船舶碰撞载荷对超大型浮式结构.doc
约91页DOC格式手机打开展开
船舶碰撞载荷对超大型浮式结构,摘 要21世纪是海洋的世纪，海洋成为国家综合国力竞争的制高点，经略海洋、兴海强国已经成为我国国家发展战略的重要内容。近年来国际海洋工程界掀起了研究超大型海洋浮式结构物(vlfs——very large floating structure 简称vlfs)的热潮。超大型浮式结构物可用于海上补给、科考、能源基地以及海上城市...
内容介绍
此文档由会员 违规屏蔽12 发布
摘 要
21世纪是海洋的世纪，海洋成为国家综合国力竞争的制高点，经略海洋、兴海强国已经成为我国国家发展战略的重要内容。近年来国际海洋工程界掀起了研究超大型海洋浮式结构物(VLFS——Very Large Floating Structure 简称VLFS)的热潮。超大型浮式结构物可用于海上补给、科考、能源基地以及海上城市等。出于我国国情，我们国家对超大型浮式结构物也开始进行了一系列概念论证。
本文研究的超大型浮式结构物由多个半潜式模块组成，各个模块间采用连接器进行连接，连接器采用柔性连接器，允许模块间的相对运动来减小连接器载荷。
超大型浮式结构物在营运过程中可能会遇到飞机坠落，船舶碰撞等事故情况。事故载荷不仅会对超大型浮式结构物的局部结构产生破坏作用，而且会对超大型浮式结构物的薄弱环节——连接器产生附加载荷。本文对船舶碰撞载荷对超大型浮式结构物载荷的影响进行了数值模拟。以船舶碰撞为例，采用简化的RMFC模型，然后通过SESAM软件计算水动力系数，将其代入多刚体运动微分方程后用数值方法求解，研究冲击载荷对连接器载荷的影响。将考虑模块间相互影响与不考虑模块间相互影响的结果进行了比较。比较表明在浪向角较大时，以及连接器刚度较大时可以不考虑模块间相互影响。
本文提出了两种数值解法，一种为简化频域解法，采用固定频率的水动力系数和波浪力，另一种为时域解法，通过频域中求得的水动力系数来计算时域的附加质量和记忆函数。两种解法表明在初步设计阶段采用简化频域方法来估算连接器载荷是可行的。
对不同连接器刚度以及不同撞击部位工况进行了比较，找到了载荷较小的连接器刚度以及导致连接器载荷最大的碰撞部位。同时比较了三种简化碰撞载荷模型，计算结果表明不同简化碰撞载荷模型差异不大，连接器碰撞载荷与碰撞冲量有关。比较了不同碰撞角度的计算结果，表明连接器载荷与碰撞的力矩很有关系。
最后本文计算了同时考虑波浪和碰撞载荷的计算结果，验证了碰撞载荷对连接器载荷影响的程度，估算出碰撞引起的连接器载荷的数量级，表明碰撞载荷对超大型浮式结构物连接器的影响不可忽略。
关键词 超大型浮式结构物；移动海上基地；连接器；碰撞；时域分析；频域分析
Abstract
The 21st century is the century of ocean. Ocean is the commanding heights of competition of comprehensive national strength. Sea power has become an important part of national development strategies. International marine engineering in recent years launched a study of very large floating structures (VLFS - Very Large Floating Structure referred to VLFS) of the boom. VLFS can be used as offshore supply, or scientific research, energy and maritime cities base. For the conditions of our country, our country has begun a series of proof of concept on VLFS.
VLFS studied in this paper is a kind of VLFS which is made up of several semi-submersible modules. The modules are connected with connectors. The connectors are soft to allow relative motion to minimize the connector load.
VLFS may meet with accidental damage due to airplane collision, ship collision, etc. Accidental loads will not only damage local structures of VLFS, but also induce additional loads on connector which is the weakest part of VLFS.The influence of ship collision on the VLFS is calculated by numerical solution.Taking ship collision as an example, by the use of simplified RMFC model, hydrodynamic coefficient is calculated by SESAM software. Then the hydrodynamic coefficient is taken into multi-body motion differential equation, and this equation is solved with numerical methods to study the influence of impact load on the connector load. The result considering the influence between modules and without considering the influence is compared. It indicates that the influence between modules can be neglected when the wave approach or the stiffness of connector is large enough.
Two numerical methods present here: the first is simplified frequency-domain solution which fixed frequency hydrodynamic coefficient and wave force is applied. The second is time-domain solution which the hydrodynamic coefficient is applied to calculate the added mass in infinite frequency and memory function. It is shown that the simplified frequency-domain solution is available in preliminary design stage of VLFS.
The result of different connector stiffness and collision position is compared. The stiffness of connector which cause minimum connector load and the collision position which cause maximum connector load is found. The three kind of simplified collision load models are compared. It is shown that there is slight difference between these models. The connector load is related with load impulse. The result of different collision angle is compared. It is shown that the connector load is related with the load moment
In the end of this paper, the connector load considering wave and collision load is calculated. The degree of influence is verified. The order of magnitude of connecter loads induced by collision is estimated. The result is shown that the influence of collision load cannot be neglected.
