Discrete element modeling of ice loads on ship hulls in broken ice fields

Ice loads on a ship hull affect the safety of the hull structure and the ship maneuvering performance in ice-covered regions. A discrete element method （DEM） is used to simulate the interaction between drifting ice floes and a moving ship. The pancake ice floes are modelled with three-dimensional （3-D） dilated disk elements considering the buoyancy, drag force and additional mass induced by the current. The ship hull is modelled with 3D disks with overlaps. Ice loads on the ship hull are determined through the contact detection between ice floe element and ship hull element and the contact force calculation. The influences of different ice conditions （current velocities and directions, ice thicknesses, concentrations and ice floe sizes） and ship speeds are also examined on the dynamic ice force. The simulated results are compared qualitatively well with the existing field data and other numerical results. This work can be helpful in the shil3 structure design and the navigation securitv in ice-covered fields.

Added Resistance Acting on Hull of a Non Ballast Water Ship

In this paper, added resistances acting on a hull of non ballast water ship(NBS) in high waves is discussed. The non ballast water ships were developed at the laboratory of the authors at Osaka Prefecture University, Japan. In the present paper, the performances of three kinds of bow shapes developed for the NBS were theoretically and experimentally investigated to find the best one in high waves. In previous papers, an optimum bow shape for the NBS was developed in calm water and in moderated waves. For a 2 m model for experiments and computations, the wave height is 0.02 m. This means that the wave height is 15% of the draft of the ship in full load conditions. In this paper, added resistances in high waves up to 0.07 m for a 2 m model or 53% of the full load draft are investigated. In such high waves linear wave theories which have been used in the design stage of a ship for a long time may not work well anymore, and experiments are the only effective tool to predict the added resistance in high waves. With the computations for waves, the ship is in a fully captured condition because shorter waves, λ/Lpp<0.6, are assumed.

Ship hull plate processing surface fairing with constraints based on B-spline

The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.

GPU-Based DEM Simulations of Global Ice Resistance on Ship Hull During Navigation in Level Ice

The ice resistance on a ship hull affects the safety of the hull structure and the ship maneuvering performance in icecovered regions.In this paper,the discrete element method(DEM)is adopted to simulate the interaction between level ice and ship hull.The level ice is modeled with 3D bonded spherical elements considering the buoyancy and drag force of the water.The parallel bonding approach and the de-bonding criterion are adopted to model the freezing and breakage of level ice.The ship hull is constructed with rigid triangle elements.To improve computational efficiency,the GPU-based parallel computational algorithm was developed for the DEM simulations.During the interaction between the ship hull and level ice,the ice cover is broken into small blocks when the interparticle stress approaches the bonding strength.The global ice resistance on the hull is calculated through the contacts between ice elements and hull elements during the navigation process.The influences of the ice thickness and navigation speed on the dynamic ice force are analyzed considering the breakage mechanism of ice cover.The Lindqvist and Riska formulas for the determination of ice resistance on ship hull are employed to validate the DEM simulation.The comparison of results of DEM,Lindqvist,and Riska formula show that the DEM result is between those the Lindqvist formula and Riska formula.Therefore the proposed DEM is an effective approach to determine the ice resistance on the ship hull.This work can be aided in the hull structure design and the navigation operation in ice-covered fields.

Ship Resistance of Quadramaran With Various Hull Position Configurations

Multihull 轮船广泛地被使用因为有四壳的海运，和那些作为 quadramarans 被知道。quadramaran 的赫尔位置配置包括钻石， tetra，和片。一般来说，以高速度旅行的 multihull 容器比 monohull 发货的有更好的水动力学效率。这研究试图为 2 m 长度， 0.21 m 宽度，和 0.045 m 厚度的壳尺寸在轮船抵抗上识别各种各样的 quadramaran 壳位置配置的可能的效果。我们进行了我们在在 0.08 和 0.62 之间的 Fr 价值改变了壳间距和速度并且用一个负担房间变换器测量了全部的抵抗的拖引的测试。试验性的结果表明最低全部的抵抗在 Fr = 与 S/L = 3/10 和 R/L = 1/2 在 Fr = 0.1-0.6 和多达 0.35 的一个有效干扰因素与一种钻石 quadramaran 配置被完成 0.62。

Reliability Analysis Based on a Direct Ship Hull Strength Assessment

基于采用 von 的直接力量计算，协定强调失败标准的可靠性分析的一个方法这里被介绍。轮船壳的短术语紧张分布结构的部件通过导致波浪的紧张历史的统计分析被识别，由短术语的加权的求和的长期的分布拉紧分布。导致波浪的长期的紧张分发与静止的水紧张被相结合。反应紧张的极端紧张分发被联合紧张的统计分析获得。可靠性分析的限制状态功能基于 von 协定压力失败标准，包括由于材料的质量的相关无常和模型无常。可靠性索引用在可靠性上有效果的每个变量的形式和敏感分析被计算也被讨论。

