基于细分曲面的船体曲面造型及静水力参数计算

提出采用细分曲面进行船体曲面造型,结合多边形及多面体的几何特性计算公式进行船舶静水力性能参数计算新方法。推导并整理出两套多边形及由三角单元围成的多面体的几何特性计算公式。根据文中方法对一组数学船型的部分静水力参数进行计算,并将计算结果与精确解进行比较,验证该方法的有效性。同时与传统的辛普生法、Maxsurf软件计算方法作了比较,说明所提出方法的有效性和通用性。     

基于参数化船模的静水力计算

船舶静水力要素全面表达了船舶浮性和稳性随吃水而变化的规律,能够综合反映船舶的静力性能。传统的二维计算方法过程较为繁琐,且计算结果精度受横剖面个数的影响。本文应用数学型线法和三维参数化建模方法,快速生成船体型线,精确构建附带属性和边界条件的船舶三维模型,通过对CATIA软件进行二次开发,将三维设计和静水力计算有效集成,提出基于船舶三维参数化建模的静水力计算方法,可以直接计算和获取其静水力要素,操作简单,结果可靠,具有较强的实用性。     

基于NURBS表达的精确自由液面修正

提出了基于三维NURBS表达的精确自由液面修正方法。对船体曲面和甲板进行NURBS表达后,通过对任意倾斜液面下的舱容及容积心的计算以及给定舱室装载量条件下舱室内液体液面的确定,可计算出任意倾斜状态下液体自由流动后产生的倾斜力矩,从而得到精确的静稳性臂修正值。通过对不同舱型的舱室在不同装载量和不同浮态下的倾斜力矩的计算和比较分析,总结规范计算结果和精确解之间存在误差的原因,分析了误差随舱型、装载量和浮态变化的规律。该方法表明了采用精确自由液面倾斜力矩计算的必要性和工程应用价值,并给出在船体设计中如何根据实际情况进行精确自由液面修正的建议。     

船舶自由浮态阻力计算的改进算法

船舶在航行过程的阻力特性直接决定了船舶的动力性能,现代船舶工业的设计与制造水平不断提高,而船舶阻力特性是船舶结构设计时需要重点分析的影响因素,因此,研究船舶自由浮态下的阻力特性有重要意义。本文首先建立船舶的阻力数学模型,然后基于一种改进的流体力学分析方法-静态平衡算法对船舶的自由浮态阻力特性进行分析,并结合计算流体力学CFD算法进行阻力特性仿真,得到了较为准确的船舶自由浮态阻力特性曲线。     

海洋平台拖航稳性三维通用计算方法

提出了一种基于三维实体造型的海洋平台拖航稳性计算方法.采用边界表达(B-Rep)实体造型技术,精确建立海洋平台的浮体模型,因而算法具有较高的精确性和通用性.提出了一种计算自由浮态下回复力臂的迭代算法,与传统的算法相比具有更高的精度和效率,而且算法稳定可靠.提出了静稳性曲面及其计算方法,利用静稳性曲面可以准确地校核海洋平台各方向的拖航稳性,比传统的稳性计算方法更为合理.该稳性计算方法与海洋平台的具体形状(例如是否离散、是否对称等)无关,理论上可以推广到各种复杂的船舶及海洋结构物的稳性计算中,具有较强的通用性.通过实例证明算法的正确性和工程实用性.     

基于差分进化算法的船舶自由浮态计算研究

及时准确获取船舶破损后的浮态参数是采取正确抗沉措施的重要前提,所以船舶自由浮态计算是船舶破损后快速扶正首先要解决的问题。采用差分进化算法对平衡多目标函数进行求解。差分进化算法采用实数编码,选择阶段采用了贪婪算法,实现更加简单。根据对2,000t专业溢油处置船的计算,并与遗传算法比较,计算结果更为精确,收敛速度相当。该方法可以在保证较高的收敛速度前提下,提高自由浮态的计算精度。     

基于四面体网格的船舶静水力计算方法精度研究

四面体方法非常适合分析多凸体(浮式海洋平台、子母船和半潜船等)结构的浮态问题,该方法已经在多个工程领域进行了应用,但是对其静水力计算方法的精度研究还未见报道.文章首先介绍了基于四面体网格的静水力计算方法,然后通过椭球算例研究了典型静水力参数的计算精度与单元尺寸的关系.算例选取了 5种不同的单元边长,针对浮体的3个典型静水力参数,进行精度分析.试验结果表明,四面体算法的精度控制水平与Maxsurf大致相当,当单元边长取为主尺度最小值的5％时,该算法即可取得满意的精度.     

