球扁钢等效方法的研究

在进行船体结构强度的计算分析时,需要将球扁钢等效为L型材或T型材进行屈服及屈曲计算。然而,现有的等效转化方法存在较为明显的问题。本文在前人研究基础上,推出两种简化等效方法,并与现有方法进行计算对比,结果表明这两种方法简单方便,精确度高。此外,本文分别使用三种转化方法,运用Mars2000软件计算某船剖面的极限强度。计算结果表明,使用本文提出的等效转化方法一计算船体结构极限强度最合理。     

小型钢船折边组合型材最佳高宽比的确定

船舶骨架一般由T型材、球扁钢、角钢或折边型材组成。由于轧制角钢中的等厚角钢和折边型材只是圆角处稍有不同,因而为简化起见,在讨论时认为其惯性矩相同。当不对称折边型材与T型材的高宽厚三项     

万吨级散货船的T型材剖面优化设计

本文应用优化思想,联系万吨级散货船的 T 型材剖面设计问题,从建立数学模型出发,推导了 T 型材剖面优化设计的求解公式,并结合35000吨级散货船和64000吨级散货船的 T 型材构件剖面设计实例,介绍了《规范》设计 T 剖面的计算步骤。     

船体肋骨三维外形检测及可视化系统研究

随着科学技术的进步,制造过程的数字化和信息化在各行各业逐渐推广开来。造船业作为国家重器的一个重要组成部分,也在推行船体设计、加工、制造的数字化和信息化。对广泛应用于工业领域的特种型材,尤其是船体肋骨所用T型钢、球扁钢的成形过程进行了简要介绍,并设计实现船体肋骨成形后外形的自动检测装置,实现检测过程的自动化、记录的数字化及检测结果的三维可视化。为船体肋骨加工过程数字化和信息化打下良好的基础。     

客滚船压筋板极限承载力数值计算及敏感性分析

针对新型客滚船上采用的槽型压筋板，利用非线性有限元软件ABAQUS中的risk算法对设置初始压制缺陷的槽型压筋板模型进行受压极限承载力计算。计算发现槽型压筋板中部与焊接扁钢的板边部分所受压屈曲极限承载力不同，因此将槽型压筋板分成2个部分进行研究。通过计算并利用MATLAB对数据回归分析后发现：对于槽型压筋板中间部分，随着槽型间距和压筋板长度的增加，线性屈曲压力减小，受压极限承载力减小，破坏时的最大挠度增加；随着厚度增加，线性屈曲压力和受压极限承载力增加较少，破坏时的最大挠度降低。针对槽型压筋板焊接扁钢的板边部分，缩短板边扁钢与旁边槽型的间距及提高焊接扁钢的腹板厚度均能提高压筋板板边的极限承载压力。设计中可通过在压筋板边焊接扁钢且增加扁钢尺寸或以焊接制造的方式增加槽型高度减小槽型间距，以提高压筋板的极限承载力。     

舷顶列板兼做拦油扁钢的可行性研究

为了研究舷顶列板兼做油船货舱区拦油扁钢的可行性,本文首先考察了该结构形式对船体梁顶部剖面模数的影响,其次评估了拦油扁钢的细网格应力,结果表明甲板、舷顶列板和双壳强框三者相交处存在应力集中的现象,导致拦油扁钢在此交点处应力较高。再次分别基于平衡分岔失稳理论和极值点失稳理论计算了拦油扁钢的弹性临界应力和极限屈曲应力,并给出拦油扁钢的极限屈曲应力曲线。最后考察了拦油扁钢的疲劳寿命。四个方面的论证结果表明舷顶列板兼做拦油扁钢是可行的,但应注意舷顶列板的顶部应避免存在豁口等结构缺陷。     

球壳屈曲特性试验与理论研究

针对不锈钢球壳进行静水压力试验,获得其屈曲载荷及最终失稳模式,并采用三维扫描及无损测厚试验获得的实际三维模型参数建立球壳模型,进行数值仿真分析.通过试验与数值计算结果的对比分析,验证了有限元数值计算的可行性及准确性,该数值仿真方法可作为预测已加工球壳屈曲特性的一种方法.此外,开展不同初始缺陷球壳的屈曲特性分析,认为轴对称初始缺陷可作为耐压球壳的初始预估缺陷,通过对此种缺陷球壳的计算,可预测球壳的极限承载力.     

