4350DWT多用途—集装箱船双层底结构的重货强度计算

双层底装载重货钢板卷筒的强度计算，因船规中无直接公式可套用，故采用直接计算法，按GL船级社要求计算船舯最小剖面模数，并在波浪动载荷的中拱，中垂状态下进行校核船体梁的设计弯曲应力，局部板架纵向应力，横向应力和剪切应力，计算结果非常满意，平板龙骨及船底板厚度比船级社的退审意见还薄了1－2mm，不但减轻了船体重量，节省造船成本，而且还降低了载重量的罚款风险。     

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注,必要时建议选择装载手册中最危险的工况开展整船屈服、屈曲和疲劳评估并作适当加强。     

多用途船集装箱装载工况直接计算分析

多用途船的货舱内装载集装箱的固定形式与普通集装箱船不同,船级社及船舶的设计、建造方对此类船舶结构强度的安全性和可靠性投入更多的关注。为此,参照中国船级社钢质海船入级规范的要求,研究提出了舱内载荷的模拟方法,以某多用途船舱段结构强度有限元计算分析为例,分析研究集装箱横向运动和垂向运动惯性力对船体结构强度的影响。为多用途船装载集装箱工况的结构设计提供准确的分析方法。     

船舶液舱受静压力作用引起的舱容量值变化的初步研究

受静压力影响,船舶在不同的装载工况下,液舱内围壁会产生不同程度的结构变形,计量测深管也会随之发生位移,从而引起舱容量值变化.本文以满载工况下的某典型油船为例,借助有限元软件MSC.Nastran和曲面积分方法分别对甲板板架、船底板架、舷侧板架和舱壁板架的变形和计量测深管的位移求解,从而对该船满载工况下受静压力影响引起的舱容量值变化进行初步研究,为船舶液货舱容量计量修正提供依据.     

船舶液舱受静压力作用引起的舱容量值变化的初步研究

受静压力影响,船舶在不同的装载工况下,液舱内围壁会产生不同程度的结构变形,计量测深管也会随之发生位移,从而引起舱容量值变化。本文以满载工况下的某典型油船为例,借助有限元软件MSC.Nastran和曲面积分方法分别对甲板板架、船底板架、舷侧板架和舱壁板架的变形和计量测深管的位移求解,从而对该船满载工况下受静压力影响引起的舱容量值变化进行初步研究,为船舶液货舱容量计量修正提供依据。     

超深水多功能钻井船总体强度直接计算分析

针对带有试采、储油功能的第七代超深水多功能钻井船的总强度,根据其功能与结构特点,选取钻井船在钻井、试采储油、自存、迁移4种工作状态下的装载工况,考虑作业、生存和迁移3种载荷工况下不同的环境条件,采用谱分析方法获得3种工况下的波浪载荷与设计波参数,完成整船有限元模型在各个设计波工况下的强度评估。对关键区域的结构进行设计改进,总结该船与常规钻井船在结构设计与应力分布上的差异,计算结果表明,带有工字型月池开口的钻井船船体强度满足规范要求。     

点蚀损伤板在复杂受力状态下的极限强度研究

采用非线性有限元软件模拟船底板单面点腐蚀,通过对边缘载荷系数比、蚀坑分布、直径、深度的改变,经过一系列的数值计算分析,结果表明横向载荷和侧压对板的极限强度影响不可忽略,计算板的极限承载能力时需要考虑计及侧压与横向载荷。在复杂受力状态下,就单考虑蚀坑深度时,板表面的蚀坑深度在0~0.5t区间变化时,极限强度相应的折减率比大于1/2板厚时更大,极限强度对蚀坑深度更加敏感。腐蚀面积不能有效表征腐蚀程度,当DOP系数相同时,点蚀后板的最小横截面决定了极限强度的大小。     

蜂窝式夹层板结构单元的防护性能分析

基于某舰船的船底板架,设计出了四边形蜂窝夹层板结构单元,比较分析了船底板架、等效平板、夹层板在典型工况(炸药量500 kg,爆距15 m)水下爆炸冲击波载荷作用下的损伤变形、结构位移、吸能及运动响应,同时对比分析不同冲击因子下3种结构的防护性能。分析表明,夹层板在水下冲击波作用下的最大变形是船底板架的2/3~1/3处,一定程度上改善了冲击环境,具有优越的防护性能。     

集装箱船舱口盖结构强度计算分析

针对集装箱船舱口盖的结构强度问题,从规范计算和有限元直接计算两方面入手,根据UR S21A和船级社规范,结合营运装载特点,应用露天载荷和集装箱载荷重点评估盖板结构的应力水平和屈曲安全因子,计算结果表明,舱口盖结构尺寸主要由混装集装箱载荷和20 ft集装箱载荷工况决定,局部板格屈曲结果不满足衡准要求,提出的加强方案可有效提高舱口盖结构强度。     

