Method for Calculating the Ultimate Strength of Pitting Corrosion Ship Structural Plates Under Combined Loads

In order to solve the problem of calculating the ultimate strength of marine plate under pitting corrosion,the plate taking from marine with pitting corrosion was studied. Based on the data of pitting corrosion recorded,the concept of pitting corrosion characteristic element matrix was proposed to describe the distribution and the forms of pitting. Moreover,the model of sensitivity calculation was established to analyse the sensitivity of pitting corrosion characteristic elements for the ultimate bearing capacity of ship structural plate. A new approach was proposed to calculate the ultimate strength of pitting damaged ship structural plate under combined loads based on the factor of rigidity reduction. Simultaneously this new approach was proven to be validated by finite element simulation. Finally,formula of ultimate strength of pitting damaged ship hull plate was established by series of numerical calculations based on the approach,and the reliability of the formula was validated as well.

A comparative study on the hull strength of a ship with thin-walled box girders

Based on the Finite Element Analysis and Thin Walled-Box girder Mechanics, two design concepts of adding box girders under main deck in order to increase the hull strength of ship are presented. By comparison and analysis on the longitudinal strength, torsion strength and deck buckling between designed concepts and the original concept, it is found that by adding box girders under the main deck, the weight of hull structure is increased by lower than 10%, but the stress on the plate of the main deck is reduced by about 10%, the stress on the plating of the second deck is reduced about 20%. The shear stress on the plating of both of the main deck and second deck is reduced, but the shear stresses in several nodes are increased. Also the capability of resisting damage to ship is obviously increased by adding box girders under the main deck. The deck buckling is also increased by more than 90%. Consequently, the box girders added under the main deck are useful and effective to increase the strength of hull and ship survivability.

Assessment of Seagoing Ships Longitudinal Strength in the Context of International Rules, Important Factor for Safe Operation

The paper is focused on the ship hull safety problems related to the longitudinal strength of the ship during design, construction and service in context of International Goal-Based Ship Construction Standards carried out by International Maritime Organization (IMO). The study underscores the importance of ship longitudinal strength for prevention of theirs losses, mentioning the most important measures taken by IMO for improvement of ship safety. In the work, a critical analysis of the methodology of the International Association of Classification Societies (IACS) for calculation of sectional efforts induced by waves in ship’s hull is described. Finally, a calculation base proposal for improvement the efforts on quasi-static layout of the ship on wave is performed.

大型耙吸挖泥船结构设计要点

为实现大型耙吸挖泥船结构设计安全、合理、可靠,以某大型耙吸挖泥船为例,分析大型耙吸挖泥船结构设计特点,从结构设计、强度评估、疲劳评估和振动评估等角度论证其设计要点,通过对泥舱结构设计分析,给出泥舱设计的关键节点,对关键节点进行强度分析和疲劳分析,结果表明,该船局部关键区域应力水平较高,低周疲劳在关键区域的疲劳中占据主要地位,建立三维有限元模型计算挖泥船固有频率,对比该大型耙吸挖泥船激励频率与固有频率,结果表明,船体总振动固有频率通常可以避开激励频率,生活楼固有频率与激励频率较为接近。

恶劣海况中大外飘型舰船的总载荷颤振响应分析

[目的]舰船遭遇恶劣海况时艏部砰击会激起船体梁颤振响应,威胁到总纵强度的安全。砰击颤振弯矩与船体刚度和外飘构型相关,但不同船型结构布置和型线差异大,有必要针对大外飘型舰船开展颤振响应分析。[方法]首先,采用COMPASS-WALCS-NE势流时域水弹性方法预报设计海况下的船体梁总载荷,并与分段自航模试验对比验证;然后,再提取艏部砰击合力、典型时刻的船体运动状态和船体梁总载荷响应的时历曲线,通过分析波浪载荷高低频分量的相位差异,研究船舯砰击弯矩与艏部砰击合力的关联性;最后,围绕船体主要设计参数进行敏感度分析。[结果]在设计海况艏部入水时,其砰击合力出现了2次峰值,分别对应于底板和外飘区域的大面积触水过程;颤振弯矩主要由艏部外飘砰击引起,受力面积大,合力距离船舯远,导致砰击弯矩达到了波浪弯矩的同等幅值;大外飘型舰船的砰击弯矩对波高变化最为敏感。[结论]对于大外飘型舰船的总纵强度评估应考虑砰击颤振的影响,对于中垂砰击弯矩需要直接与静水成分、低频的波浪成分叠加,而中拱砰击弯矩应考虑阻尼耗散,可先折减再叠加。

