Effects of Crack Damages on the Structural Response of Offshore Structures

裂纹损伤对海上结构物结构响应的影响

基本信息

批准号：
02302052
负责人：
YAO Tetsuya
金额：
$ 1.79万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Co-operative Research (A)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02302052/
关键词：
Offshore Structure Tubular Member Crack Damage Ductile Crack CTOD CTOA Elastoplastic Analysis Idealized Structural Unit 円筒ブレ-ス材弾塑性大たわみ解析理想化構造要素亀裂進展 J積分 CTOD

项目摘要

1. A survey of the crack damages of offshore structures was made. It was shown that the crack damages were most likely to take place at the tubular joints and that the dented damages caused by collisions or object fallings acted as a crack initiator because of a large strain concentration at the bottom of the dent.2. A series of pure tensile and pure bending tests of a tubular member having a circumferential through-thickness crack was carried out. The rigidity and load carrying capacity of the cracked tubular members were investigated considering the effects of ductile crack growth.3. Based on the experimental results, the generation phase analysis was performed with the finite element method. It was found that CTOD and CTOA were the fracture parameters effective for the crack growth initiation and continuation, respectively.4. The theoretical formula for the estimation of CTOD and CTOA were derived based on the semi-membrane shell theory and the assumption of Dugdale model.5. The idealized structural unit method for a circumferentially through-thickness cracked tubular member was newly developed considering the ductile crack growth. A crack spring element was inserted between two intact beam-column elements in elastic analysis, while a plastic hinge was inserted in elastoplastic analysis based on the plastic node method.6. Several numerical examples including a statically indeterminate portal frame with a crack damage showed the accurate and efficient capability of the proposed method.

1.对海上结构物裂纹损伤进行了调查。结果表明，裂纹损伤最容易发生在管接头处，而碰撞或物体坠落造成的凹痕损伤，由于凹痕底部应变集中大，是裂纹的引发源。 2．对具有周向全厚度裂纹的管状构件进行了一系列纯拉伸和纯弯曲试验。考虑延性裂纹扩展的影响，研究了含裂纹管件的刚度和承载能力。 3．根据实验结果，采用有限元方法进行生成阶段分析。发现CTOD和CTOA分别是裂纹萌生和延续的有效断裂参数。 4．基于半膜壳理论和Dugdale模型的假设，推导了CTOD和CTOA估计的理论公式。 5．考虑延性裂纹扩展，新开发了周向全厚度裂纹管件的理想化结构单元方法。弹性分析时在两个完整的梁柱单元之间插入裂纹弹簧单元，弹塑性分析则基于塑性节点法插入塑性铰。 6．包括具有裂纹损坏的超静定门式框架在内的几个数值算例表明了该方法的准确和高效的能力。