【作者】 张艳萍；

【导师】 刘土光；

【作者基本信息】 华中科技大学 ， 船舶与海洋结构物设计制造， 2007， 硕士

【摘要】 结构物入水冲击问题广泛存在于船舶工业及海洋工程中,入水冲击的研究对于结构设计的重要性已经有70多年的历史。船舶在波涛中航行时,船艏、艉会频繁地与水面发生撞击,在结构上引起很大的瞬间压力,这种作用力可以导致船体和海洋结构物的严重损坏。因此,研究海洋结构物的入水过程中砰击载荷及其特性对确定船舶的设计载荷和保证船舶安全具有十分重要的现实意义。本文的目的是运用ANSYS/LS-DYNA这一有限元显式非线性动力分析软件,对工程上常用剖面型式的二维船体结构入水问题进行仿真模拟,以此来分析这些结构在入水过程中的砰击载荷及其特性,以及结构的响应规律,主要包括如下内容:1、通过前人的研究,了解到了国内外对海洋结构物入水问题的研究概况。并对现有的砰击理论进行了消化、吸收和整理,给出了二维平底体结构和二维楔形体结构入水的基本理论;2、采用仿真的方法对二维平底体结构的入水冲击问题进行了分析,分析得到了刚性平底体结构入水过程中砰击面上的压力及其分布,并讨论了入水速度和结构质量对砰击压力的影响;在此基础上进一步分析了弹性效应(平底面厚度t、弹性模量E和弯曲刚度D)对弹性平底体结构入水过程中砰击压力和结构响应的影响;3、采用仿真的方法对二维楔形体、U型体和球鼻艏体结构的入水问题进行了分析。分别给出了三种不同结构型式砰击面上的压力及其分布、流场内压力波云图和液面升高图,讨论了楔形体入水角度对砰击压力峰值的影响,并将U型体底面上砰击载荷变化规律与平底体结构进行对比,得到了一些有意义的结论。更多还原

【Abstract】 The problem of water entry impact of the marine structure is widely existed in Naval Architecture and Ocean Engineering, and the research of water entry impact for structure design has been important for more than 70 years. When ships sail in the foul wave, both the bow and the stern would impact on water surface continually, and there will be great instantaneous pressure on structure surface which can lead to serious damage. So the research of impact pressure as well as it’s characteristic is practically important for structure design and safety.In this thesis, the finite element software ANSYS/LS-DYNA is used to simulate two-dimensional water entry problem of marine structure in common use, and the analysis of impact pressure as well as the response of structure is done according to the simulation. Including:1、According to prehuman’s research, we have known the general situation of water entry problem in and abroad, as well as digested and absorbed the existing theory. Then the basic theory of two-dimensional water entry problem of flat-bottom and wedge-shaped structure is given.2、The two-dimensional water entry of flat-bottom marine structure is simulated, and the impact pressure as well as it’s distribution is gained. Then we discuss the effects of velocity and mass to impact pressure, and the effects of elasticity (including thickness of the flat bottom、elastic modul and flexual rigidity) to the response of structure.3、The two-dimensional water entry of wedge-shaped、U-type marine structure and bulbous bow is simulated. We gain the impact pressure as well as it’s distribution, the pressure variety of liquid and the rise of free surface. Then we discuss the effects of angle to the peak impact pressure, and compare the pressure variety between flat-bottom and U-type structure. In the end, we gain a lot of significative conclusions.更多还原