巻号一覧
49 巻 (2011)
- 6 号 p. 262-
- 5 号 p. 216-
- 4 号 p. 148-
- 3 号 p. 96-
- 2 号 p. 44-
- 1 号 p. 4-
前身誌
49 巻, 4 号
選択された号の論文の5件中1～5を表示しています
- |<
- <
- 1
- >
- >|
論文
-
大畑 充, 山口 亮, 南 二三吉, 崎本 隆洋, 伊木 聡原稿種別: 論文
2011 年 49 巻 4 号 p. 148-156
発行日: 2011/07/25
公開日: 2012/01/06
ジャーナル フリーThe tensile strain limit for leak of high pressure pipe with circumferential surface notch is simulated by FE-analysis based on the proposed damage evolution models, and compared with the experimental results. The simulation model for ductile crack growth accompanied by penetration through wall thickness consists of two criteria. One is criterion for ductile crack initiation from the notch-tip, in which plastic strain at notch-tip at onset of ductile cracking can be constant independent of shape and size of components as well as loading mode. The other is damage-based criterion for simulating ductile crack extension associated with damage evolution influenced by plastic strain as well as stress triaxiality ahead of the extended crack-tip. In this report, it is demonstrated that the simulation model can be applicable to predicting ductile crack growth behaviors of a SENT (Single Edge-Notched Tension) specimen and a circumferentially notched pipe with internal high pressure subjected to tensile loading.抄録全体を表示PDF形式でダウンロード (990K) -
崎本 隆洋, 伊木 聡, 遠藤 茂, 大畑 充, 南 二三吉原稿種別: 論文
2011 年 49 巻 4 号 p. 157-164
発行日: 2011/07/25
公開日: 2012/01/06
ジャーナル フリーIn recent years, construction of natural gas pipelines is expanding to severe environmental area such as seismic or permafrost region. In these regions, it can be expected that pipelines will be subjected to large deformation due to large ground movement associated with liquefaction in seismic region or frost heave in permafrost. In that case, it is focused on ductile fracture from circumferential flaw as a main failure mode. However, it has not been fully understood ductile fracture behavior under biaxial loading such as hoop stress from internal pressure and longitudinal stress.
This paper presents the influence of internal pressure on ductile fracture conducting full-scale pipe tests on machined surface notches with⁄without internal pressure. Especially, it is focused on investigation of ductile tearing from circumferential surface defect. Ductile tearing resistance curves (R-curves) obtain from pressurized and un-pressurized pipe tests show a good agreement. On the other hand, internal pressure increases the notch tip opening displacement of a circumferential surface defect at equal levels of applied longitudinal strain because a pressurized pipe is constrained in circumferential direction by internal pressure. These results indicate that high internal pressure decreases the longitudinal strain at ductile crack initiation or penetration from a circumferential surface defect.抄録全体を表示PDF形式でダウンロード (829K) -
Md. Shafiul FERDOUS, Masaki FUJIKAWA, Tatsujiro MIYAZAKI, Chobin MAKA ...原稿種別: 論文
2011 年 49 巻 4 号 p. 174-183
発行日: 2011/07/25
公開日: 2012/01/06
ジャーナル フリーThe stress concentration factor is an important parameter for evaluation of the strength of notched materials and critical stress at crack initiation of notched materials. The value of the stress concentration factor is determined according to the geometry of the notched materials. In the present study, to understand the evaluation method of the stress concentration factor for double-notched specimens, a series of double-notch patterns has been developed and computed by the body force method. For the calculation, a double notch was positioned at the edges of the calculation model of a finite plate under tensile stress and the double notch was symmetrical with the center axes of the calculation model. The effect of the shape of the second notch which was cut at the notch bottom of the first notch on the value of the stress concentration factor was examined, and the evaluation method of the stress concentration factor of a double-notched plate with finite width is discussed. Care was taken that the second notch size was relatively smaller than that of the first notch due to considerations of the applicability of the double-notch concept and the equivalent notch concept.抄録全体を表示PDF形式でダウンロード (1282K) -
三村 宏原稿種別: 論文
2011 年 49 巻 4 号 p. 184-191
発行日: 2011/07/25
公開日: 2012/01/06
ジャーナル フリーFracture toughness such as CTOD or Kca is applied to steel plates of the thickness used in actual constructions. On the other hand, K1c or K1a is to plates in the plane strain condition. Plate thickness dependence of the former stated in the standard of The Japan Welding Engineering Society (WES 3003) and High Pressure Institute of Japan (HIPS B102) is compared with that of the latter. Dependence of CTOD on plate thickness is fairly well compared to that of K1c, when expressed in terms of the shift in the transition temperature. K1a does not depend on plate thickness whereas Kca shows the clear dependence on plate thickness, which is explained by a naive model taking into account the effect of side ligaments.抄録全体を表示PDF形式でダウンロード (195K)
解説
-
川口 忍原稿種別: 解説
2011 年 49 巻 4 号 p. 165-173
発行日: 2011/07/25
公開日: 2012/07/25
ジャーナル フリーThe recommended practice proposed by the Japanese government describes the base requirements for design, operation, and maintenance of secure natural gas pipelines, in which operators are required to prevent serious leakage from the pipelines even in the rare event of third-party mechanical impact, as this can cause several types of large-scale fracture resulting in serious leakage of flammable natural gas, including brittle fractures and serious ductile fractures such as a rupture and a dynamic ductile fracture. These large-scale fractures can be perfectly controlled by the following measures: (1) specifying the fracture toughness of the line-pipe material, that is, the appropriate values of shear fracture area percent from the drop-weight tear test (DWTT) to prevent brittle fractures, and absorption energy from the Charpy impact test to prevent ductile fractures;and (2) applying the lower design factor to the pipelines, which is the ratio of the hoop stress to the flow stress of the pipe material. The required values of the Charpy energy for secure pipelines could be calculated using the conventional equation or evaluation method; however, it is noted that recent studies clarify that these sometimes give non-conservative results regarding fracture criteria when evaluating integrity of recent higher-pressurized gas pipelines applying line-pipe steel having a higher strength and a higher fracture toughness.抄録全体を表示PDF形式でダウンロード (1041K)
- |<
- <
- 1
- >
- >|