中小型LNG船鞍座及附近船体结构强度分析

摘要

The structure and equipment of the small and medium LNG carrier are quite different from large-scale LNG carrier.When the ship is sailing at sea, the static and dynamic loads act on the bearings simultaneously.So the structure stress of the bearings will be very complicated.The stress distribution at the bearings and at the nearby hull structure is directly related to the reliability and security of this type of LNG carrier.The types and the functions of the C-shape independent liquid tank's bearing of the small and medium LNG carrier are described in detail in this paper.Combining with the Rules for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk of the China Classification Society, the radial force distribution function of the bearing-load area is deduced under various working conditions, including still water, heave only, rolling only,and heave and rolling simultaneously.The finite element model for the bearings and the nearby hull structure of a 6400m3 LNG carier is created.The loads required by the rules are imposed on the model with loads superposed method.The stress results are obtained and analyzed, and the dangerous working condition and the dangerous position are found.Referring to the stress distribution, structure improvement measures are provided.The research is meaningful for structure strength analysis and structure design of the similar bearing and the nearby hull structure.%中小型LNG船与传统大型LNG船相比,在结构设置和内部设备等方面有着很大差别.船在海上航行时,受动、静载荷的综合作用,鞍座的应力分布比较复杂.因此鞍座及附近船体的应力分布情况直接关系到此种LNG运输船使用的可靠性与安全性.详细介绍了中小型LNG船C型独立液货舱货罐鞍座的结构及其承载作用.结合中国船级社<散装运输液化气体船舶构造与设备规范>,推导出船舶在静水、仅垂荡、仅横摇以及垂荡和横摇并存状态下鞍座承载区域所受径向力的分布函数.利用 ANSYS 软件,对一艘6400m3LNG船的鞍座及附近船体结构进行有限元建模.针对不同工况,采用载荷叠加法,施加规范要求的载荷,得出应力分布结果.对计算结果进行分析,找出危险工况及危险部位,并针对应力分布,给出结构改进措施,为类似鞍座结构强度分析与结构设计提供一定的参考.