基于非线性有限元法的船舶冰区破冰数值模拟

应用非线性有限元法进行了破冰船冰区破冰数值模拟。通过比较数值模拟结果和试验结果,对冰体材料模型进行了验证;采用该冰体材料模型,对破冰船以不同航速在不同厚度的层冰中破冰航行时的动态响应进行了数值研究,给出了破冰过程中层冰的变形、冰力的大小以及冰的变形能和动能变化,分析了船速、冰层厚度对破冰阻力的影响。该研究结果对分析破冰船在层冰中破冰时的动态响应特性具有一定的参考价值。     

Dilated-polyhedron-based DEM analysis of the ice resistance on ship hulls in escort operations in level ice

The ice resistance on ships in escort operations in level ice are investigated using the discrete element method (DEM). A dilated polyhedron—generated by the Minkowski sum of a sphere and a polyhedron—is employed in the DEM; this dilated polyhedron-based DEM (DPDEM) is adopted to simulate the ship–ice interaction, wherein the contact force and bond-failure criterion are considered for the collision and fracture of sea ice, respectively. A three-point bending test was simulated with DPDEM, and a field test was conducted in the Bohai Sea to validate the DEM results. Further, a parametric analysis of flexural strength was conducted to identify the parameters involved in the bond-failure criterion. The ice resistance on icebreakers and cargo ships in level ice are simulated using DPDEM. The simulated ice resistances are compared with the Lindqvist and Riska formulas and the model test, which proves the validity of the DEM simulation. The interaction between ships and level ice is simulated parametrically to investigate the ice resistance on cargo ships with and without the icebreaker escort. Influencing factors such as ship speed, ice thickness, and ship breadth were examined to investigate the ice resistance on the escorted cargo ship. Analysis and change rules of the ice resistance on cargos affected by those factors were given.     

基于改进蚁群算法的船舶冰区航行路径规划

在北极航道开通的背景下,针对在冰区航行环境中船舶航行路径选择的特殊性,通过改进蚁群算法提高船舶航行路径的规划效果。综合考虑航线距离、航行操作复杂度和流冰规避在内的冰区航行路径影响因素,建立路径选择多目标规划模型,结合人工势场法对蚁群算法进行改进,通过人工势场法获得初始路径和节点间距离因素构造启发信息,并以电子海图为基础建立海冰覆盖率分别为30%和50%情况下的冰区航道环境栅格模型,将算法应用在栅格模型中对算法进行验证。结果表明:该算法实现简单,规划的路径优良,能够有效地满足船舶在冰区复杂环境中航行路径规划的需要。     

破冰船冲撞式破冰结构强度数值仿真方法研究

本文基于瞬态动力学分析法对破冰船冲撞式破冰过程进行有限元数值仿真研究.针对该方法中的船冰撞击分析、海冰浮力模拟等一些关键问题进行研究,根据上述方法对某破冰船冲撞式破冰过程进行数值模拟,并对应力计算结果进行校核.总之,本文建立的一套评价破冰船冲撞式破冰过程船体应力方法,对于中国老龄破冰船的强度评估具有重要意义.     

破冰船冲撞式破冰模拟及结构损伤分析

提出一种适用于船冰碰撞的海冰材料模型。基于该材料模型,通过非线性有限元模拟冰台撞击刚性墙,验证该模型的正确性,并成功将其运用于某PC3冰级破冰船冲撞式破冰过程数值模拟中。研究破冰船冲撞不同厚度层冰的动响应结果,总结船冰相互作用过程中碰撞力和能量的变化、船体结构损伤特性和破冰能力,研究成果可为破冰船结构设计提供参考。     

Identification of ice loads on shell structure of ice-going vessel with Green kernel and regularization method

Ice loads are important environmental loads that can influence the structural safety of ships during navigation in ice-covered waters. The identification of ice loads on ship hulls is the core of ice load monitoring. In this study, a new ice load identification model based on Green kernel and regularization methods is established. First, the forward model for ice load identification is developed through the discretised convolution integral of ice loads. Next, three commonly used regularization methods, including Tikhonov, truncated singular value decomposition, and least square QR-factorization (LSQR) are adopted to reduce solution errors. The LSQR method is thereafter selected as the optimal regularization operator, and its regular property is proved by numerical cases with ice-induced strains that contain noise. Finally, two load identification cases are conducted on an experimental rig to evaluate the feasibility of the model in ice load identification. The identified loads can determine the signal features of applied loads in the time domain with good accuracy. This identification model provides new insights for full-scale ice load monitoring.     

