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Study on Fracture Safty Assessment of Structures

结构断裂安全评价研究

基本信息

批准号：
06302066
负责人：
MACHIDA Susumu
金额：
$ 14.21万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

In order to establish the fracture safety assessment system of structures, such basic researches as 1) study on inspection of ship structures, 2) Baysian reliability analysis for non-periodic inspection, 3) evaluation methods of CTOD for highly strain concentrated structural components, 4) strength assessm ent method of structures by Ultrasonic Testing, 5) study ondistribution of fracture toughness and 6) reliability approach to the defects assessment of structures are carried out.The results of this investigation are summarized as, 1) based on the enquete research data of ship structures, characteristics of the pre-existing cracks are made clear, 3) Baysian reliability analysis is developed for generating appropriate non-periodic structural inspection schedule, 3) estimation method of CTOD value of cracks existing in the structural stress concentration is proposed, 4) Ultrasonic Testing as a tool of NDI is studied and the validity of fracture strength assessment using Ultrasonic Testing is discussed, 5) a new model on the distribution of measured fracture toghness values in weld joints is proposed which can explain the wide scatter of the fracture toghness and 6) the reliability approach is introdued to the crack assessment method where the concept of partial safety factors are adopted to keep reliability level of judgment.These results will play an essetial role in the process of constructing the appropriate method of fracture safety assessment in the near future.

为建立结构断裂安全评估体系，开展了1）船舶结构检验研究、2）非定期检验贝叶斯可靠性分析、3）高应变集中结构件CTOD评价方法、4）结构超声检测强度评估方法、5）断裂韧性分布研究、6）结构缺陷可靠性评估方法等基础研究。本次调查的结果概括为：1）基于船舶结构的大量研究数据，明确了预存裂纹的特征；3）开发了贝叶斯可靠性分析，以生成适当的非定期结构检查计划；3）提出了结构应力集中中存在的裂纹CTOD值的估计方法；4）研究了作为NDI工具的超声波检测，并提出了超声波检测的方法。讨论了使用超声波测试进行断裂强度评估的有效性，5）提出了一种关于焊接接头中测量的断裂韧性值分布的新模型，可以解释断裂韧性的广泛分散性，6）将可靠性方法引入裂纹评估方法，其中采用部分安全系数的概念来保持判断的可靠性水平。这些结果将在构建适当的断裂安全方法的过程中发挥重要作用近期内进行评估。