【作者】 何欢；

【导师】 马骏；

【作者基本信息】 大连理工大学 ， 船舶与海洋结构物设计制造， 2014， 硕士

【摘要】 船舶舷外水对于船舶总体振动的固有频率有着极为重要的影响。总体振动对于营运过程中的船舶是极为重要而特殊的问题,当共振时,总体振动产生的振动应力和最大振幅能超出振动规范要求的10倍以上,不仅会对船体结构和机器设备坏,还会严重危害人的身体健康,而且总体共振一但出现,补救和加强措施成本非常高。船舶舷外水的计算方法与总体振动的固有频率有着密切的关系,对船舶总体振动进行预报时,必须考虑舷外水的影响。本文选取一艘87000t的集装箱船和一艘210000DWT的散货船为目标船进行研究。研究内容包括以下四个方面：(1)刘易斯算法的附加质量计算与分析；(2)流固耦合算法的附加质量计算与分析；(3)边界元法的附加质量计算与分析；(4)三种算法的比较与分析。首先,本文对传统刘易斯公式对附加水质量的计算方法进行了介绍,并列举出本文所采用的附加水质量计算表格,对本文目标船的垂向振动和水平-扭转耦合振动的附加水质量进行了计算。并基于刘易斯方法对目标船的总体振动的固有频率进行了计算。其次,本文基于流固耦合理论,对附加水质量进行了流固耦合理论分析。通过对船体结构部分和流域部分分别划分有限元进行离散,建立了流固耦合模型,计算了目标船的垂向振动固有频率,水平振动固有频率和扭转振动固有频率。再次,本文介绍了边界元法来求解附加水质量的理论,并用有限元程序MSC/NASTRAN的虚拟质量法,即边界元法,对目标船在各种工况下的总体振动固有频率进行了计算。最后,本文对上述介绍的三种方法所得的数值结果进行了比较和详细分析,并总结了三种方法的相对误差以及可适用性。更多还原

【Abstract】 Outboard water of Ship hull has an important effect on ship hull’s global vibration. Global vibration is a distinctly important and special issue for ship in the process of operating. Vibration stress and the maximum amplitude due to global vibration are more than ten times as much the requirement of vibration regulation law. Under the effect of such harmful exciting force, global vibration will not only bring great harm to hull structure, but also have a bad effect on human body. Once the resonance of global vibration happened, the cost of reinforce and remedy is very high. The computing method of outboard water has a closely relationship with the inherent frequency of global vibration. Therefore, it is necessary to take account of the influence of outboard water when forecasting the global vibration.In this article, our ship model is one87000t container ship and one210000DWT bulk cargo ship. In the paper, the main contents include the following four aspects:(1) The calculation and analysis of the added mass of Lewis Theory.(2) The calculation and analysis of the added mass of fluid-structure interaction.(3) The calculation and analysis of the added mass of boundary element method.(4) The comparative analysis of three kinds of algorithm.Firstly, the paper introduces the Lewis calculating theory. The added mass of target ship is calculated based on the Lewis theory. Then the inherent frequency of global vibration is calculated based on the added mass of Lewis formula.Secondly, in this paper, based on the fluid structure interaction theory, the fluid structure interaction theory is carried on for the added mass. Through meshing the structure and the fluid respectively, the fluid-structure coupling model is built. Then the inherent frequency of vertical vibrationN horizontal vibration and torsion vibration is calculated.Additionally, the paper describes the boundary element method used to calculate the added mass, as well as use MSC/NASTRAN to calculate the inherent frequency in different loading conditions by BEM.Finally, the paper has carried on the comparative analysis of three methods of the above introduction, In addition, average ralative deviation and applicability of three methods are summed up.更多还原