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。

船舶用AH32钢常温抗拉强度测量结果不确定度评定

开展船舶用AH32钢抗拉强度测量结果的不确定度评定,对规范试验过程和合理使用抗拉强度数据具有重要意义,也可为其他船舶用钢抗拉强度不确定度分析提供参考。对船舶用AH32钢的拉伸试验测量结果不确定度进行评定及分析,依据GB/T 228.1—2021相关要求开展拉伸试验及不确定度评价,合理地确定相关不确定度来源,对材料性能做出适当评价具有可操作性。在某些质量可靠性高的不确定度分析中,引入拉伸速率不确定度,识别不确定度分量的影响程度,可以使不确定度评价具有规范性和针对性。

含起重设备的船舶上层建筑吊装强度有限元分析

为准确计算船舶上层建筑吊装强度,采用MSC.Patran和MSC Nastran软件对175000 t散货船上层建筑吊装建立整体结构有限元模型。采用含起重设备的有限元分析法计算上层建筑在吊装过程中的结构响应,并与直接约束法和惯性释放法进行对比分析,比较3种有限元分析法计算得到的应力、变形和吊点支反力情况,分析含起重设备的有限元分析法的准确性。结果表明,含起重设备的有限元分析法可对结构的应力、变形和吊点支反力进行较为准确的计算,优于直接约束法和惯性释放法。含起重设备的有限元分析法对船舶上层建筑吊装强度和吊装方案的评估具有一定的工程价值。

邮轮结构详细设计与分析

为保障邮轮的结构安全性和空间利用性,并满足乘客的度假需求,以国产首制大型邮轮为例,对其结构详细设计工作进行介绍,并对设计流程、原则和内容进行总结。研究成果可为邮轮的详细设计工作提供一定参考。

3000 t·h^(-1)桥式抓斗卸船机风载下强度计算及机械故障分析

以3000 t·h^(-1)桥式抓斗卸船机作为分析对象,计算结构在非工作状态下的风载。以最大风速55 m·s^(-1)、风压1900 N·mm^(-2)作为风载输入,按风向转化为3种工况并与固定载荷结合。计算结果表明,在固定载荷+侧风与后侧风组合载荷作用下结构应力达到最大,为114.728 MPa,较其他2种工况高约14.5%。然后,结合实际应用梳理和统计故障。由于卸船机结构大、零件多、故障点多,按照故障来源分类卸船机机械故障,并对各类故障的消除提供具体的方法和措施。在实践过程中发现,采用现代智能手机对噪声进行实时监控,具有成本低、监控效果良好等诸多优点,能够对故障的预警和故障源的查找起到很好的作用。在卸船机或相近设备的维护过程中,可以推广并利用这些手段。

24000TEU集装箱船特厚规格高强船板保心部低温冲击性能研究

为保证24000TEU集装箱船特厚规格高强船板保心部低温冲击性能,采用低碳+Ti+Nb+Ni的成分体系,即可保证强度,亦可保证较高要求的韧性。采用大变形量、低温控轧、DQ模式5 kg水冷,获得以针状铁素体(AF)/贝氏体(B)为主,并有少量的多边形铁素体的多相组织,心部冲击均值达到200 J以上。通过除鳞速度和道次的优化,解决特厚高强船板表面水纹花斑问题。成功研发保心部低温冲击性能的特厚规格高强船板,具有良好的强韧性能、焊接性能和表面质量。

超大型集装箱船体结构极限强度研究方法

为增强超大型集装箱船船体结构的稳定性,对迭代增量法、理想结构单元法和非线性有限元法等应用较为广泛的船体结构极限强度研究方法的基本思路和优缺点进行归纳和总结。在此基础上,提出未来超大型集装箱船船体结构极限强度研究方法的改进建议。研究结果可为超大型集装箱船体结构的稳定性研究提供一定参考。

多工况下卸船机钢结构的静载强度分析

针对卸船机钢结构进行技术分析,依托卸船机的实际结构和载荷条件,构建条理清晰、结构合理的有限元模型,对卸船机钢结构静载强度设定相应的输送量与螺距,以预测其在不同工况下的性能表现。结果表明,卸船机钢结构在外部作用力的影响下,钢结构静载强度在不同工况下呈现明显的差异。进一步进行了有限元仿真结果分析和静载强度检测结果分析,对卸船机钢结构的静载强度进行了全面评估。本研究为相关领域的工程实践以及设计和优化卸船机钢结构提供了参考。

