船舶与浮式海洋平台碰撞的动力响应研究

发布时间：2018-06-02 03:37

本文选题：深水半潜式平台 + 碰撞　；参考：《江苏科技大学》2015年硕士论文

【摘要】：当今世界上,海洋油气资源的开发已经具有了非常大的潜能,目前海洋工程领域,已逐步实现了由近海向远海乃至深海的发展,我国海洋/深海油气资源特别丰富,其中的油气资源储备量大约是246亿吨,占我国石油、天然气资源总量的30%左右。在作业海域上,半潜式海洋平台开展钻井或采油时,在随机复杂的海洋环境下,除了受环境载荷的时刻作用外,过往的船只、守卫船、补给船等各种船舶由于航行操作过失或停靠被供给平台时,风、浪、流等环境载荷的作用,经常不可避免的发生与平台碰撞事故,并可能造成环境污染、结构损坏、重大的经济损失、人员伤亡等一些灾难性后果。特别是在深水和超深水海域,由于海况一般更为恶劣,则碰撞事故更容易发生。本文为了分析随机海洋环境载荷作用下,船舶与海洋平台碰撞的外部动力学问题,利用非线性显式有限元软件ANSYS/LS-DYNA建立了半潜式平台和供给船船尾的三维有限元模型,通过DYNA计算了船尾以2m/s速度垂直正碰半潜式海洋平台立柱的工况,获得了真实的碰撞力的时序结果。然后在此基础上结合外部动力学原理,将真实的碰撞力导入到水动力软件AQWA中,将半潜式平台在碰撞力和风、浪、流联合作用下进行时域耦合的水动力数值计算,得到了平台运动响应结果和不同系泊缆的受力情况。综上,本文将对船舶与半潜式海洋平台的碰撞进行数值计算研究。本论文主要研究内容包括:(1)进行了供给船船尾和半潜式海洋平台的模型化研究,其中半潜式海洋平台建立整体有限元模型,考虑到其碰撞受损伤位置主要是立柱区域,对立柱部分进行了详细的建模,同时为了减少模型的计算机时,对浮筒及上壳体内部做了大量的简化处理,甲板以及甲板以上的结构用一层加厚的甲板和质量块来代替,对于这些简化部分的重量以及它们的重心位置,可以在结构的对应部分通过LS-DYNA来控制其密度的方法来调整。船尾方面则考虑到船尾的刚度相对海洋平台立柱结构大的多,故模型中船尾简化为刚性模型,但计算结果相对保守。最终基于ANSYS软件建立平台和船尾的三维模型并划分有限元网格,并在此基础上利用非线性显式有限元软件LS-DYNA进行碰撞模拟仿真。(2)应用ANSYS/LS-DYNA显式非线性动力商业软件,采用Cowper-Symonds本构物理模型,用附加水质量方法对一艘5000t的补给船船尾以2m/s速度垂直撞击半潜式海洋平台立柱的例子进行数值仿真,对立柱部分做重点分析,获得了碰撞力的时序结果,部分关键时刻碰撞的应力云图,将碰撞力曲线不做任何简化的加载到水动力模型上进行水动力分析。水动力数值模拟分析主要有:频域和时域计算两部分。本文既应用时域分析方法,又应用频域分析方法对海洋结构物及其系泊系统在碰撞力作用下进行水动力性能分析研究。(3)频域分析结果主要表征海洋结构物在各个不同频率下的附加质量系数和辐射阻尼系数,还可以得到不同浪向下的运动响应RAO、一阶、二阶波浪力和传递函数等。本文将不作任何简化的碰撞力时程曲线导入到AQWA中,并借助水动力软件AQWA-Line,采用三维势流理论,对被碰撞的半潜式平台进行数值计算,得到相关的水动力参数。(4)时域分析方法主要是研究海洋结构物及其系泊系统在一定海洋环境条件下其运动响应和每根系泊缆的受力状况,求证其是否能够满足规范的要求。本文采用AQWA-Drift水动力软件对该半潜式平台进行时域耦合数值模拟,模拟计算了在碰撞力和风、浪、流联合作用下的平台的运动响应情况,不同系泊缆的受力情况。(5)由计算分析结果可见,由于碰撞位置发生在平台左舷后侧的立柱部位,有碰撞力作用的情况下,横荡、横摇和首摇的变化非常大,说明碰撞力的大小、方向和变化趋势对平台的运动响应有着直接和重要的影响,进而影响其作业效率和安全性,因此研究在实际作业过程中的平台碰撞是很有意义的。
[Abstract]:The development of marine oil and gas resources has been of great potential in the world today. At present, the marine engineering field has gradually realized the development from offshore to far sea and even deep sea. The marine / deep-sea oil and gas resources are very rich in our country, and the reserves of oil and gas are about 246 million tons, accounting for 30% of the total of China's oil and natural gas resources. Right. On the operating sea, when the semi submersible offshore platforms carry out drilling or oil production, in the random and complex marine environment, in addition to the time effect of the environmental load, the ships of the past, the guard ship, the supply ship and other ships are often unavoidable because of the environmental loads such as wind, waves, and streams due to the fault of the navigation operation or the supply platform. There are some catastrophic consequences such as environmental pollution, structural damage, major economic losses and casualties. Especially in deep water and ultra deep waters, the collision accidents are easier to occur because the sea conditions are generally worse. In order to analyze the load of the random marine environment, the ship and the ocean are analyzed. The three-dimensional finite element model of the semi submersible platform and the ship's tail is established by using the nonlinear explicit finite element software ANSYS/LS-DYNA. The working conditions of the stern with the vertical collision and semi submersible platform column of the ship's tail are calculated by DYNA, and the real time sequence results of the collision force are obtained. On the basis of the principle of external dynamics, the real collision force is introduced into the hydrodynamic software AQWA, and the hydrodynamic numerical calculation of the semi submersible platform is carried out in time domain coupled with the impact force, wind, wave and flow, and the results of the platform motion response and the force of different mooring cables are obtained. The main research contents of this paper are as follows: (1) a model study of the ship's stern and semi submersible offshore platform is carried out, in which the semi submersible offshore platform is established as a whole finite element model. Considering that the damage position of the offshore platform is mainly the vertical column area, the vertical column part is modeled in detail. In order to reduce the model computer, a large amount of simplification is done to the buoy and the interior of the upper shell. The deck and deck above are replaced by a thick deck and mass block. For the weight of these simplified parts and the position of their center of gravity, the density can be controlled by LS-DYNA in the corresponding part of the structure. At the end of the ship, the tail stiffness is much larger than that of the offshore platform column, so the tail of the ship is simplified as a rigid model, but the calculation results are relatively conservative. Finally, the three-dimensional model of the platform and the stern is established based on the ANSYS software and the finite element mesh is divided, and on this basis, the nonlinear explicit finite element software L is used. S-DYNA is used to simulate the collision. (2) using the ANSYS/LS-DYNA explicit nonlinear dynamic commercial software, using the Cowper-Symonds constitutive physical model, the numerical simulation of the vertical impact of the tail of a recharge ship on a semi submersible platform column at 2m/s speed is simulated with the additional water quality method. The time sequence result of collision force, the stress cloud of some critical moments, the collision force curve is not loaded into the hydrodynamic model to carry on the hydrodynamic analysis. The hydrodynamic numerical simulation analysis mainly includes two parts: frequency domain and time domain calculation. This paper applies the time domain analysis method and the frequency domain analysis method to the ocean junction. The hydrodynamic performance analysis of the structure and mooring system under the impact of the collision force. (3) the frequency domain analysis results mainly represent the additional mass coefficient and the radiation damping coefficient of the marine structures at various frequencies, and can also get the different wave motion response RAO, the first order, the two order wave force and the transfer function. Any simplified collision force time history curve is introduced into AQWA, and with the help of the hydrodynamic software AQWA-Line, the three-dimensional potential flow theory is used to calculate the collided semi submersible platform, and the related hydrodynamic parameters are obtained. (4) the time domain analysis method is mainly to study the transport of the marine structures and their mooring systems under certain marine environment conditions. The dynamic response and the force condition of each root system can prove whether it can meet the requirements of the standard. In this paper, the AQWA-Drift hydrodynamic software is used to simulate the time domain coupling of the semi submersible platform, and the dynamic response of the platform under the impact force and wind, wave and flow is simulated and the force conditions of different mooring cables are calculated. (5) The results show that the change of the size, direction and trend of the collision force has a direct and important influence on the motion response of the platform, which affects the efficiency and safety of the platform, as the collision position occurs on the post side of the platform side of the platform. Therefore, it is meaningful to study the platform collision in the actual operation process.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE95

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