Numerical Simulation of Turret Moored Ship Performance in Variable Ice Drift Based on Heading Control

The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action.     

Design and implementation of a visual monitoring system to ensure safety in the water surrounding a container vessel

Container vessels navigate among the world's ports, frequently passing through narrow and congested waters. Due to the many layers of containers on a container vessel's decks, it is difficult for the crew to be aware of all fishing vessels and other obstacles in a container vessel's radar observation blind zone. This greatly increases the risk of collisions and other accidents. Given such great challenges to safe navigation and safety management with container vessels, their security risks are severe. An effective visual monitoring system can improve the safety of the water area surrounding container vessel by eliminating a vessel's observation blind zone, providing an effective safety measure for vessels navigating fishing zones and other troublesome areas. The system has other functions, such as accident recording, ship security, and monitoring of loading and unloading operations, thus ensuring the ship operates safely. Six months' trial operation showed that the system facilitates safe navigation of container vessels.     

桥梁主通航孔施工期通航方案及保障措施

我国内河水域新建桥梁在对主墩进行施工过程中,为了确保船舶正常通航,海事部门要求实行单向通航。因此,主墩施工期间桥区水域可能出现船舶排队等候过桥的现象,船舶等候过桥势必增加桥区水域复杂的通航环境,目前海事部门规定桥区水域(单向通航)航行的船舶之间应保持足够的安全距离。通过建立数学计算模型对桥区水域(单向通航)通航船舶之间安全距离进行量化研究,探讨出桥区水域船舶之间安全距离计算方法。为海事部门制定桥区水域通航安全管理规定、维护桥区水域良好的通航秩序和船舶过桥安全提供科学的理论依据。     

基于SPH方法的连续式破冰数值模拟

根据海冰的力学性质,采用光滑粒子流体动力学(SPH)方法建立海冰本构模型,模拟冰锥实验并与实验结果对比,对冰材料模型准确性进行验证.利用显式动力分析软件LS-DYNA模拟破冰船连续式破冰,得到了海冰的损伤变形和破冰阻力,同时研究了船舶航速和海冰厚度等参数对冰载荷的影响.分析研究表明:应用SPH方法建立的海冰模型能够真实的反映海冰的力学性能,对连续式破冰过程实现较为准确的模拟,为船冰碰撞的数值模拟提供了新思路.     

破冰船动力系统及主推进器发展现状

针对海洋科考、极地航道、极地资源探索等重要的国家需求,破冰船对于我国极地方针的重要性日益突显.通过搜集、整理、分析世界主要破冰船数据,按照注册冰级对现有破冰船进行分级,阐述世界各国破冰船发展规模,并对各类推进系统及主推进器在破冰船上的应用现状和特点进行分析和总结,以期为我国自主研发破冰船推进方案的选取提供参考.     

基于MD Nastran的船-冰碰撞数值仿真研究

船舶与海冰的碰撞过程十分复杂,涉及多种非线性问题。文章运用 MD Nastran对船舶艏部与冰的碰撞进行数值仿真计算,来模拟这一过程。得到了碰撞结束后,船首和海冰的损伤变形情况,船体结构的应力应变情况,以及在船—冰相互作用过程中的能量变化,应力应变变化。研究结果描述了船舶与冰碰撞的详细过程,揭示了冰载荷作用下船体结构的响应规律,可为船舶抗冰载荷设计提供参考。     

解析船舶安全航行的桥楼航行值班报警系统

桥楼航行值班报警系统(BNWAS)旨在通过安全监视功能来监视驾驶室值班员的活动,当值班驾驶员(OOW)失去履行其职责的能力而发出警报时,以尽可能避免与驾驶台操作有关的海上事故[1-2]。该系统对海上船舶的安全航行尤为重要,但仍存在某些不足。通过对该系统组成、功能和原理的分析,提出使用中的一些疑惑和自己的理解及建议,为提高船舶安全航行提供参考。     

