应用断裂特征分析图评定船体钢的动载适应性

研究了工程结构在高加载速率条件下的脆断评定问题。分析了传统的脆性转变温度判据和PELLINI提出的断裂分析图的局限性。扼要介绍了近期提出的断裂特征分析图的结构和应用特点，构建了一种船体钢的断裂特征分析图，并分析了其对动载荷的适应性。结果表明，该钢种对K≈10^5MPa√m／s以下动载荷有较好的适应性，而在K≈10^7MPa√M／s动载荷下处于平面应变状态时，则表现出明显的不适应。研究还表明，具有优异的低温韧性的钢种在高加载速率条件下并不一定具有良好韧性。     

动态载荷作用下焊接点线弹性裂纹的弯曲扩展路径的预测(英文)

利用二阶摄动方法研究了动态载荷作用下结构线弹性断裂裂纹的弯曲延伸扩展问题并求解了动态应力强度因子。利用二阶摄动方法研究了动载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系。就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的动态裂纹路径。但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则。作为二阶摄动方法的实际运用,研究了焊接结构中动态线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出动态载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线。     

舰船结构防断选材可靠性分析方法的探讨

本文以船舶结构主承载件材料韧性要求作为断裂控制准则，将材料韧性要求纳入结构防断体系，采用转变温度、断裂力学方法建立断裂失效极限状态方程，以一阶二次矩方法对舰船结构防断选材的可靠度进行分析计算。     

用SZ法测试焊缝金属延性断裂韧度的研究

采用SZ法对焊缝金属的延性断裂韧度进行了测定并作了线性回归分析，分析了SZ法的特点，并对其关键技术作了探讨。最后建议对于高延性材料采用SZ法，用实测钝化线与阻力曲线的交点所对应的延性断裂韧度值作其临界值。     

疲劳载荷作用下焊接点三维线弹性弯曲裂纹路径预测

利用二阶摄动方法研究了疲劳载荷作用下结构线弹性裂纹的弯曲扩展问题并求解了三维动态应力强度因子.利用二阶摄动方法研究了疲劳载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系.就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的三维疲劳弯曲裂纹扩展路径.但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则.作为二阶摄动方法的实际运用,研究了焊接结构中疲劳线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出疲劳载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线.     

疲劳载荷作用下焊接点三维线弹性弯曲裂纹路径预测（英文）

利用二阶摄动方法研究了疲劳载荷作用下结构线弹性裂纹的弯曲扩展问题并求解了三维动态应力强度因子。利用二阶摄动方法研究了疲劳载荷作用下裂纹路径预测时的应力准则与能量准则之间的关系。就均匀物质而言,在二阶摄动分析理论的框架内,两种准则指明了相同的三维疲劳弯曲裂纹扩展路径。但在具有非均匀断裂韧度的物质中,能量准则优越于应力准则。作为二阶摄动方法的实际运用,研究了焊接结构中疲劳线弹性裂纹的形态特征和弯曲扩展路径问题,综合考虑了诸如远场动态作用应力、焊接残余应力、局部物质衰变以及不同尺寸的缺陷的存在等因素,绘制出疲劳载荷作用下退化区域中裂纹弯曲扩展的临界轨迹曲线。     

基于平均应变能密度准则的裂纹断裂扩展特性分析

考虑裂纹尖端应力场常数项T应力对裂纹断裂特性的影响,对平均应变能密度准则进行修正,建立混合型裂纹扩展条件计算式。在此基础上,系统分析常数项T应力对Ⅰ型、Ⅱ型、Ⅰ-Ⅱ混合型裂纹断裂判据的影响。结果表明,常数项T应力降低了材料裂纹起裂阻力,且参数|Bα|越大裂纹断裂极限值越低,|Bα|相同时,正T应力要比负T应力更容易发生断裂。基于修正平均应变能密度准则,预测双轴疲劳载荷作用下平板表面Ⅰ型裂纹扩展寿命。结果表明,考虑常数项T应力影响后的疲劳裂纹扩展寿命约为传统疲劳裂纹扩展寿命的49%。     

潜艇耐压锥柱结合壳断裂失效J积分有限元分析

总结了基于有限元方法的断裂力学J积分理论．利用MARc软件建立了潜艇锥柱结合壳有限元分析模型，计算潜艇典型裂纹承受300m静水压力和不同炸药重量及距离下的J积分。通过对典型裂纹J积分有限元计算，从中获得典型裂纹在一次性受载(包括各种冲击载荷)下的应力强度因子。最后，根据材料的起裂韧度(KIC)对该潜艇耐压壳结构进行断裂评价。     

