Experimental and numerical investigation of lashing bridge and container stack dynamics using a scaled model test

Previously reported container losses were generally attributed to extremely violent motions of containerships due to adverse weather conditions. However, most existing specifications or standards adopted for containers and lashing equipment meet the requirement of static conditions. Hence, further researches on safer container shipping under heavy sea states are required. Consequently, an experimental study method is proposed to measure the dynamic response of 1/10 scaled lashing bridge and container stack. The scaled model of the lashing bridge is constructed based on the similarity theory. Based on two dimensionless numbers, Froude's number and Cauchy's number, eleven container scaled models are employed. A series of experiments with controlled parameters are performed using a three-degrees shaking table (roll, pitch, heave) to present sufficient data to verify the effectiveness of the numerical model. The results of experiments, numerical simulations and calculations of the VERISTAR procedure (developed according to the BV rule) are compared. This study aimed to explore the mechanical behavior of the lashing bridge and container stack under predetermined driving excitations (roll and pitch) which simulated heavy sea states. According to the results, the model can predict conditions similar to real situations of the lashing bridge and container stacks while storages on the weather deck.     

船运木材货物的注意事项

介绍了木材货物在甲板及舱内积载时的注意事项、系固绑扎方法及船舶航行途中应采取的措施,提出一些有益的建议,对木材船的安全运输有一定的帮助。     

Evaluation of expected maximum values of forces acting on containers and lashing rods on a container ship

The appearance of a number of large container ships in the 8000 TEU range raises the importance of a plan for container lashing arrangements on deck in relation to the design of the ship. Therefore, it is expected that a new method for evaluating the lashing arrangements on deck will be introduced which is applicable regardless of the ship's size and the lashing pattern, instead of using the standards of several different societies, as happens at present. To evaluate the lashing arrangements on deck, the expected maximum values of the forces acting on the containers and lashing rods should be evaluated. This paper presents a new method of evaluating the container lashing arrangements on a container ship using an "acceleration ellipsoid." The applicability of the acceleration ellipsoid to an evaluation of the expected maximum values of the forces was examined by comparing the expected maximum values of the forces calculated by the long-term distribution calculation known as the "Fukuda method," to those calculated using the acceleration ellipsoid. By comparing these results, it was confirmed that the expected maximum values of the forces calculated using the acceleration ellipsoid were not less than those calculated through by the long-term distribution calculation. It is concluded that the acceleration ellipsoid can be used to evaluate the expected maximum values of the forces acting on containers and lashing rods. Received: December 14, 2000 / Accepted: March 22, 2001     

Statistical study of lashing forces measured on-board a PCTC vessel

Lashing forces and reaction forces between the car tyres and ship deck were measured on-board a PCTC vessel operating in the North Atlantic and statistically evaluated. A study was done of the characteristics of lashing forces and defined required friction coefficient. The lashing forces and the required friction coefficient were found to be small. The influence of wave direction on the forces was also small.     

恶劣海况下拼装式机库受力和绑扎加强研究

为便于在动员民船上快速加装,某型直升机机库采用集装箱拼装结构。针对恶劣海况下机库的整体稳定性和安全性问题,研究通过采用绑扎的方式进行加强。本文首先分析了组成机库的单个集装箱、机库侧壁等组件在非绑扎和绑扎状态下的受力与变形；然后输入恶劣海况下的极端工况数据进行计算,结果显示机库部件受力和变形将对机库安全造成不利影响,应进行绑扎加强；最后通过绑扎后机库整体稳定性和抗侧力计算,结果显示机库整体和侧壁的受力可完全被绑扎杆拉力抵消,绑扎加强能够提高机库的安全性。     

叠船运输方式下的半潜船耐波性分析

以叠船运输方式下的半潜船为研究对象,采用CATIA软件进行三维建模。基于AQWA软件计算在规则波中不同浪向、不同航速和不同吃水下的响应幅值算子(Response Amplitude Operator, RAO),分析在不规则波中不同海况条件下货物绑扎设计关键点的加速度变化,发现浪向、航速和吃水等因素对RAO的影响规律。研究结果可为叠船运输方式下的半潜船安全运输提供运动预报,为货物绑扎设计提供依据。     