深远海多功能原油转驳船全船有限元分析

为实现深远海石油的安全高效运输,开发了具有全新船型的深远海多功能原油转驳船(Cargo Transfer Vessel,CTV)。根据原油转驳船工作海域的环境特点,使用有限元计算软件包Sesam,建立了有限元分析结构模型,采用了等效设计波方法对该类型船只进行频域水动力分析,并对主要负载进行长期预测,然后将波浪载荷施加于结构模型中进行强度校核。通过校核不同工况下原油转驳船的屈服强度、屈曲强度,并基于谱疲劳分析与子模型技术对易于产生疲劳破坏的节点进行疲劳分析,优化了船体设计结构。计算分析结果表明:原油转驳船的设计强度与疲劳寿命均满足DNV的规范要求,载荷下船体结构应力均低于320 MPa,具有足够的承载能力。通过添加水密补板,优化后的舷侧肋位处纵骨过梁孔有效提高了疲劳寿命,对后续系列船的设计与校核具有一定参考价值。

轴向循环载荷下扁钢加筋板极限强度研究

为分析带板厚度、加强筋尺寸及循环加载模式对扁钢加筋板极限强度的影响,采用有限元软件ABAQUS,基于初始变形、焊接残余应力和鲍辛格效应,针对不同带板厚度和加强筋尺寸的扁钢加筋板开展了3种轴向循环载荷模式下的极限强度数值模拟。研究结果表明:当扁钢加筋板的带板厚度相同时,经循环载荷后,加筋板的极限强度随加强筋尺寸的增加而下降,其下降程度减缓;当加强筋尺寸相同时,经循环载荷后,加筋板的极限强度随带板厚度的增加而下降,其下降程度加剧;当循环载荷的幅值由大到小时,扁钢加筋板的极限强度下降程度最大;在等幅循环载荷时,扁钢加筋板循环后的极限强度下降程度最小。

双燃料集装箱船B型LNG燃料舱疲劳强度研究

基于DNV-GL规范要求,对某大型双燃料集装箱船B型LNG燃料舱结构进行疲劳强度研究。根据规范给出燃料舱及其支撑结构的疲劳分析流程以及疲劳热点筛选方法,分析不同关键节点的疲劳强度,并提供改善疲劳问题的优化设计方案。为配置B型LNG燃料舱的相关船型的设计开发提供参考。

风电安装船主弦管吊装工装设计与强度校核

为保证海上风电安装船吊装的绿色和经济性,以某风电安装船桩腿主弦管吊装为例,对现行船厂主弦管吊装方案进行分析,提出新型主弦管吊装工装结构,并采用有限元方法对不同工况下主弦管起吊阶段的受力与变形情况进行分析。结果表明:新型主弦管吊装工装结构的强度满足规范要求。研究成果可为风电安装船主弦管吊装工装设计提供一定参考。

FPSO Global Strength and Hull Optimization

Global strength is a significant item for floating production storage and offloading(FPSO) design, and steel weight plays an important role in the building costs of FPSO. It is the main task to consider and combine these two aspects by optimizing hull dimensions. There are many optional methods for the global strength analysis. A common method is to use the ABS FPSO Eagle software to analyze the global strength including the rule check and direct strength analysis. And the same method can be adopted for the FPSO hull optimization by changing the depth. After calculation and optimization, the results are compared and analyzed. The results can be used as a reference for the future design or quotation purpose.

Ultimate Strength Assessment of a Tanker Hull Based on Experimentally Developed Master Curves

几何上类似的可伸缩由制造了的 A 到照原尺寸的使硬的面板然后他们的倒塌行为的小规模的标本被调查。这被考虑使硬的面板压缩最终的力量测试根据几何可伸缩的法律被设计以便测试的输出能受到垂直弯曲的油轮壳的压缩地区的使硬的面板被用作代表性时刻。油轮壳的最终的力量被 FE 分析用被横梁紧张测试和使硬的面板的压缩测试获得的试验性地发达的主人压力紧张曲线分析，并且当时与进步倒塌方法完成的结果相比。

Finite element and experimental analysis of pinion bracket-assembly of three gorges project ship lift

The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.