【作者】 张琴；

【导师】 刘敬喜；

【作者基本信息】 华中科技大学 ， 船舶与海洋结构物设计制造， 2012， 硕士

【摘要】 船舶结构在服役过程中，可能会遭受各种形式的损伤。除了腐蚀损伤以外，疲劳损伤是最为常见的一种损伤形式。在载荷作用下，裂纹可能产生于结构应力集中的焊接节点以及局部区域，且裂纹可能会伴随着船舶的整个寿命周期。目前基于断裂力学的相关理论对疲劳裂纹问题进行研究的较多，但对含裂纹船舶结构的剩余极限强度研究相对较少。从长远来看，这方面的研究将有利于评估老龄化船舶结构的结构完整性。基于此，本文应用有限元工具对船舶典型结构（如板和加筋板）受单轴向压缩载荷作用下的极限强度进行了研究，分析了其受载的力学特性。首先考虑了加筋板壳板的柔度系数、加筋板的柔度系数以及加强筋形式等参数对完整加筋板极限强度的影响。然后对含裂纹的矩形板进行了无量纲参数化分析和计算，主要考察了不同裂纹特征（裂纹长度、裂纹位置）以及几何特征（板厚、板的长宽比）的矩形板剩余极限强度的变化，并详细讨论了多裂纹存在下，干扰裂纹对主裂纹的裂纹尖端应力分布等的干扰作用。在矩形板的基础之上，进一步分析了裂纹形式、裂纹长度及裂纹位置对含裂纹加筋板以及加筋板板架的剩余极限强度的影响。最后，针对船体构件（如加筋板）因屈曲/屈服而导致其承载能力减弱的问题进行了分析，对某化学品船立体舱段取其箱型梁截面，利用Smith方法，通过逐步破坏分析求得其船体舯剖面的极限弯矩，进行总纵极限强度分析和校核。分析所得到的结论将有利于基于极限状态分析的老化开裂结构的时变可靠性评估。更多还原

【Abstract】 Ship structure may be suffered from many types of damages during its service. Thefatigue damage is the main damage style, in addition to corrosion damage. Anexamination of the cracking damage position confirms a such fact that the damages oftenappear in welded joints and local areas of stress concentrations under the periodical loadand the crack may be accompanied with the ship whole life. Fatigue cracking was studiedbased on fracture mechanics theory. While it is also important to understand the effect of acrack on the collapse response of a cracked member under monotonic loading and henceto evaluate the reduction in ultimate strength. In the longer term this understanding isexpected to contribute in the formulation of standards to assess the structural integrity ofageing structures.In this thesis, a numerical study on the residual ultimate strength of ship structuressubjected to axial compressive is carried out. At first, numerical analyses on the ultimatestrength of perfect stiffened plates are investigated considering the effects of severalparameters such as flexible factor of plates, flexible factors of stiffened plates andcharacteristics of stiffeners. In addition, the residual ultimate strength reductioncharacteristics of plate elements and stiffened plates due to cracking damage areundertaken with varying size, shape and location of the cracking damage and varyingthickness and aspect ratio of the plate’s geometrical dimensions. And also, A series ofnonlinear finite element analyses for plate elements including two parallel cracks areperformed.At last, buckling problems of the ship structural details are also discussed, suchas the problem that the capacity of stiffeners will reduce because of buckling/plasticity. Bytaking the transverse section of the box-shape girder for the chemical tanker bulkhead,according to Smith method, the ultimate vertical bending moment of amidships is obtainedwith progress collapse analysis. The results of the numerical computations obtained aredocumented. The insights developed will be very useful for the ultimate limit state basedrisk or reliability assessment of aging steel plated structures with cracking damage.更多还原