三体船屈服强度的可靠性研究

Research on reliability of trimaran yield strength

[目的]三体船作为一种高技术新型船舶,需要特别关注其结构强度问题。传统的数值方法是以确定性的方法进行分析,然而作用在船体上的载荷、结构形式和材料性能等随机因素均具有不确定性,因此需采用可靠性的方法来计及这些随机因素对船体强度的影响。[方法]将三维势流理论与船体强度直接计算相结合,得到三体船某特殊结构单元von Mises应力的短期时历分布,进而得到应力的长期分布和序列统计的极值分布。综合单元极限强度和载荷要求,列出极限状态方程,得到可靠性指标。对典型结构的失效概率、安全系数进行计算,并对一些随机变量进行影响分析。[结果]研究表明:三体船连接桥处应力集中系数较大,安全系数为0.86,而由于甲板的中和轴较高,甲板安全系数为2.4,材料不确定性对可靠性指标的影响更大。[结论]提出的三体船屈服强度可靠性研究方法可为后续三体船优化提供良好的数据支撑。

[Objectives]As a high-tech ship,the trimaran is particularly prominent in structural strength.Traditional numerical methods are analysed by deterministic methods.However,such variables as the loads acting on the hull,the uncertainty of the calculating model and the performance of the material are random.Therefore,reliability measures are taken to account for the influence of these factors on hull strength.[Methods]The three-dimensional potential flow theory and direct calculation of strength for the hull structure are used in this paper to obtain the short-term time-period distribution of the von Mises stress of special structural elements,then the distributions of long-term von Mises stress and sequence statistics of extreme value are obtained.The limit state equation is listed in combination with the structural capacity and load requirements of the units to obtain the reliability indexes.The failure probability and safety factor of typical structures are calculated,and certain random components are analysed on impact.[Results]The research shows that the structural strength of a trimaran is concentrated at the connecting bridge,the safety factor is 0.86 and the deck safety factor is 2.4.Due to the high neutral axis,the material uncertainty has a greater influence on the reliability indexes.[Conclusions]The method of yield strength reliability research for trimaran proposed in the study can provide good data-support for the optimization of trimarans.