A Study on the crack initiation strength of Ship Hull Structure after Buckling

船体结构屈曲后起裂强度研究

基本信息

批准号：
07305045
负责人：
YAJIMA Hiroshi
金额：
$ 5.57万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07305045/
关键词：
Ship hull structure Buckling collapse Compressive plastic strain Cyclic compressive strain Mechanical properties Fracture toughness Crack initiation strength Elastoplastic large deformation analysis 座屈・塑性崩壊 V-ノッチシャルピー衝撃試験切欠靱性低下溶接構造

项目摘要

It is well known that ship hull structural members might buckle due to overloads, when they are subjected to the stormy weather, or the plate thickness wastes owing -to corrosion and ageing deterioration. Since the parts at the compressive sides of the buckled structural members, in other word, the parts with large compressive stains become brittle, and the fracture toughness decreases, it is of high possibility that cracks are initiated in advance. That is to say, it is quite often that the buckled structural members would result in the serious fracture accidents. At present, some serious fracture accidents of the large ships due to this cause have been reported.In this research, during three years from 1995 to 1997, the achievements including the various test results with four kinds of steel plates and the results of elastoplastic large deformation analysis by Finite Element Method, are summarized as follows.1. The effects of the axial compressive prestrains on the mechanical properties and fracture toughness have been made clear.2. The crack initiation strength (the small crack initiation criteria) of the strip specimens buckled only once has been quantitatively evaluated.3. The crack initiation strength and fracture strength of the strip specimens and the fillet welded specimens under the cyclic bending loads have been made clear.It is can be said that the fundamentals of Fracture Controlled Design Method are established based on the results of this research, by which the serious fracture accidents of the structures would be prevented. Moreover, although some researches on the material deteriorations due to the compressive prestrains have been done, this might be the firsttime that the crack initiation strength is evaluated quantitatively.

众所周知，船体结构构件在遭受暴风雨天气时，可能会因超载而弯曲，或因腐蚀、老化劣化而导致板厚浪费。由于屈曲结构件的受压侧部分，即压缩应变大的部分变脆，断裂韧性下降，因此裂纹提前萌生的可能性很高。也就是说，结构构件发生屈曲而导致严重断裂事故的情况是经常发生的。目前，因该原因造成的大型船舶严重断裂事故已有报道。本研究从1995年到1997年三年间，取得了四种钢板的各种试验结果和大型弹塑性试验结果。采用有限元法进行变形分析，总结如下： 1．明确了轴向压缩预应变对力学性能和断裂韧性的影响。 2．对一次屈曲后的条状试件的裂纹萌生强度（小裂纹萌生标准）进行了定量评价。 3．明确了带状试件和角焊缝试件在循环弯曲载荷作用下的裂纹萌生强度和断裂强度。可以说，基于本研究的结果，建立了断裂控制设计方法的基础。避免结构严重断裂事故的发生。此外，虽然已经对压缩预应变引起的材料劣化进行了一些研究，但这可能是第一次定量评估裂纹萌生强度。