船体破损后总纵剩余强度预报

阐述采用符拉索夫拉沉性计算方法解决破损船舶总纵强度计算中的外载荷和破损模型等问题。研究破损船舶问题是在不沉性理论基础上进行的。首先从研究在静水中既朋纵倾又有横倾时船舶浮态参数入手，进而研究静置在波浪上的船舶浮态参数、波浪弯矩和波浪剪力。     

液货船稳性计算及校核方法研究

在现有船舶稳性计算方法的基础上,分析了各种船舶稳性计算的特点,包括船舶的浮态、静稳性、动稳性、初稳性、大倾角稳性和气象衡准。考虑到液货船舶的纵倾和自由液面对船舶浮性和船舶稳性的影响,探讨任意载况下自由液面对稳性曲线修正的计算方法,实现了液货船稳性曲线修正的实时计算。最后以一艘大型LNG船舶为例,对该船舶在港时的浮态、静稳性进行了计算,并与该船的装载手册进行了对比,验证了所述计算方法的精度和可行性。     

基于CATIA的三维船舶静水力计算研究

传统的基于二维插值的近似计算船舶静水力性能的方法在精度上有不可避免的劣势,且操作也较为繁琐。提出了一种基于船舶三维实体模型计算静水力性能的方法,该方法脱离了二维插值,以三维实体模型为基础进行计算。在CATIA平台环境下,通过制作船舶三维实体模型,再应用VB对CATIA进行功能上的二次开发来编制船舶静水力计算程序,从而实现自动提取实体模型信息,并应用这些信息进行静水力计算。最后,通过一个算例证明了该方法的易于操作性和计算可靠性。     

船舶轴系扭振计算和测试实例分析

船级社规范对轴系扭振提出了计算和实测的要求。本文对若干轴系固有频率的实测值与计算值不一致的船舶进行了分析，并给出了对影响其相应计算精度的减振器、曲轴、联轴节刚度等扭振参数进行了修正的实例；通过实测，对无阻尼自由振动计算的振型精度亦进行了分析，按振型推算系统响应超规范要求的船舶，可根据实测振幅来调整阻尼参数并用解析计算法来评价轴系扭振特性。结果表明，精确测定出系统的固有频率和振幅，从而核定轴系的扭振参数，是提高扭振计算精度的关键所在。     

A non-geometrically similar model for predicting the wake field of full-scale ships

The scale effect leads to large discrepancies between the wake fields of model-scale and actual ships, and causes differences in cavitation performance and exciting forces tests in predicting the performance of actual ships. Therefore, when test data from ship models are directly applied to predict the performance of actual ships, test results must be subjected to empirical corrections. This study proposes a method for the reverse design of the hull model. Compared to a geometrically similar hull model, the wake field generated by the modified model is closer to that of an actual ship. A non- geometrically similar model of a Korean Research Institute of Ship and Ocean Engineering (KRISO)’s container ship (KCS) was designed. Numerical simulations were performed using this model, and its results were compared with full-scale calculation results. The deformation method of getting the wake field of full-scale ships by the non-geometrically similar model is applied to the KCS successfully.     

用于船舶伴流场预报的一种非几何相似的模型（英文）

The scale effect leads to large discrepancies between the wake fields of model-scale and actual ships, and causes differences in cavitation performance and exciting forces tests in predicting the performance of actual ships. Therefore, when test data from ship models are directly applied to predict the performance of actual ships, test results must be subjected to empirical corrections. This study proposes a method for the reverse design of the hull model. Compared to a geometrically similar hull model, the wake field generated by the modified model is closer to that of an actual ship. A non- geometrically similar model of a Korean Research Institute of Ship and Ocean Engineering(KRISO)'s container ship(KCS) was designed. Numerical simulations were performed using this model, and its results were compared with full-scale calculation results. The deformation method of getting the wake field of full-scale ships by the non-geometrically similar model is applied to the KCS successfully.     