曲线形T形梁装焊自动线的设计

一、前言现代造船技术,已经从原始的零部件整体建造法,发展到分段装配;由单一的、分散的作业,发展到按生产流程组织的流水线作业。不管分段的形式如何,组成分段的零件大都是板材和型材。由于组合T型钢结构较之其他型钢(如角钢、球扁钢等等)受力状态好、截面尺寸合理,因而可以减轻自重,节省材料。作为船体纵向和横向封闭的强框架,几乎都由组合T型钢组成。其数量相当大,而且绝大部分是曲线     

基于设计波的载重3600t干货船结构强度直接计算分析

为准确评估超规范的载重3600t大通舱干货船的弯扭强度及变形水平,采取全船水动力分析及全船有限元直接计算的方法,对各工况下的主要载荷参数进行长期预报,推导出对应等效设计波各参数。根据等效设计波求出各工况全船所受的波浪诱导动载荷,施加到全船有限元模型上,进而对船体弯扭强度及变形水平进行评估。比较了单舱船及货舱中部设一道横舱壁的两舱船,得出单舱船屈曲强度不足的结论,并提出改善屈曲强度的方案。     

球扁钢肋骨纵向弯曲火工矫正研究

针对船体球扁钢肋骨三角形加热矫正纵向弯曲变形时加热区的计算,通过全站仪测量肋骨与板材线型,使用非均匀B样条拟合曲线后计算了两者的装配偏差。研究了矫正时加热区的计算算法和计算流程,在MATLAB的GUI模块中开发了球扁钢肋骨三角形加热区预报系统,实现了肋骨与板材线型测量数据的导入、曲线的拟合、装配偏差的计算、三角形加热的位置与工艺参数的准确预报。研究内容和成果对火工矫正球扁钢肋骨纵向弯曲变形的现场施工提供了一定的参考和指导。     

特征载荷下海工管状结构屈曲临界载荷分析

圆柱形管状结构在海洋工程领域中应用较多,在进行结构设计时,需重点关注其侧向受载时的屈曲强度问题。通过理论分析和数值模拟,对比研究径向线性载荷变化下圆柱壳的屈曲行为,以经典的Donnell壳体理论为基础,得到圆柱壳的屈曲控制方程,并通过本征值分析方法得到结构屈曲的临界条件。采用有限元软件ABAQUS对线性变化径压下圆柱壳的屈曲进行数值仿真。分析得出径厚比是径向线性分布载荷下圆柱壳屈曲临界载荷的主要影响因素,三角形径压下屈曲临界载荷值约为均布径压下屈曲临界载荷值的2倍。     

Laboratory tests and thermal buckling analysis for pipes buried in Bohai soft clay

Upheaval buckling of submarine pipelines occurs due to relative movement of pipeline and surrounding soil and is often triggered by high operational temperature of the pipeline, initial imperfection of the pipeline, or a combination of both. Since buckling can jeopardize the structural integrity of a pipeline, it is a failure mode that should to be taken into account for the design and in-service assessment of trenched and buried offshore pipelines. In this study, a series of vertical (uplift) and axial pullout tests were carried out on model pipe segments buried in soft clay deposit similar to that present in Bohai Gulf, China. Pipe segments with three different diameters (= 30 mm, 50 mm and 80 mm) were buried in different depth-to-diameter ratios ranging from 1 to 8. Based on the results of laboratory tests, nonlinear force–displacement relations are proposed to model soil resistance mobilized during pipeline movement. The proposed nonlinear soil resistance models are employed in finite element analysis of buried pipelines with different amplitudes of initial geometric imperfections. Thermal upheaval buckling behavior of pipelines operating at different temperatures is studied. Results show that the capacity of pipeline against thermal buckling increases with the burial depth and decreases with the amplitude of initial imperfection.     

Antisymmetric thermal buckling triggered by dual distributed buoyancy sections

Rogue buckles may occur for unburied subsea pipelines operating under high temperature and high pressure conditions. Distributed buoyancy section (DBS) is often installed to trigger pipeline lateral buckling. Single distributed buoyancy section (SDBS) is normally adopted to trigger a symmetric lateral buckling mode. But in some cases, dual distributed buoyancy sections (DDBS) with a gap between them are utilised to trigger an antisymmetric lateral buckling mode. This paper concerns the behaviour of antisymmetric lateral buckling triggered by DDBS. First, the locations of the maxima of the deflection and bending stress are determined. Then, comparisons of the post-buckling behaviour between antisymmetric buckling mode, triggered by DDBS, and symmetric buckling mode, triggered by SDBS, are presented and discussed. The influences of the spacing between dual buoyancy sections and the parameters of the DBS on the buckled configuration and post-buckling behaviour are presented. Finally, the effects of the DBS on the minimum critical temperature difference, the maxima of the deflection and stress are discussed. The results show that the maxima of the deflection and stress of the antisymmetric mode are much smaller than that of the symmetric mode under the same operating conditions. During the design process, the spacing between dual buoyancy sections, the length and the weight ratio coefficient of the DBS should be determined in sequence.     

