Fracture of Stiffened Shell Plating caused by Multiple Site Damage

多处损坏引起的加劲壳板断裂

• 批准号: 06452348
• 负责人: SUMI Yoichi
• 金额: $ 4.86万
• 依托单位: Yokohama National University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06452348/
• 关键词: stiffened panel; multiple cracks; fatigne crack; unstable fracture; 疲労き裂

Crack growth of a single or periodical array of cracks initiated at the stiffeners in a stiffened panel hasbeen investigated. Using stiffened panel specimens, fatigue crack propagation tests have been carried out. The corresponding numerical simulation has also been performed, and the results have shown that in case of stiffened panel with multiple cracks, the crack growth rate is higher compared with that witha single crack, because the multiple damaged stiffeners increase the stress intensity factors ahd also the adjacent cracks interact with each other for the case of multiple cracks. For a deck structure of an actual ship, the ratio of the crack growth lives for multiple site damage (MSD) cracks and for asingle site damage (SSD) crack have been studied. It is found that the crack propagation rate of MSD is several times higher than that of SSD .In the second part of the study, a testing apparatus has been designedand produced in order to examine the final unstable failure of a stiffened panel with MSD under excessive lateral pressure. A preliminary test has beencarried out by using a aluminum plate specimen with a single crack. The lateral pressure, strain, and crack velocity of the specimen were measured successfully.In the third part of the study, a general theory of cracking formation of a system of interacting cracks in heterogeneous materials is proposed for quasi-static brittle fracture under a monotonic loading condition and for fatigue crack propagation under a combined stress condition. Based on the present theory, a computational method for the prediction of the cracking formation of a system of interacting cracks is developed, in which a step-by-step formation of a cracking pattern is predicted by using the finite element method taking account of the interaction of all active (extending) cracks. Numerical results are given, and the validity of the method are confirmed.

本文研究了加筋板中由单个或周期性裂纹阵列起始的裂纹扩展问题。利用加筋板试件进行了疲劳裂纹扩展试验。结果表明，多裂纹加筋板的裂纹扩展速率比单裂纹加筋板的裂纹扩展速率要大，这是由于多裂纹加筋板的多个损伤使应力强度因子增大，而且多裂纹加筋板中相邻裂纹之间存在相互影响。针对实船甲板结构，研究了多处损伤（MSD）裂纹与单处损伤（SSD）裂纹的裂纹扩展寿命比。本文的第二部分设计并制作了一台试验装置，用于研究带有MSD的加筋板在过大侧压作用下的最终失稳破坏。本文用单裂纹铝板试件进行了初步试验。在第三部分的研究中，提出了非均匀材料中相互作用的裂纹系统的裂纹形成的一般理论，用于在单调加载条件下的准静态脆性断裂和在复合应力条件下的疲劳裂纹扩展。在现有理论的基础上，提出了一种预测相互作用裂纹系统裂纹形成的计算方法，其中通过考虑所有活动（延伸）裂纹的相互作用，使用有限元方法预测裂纹图案的逐步形成。给出了数值结果，验证了该方法的有效性.

项目成果

Y.Sumi: "Multiple Fatigue Cracks Propagating in a Stiffened Panel" Journal of the Society of Naval Architects of Japan. Vol.179(in press). (1996)

Y.Sumi：“加筋板中传播的多重疲劳裂纹”日本造船学会杂志。

角洋一: "不均質材中のき裂群の伝播形態に関する研究(その1)" 日本造船学会論文集. 177(印刷中). (1995)

Yoichi Kaku：“异质材料中裂纹群传播模式的研究（第 1 部分）”日本造船学会汇刊 177（出版中）。

角 洋一: "不均質材中のき裂群の伝播形態に関する研究" 日本造船学会論文集. 177. 287-292 (1995)

Yoichi Kaku：“异质材料中裂纹群传播模式的研究”日本造船学会汇刊 177. 287-292 (1995)。

角洋一: "不均質材中のき裂群の伝播形態に関する研究" 日本造船学会論文集. 177. 287-292 (1995)

Yoichi Kaku：“异质材料中裂纹群传播模式的研究”日本造船学会汇刊 177. 287-292 (1995)。

Y.Sumi: "Multiple Fatigue Cracks Propagating ina Stiffened Panel" 日本造船学会論文集. 179(印刷中). (1996)

Y.Sumi：“加筋板中的多重疲劳裂纹”，日本造船学会汇刊 179（出版中）。