Forecasting fishing vessel responses in coastal areas

A system for forecasting the operability of ships was developed by extending a wave forecasting system with the ship responses to the forecast sea states. The system produces 4-day wave forecasts in an implementation for the Portuguese Exclusive Economic Zone, where the vessels’ seakeeping performance is forecast, although the method presented could well be applied to any other coastal region. The proposed procedure requires the knowledge of the transfer functions for different ship speeds and headings. The computations are made for two different types of fishing vessels that currently operate in the Portuguese coast. Ship motions and derived responses are evaluated with a strip theory code and compared with the prescribed values of relevant seakeeping criteria that represent the limit conditions that still allow standard operational conditions for those vessels. For each forecast sea state at each grid point at a given time, the response spectrum is calculated and operability indexes are computed and compared with the maximum allowed values for a specific operation criterion. The results are presented as operational index maps for various areas of the Portuguese coast, and the information provided by system will help ship masters to plan the operation of their ships, namely to decide the areas to operate in anticipation. In this way, they can identify areas in which the level of operationally of their ships will be degraded due to weather conditions and avoid them.     

重大件货物刚性系固中的外力计算

利用特别设计的支架,将重大件货物固定于支架上,并将货物和支架一起固定于船的承载部位,此种系固方法通常称为刚性系固。刚性系固是海上重大件货物（尤指超长、超宽、超重大件货物）运输安全的必要保证。本文应用船舶耐波性理论和方法,建立了作用于货物单元上运动惯性力的计算公式,从而为货物支架的设计和刚性系固系统的强度校核提供了比较精确和可靠的力学依据。     

Structural behaviour of a high tensile steel deck using trapezoidal stiffeners and dynamics of vehicle–deck interactions

As an early part of a large design and fabrication-oriented project FasdHTS funded by the GROWTH programme of the European Commission, an exotic concept ship was designed in very high tensile steel (EHS690) with the purpose of finding out consequences for design and production. The project has already produced a considerable bank of knowledge for design and shipyard production in this material.This paper presents analysis and discussions on static and dynamic behaviour of a high tensile steel deck designed with trapezoidal stiffeners. First, a finite element model of the deck structure is created. The influence of support condition for the longitudinal girders, and the contact area between the vehicle tyre and panel were analysed. The results from modal analysis of the structure under different load conditions are presented. The different load conditions comprise the unloaded and loaded deck, and the load type, i.e. cargo loads or vehicle loads (car loads or truck loads). From the frequency response analysis under harmonic excitation, it shows how the locations and numbers of cars parked on the deck influence the dynamic response of the structure. Furthermore, by studying the car–deck interaction, it is found that the effects of normal cargo loads are quite different from the vehicle loads due to the spring/damping effects of the vehicles. It is suggested that the carloads have a similar mechanism to that of tuned mass dampers. Finally, two transient analyses of the structure due to excitations transferred from deck supports and lorry braking-induced loading are performed. It is suggested that the deck structure and vehicle design could have more interactions with each other.     

滚装船在波浪中横摇时船上滑动重载荷的同步效应

滚装船中车辆等重载荷由于固定装置失效而随船摇荡作自由滑动时,往往由于反复碰撞致使在甲板上作自由滑动的重载荷随着时间增多.由于波浪和内部滑动车辆共同作用,使滚装船的横摇加剧.这是许多滚装船发生倾覆的重要原因之一.本文对由滚装船和两辆滑动车辆组成的浮基多体系统,取滚装船的横摇角和两辆自由滑动车辆在甲板上的横向位移为此系统的三个自由度,运用多体系统动力学方法,建立了系统的动力学方程.以某型海峡滚装渡轮为例,对在两辆车自由滑动和波浪共同作用下的滚装船浮基多体系统的横摇响应和车辆位移响应进行了数值计算,得出了多个自由滑动的重载荷因相互碰撞在舷侧舱壁的约束下随着时间的延长其运动将趋于同步的结论.     