平面状态下EWK延性断裂准则与K准则对比研究

为研究EWK延性断裂准则对金属起裂及扩展的预测能力,将EWK断裂算法嵌入ABAQUS主程序。针对金属I型裂纹,在平面应变条件下,通过试验与有限元计算相互对比的方法,研究了该准则与应力强度因子K准则对紧凑拉伸CT试样起裂的预测结果,发现两者有近似等效性。在平面应力条件下,以紧凑拉伸CS试样为模型,通过有限元计算,提取由EWK控制断裂的结构KR-曲线,将该曲线与试验资料对比,发现两者吻合良好。     

用SZ法测试焊缝金属延性断裂韧度的研究

采用SZ法对焊缝金属的延性断裂韧度进行了测定并作了线性回归分析，分析了SZ法的特点，并对其关键技术作了探讨。最后建议对于高延性采用SZ法，用实测钝化线与阻力曲线的交点所对应的延性断裂韧度值作其临界值。     

Fracture toughness of steel plate from MV Kowloon Bridge

Chemical analysis, tensile, Charpy, DW NDT and fracture mechanics toughness data are presented for a grade A steel plate from the Kowloon Bridge, a sister ship of Derbyshire. The plate is shown to have poor toughness under dynamic loading conditions. The results leave open the possibility that brittle fracture could have contributed to a structural failure in the Derbyshire even at the high temperature of +30°C which is reported to have existed at the time of the ship's disappearance. The results are felt to support the proposition that present classification society rules need tightening to reduce the risk of brittle fracture in ships.     

船舶焊接钛合金拉伸疲劳断裂机理的研究

通过对TC4钛合金焊接试样拉伸疲劳断裂试验结果及其断口和卸载表面观察分析,发现试样断口上有明显的河流花纹走向和起裂源,并伴有韧窝和韧性条带特征。起裂源常位于断口表面角落附近。其断裂机理是疲劳拉伸载荷作用下,在应力值比较高的时候一些沿层裂纹开始出现并扩展,当疲劳裂纹的长度达到与疲劳外加力所匹配的临界裂纹长度时,突然发生准解理断裂。试样断口呈现出准解理与韧窝断裂的混合特征。     

浅谈极限强度在船舶结构设计的运用

船舶其全寿命周期内可能遭受各种载荷和变形,在结构设计中应充分考虑其安全性。随着共同结构规范(CSR)于2006年4月1日生效,不但要满足常规的许用应力衡准,而且还应满足极限强度衡准。本文通过对VLCC和大巴拿马型散货船的极限强度分析,探讨了极限强度在船舶结构设计的运用,希望能为船舶结构规范设计提供参考。     

Fracture control of extremely thick welded steel plates applied to the deck structure of large container ships

The rapid enlargement of the size of container ships has led to the application of extremely thick plate in the deck structures, which may grow concerns about the fracture toughness at the butt-weld with large amount of heat input, and the arrest toughness of brittle crack propagation in the base metal of such thick plates. Also, slam-induced whipping stresses might affect the fatigue crack propagation and the initiation of a brittle crack in a container ship. In order to prevent the catastrophic failure of deck structures by brittle fracture, national joint research projects, which focused on the safety-related issues of extremely thick steel plate applied to hull of large container ships, were formed from April 2007 to March 2011 organized by the Japan Ship Technology Research Association (JSTRA) supported by the Japanese Government in collaboration with universities, national research institute, classification societies and relevant industries including shipbuilding, steel manufacturing and shipping companies. The joint research projects have carried out the investigations on crack initiation toughness of the weld, fatigue crack propagation under seaway loading, the potential of defect detection by ultrasonic testing, and the crack-arrest methods after brittle crack propagation. Practical recommendations to prevent brittle fracture of large container ships were proposed based on these comprehensive investigations. The essential parts of the above research activities are presented in this paper.     

A break-even model for evaluating the cost of container ships waiting times and berth unproductive times in automated quayside operations

