中文摘要：

基于对波浪载荷所引起的交变应力范围数据统计分析的结论，建议用一类双峰正态混合分布拟合．利用EM算法对混合分布的参数进行估计，借助估计出的参数值，揭示了在一定条件下船体不同部位疲劳载荷的固有关系．船体波浪载荷应力在船首处尤为复杂，双峰对称正态逆高斯混合分布对该处波浪载荷所引起的交变应力范围数据拟合效果更好．实证分析表明，所提供的概率分布参数能够反映船体不同部位的疲劳载荷大小，所得到的关于船体不同部位疲劳载荷固有关系的结论可为船舶运行品质研究提供理论基础．

英文摘要：

Based on the descriptive statistical analysis for the alternating stress range data,this paper sug- gests to model the data by a class of normal mixture distributions with two peaks. The parameter of the mixture distribution can be estimated by the EM algorithm. Employing the estimated parameter values of the mixture distribution,some inherent relationships of the fatigue loads in different parts of the hull under certain conditions were revealed. The wave-induced hull stresses are particularly complex at the bow,sym- metric normal inverse Gaussian mixture distributions are more suitable to fit the alternating stress range data. The empirical analysis shows that the parameter of the proposed probability distribution can reflect the size of the fatigue loads in different parts of the hull,and the conclusion of inherent relationships of the fatigue loads in different parts of the hull provides a theoretical foundation for the operation quality re- search of the ship.