Numerical Simulation of the Stokes Wave for the Flow around a Ship Hull Coupled with the VOF Model

流动在在水的免费表面附近移动的轮船壳附近产生的表面波浪在这研究数字地被模仿。三维的含蓄的有限体积方法(FVM ) 被使用解决雷纳兹平均海军司烧(RANS ) 方程。可实现的 k-e 骚乱模型被实现了在免费表面地区在轮船壳附近捕获狂暴的流动。方法结合了的液体(VOF ) 的体积 Stokes 波浪理论被用来决定水的免费表面效果。由使用是一自由的六度当模特儿，轮船壳运动数字地一起与 Stokes 波浪被解决。在行动下面司烧海，在空气之间的接口和在一样的常规模式并且那么的水波浪上的波浪做压力和垂直速度。轮船壳搬到象波浪的一样的方法。轮船壳举的振幅是不到波浪高度因为抑制的粘性。这个方法能为轮船运动，波浪和水动力学的学习提供一本重要参考书。

Collision Analysis of the Unconventional Double Hull of a Ship

Following to the great accidents the interest in preventing environmental pollution and the safety of people and means of maritime transport have increased. The idea of developing new, unconventional structures, imposed by the new requirements of Shipbuilding Rules related to safety and pollution is analyzed in the paper. The behavior of the unconventional double hull of a ship structure concept, named ARC, loaded to transversal impact is treated. In the paper the finite-element analysis is used because is important to provide the structural designer that no stress concentrations exist in a certain design. The results obtained for energy absorption and general ship hull behavior encouraged the authors to introduce in shipbuilding the unconventional double hull of the ship structure concept.

3D Layout Algorithm for Laying Rectangular Tiles on Ship Hull

A new 3D layout algorithm to lay rectangular tiles on the 3D hull surface model is proposed to improve the algorithm performance in accelerating layout process and enhancing design accuracy. Three times optimizations are carried out upon the original basic algorithm, namely optimization of calculating range, separation of surface flattening computation from laying computation, and optimization of interior point distribution. By testing, the generated surface layout drawing by the refined system is fairly applicable to guide the actual tiles＇ coating process.

面向CAD/CAE一体化的船体结构有限元建模方法

船体结构有限元分析是船舶研制中的一项重要工作。其中,船体结构有限元网格的质量对分析结果有着重要影响。随着CAD/CAE一体化的发展,直接将CAD设计模型转换为CAE有限元分析模型已成为普遍做法,然而船体结构复杂,仍需耗费大量人工时间对生成的有限元分析模型进行网格调整与优化,这严重影响了设计效率和质量。针对这一问题,本文提出一种船体结构有限元建模方法,将主流网格处理软件与专项功能开发结合,实现网格自动优化,减少人工处理工作量。以某集装箱船的货舱舱段进行了验证。结果表明,本方法在确保网格质量满足要求的同时,能够减少设计人员工作量,提高网格处理效率。

豪华邮轮全船线型优化及截流板设计

为了降低航行阻力,满足豪华邮轮营运经济性的需求,对某8万总吨级豪华邮轮进行了基于阻力性能的全船线型优化及截流板设计。首先,结合CAESES的半参数化变形和SHIPFLOW的势流计算方法,针对目标船进行了兴波阻力最小化的线型优化,再对典型优化方案采用STAR-CCM+计算粘流总阻力,评估优化效果;其次,针对优化的船型方案进行了截流板的设计,进一步降低船型总阻力;最后,通过模型试验验证优化效果。试验结果显示,优化线型安装优选截流板后相对于原型实船有效功率下降了7.8%,证明了所采用的豪华邮轮线型优化和截流板设计方法的可行性。

FPSO Hull项目进度测量系统的建立

对国内造船企业的项目进度测量现状进行了分析,并根据FPSOHull建造的管理要求和船舶企业的管理特点,详细论述船舶企业建立FPSOHull建造的进度测量系统原则、思路和方法.提出的思路与方法不仅适用于船舶企业的FPSOHull的建造的进度测量,亦适用于一般船舶的建造进度测量.

船舶骑冰事故下船体梁结构强度特征分析

[目的]针对船体梁与冰层相互作用后的结构强度变化问题,提出骑冰工况下船体梁结构强度分析方法,揭示相应的结构强度特征。[方法]首先,建立船体梁结构强度分析模型,并根据各分段属性建立对应的船体梁载荷分析模型;然后,在载荷分析模型中求解得到骑冰工况的浮力分布并代入结构强度分析模型中,以考虑骑冰带来的浮力变化;最后,施加重力及冰层支反力,进行结构强度计算,并分析抬升位置和抬升高度对船体梁浮力、剪力、弯矩以及局部应力分布的影响。[结果]结果显示,当船首抬升高度变化时,船体梁存在浮力与剪力不随抬升高度变化的点,该点分别位于船体梁后半段以及船中;当抬升位置位于球鼻艏时,该部位的舷侧外板更接近于垂直,不利于抵抗冰层支反力,导致高应力面积相对较大,更危险。[结论]采用所提方法能够计算船体梁结构在船首大幅度抬升情况下的结构响应,计算效率高,可初步判断危险骑冰工况下船体梁的结构强度。