336TEU集装箱船横向强度有限元直接计算

利用MSC/PATRAN、MSC/NASTRAN对336TEU集装箱船的横向强度进行了有限元强度计算。给出了外载荷的计算方法和边界条件的施加方法,并在10种工况下对336TEU集装箱船进行了横向强度有限元分析。通过有限元分析得到的结论可用于指导集装箱船的结构设计与优化。计算结果表明结构强度满足强度要求。     

大型集装箱船在斜浪工况下的扭矩特征研究及结构强度分析

随着大型集装箱船的发展,针对斜浪条件下扭矩载荷特性及其结构强度的分析研究日益重要.本文采用选定的某大型集装箱船开展动态载荷(DLA)分析,建立了水动力湿表面计算模型和质量模型,研究基于扭矩传递函数和主要载荷控制参数的斜浪设计波参数确定方法,分析超越概率水平对扭矩载荷计算结果的影响.考虑典型斜浪参数和超越概率水平,分析对比DLA扭矩与船舶规范(ABS和HCSR)扭矩的差异及原因,提出集装箱船扭矩载荷计算与应用的建议.在此基础上,选定3个斜浪计算工况(45°,60°和75°)开展结构强度分析,通过分析应力计算云图,研究扭矩载荷下船体结构响应的关键位置及其应力趋势.该研究可为大型集装箱船结构设计过程中船体梁扭转强度计算、舱口角隅设计、抗扭箱强度评估等方面提供有益的参考.     

Ultimate strength of container ships subjected to combined hogging moment and bottom local loads,Part 2: An extension of Smith's method

This paper is the second of two companion papers concerning the ultimate hull girder strength of container ships subjected to combined hogging moment and bottom local loads. The nonlinear finite element analysis in Part 1 has shown that local bending deformation of a double bottom due to bottom lateral loads significantly decreases the ultimate hogging strength of container ships. In this Part 2, extending Smith's method for pure bending collapse analysis of a ship's hull girder, a simplified method of progressive collapse analysis of ultimate hogging strength of container ships considering bottom local loads is developed. The double bottom is idealized as a plane grillage and the rest part of the cross section as a prismatic beam. An average stress-average strain relationship of plate/stiffened plate elements employed in Smith's method is transformed into an average stress-average plastic strain relationship, and implemented in the conventional beam finite element as a pseudo strain hardening/softening behaviors. The extended Smith's method is validated through a comparison with nonlinear finite element analysis.     

船体典型结构局部强度考核试验模型设计

针对船体舱段模型典型结构,设计易于实际操作实施的缩比模型试验方案;通过有限元软件对板架水下爆炸响应进行分析．对比各个缩比模型在水下爆炸载荷作用下的响应规律．寻找为完成不同试验目的而设计的最佳试验方案。数值分析结果表明：纵桁和实肋板梁模型在水下爆炸作用下的动力响应可验证梁在爆炸冲击载荷作用下的理论分析方法,十字交叉梁塑性变形可验证实船板架结构中交叉梁系的结构动力响应分析方法。双层底板架结构的塑性变形可对舰船局部强度考核的理论分析提供基础,缩比模型计算结果与实船较为一致。计算结果对舰船型号研制和强度考核具有理论指导意义。     

轮印载荷下I型夹层板架结构静强度力学性能试验研究

现代舰船的直升机起降时会通过轮胎将载荷作用于飞行甲板的板架上,这种载荷通常被称为轮印载荷。除此之外,相对于传统加筋板结构形式,I型夹层结构具有轻质、高比强度等优点,是一种可以应用于船舶飞行甲板的新型结构形式。本文针对轮印载荷局部重载和位置不确定的特点,设计了合理的试验贴片方案及加载程序,并将试验数据与理论值对比,分析误差原因,研究I型夹层板架结构的板格在四种典型位置轮印载荷作用下的静强度力学性能。试验结果表明,夹层板架结构在载荷附近测点的应力水平较大,同时其上面板沿船宽方向的弯曲应力大于沿船长方向的弯曲应力,而下面板2个方向的弯曲应力特性与上面板相反。这些结论对于I型夹层板架结构在轮印载荷下的力学性能研究具有重要意义。     

Ultimate strength of container ships subjected to combined hogging moment and bottom local loads part 1: Nonlinear finite element analysis