龙溪口枢纽最低蓄水位下船闸上游通航条件及改善措施

岷江龙溪口航电枢纽工程第3期导流期间利用右岸船闸临时通航，由于上游蓄水位相对较低，汛期大流量条件下船闸上游引航道口门区与连接段水域存在较大的通航风险。为确保施工期通航安全，结合枢纽施工导流及通航模型试验结果，开展了最低蓄水位下船闸上游通航条件数值模拟研究，并提出优化上引航道左导墙结构形式、降低鸡公嘴开挖高程以及抛填深沱等工程措施。结果表明，上游通航水流条件明显改善，可满足施工期通航要求。     

Analysis of ship drifting in a narrow channel using Automatic Identification System (AIS) data

With maritime transportation has played an important role in global economy development, ship traffic has become more congested. Therefore, ships navigate under risk conditions, and thus maritime accidents have occurred frequently. Especially, ship passing through a narrow channel is even more dangerous. Because, the ships are easy to be affected by external forces such as wind and currents that can cause ship drifts. Many latent risks are present during navigation. In order for the development of a sensible and appropriate traffic model for the safety and efficiency ship navigation, this study has focused on the actual ship behavior to understand the ship drift in the Kurushima Strait, Japan, which is one of the most dangerous routes in Japan. The analysis of ship behavior was carried out using the Automatic Identification System (AIS) data. As a result, the ships drift was understood in detail, and the latent risk was unveiled when ships pass through the narrow route. Moreover, the risk areas were obtained and visualized by the ship drift behavior analysis. The obtained results can be applied to ensure safe navigation and the development of an eco-friendly and economy efficient for ship navigation.     

基于模糊层次分析法的天津港复式航道通航安全综合评价

通过构建天津港复式航道通航安全综合评价指标体系,建立复式航道通航安全评价模型,利用模糊层次分析法对天津港复式航道进行通航安全综合评价,为天津港港口营运与管理、海事监管与通航秩序维护提供理论支撑。     

辽东湾北部浅水区海冰对航行的影响及对策

辽东湾北部浅水区有许多石油开发区块,由于水浅有冰等因素,使在现有的破冰船和冰区航行技术条件下的航行十分困难。分沿岸冻结区、滩涂堆积区和流冰区等不同区带讨论辽东湾北部海冰存在特征以及海冰对航行的影响,并根据海冰存在特点和海域工程的具体特性提出相应的对策。     

冰区船舶操纵

本文详细分析了船舶在冰区航行时靠离码头，冰流中锚泊，冰中救助等冰区船舶操纵特殊情况，并总结经验。其对船舶在冰区安全航行具有很好指导意义。     

Arctic shipping scenarios and coastal state challenges

The Arctic Council, an intergovernmental forum of the eight Arctic states, is currently embarked on a comprehensive assessment of Arctic marine activity in the 21^st century — the Arctic Marine Shipping Assessment (AMSA). One of the challenges for theAMSA study team has been to identify the major uncertainties that will be central to shaping the future of Arctic marine use in 2020 and 2050. Using scenario planning, AMSA has identified two primary drivers and uncertainties: (A) Resources and trade; and, (B) Governance. Four scenario narratives have been developed with these two, key uncertainties as the framework elements. The main arguments focus on the fact the Arctic has experienced globalization early in the century and that the global maritime industry has already ventured into the Arctic Ocean. Marine access in the Arctic Ocean is also changing in unprecedented ways and the extraordinary transformation Arctic sea ice is undergoing — thinning, extent reduction, and a reduction in the area of multiyear ice in the central ocean — has significant implications for longer seasons of navigation. However, the high prices of global commodities such as oil, gas, and hard minerals (for example, copper, nickel and zinc) have generated high levels of demand for Arctic natural resources. The Arctic states are challenged by an overall lack of maritime infrastructure to adequately support current and future levels of Arctic marine operations; ports, communications, environmental monitoring, search & rescue, incident response, aids to navigation, and coastal charting, to name a few, require substantial and timely investment by the coastal states and marine operators. A second challenge is the ongoing development of an integrated system of rules and regulations governing Arctic navigation that will enhance marine safety and ensure marine environmental protection throughout the basin. These challenges will require historic levels of cooperation among the Arctic states and broad engagement with the many, non-Arctic stakeholders and actors within the global maritime industry.