Onboard monitoring of fatigue damage rates in the hull girder

Most new advanced ships have extensive data collection systems to be used for continuous monitoring of engine and hull performance, for voyage performance evaluation etc. Such systems could be expanded to include also procedures for stress monitoring and for decision support, where the most critical wave-induced ship extreme responses and fatigue damage accumulation can be estimated for hypothetical changes in ship course and speed in the automatically estimated wave environment.The aim of this paper is to outline a calculation procedure for fatigue damage rate prediction in hull girders taking into account whipping stresses. It is conceptually shown how such a method, which integrates onboard estimation of sea states, can be used to deduce decision support with respect to the accumulated fatigue damage in the hull girder.The paper firstly presents a set of measured full-scale wave-induced stress ranges in a container ship, where the associated fatigue damage rates calculated from a combination of the rain-flow counting method and the Palmgren-Miner damage rule are compared with damage predictions obtained from a computationally much faster frequency fatigue analysis using a spectral method. This analysis verifies the applied multi-modal spectral analysis procedure for fatigue estimation for cases where hull girder flexibility plays a role.To obtain an automated prediction method for the fatigue damage rates it is in the second part of the paper shown how a combination of the full-scale onboard acceleration and stress measurements can be used to calculate sea state parameters. These calculated environmental data are verified by a comparison to hindcast data.In the third part of the paper the full-scale fatigue stress ranges are compared to results from an analytical design oriented calculation procedure for flexible ship hulls in short-term estimated sea states.Altogether, it is conceptually shown that by a combination of the onboard estimated sea state parameters with the described analytical fatigue damage prediction procedure a method can be established for real-time onboard decision support which includes estimates of fatigue damage rates.     

一种减小中拱中垂对测深表影响的方法

针对实船测试数据反映出的中拱、中垂变形会对测深表的精度产生影响的问题,采用曲线拟合的方法精确计算船舶的实际倾斜状态,计算结果表明,使用经过曲线模拟推导出的纵倾修正公式后,计算的舱容数据更接近实际情况。通过这种方法可以有效减少中拱中垂对测深表的影响。     

舰艇浮稳性保持与优化计算机辅助决策系统

浮稳性对于舰艇航行的安全性有重大影响。与民用船舶不同的是,舰艇还面临着在战斗中遭受损坏的危险,所以对于舰艇而言,做好浮稳性的优化和保持工作是一项重要的任务。本文详细介绍了所开发的舰艇浮稳性保持与优化计算机辅助决策系统(简称WFSMO-CADS),该系统具有较为全面的为舰艇浮稳性保持与优化工作提供辅助决策的功能,主要包括自动计算任意装载状态下的舰艇浮稳性性能指标、自动提供日常使用中舰艇浮稳性最优保持方案以及自动生成舰艇受损进水后的最优科学抗沉方案等方面的功能。     

滚装重荷载应急卸载过程的浮基多体系统动力学分析

在救灾和战争等非常情况下，利用中小型近海滚装渡轮或改装后的渔轮渡海输送重荷载，具有可征用船只数量多和装卸载不依赖吊装设备等优点。缺乏港口屏蔽的海浪环境中重荷载进行滚动卸载时，必须考虑波浪对船的作用和重荷载与船的相互作用。本文通过对船在波浪中所受表观重力和表观浮力的分析，导出波浪作用力矩的计算公式。运用浮基多体系统动力学方法，建立波浪-浮基-重荷载系统的动力学方程。使用标准的龙格-库塔四阶方法进行数值积分求解。考虑海况、船型和重荷载在船上运动参数等因素，计算了各工况下的横摇运动响应。进而给出了重荷载安全快速卸载的驾驶操作要求及相关运动规律。     

型船空船重量推算法

推算型船的空船重量是船舶总体设计人员在确定设计方案或进行设计审核时常要做的关键性工作。利用静水力曲线的近似计算公式,分别根据型船设计吃水和结构吃水两个载重量来推算空船重量,并与其他方法进行比较 可供总体设计人员对型船分析换算时作为参考。     

Prediction of the vibratory properties of ship models with realistic structural configurations produced using additive manufacturing

The use of flexible ship models to determine the dynamic behaviour of full-scale ships in waves and to compare the accuracy of numerical predictions has increased in the past few years. Segments attached to a flexible uniform backbone of suitable but simple cross section is the preferred solution. Although such models are relatively easy to manufacture with conventional processes, they do not represent accurately the structural detail, for example, of a container ship. The limitations of conventional manufacturing constraints can be potentially overcome by use of modern technologies such as additive manufacturing. Designing detailed elastic ship models requires the determination of dynamic material properties, in addition to the manufacturer mechanical properties.In this investigation, a detailed but easy-to-implement method is developed, and applied to a uniform container ship-like model, to identify the material properties that are relevant to the calculation of the natural frequencies of 3D printed thin-walled structures. It is demonstrated that modal testing of 3D printed specimens, combined with FEAmodelling, can be used to accurately predict the natural frequencies of much more complex thin-walled structures. This method allows investigators to acquire all information necessary during the design stage of 3D printed structures without having to resort to full material characterisation.