Key words: Very Large Floating Structure, Mobile offshore base, Connector, Collision， Time-domain solution, frequency-domain solution
目..
21世纪是海洋的世纪，海洋成为国家综合国力竞争的制高点，经略海洋、兴海强国已经成为我国国家发展战略的重要内容。近年来国际海洋工程界掀起了研究超大型海洋浮式结构物(VLFS——Very Large Floating Structure 简称VLFS)的热潮。超大型浮式结构物可用于海上补给、科考、能源基地以及海上城市等。出于我国国情，我们国家对超大型浮式结构物也开始进行了一系列概念论证。
本文研究的超大型浮式结构物由多个半潜式模块组成，各个模块间采用连接器进行连接，连接器采用柔性连接器，允许模块间的相对运动来减小连接器载荷。
超大型浮式结构物在营运过程中可能会遇到飞机坠落，船舶碰撞等事故情况。事故载荷不仅会对超大型浮式结构物的局部结构产生破坏作用，而且会对超大型浮式结构物的薄弱环节——连接器产生附加载荷。本文对船舶碰撞载荷对超大型浮式结构物载荷的影响进行了数值模拟。以船舶碰撞为例，采用简化的RMFC模型，然后通过SESAM软件计算水动力系数，将其代入多刚体运动微分方程后用数值方法求解，研究冲击载荷对连接器载荷的影响。将考虑模块间相互影响与不考虑模块间相互影响的结果进行了比较。比较表明在浪向角较大时，以及连接器刚度较大时可以不考虑模块间相互影响。
本文提出了两种数值解法，一种为简化频域解法，采用固定频率的水动力系数和波浪力，另一种为时域解法，通过频域中求得的水动力系数来计算时域的附加质量和记忆函数。两种解法表明在初步设计阶段采用简化频域方法来估算连接器载荷是可行的。
对不同连接器刚度以及不同撞击部位工况进行了比较，找到了载荷较小的连接器刚度以及导致连接器载荷最大的碰撞部位。同时比较了三种简化碰撞载荷模型，计算结果表明不同简化碰撞载荷模型差异不大，连接器碰撞载荷与碰撞冲量有关。比较了不同碰撞角度的计算结果，表明连接器载荷与碰撞的力矩很有关系。
最后本文计算了同时考虑波浪和碰撞载荷的计算结果，验证了碰撞载荷对连接器载荷影响的程度，估算出碰撞引起的连接器载荷的数量级，表明碰撞载荷对超大型浮式结构物连接器的影响不可忽略。
关键词 超大型浮式结构物；移动海上基地；连接器；碰撞；时域分析；频域分析
Abstract
The 21st century is the century of ocean. Ocean is the commanding heights of competition of comprehensive national strength. Sea power has become an important part of national development strategies. International marine engineering in recent years launched a study of very large floating structures (VLFS - Very Large Floating Structure referred to VLFS) of the boom. VLFS can be used as offshore supply, or scientific research, energy and maritime cities base. For the conditions of our country, our country has begun a series of proof of concept on VLFS.
VLFS studied in this paper is a kind of VLFS which is made up of several semi-submersible modules. The modules are connected with connectors. The connectors are soft to allow relative motion to minimize the connector load.
VLFS may meet with accidental damage due to airplane collision, ship collision, etc. Accidental loads will not only damage local structures of VLFS, but also induce additional loads on connector which is the weakest part of VLFS.The influence of ship collision on the VLFS is calculated by numerical solution.Taking ship collision as an example, by the use of simplified RMFC model, hydrodynamic coefficient is calculated by SESAM software. Then the hydrodynamic coefficient is taken into multi-body motion differential equation, and this equation is solved with numerical methods to study the influence of impact load on the connector load. The result considering the influence between modules and without considering the influence is compared. It indicates that the influence between modules can be neglected when the wave approach or the stiffness of connector is large enough.
Two numerical methods present here: the first is simplified frequency-domain solution which fixed frequency hydrodynamic coefficient and wave force is applied. The second is time-domain solution which the hydrodynamic coefficient is applied to calculate the added mass in infinite frequency and memory function. It is shown that the simplified frequency-domain solution is available in preliminary design stage of VLFS.
The result of different connector stiffness and collision position is compared. The stiffness of connector which cause minimum connector load and the collision position which cause maximum connector load is found. The three kind of simplified collision load models are compared. It is shown that there is slight difference between these models. The connector load is related with load impulse. The result of different collision angle is compared. It is shown that the connector load is related with the load moment
In the end of this paper, the connector load considering wave and collision load is calculated. The degree of influence is verified. The order of magnitude of connecter loads induced by collision is estimated. The result is shown that the influence of collision load cannot be neglected.
Key words: Very Large Floating Structure, Mobile offshore base, Connector, Collision， Time-domain solution, frequency-domain solution
目..