The planning, design and development of a container terminal with optimum size and capacity and with a minimum capital cost is fundamentally dependent upon the loading and discharging operations at the quayside. The quayside function of container terminals is dependent basically on the number of berths available to service the incoming container ships. The objective of the container terminals dealing and admitting the ongoing ship calls is to provide immediate berth and loading and discharging services to the container ships with a minimum costly waiting time and a maximum efficiency. Previously terminal planners used to build extra berths to provide service. During the last two decades the terminal operators have adopted automation technologies in loading and discharging operation of the container ships as an alternative to designing extra berths. Ship owners naturally expect least waiting times for their container ships. On the other hand, it is also natural for port operators in a container terminal with costly facilities to see a high berth occupancy and productivity at the quayside. This study uses queuing theory to find a break-even point as a way of evaluating the cost of container ship waiting times and the cost of berth unproductive service times for container terminals aiming to automate their quayside operation. The analysis illustrates that automation devices installed on conventional Quayside Cranes (QSCs) significantly reduce the turnaround time of the container ships calling at the ports. It argues, however, that there should be a balance between the cost of berth unproductive service times and the cost of vessel waiting times. The study introduces a break-even point to be considered as a benchmark for calculating such a balance. The analysis in this study can be used as a decision tool for the operators of container terminals in the medium to small ports to appraise the feasibility of an investment in automation or expansion of the quayside facilities.     

Numerical simulation of fatigue crack propagation under biaxial tensile loadings with phase differences

Fatigue crack propagation under the biaxial tensile loading, which loading directions are normal and parallel to the initial crack position, is highlighted in this study. Most of in-service structures and vessels are subjected to many types of loading. Generally, these loadings have different axial components with different phases. However, the structural integrities of structures and vessels are evaluated according to design codes based on theoretical and experimental investigations under a uniaxial loading condition. Most of these codes are based on the S–N curves approach. An approach that does not use S–N curves has been favored by researchers, with the fracture mechanics approach preferred for evaluating the fatigue life of structures. An advanced fracture mechanics approach was developed based on the Re-tensile Plastic zone Generating (RPG) stress criterion for fatigue crack propagation. In this study, fatigue crack propagation tests under biaxial loading with six different phase and loading conditions are performed and the effect of the phase difference under biaxial loading is evaluated. A numerical simulation method of fatigue crack propagation based on the RPG stress criterion under different biaxial loading phase conditions is presented and compared to measured data.     

“木兰”船体分段拖航过程中折断事故分析

以"木兰"船体分段拖航折断事故为工程案例,分别采用许用应力设计法、极限状态设计法两种分析方法对该船体梁强度进行校核,分析舱室进水对设计载荷的影响。结果表明:基于有限元的极限状态分析方法能够准确地得到结构极限承载能力,其损伤模式及过程与事故吻合较好,是可靠的事故分析方法。该船体分段在6级风浪载荷下的极限强度满足规范要求,但舱室进水严重恶化了中垂情况下船体梁的受力状态,最终导致了船体中垂折断事故的发生。     

IMO第二代完整稳性衡准对现有万箱船设计的影响

国际海事组织（IMO）正在制定基于水动力学的第二代完整稳性衡准,新衡准的实施必然对现有船舶的设计带来巨大影响。集装箱船大型化是航运界的发展趋势,万箱船船型订单近年也大幅上升。已有的事故发现大型集装箱船对参数横摇、过度加速度等衡准相对敏感,但现有船舶的设计对此类事故模式考虑较少,因此有必要开展相关研究。本文选取了某万箱集装箱船,对其大量装载工况进行四种稳性失效模式的计算分析,研究了第二代完整稳性的实施对大型集装箱船的稳性影响,并对其装载、设计等提出一定的建议。     

Ship service life extension considering ship condition and remaining design life

Reliable and continuous operation of ships is vitally important to the decision-makers. Driven by the rising cost of newbuilding ships, maintenance actions are needed on existing ships to ensure safe and enduring service beyond their initial design life. Extending ship service life can provide economic operating profit and promote sustainability. Meanwhile, ships during their extended service life may involve higher failure risk and additional maintenance expenditure. Therefore, a cost-benefit evaluation is imperative for determining the optimal duration of service life extension (SLE) and the associated maintenance actions. In this paper, a novel method for this purpose is proposed. Two cost-benefit indicators, benefit-cost ratio (BCR) and net present value (NPV) are used to optimize the duration of SLE. Using Bayesian updating, information on the remaining design life and the structural condition at the SLE decision is incorporated into the optimization process to better inform SLE decision-making. The proposed method is illustrated by a fatigue-sensitive very large crude carrier (VLCC) at both structural component and structural system levels.     

鸭绿江口4万吨级双浮筒系泊系统设计与计算

为了在鸭绿江口设计一双浮筒系泊系统,用于4万吨级散货船的载驳作业,根据该海域的水文气象条件和船舶的有关资料及国家的有关规范,对双浮筒系泊系统所受风作用力、流作用、波浪作用力和合外力进行计算,依据计算结果对双浮筒系泊系统进行设计,确定系泊浮筒型号、锚链尺寸和长度及沉锤大小和掩埋深度,实际施工情况依照该设计方案效果良好,证明该计算和设计方法有效可行。