EFD and CFD for KCS heaving and pitching in regular head waves

The KCS container ship was investigated in calm water and regular head seas by means of EFD and CFD. The experimental study was conducted in FORCE Technology’s towing tank in Denmark, and the CFD study was conducted using the URANS codes CFDSHIP-IOWA and Star-CCM+ plus the potential theory code AEGIR. Three speeds were covered and the wave conditions were chosen in order to study the ship’s response in waves under resonance and maximum exciting conditions. In the experiment, the heave and pitch motions and the resistance were measured together with wave elevation of the incoming wave. The model test was designed and conducted in order to enable UA assessment of the measured data. The results show that the ship responds strongly when the resonance and maximum exciting conditions are met. With respect to experimental uncertainty, the level for calm water is comparable to PMM uncertainties for maneuvering testing while the level is higher in waves. Concerning the CFD results, the computation shows a very complex and time-varying flow pattern. For the integral quantities, a comparison between EFD and CFD shows that the computed motions and resistance in calm water is in fair agreement with the measurement. In waves, the motions are still in fair agreement with measured data, but larger differences are observed for the resistance. The mean resistance is reasonable, but the first order amplitude of the resistance time history is underpredicted by CFD. Finally, it seems that the URANS codes are in closer agreement with the measurements compared to the potential theory.     

飞机轮载作用下的甲板动响应

本文从工程应用的角度出发，提出了一个逆求飞机起落架系统非线性动力特性的方法，并将飞机起落架系统以及在波浪运动的船体国反结构看作一个耦合的动力学系统，建立了一套着舰飞机与甲板瞬态相互作用的动力学分析方法，用该方法可以预报在各种海况，航速及机降工况下舰船甲板的动应及飞机承受的冲击过截，本文给出了计算例子。     

超大型集装箱船甲板最大堆重研究

德国劳氏船级社规范(GL-2013)对集装箱船尤其是超大型集装箱船的横向加速度系数计算进行了调整,大幅度提高了甲板上集装箱堆重。文章根据绑扎计算结果,将规范变化前后的横向加速度系数和最大堆重进行对比,以及对2层箱高绑扎桥和3层箱高绑扎桥的最大堆重进行对比。结果显示,随着规范的更新及绑扎点高度提高,集装箱甲板最大堆重显著增加,堆重分布更加优化合理,为今后超大型集装箱船甲板面堆重设计参数的合理选取提供了一定的参考。     

Cargo ship aft panel stresses prediction by deconvolution

This article introduces novel extreme value prediction method that can be used for a variety of offshore engineering applications. First, to demonstrate the novel method, fictitious data from a non-linear Duffing oscillator and measured wave heights were used as examples. The second incident included a container ship that experienced significant deck panel strains while traveling across the Atlantic Ocean in bad weather. The main concern for cargo ship transportation is potential loss of container owing to violent movements. It is challenging to model such a situation because waves and ship motions are both non-stationary and complicatedly nonlinear. Extreme motions greatly increase the role of nonlinearities, activating effects of second and higher order.Furthermore, due to the scaling and the choice of sea state, laboratory testing may also be called into doubt. Therefore, data collected from actual ships during difficult weather voyages offers a special perspective on the statistics of ship motions.This paper aims to highlight an alternative method of extrapolation that is based on intrinsic properties of the data set itself and does not assume any extrapolation functional class. Extreme value predictions typically originate from certain statistical distribution functional classes to fit the data and then extrapolate. Engineering design can make use of the unique extrapolation method that has been proposed. The proposed method's forecast accuracy has been verified in comparison to the Averaged Conditional Exceedance Rate (ACER) extrapolation method.     

波浪引起破损船的垂向运动和弯矩（英文）

The wave-induced vertical ship motions and bending moments of a double hull-oil tanker in realistic flooding conditions are studied. The scenarios investigated are represented by water ingress into the starboard ballast tanks for collision damage cases and both starboard and portside ballast tanks for grounding situations. Seakeeping computations are performed for eight damage scenarios and for the intact condition, each corresponding to different changes in displacement, trim, and heel. For each of the damage conditions, transfer functions of vertical motions and loads are calculated using a potential linear 3 D panel hydrodynamic code in the frequency domain that includes effect of the motion of the water in flooded tanks. A MATLAB code is developed to facilitate automated hydrodynamic simulation of many damage scenarios. Verification of seakeeping results is performed by comparing transfer functions with results of the previous study. Wave-induced vertical responses of damaged ship are then compared to those of intact ship using two spectral-based methods originating from uncertainty analysis of wave loads, which are convenient tools to assess consequences of damage on short-term ship responses. Generally, observed trend is that vertical wave-induced responses of damaged ship converge toward those of intact ship with increasing wave period. Fairly small differences between responses of asymmetrically damaged ship with respect to the symmetrical incoming wave directions are found. The results of the study are an efficient method for seakeeping assessment of damaged oil tankers and the framework for evaluating consequences of damage scenarios, heading angles, and sea conditions on seakeeping responses of damaged ships.The results can be used to decide if the intact ship model can be used instead of the damaged one for the emergency response procedure or for the risk assessment studies when modeling and computational time represent important limitations.     

