谱下应力范围的分布模型，从而解决宽带随机载荷下求解疲劳寿命问题.研究结果表明：考虑宽带影响因素后，两种方法虽然采用模型不同，但结果相接近或趋势相同，证明两种方法对解决宽带下疲劳问题都有一定可行性；但谱分析法求解时采用多种等效应力近似模型，可满足不同带宽下的疲劳强度计算，结果更加准确可信.
In view of the problem that the alternative stress responses resulted from external load and waves loads were treated as a narrow band model in fatigue calculation process, while the actual sea state model was closer to a broadband mode, and the stress range distribution was considered as the breakthrough point, taking the real ship structure as the study object, the fatigue problems were resolved by using two direct calculation methods—HCSR and spectral analysis method under broadband random loads. For spectrometry based on Rice distribution, the approximate model of the equivalent stress range was set up under broadband loads. For direct calculation method based on HCSR, a continuous model—Weibull model was used to represent the stress range distribution model under broadband spectrum to solve the fatigue problem under broadband random loads. Results show that considering the influence of broadband factors, two kinds of methods while using different models, but the results are close to or the same trend, which prove that the two methods have certain feasibility to solve the fatigue problem of broadband, but spectral analysis method using a variety of equivalent stress model to calculate the fatigue strength under different bandwidth, therefore the results are more accurate and reliable.