摘要船体极限强度是衡量船舶最大承载能力的标准之一。随着经济的不断发展，海上贸易量越来越大，船舶在货物运输等方面发挥了举足轻重的作用。但船舶灾难事件的频发，不仅造成了巨大的经济损失，而且危害了船员的生命安全。同时船舶结构在营运期间会出现裂纹缺陷，裂纹对船体极限强度的影响很大，因此研究含裂纹的船体极限强度，对船舶安全性能具有重要意义。

本文简单描述了选题的目的和意义，国内外研究现状，裂纹对船舶极限强度的影响，并通过有限元软件ANSYS分别对含中心穿透裂纹矩形板的极限强度，含垂直穿透裂纹的加筋板极限强度和含裂纹船体板架结构极限强度进行分析研究，给出裂纹尺寸对板架结构极限强度的影响，然后通过Paris公式简要研究疲劳裂纹扩展问题，最终将结论用图表的形式表示。81907

研究结果表明，在拉伸情况下，裂纹会严重削弱板架的极限承载能力，当超过临界数值时，板架的承载能力会急剧减少。在压缩情况下，裂纹会发生闭合现象。

毕业论文

关键词：极限强度；有限元；疲劳裂纹扩展

Abstract The ultimate strength of hull was one of the standards to measure the maximum bearing capacity of the ship。 With the continuous development of economy, there were more and more large amount of maritime trade and the ship played an important role in the transportation of cargo。 However, the frequent occurrence of ships’ disaster events, not only caused huge economic losses, but also endangered the lives and safety of the crew。 But during the operation of the ship's structure, cracks’ defect would occur, which had great effect on the ultimate strength of the ship hull。 So it was very important to make research on the ultimate strength of the ship hull with cracks。

The purpose and significance of the topic, the present situation in domestic and foreign research, the influence of the ultimate strength of the ship with crack were briefly described in this paper, and the ultimate strength of rectangular plate with center through crack, the ultimate strength of stiffened plate with vertical penetrating cracks and the ultimate strength of the ship hull with cracks, the effect on given cracks’ size on the ultimate strength of ship structure were respectively studied by the finite element software ANSYS。 Then studied on fatigue crack growth by Paris formula in brief。 Finally, the conclusions were given by chart forms。

In this paper, the effect of the residual stress and initial deformation were neglected, and only considered the effect of crack on the ultimate strength of the hull。

The results show that, in the case of tension, the bearing capacity of the plate frame with the crack would be seriously weakened。 When the critical value was exceeded, the bearing capacity of the plate would be reduced dramatically。 In the case of compression, the crack was closed。

Keywords: the ultimate strength; finite element; fatigue crack growth。

目  录

第一章  绪论 1

1。1 选题的目的和意义 1

1。2 船舶极限强度国内外研究现状及存在的问题 2

1。2。1 直接方法 2

1。2。2 逐步破坏法 3

1。2。3 实船事故调查和模型试验 7

1。3 疲劳裂纹扩展国内外研究现状 8

1。4 本文主要研究内容 9

第二章  结构极限强度理论 10

2。1 引言