三维波对船舶运动响应影响研究

通常情况,实际海况的波浪更接近三维波,而在船舶运动预报时,目前主要考虑二维波(长峰波)中的响应,不能真正反映船舶在实际海浪中的运动.文中利用不同方法(频域方法、时域方法以及模型)研究了三维波的方向扩散性对船舶运动响应的影响.三种方法得到的三维波对船舶运动的影响是一致的.结果显示,在研究实际海况中的船舶运动时,考虑三维波的方向扩散性是非常重要的.     

集装箱绑扎和紧固技术及产业发展浅析

介绍了集装箱绑扎和紧固技术,梳理了集装箱绑扎件行业的标准现状、技术现状,系统地回顾了集装箱绑扎和紧固件的制造发展历程及市场分布,最后分析了集装箱运输产业的发展现状及趋势,为产业的优化改进提供方向,也为绑扎和紧固技术的发展提供参考.     

Practical estimation methods of the design loads for primary structural members of tankers

Various design loads used in the strength evaluation of ship structures have been introduced currently by classification societies. As most of these design loads have been determined as the standard loads for the sake of convenience, the relationships between the design loads and the sea states actually encountered by ships seem to be weak. Accordingly, it may be difficult to refer and utilize them as the fundamental design concepts for ship designers or the operational guidelines for ship operators. To overcome these difficulties, the authors have developed practical estimation methods of the design loads having transparent and consistent backgrounds to the actual loads acting on primary structural members of tankers. In this paper, the design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are firstly proposed. Secondly, the practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative tankers. Thirdly, the practical estimation methods of design regular waves resulting in the same level of stresses with that induced in irregular waves under the design sea states are proposed. Finally, the practical estimation methods of the design loads such as ship motions, accelerations, hull girder bending moments and hydrodynamic pressures that are induced under design regular waves are proposed.     

大型集装箱船甲板堆重的影响因素

以某14 500 TEU集装箱船为对象,基于DNV GL规范对影响集装箱船甲板堆重的主要因素进行分析。首先介绍新规范采用的横向加速度系数计算方法,对比新旧方法对甲板许用最大堆重的影响;然后对比分析绑扎形式以及绑扎桥层数对甲板许用最大堆重和系固系统设计的影响。结果表明:随着规范的更新,集装箱横向加速度系数明显降低;同时,由于采用外绑形式和3层绑扎桥,大型集装箱船甲板堆重能力明显提高,但这也对集装箱系固系统设计带来了一些新的影响。     

The overall motion induced interruptions as operability criterion for fishing vessels

A new index, namely the overall motion induced interruptions (OMII), is proposed as a seakeeping criterion for fishing vessels, to compare ships having different hull forms and dimensions by means of an only parameter, in a human centred approach, mainly related to the onboard risk level. Therefore, the first aim of the paper is to investigate the factors affecting fishing vessels’ seakeeping performances to improve them to reduce the high number of injuries occurring during fishing operations, mainly related to both risk perception and harsh weather conditions. Despite the classical approach, where motion induced interruption is determined for a certain sea state with regard to several location points, the new index accounts for all crew members’ positions on the working deck, all heading angles the vessel may experience during fishing operations, based on relevant operating scenario, and all sea states the ship may encounter in the fishing area. The influence of position, heading angles and sea states on the attained risk level is fully investigated, analysing seakeeping performances of four fishing vessels with different hull forms and dimensions. Finally, a new operability criterion is proposed, based on OMII, to investigate the influence of ship size and operating scenario on the risk of injuries during fishing operations. Main factors affecting fishing vessels’ seakeeping performances are fully discussed, paying attention to relevant correlation with ship roll natural period.