This paper is the first of two companion papers concerning the ultimate hull girder strength of container ships subjected to combined hogging moment and bottom local loads. In the midship part of container ships, upward bottom local loads are usually larger than the downward ones. This leads to the increase of biaxial compression in the outer bottom plating and the reduction of the ultimate hull girder strength in the hogging condition. In this Part 1, the collapse behavior and ultimate strength of container ships under combined hogging moment and bottom local loads are analyzed using nonlinear finite element method. Buckling collapse behavior of bottom stiffened panels during the progressive collapse of a hull girder is closely investigated. It has been found that major factors of the reduction of ultimate hogging strength due to bottom local loads are (1) the increase of the longitudinal compression in the outer bottom and (2) the reduction of the effectiveness of the inner bottom, which is on the tension side of local bending of the double bottom. The obtained results will be utilized in the Part 2 paper to develop a simplified method of progressive collapse analysis of container ships under combined hogging moment and bottom local loads.     

Research on the dynamic buckling of a typical deck grillage structure subjected to in-plane impact Load

The dynamic buckling of the main deck grillage would result in the total collapse of the ship hull subjected to a far-filed underwater explosion. This dynamic buckling is mainly due to the dynamic moment of the ship hull when the ship hull experiences a sudden movement under impact load from the explosion. In order to investigate the ultimate strength of a typical deck grillage under quasi-static and dynamic in-plane compressive load, a structure model, in which the real constrained condition of the deck grillage was taken into consideration, was designed and manufactured. The quasi-static ultimate strength and damage mode of the deck grillage under in-plane compressive load was experimentally investigated. The Finite Element Method (FEM) was employed to predict the ultimate strength of the deck grillage subjected to quasi-static in-plane compressive load, and was validated by comparing the results from experimental tests and numerical simulations. In addition, the numerical simulations of dynamic buckling of the same model under in-plane impact load was performed, in which the influences of the load amplitude and the frequency of dynamic impact load, as well as the initial stress and deflection induced by wave load on the ultimate strength and failure mode were investigated. The results show that the dynamic buckling mode is quite different from the failure mode of the structure subjected to quasi-static in-plane compressive load. The displacements of deck edge in the vertical direction and the axial displacements are getting larger with the decrease of impact frequency. Besides, it is found that the dynamic buckling strength roughly linearly decreased with the increase of initial proportion of the static ultimate strength P₀. The conclusions drawn from the researches of this paper would help better designing of the ship structure under impact loads.     

横向载荷作用下小水线面双体船结构校核与优化

采用有限元仿真方法对一艘新型小水线面双体船进行强度校核，研究该船形在横向载荷作用下的结构强度和应力分布特性，进而给出结构优化设计方案，在确保结构安全的基础上达到严格控制重量的目的，形成的校核流程方法及优化设计方案可为同类船舶提供设计与校核指导。     

船体结构疲劳强度校核的许用应力范围衡准

本文给出了船体结构疲劳强度校核的许用应力范围衡准的一般形式，以及当应力范围服从Weibull分布时用一生中一遇最大应力范围表示的衡准形式。对有关影响因素及设计应力范围计算作了简要的讨论，并着重研究了集装箱船的疲劳强度校核问题，给出了例题。     

New insight into the wave-induced nonlinear vertical load effects of ultra-large container ships based on experiments

Accurate estimation of the wave-induced extreme hogging vertical bending moment (VBM) is of vital importance for the design of container ships because container ships are normally under hogging conditions in still water. According to the empirical formulas proposed by the classification society rules, the design hogging VBM can be approximately 20 % smaller than the design sagging VBM for vessels with small block coefficients. High-order harmonic components in the vertical load effects, which are induced by the nonlinearities in the hydrodynamic forces and ship hull geometry, contribute to the asymmetry. Previous studies have shown that the nonlinear hydrostatic and Froude–Krylov forces increase the sagging VBM significantly. Current numerical tools are able to reveal this asymmetry to a certain extent. There is, however, little focus on the nonlinear pressure under the bow bottom, which is a more likely contributor to the hogging VBM. Several unexpected phenomena have been observed for large container ships. The wave-frequency sagging and hogging VBMs followed each other closely, and hence did not reflect the significant nonlinear factors as expected. In this paper, the test data of two (8600-TEU and 13000-TEU) ultra-large containership models in both regular and irregular head waves are systematically studied. In regular waves, the influence of the second and third harmonics on the fundamental hogging peaks and sagging troughs is estimated by comparing both the amplitude and phase difference relative to the first harmonic peaks. In irregular waves, the focus is on the statistical characteristics of the wave-induced nonlinear vertical load effects. To achieve a balance between results in regular and irregular waves, the influence of the second harmonics is evaluated through bispectral analysis.