1 0 0 0 OA 欠陥を有する溶接部の信頼性解析 (第1報)
- 著者
- 板垣 浩 豊田 政男 真島 篤 朝田 洋雄
- 出版者
- The Japan Society of Naval Architects and Ocean Engineers
- 雑誌
- 日本造船学会論文集 (ISSN:05148499)
- 巻号頁・発行日
- vol.1981, no.149, pp.287-297, 1981 (Released:2010-01-25)
- 参考文献数
- 20
The role of adequate non-destructive inspections and following repairs of detected flaws is essential in order to continue the integrity of welded structures. It is, however, pointed out that catastrophic failures sometimes happen due to insufficient repairs having no regard for unfavorable effects of repair.In case of welded joints, when a detected flaw is repaired by renewed welding, the fracture toughness of a flaw which is not discovered and adjacent to the detected flaw becomes smaller because of so-called the Hot Straining Embrittlement. Therefore, if such effect mentioned above is not taken into account, the reliability of the welded joint must be overestimated.The purpose of the research is to investigate the effect of the Hot Straining Embrittlement giving rise to serious deterioration of fracture toughness and evaluate the optimum range of repair in order to prevent an unexpected failure with the aid of reliability analysis.This report, at first, describes deterministic or probabilistic factors which should be adopted in the reliability analysis, a model and formulations of the analysis, and then, presents the comparison between estimated reliabilities of various cases, i. e., no repair, repair with or without the Hot Straining Embrittlement (HSE).From the results of numerical examples, it is shown that, 1) the probability of failure of repair with HSE is extremely larger than that of repair without HSE, 2) when the detected flaw is small, the probability of failure of no repair becomes smaller than that of repair with HSE, and 3) the important results are obtained on the range of repair with HSE.
1 0 0 0 OA 各種構造用材料のボイド発生・成長挙動に注目した延性き裂発生特性に関する考察
- 著者
- 平松 秀基 豊田 政男
- 出版者
- 公益社団法人日本船舶海洋工学会
- 雑誌
- 日本造船学会論文集 (ISSN:05148499)
- 巻号頁・発行日
- no.190, pp.591-598, 2001-12
- 被引用文献数
- 2 5
The importance of investigations of ductile crack initiation characteristics increases in the evaluation of the structure of integrity and the plastic forming of metal materials. A lot of examinations shout ductile crack initiation behavior for ferrite-pearlite steels have been carried out. However, for other structural materials, enough examination has not necessary been carried out. In this study, ductile crack initiation characteristics of SM 490 A, stainless steel SUS 316, high tension steel HT 950 and aluminum alloy A 5083(O) have been investigated by using notched round bar specimens. Dynamic tensile test has also been conducted for SUS 316. And the critical equivalent plastic strain as a function of the stress triaxiality at ductile crack initiation has been estimated by using FE analyses (ABAQUS ver. 5.7). The ductile crack initiation is triggered by the microvoid nucleation for SUS 316 and HT 950, and it was controlled by the void growth for SM 490 A and A 5083(O). The influence of stress triaxiality to critical equivalent plastic strain varies in the material. That relates to the process of ductile crack initiation of the material. The microvoid nucleation is seemed to be affected by stress triaxiality more strongly than the void growth.
1 0 0 0 OA 応力三軸度が小さい力学状態における構造用材料の延性き裂発生特性
- 著者
- 平松 秀基 道場 康二 豊田 政男
- 出版者
- The Japan Society of Naval Architects and Ocean Engineers
- 雑誌
- 日本造船学会論文集 (ISSN:05148499)
- 巻号頁・発行日
- vol.2002, no.192, pp.563-571, 2002 (Released:2007-05-30)
- 参考文献数
- 16
- 被引用文献数
- 7 8
Significance of investigation of ductile crack initiation characteristics in the evaluation of structure of integrity is on the increase. It is significant to predict ductile crack initiation in plastic forming of metal materials. A lot of examinations about ductile crack initiation behavior under high stress triaxiality for structural steels have been conducted using notched round bar tensile specimens. Satisfactory examination under low stress triaxiality, however, has not necessary been conducted thus far.Ductile crack initiation characteristics of aluminum alloy A 5083-O and high strength steel HT 950 under low stress triaxiality have been investigated using plate tensile specimens in this study. The critical equivalent plastic strain as a function of the stress triaxiality at ductile crack initiation has been estimated using FE analyses.The ductile crack initiation is triggered by secondary void nucleation under low stress triaxiality, and it is controlled by initial void growth under high stress triaxiality for A 5083-O. The ductile crack initiation is triggered by void nucleation under the wide range of stress triaxiality. The critical diameter of void at ductile crack initiation varies with stress triaxiality for both materials. The critical equivalent plastic strain at ductile crack initiation under low stress triaxiality is seemed to be overestimated by extrapolation using curve fitted to test results under high stress triaxiality on the assumption that critical void diameter would be constant.