支线集装箱船整船强度和疲劳有限元分析

在分析UR S11A和S34生效后的集装箱船整船屈服、屈曲要求的基础上,以1艘支线集装箱船为对象,计算得到目标船整船结构各个计算工况下的应力分布,完成整船屈服、屈曲强度评估和疲劳筛选及评估,分析发现支线集装箱船艏、艉非货舱区域结构和货舱区域的横向结构,以及整船重点区域的疲劳问题不容忽视.在设计时,对上述区域结构应重点关...     

Lateral buckling of subsea pipelines triggered by combined sleeper and distributed buoyancy section

In order to release the axial compressive force resulting from high-temperature conditions, sleepers or distributed buoyancy sections are usually installed along the route of the subsea pipeline as the buckle initiation facilities to trigger lateral buckles. DNV-RP-F110 suggests that the individual buckle initiators can be combined to further increase the reliability of buckle formation. In this study, an improved buckle initiation technique, called the combined sleeper and distributed buoyancy section, is investigated. A generalised mathematical model is proposed to simulate lateral buckling triggered by the combined sleeper and distributed buoyancy section, and it can also be applied to simulate lateral buckling triggered by an individual technique, such as triggered only by sleeper or only by distributed buoyancy section. The mathematical model is verified by comparing with the solutions in the literature. The parametric analysis shows that the buckle formation reliability can be improved when the combined sleeper and distributed buoyancy section is employed. Moreover, both the axial force and the maximum stress along the buckled pipeline in the post-buckling stage are at a lower level, so the pipeline will be safer when the combined sleeper and distributed buoyancy section is utilised as the triggers.     

Analytical study on controlled lateral thermal buckling of antisymmetric mode for subsea pipelines triggered by sleepers

Subsea pipelines exposed to high temperature and high pressure (HTHP) conditions is susceptible to lateral buckling. In order to control lateral buckling, engineered buckle initiators, such as sleepers, are introduced to initiate planned lateral buckles along the pipeline at specific locations in order to ensure that the stress in each lateral buckle remains acceptable. In this study, taking the interaction of adjacent buckles into account, analytical solutions of antisymmetric lateral buckling mode triggered by sleepers are derived. With the proposed formulations, the method to obtain the accurate locations of lateral displacement amplitude and maxima of bending stress is presented and discussed. And a detailed comparison between symmetric and antisymmetric mode of lateral buckling triggered by single sleeper is presented. Moreover, the influence of the sleeper spacing on controlled lateral buckling behaviour with the consideration of axial interaction between adjacent buckles is conducted. Finally, a detailed analysis about the influence of the sleeper height, lateral frictional coefficient and submerged weight of the pipeline on the controlled post-buckling behaviour is presented. Our results show that, for smaller sleeper friction or smaller sleeper height, the symmetric mode is more likely to happen, while the antisymmetric mode is prone to occur for larger sleeper friction and larger sleeper height. One effective method to reduce displacement amplitude and maximum stress is to decrease the sleeper spacing. The minimum critical temperature difference decreases with increasing sleeper height and increases with increasing lateral friction coefficient or submerged weight of the pipeline. And an alternative way to reduce the maximum stress is to reduce the lateral friction coefficient or submerged weight of the pipeline even though the displacement amplitude increases.     

组合应力作用下含腐蚀缺陷海管安全工作压力评价方法

在较高温度和压力作用下,由于土壤的摩擦阻力,海管会产生很大的轴向压力,以及由侧向屈曲引发的弯矩。因此对含腐蚀缺陷管道安全工作压力的评价,须考虑轴向压应力的影响。对目前工程界的评价方法进行对比分析,在内压和轴向压应力组合作用下,含腐蚀缺陷海管的安全压力评价方法还很不完善,尤其是复杂缺陷,目前的规范还不完全适用。通过对许用应力法安全系数的讨论和分析,基于Von Mises准则和有限元分析,提出了组合应力作用下含腐蚀缺陷海管的安全工作压力评价方法。通过该方法对某运行了近三十年的管道进行了安全工作压力的评估,同时考察了轴向压应力对安全工作压力的影响。此方法对应的轴向压应力限值和安全等级以及安全系数相关,当安全等级低时,其值和DNV-RP-F101规范值基本一致,当安全等级高时,其值比DNV-RP-F101规范值大。     

基于改进的屈曲模态阵型的锥形连续柱体结构屈曲分析（英文）

Elastic critical buckling load of a column depends on various parameters, such as boundary conditions, material, and crosssection geometry. The main purpose of this work is to present a new method for investigating the buckling load of tapered columns subjected to axial force. The proposed method is based on modified buckling mode shape of tapered structure and perturbation theory. The mode shape of the damaged structure can be expressed as a linear combination of mode shapes of the intact structure. Variations in length in piecewise form can be positive or negative. The method can be used for single-span and continuous columns. Comparison of results with those of finite element and Timoshenko methods shows the high accuracy and efficiency of the proposed method for detecting buckling load.