【作者】 李景阳；

【导师】 崔维成；

【作者基本信息】 上海交通大学 ， 船舶与海洋结构物设计制造， 2009， 硕士

【摘要】 船舶结构强度是反映船舶结构安全性能的一项重要指标,是船舶结构设计、建造和使用过程中最主要的考查因素之一。板和加筋板作为船舶结构最基本的结构形式,其强度评估显得尤为重要。结构存在的缺陷以及使用过程中复杂载荷形式的影响,使得结构的强度会显著降低,甚至导致结构的破坏。所以正确评估受损船舶结构的剩余极限强度具有较高的研究价值和工程实用价值。裂纹是最为常见的一种损伤缺陷,然而,由于含裂纹结构应力分布的复杂性以及剩余强度影响参数的多样性,其极限强度的评估方法与完整结构强度的评估方法有所不同。目前,这方面的系统研究较少,以分析裂纹问题为目的的断裂力学理论还具有一定的局限性,并且研究结果很难直接应用到工程上。船舶结构剩余强度的研究作为一个新的研究领域,它目前仍处于发展阶段,进一步研究各种损伤形式对结构极限承载能力的影响规律,建立合理的结构损伤分析模型是船舶与结构强度研究的重要方向。本文的目的是综合分析当前含裂纹结构剩余强度研究的概况,对双向拉伸载荷作用下的含裂纹的船舶结构的剩余极限强度的评估方法做一较为深入系统的研究,综合考察复杂载荷作用下裂纹缺陷以及载荷形式对船舶结构剩余极限强度的影响,给出带裂纹构件的极限强度评估方法;同时在考虑了船舶结构存在的初始挠度的基础上,研究轴向压缩载荷作用下的含中心穿透裂纹板的剩余极限强度变化规律。本文的研究工作表明:非线性有限元法能够合理地分析裂纹对结构剩余极限强度的作用,裂纹的存在对结构的剩余极限强度有削弱作用,在工程结构强度评估中应该受到足够的重视。同时,船舶结构中的多裂纹分布的数量和分布位置是随机的,本文的工作为含随机多裂纹板的剩余极限强度分析奠定了基础。更多还原

【Abstract】 The strength of the ship hull structures is one of the most important index to expressing the safety and reliability of the ships. It is also one of the most important factors which have to be reviewed during the design, construct and the service of the ships. Plates and stiffened panels are two kinds of basic structure components of the ships and ocean engineering structures, the strength evaluation of these structures is very important. The initial damage and the complex loading condition will reduce the strength of the structures significantly. It is of crucial importance and to estimate the ultimate strength of the damaged structures.Crack is one of the most common types of damages in the aging ships. As a result of the complexity of the stress distribution around the crack and the diversity of the parameters, the strength assessment of cracked structures is different from the integrated ones. Systematic analyses are insufficient currently and the research method relating to crack problems is generally limited to theoretical elastic fracture mechanics or fully plastic estimation method, which could not be conveniently applied in engineering practice. As one of the new research field, the ultimate strength analysis of the ship structures is still in its initial developing phase. The investigation of the relationship between the damages and the strength of the structures and the establishment of the reasonable analysis model are new research directions of the assessment of the strength of the ships.The objective of this thesis is to investigate the general situation of the analysis of the ultimate residual strength of the cracked structures. A serious of researches are carried out to find out how the dimension of crack and the loading condition affect the ultimate residual strength of cracked structures under two direction of tensive stresses. At last we analyze the ultimate strength of cracked structures under compressive stresses considering the effect of the initial deformation. The work we done in this thesis shows that: we can find out how the crack affect the ultimate residual strength of the structures using the nonlinear finite element method; the existence of the crack weaken the strength of the structures definitely. We have to pay enough attention to the effect of the cracks when evaluating the strength of the ships and ocean engineering structures. Actually, the number and the location of the cracks in the ships in service are stochastic. Based on the conclusion we obtained in this thesis, we can analyze the strength of structure with random multiple crack damages in succession更多还原