著者

升田 利史朗

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.28, no.312, 1979-09-15

著者

藤原 源吉

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.45, no.1, pp.2-8, 1996-01-15

被引用文献数

13

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This article describes the findings of research for some recent transport airplane's accidents related to fatigue cracks. One is a B747SR's accident due to crack initiating at the fastener holes (to say Multiple-Site Damage). The other describes the crash of UAL's DC10-10 (N1819U), in Sioux City, Iowa, U.S.A., on July 19, 1989, which experienced a catastrophic failure of the No.2 tail-mounted engine during cruise flight. The third explains the in flight separation of the No.2 engine and engine pylon from B747-100F, shortly after departure from Anchorage International Airport, Anchorage, Alaska, on March 31, 1993. As a result of investigation for B747-100F's accident, National Transportation Safety Board made some important recommendations (One is to amend the design load requirements of Title 14 Code of Federal Regulations Part 25 to consider multiple axis loads encountered during severe turbulence) to the Federal Aviation Administration. Also, current aging airplane service data have identified that there are more cracked airplanes with increasing fleet edge, and possibly several fatigue cracks in some of the cracked airplanes. Especialy, MSD helped focus the attention of the aeronautical field on the problems of operating an aging transport airplanes. Therefore, FAA proposed to rivise the Advisory Circular No.25·571-1A (Damage tolerance and fatigue evaluation of structure) on 3/5/1986. This article describes one operator's viewpoint on the means to maintain the safety of aircraft structures in consideration of the revised structural fatigue evaluation standards.

著者

藤原 源吉

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.43, no.493, pp.1188-1194, 1994-10-15

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Well Over 32 percent of the commercial air carrier fleet, worldwide, are beyond their original 20-year design life goal. In the past, 20-year old aircraft were most often replaced by newer aircraft for airline service. However, this is no longer true, and by the turn of the century, 64 percent of the current fleet will be at least 20 years old. This is because economic and market conditions have resulted in the use of commercial jet airplanes beyond their original economic design life objectives. As aircraft exceed their economic design life objectives, the incidence of fatigue increases and corrosion may become more widespread. The purpose of this paper is to discuss our experience with aging aircraft, the basic considerations of fracture mechanics treatment of cracks initiating at rivet holes(to say Multiple-Site Damage) and some problems due to fatigue cracks in aircraft components from the operators viewpoint.

著者

丁 勇 尾坂 明義 三浦 嘉也 難波 徳郎

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.43, no.489, pp.618-623, 1994-06-15

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Precipitation of LaBO_3 on the surface of a glass of composition 0.1Cr_2O_3・25Li_2O・10La_2O_3・65B_2O_3 (in mol%) was enhanced due to ultrasonic surface treatment (UST) with aqueous and ethanol suspensions of LaBO_3 particles. The aqueous suspension gave a higher efficiency than the ethanol suspension. The crystallites were almost uniform in size distribution, and grew irregularly : increase-decrease-increase in size when heated at 580℃. Preferred growth of (200) was detected. The mechanism of UST enhanced crystallization is proposed.

著者

内藤 武志 植田 秀夫 菊池 雅男

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.32, no.361, pp.1162-1166, 1983-10-15

被引用文献数

8 23

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Rotating bending fatigue tests were conducted on the gas carburized specimens with internal oxides and non-martensitic microstructure beneath the surface. The fracture surface and the axial section at the fatigue fracture origin were observed using a scanning electron microscope. The following results were obtained. (1) The S-N diagram of gas carburized steel with internal oxides and non-martensitic microstructure revealed two knees on its curve. The test results appeared to be divided into two groups: a group with the number of cycles to failure N_f under 10^5, and that with N_f over 10^6. (2) The fractographic feature of the group with N_f<10^5 was intergranular fracture from the surface to the depth of 25μ, followed by transgranular fracture reflecting martensitic microstructure. (3) For the group with Nf>10^6, fracture surface inclined about 45° to the specimen axis was observed. This surface was smoothened by rubbing each other with another surface during the fatigue test. The depth of the inclined smooth fracture surface reached to the depth of 100μ from the surface. It was concluded that the inclined smooth fracture surface consisted of the Stage 1 cracks and Stage 2a cracks.

著者

稲田 貞俊 花岡 公司 近藤 正多嘉

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.16, no.170, pp.883-889, 1967-11-15

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We designed the measuring instrument of thickness variation of bulged foil, and by using this apparatus, studied the configuration of bulged surface of aluminum foil. (1) The bulged surface of aluminum foil is composed by two parts; one part near the appex is spherically constant in thickness, the other part is settled inside the sphere. (2) The instable state of bulged surface of alumium foil occurs before the initiating point destructions. (3) The bulged height corresponding to the initiating instable state is detected by measuring the thickness variation.