基于水动力载荷混合数据集的高精度神经网络代理模型构建

In this work,we constructed a neural network proxy model(NNPM)to estimate the hydrodynamic resistance in the ship hull structure design process,which is based on the hydrodynamic load data obtained from both the potential flow method(PFM)and the viscous flow method(VFM).Here the PFM dataset is applied for the tuning,pre-training,and the VFM dataset is applied for the fine-training.By adopting the PFM and VFM datasets simultaneously,we aim to construct an NNPM to achieve the high-accuracy prediction on hydrodynamic load on ship hull structures exerted from the viscous flow,while ensuring a moderate data-acquiring workload.The high accuracy prediction on hydrodynamic loads and the relatively low dataset establishment cost of the NNPM developed demonstrated the effectiveness and feasibility of hybrid dataset based NNPM achieving a high precision prediction of hydrodynamic loads on ship hull structures.The successful construction of the high precision hydrodynamic prediction NNPM advances the artificial intelligence-assisted design(AIAD)technology for various marine structures.

基于动刚度法的水面船舶桨-轴-船体耦合系统

为分析在低频段内船体两侧螺旋桨激励相位差对船体振动的影响,基于动刚度法建立水面船舶桨-轴-船体耦合系统的横向振动3梁耦合模型。将动刚度法的计算结果与有限元法进行对比,表明动刚度法具有良好的精度。分析桨-轴-船体耦合系统的垂向固有振动特性。在低频段内该系统主要表现为船体梁的振动,推进轴系对船体梁的固有特性影响较小。对左右双桨分别施加不同相位差的单位垂向简谐力,计算由各轴承位置输入至船体梁的功率流。结果表明,双桨激励相位差的增大会使输入至船体梁的功率流变小。因此,在对桨-轴-船体耦合系统的横向振动控制方面,应重点关注双桨激励相位差较大时的工况。

考虑跨洋特征及碎冰对快速性影响的极地探险邮轮型线优化

[目的]全球减碳背景下,为应对极地船舶设计建造的环保要求,需开展跨洋航行时碎冰水域对极地探险邮轮船体型线优化设计的影响规律研究,以获得最佳节能型线。[方法]针对极地探险邮轮的跨洋航行特征,采用航区权重方法进行量化评估,分析碎冰对阻力和推进效率的影响。应用计算流体力学耦合离散元法(CFD-DEM)来分析螺旋桨的碎冰水域性能,建立以联合自航功率为目标的优化模型,进而对全船参数化模型开展设计航速下的优化计算。[结果]计算结果表明,优化后的船型可以满足排水量要求,有效降低了2种水域下的航行功率,其联合自航功率降低了9.71%。[结论]研究成果验证了基于权重优化方法的可行性和合理性,可为极地探险邮轮的型线和推进器优化设计提供参考。

改进高效全局优化算法在船型优化中的应用

船型优化问题的复杂度越来越大,导致昂贵数值计算量越来越大,进而优化成本越来越高,对优化技术提出了更高的要求:精简计算量,降低优化成本。本文针对高效全局优化算法进行研究和开发,对其初始样本点、加点法则以及收敛条件等进行了探讨,采用多种初始样本点数启动优化,采用“期望函数”作为单目标加点法则以及欧氏距离EIM函数作为多目标加点法则,使用遗传算法对加点函数进行寻优精确定位最佳新增样本点,并通过标准优化测试函数进行了验证。为船型优化问题提供了新的思路。

船体外板板材规范设计

在超大型集装箱船船体结构详细设计中,改变以往主要参照母型船板材尺寸开展设计的做法,引入规范软件核算全船外板板材的规格。根据船体结构的线型特点统筹规划外板板材,重点分析常规船体外板板材的布置形式和艏艉波浪砰击作用下的船体外板板材布置形式,并对相关参数进行计算,以期在保证船体结构强度满足要求的同时提升板材的利用率。船体艉部砰击外板板材和艏部砰击外板板材计算结果表明,尽管计算结果会受到多种因素的影响,但最主要的因素是肋骨间距。该船体外板板材规格核算方法有效,后续可延伸到其他类型船舶中,供其船体板材规范计算参考。

面向智能化船舶的船体设计新思路与新方法探究

文章总结了基于人工智能的船体设计与优化算法在智能化船舶中的应用,以及智能化工艺与制造技术在船体加工中的实际应用。同时,探讨了数据驱动的船体设计与优化方法在实际船舶设计中的应用,以及如何将新方法和新技术与船体设计有机结合。通过对船体设计新思路与新方法的探究,为智能化船舶的建造和发展提供了新的思路与方向。