著者

日野谷 重晴 池田 昭夫 寺崎 富久長

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.27, no.292, pp.81-86, 1978

被引用文献数

1

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The fracture surfaces of ferritic-perlitic steel caused by hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) under the wet H₂S environment were investigated by a scanning electron microscope. It was clarified that HIC and SSC were caused by hydrogen embrittlement. The cracks of HIC initiated around the nonmetallic inclusions (MnS) and they grew in a step-wise manner by connecting each other. On the other hand, the process of SSC took place as follows; the separated small cracks of HIC were connected by the cracks perpendicular to the stress axis. The fracture due to hydrogen embrittlement exhibited some characteristic fracture patterns, such as a river like pattern, flat pattern and so on. It was supposed that these fracture patterns were formed depending on the crystallographic orientation of grains. The striation type pattern was observed on the river like pattern as well as on the flat pattern. This striation type pattern seemed to correspond to the discontinuous propagation of hydrogen embrittlement cracking. In order to determine the sharp of the river like pattern, the stereo-matching technique was applied and it was found that this pattern could be classified into three types.

著者

山田 文二郎

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.16, no.169, pp.800-808, 1967

著者

岸本 秀弘 上野 明 河本 洋 浦 幸雄

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.38, no.424, pp.32-38, 1989

被引用文献数

1 7

---

Tensile tests were carried out on sintered Si₃N₄ at room temperature under the ambient condition, and the influence of defects upon the fracture stress was discussed. As the surface of specimens was prepared carefully, fracture of 57 specimens out of 60 originated from the defects such as voids or inclusions which resulted from the sintering process. As a parameter to describe the size of the defect, &radic;<i>area</i> was used which is the square root of the area of a 3-dimensional defect projected to the direction of the maximum principal stress. The results obtained are as follows.<br>(1) &radic;<i>area</i> of defects which caused fracture nearly conforms to the first asymptotic distribution of the largest value and the fracture strength conforms to Weibull distribution.<br>(2) &radic;<i>area</i> is a good parameter to describe the size of the defect from the standpoint of fracture.<br>(3) Defects such as voids and inclusions act exactly as cracks of the same size.<br>(4) The fracture strength can be estimated by using the distribution of &radic;<i>area</i>, the fracture toughness and the mean grain size of Si₃N₄.

著者

遠藤 正浩

出版者

社団法人日本材料学会

雑誌

材料 = JOURNAL OF THE SOCIETY OF MATERIALS SCIENCE, JAPAN (ISSN:05145163)

巻号頁・発行日

vol.55, no.10, 2006-10-15

著者

鎌田 浩毅 須田 恵理子 齋藤 武士 飯澤 功 酒井 敏

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.51, no.2, pp.168-175, 2002-02-15

参考文献数

28

---

Volcanic debris avalanche is a large-scale landslide which occurs at unstable volcanic edifice and often creates horseshoe-shaped crater at its source with hummocky deposits of volcanic debris including large blocks inside. Dynamic pressure model has recently been proposed to explain flow behavior of volcanic debris avalanches: Kinetic friction of debris avalanche decreases systematically at threshold of a certain critical speed for flotation. We have done a sliding experiment using flour powder as debris avalanche matrix and metal disks that slide on a powder layer as incorporated large blocks. Sliding traces left on a powder layer showed that a disk was floating over a certain critical speed. Kinetic friction coefficients, calculated by the position of a sliding disk recorded on a digital video, become small at a higher speed which exceeds critical floating speed, and provide smaller coefficient than those of normal surface of a rigid body. The critical floating speed deduced from dynamic pressure model is consistent with our experiment. In order to verify this model as the major driving force to float megablocks incorporated commonly in a volcanic debris avalanche, critical floating speeds for two geological cases at the collapses of 1980 Mount St. Helens and 1984 Ontake, central Japan, are examined and compared with the observed flow velocities. Estimated velocities deduced from the dynamic pressure model correspond fairly well to the actual velocities. This strongly suggests that the model gives the most convincing explanation for transportation and deposition mechanism of volcanic debris avalanche.

著者

仲村 匡司 坂井 崇俊 増田 稔

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.51, no.4, pp.398-403, 2002-04-15

参考文献数

16

被引用文献数

1 4

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Visual characteristics of wood which influence visual hardness of it were studied. Thirty-four photographs of H-shaped wooden backs of chairs were prepared as specimens. Questionnaires regarding visual hardness and &ldquo;deluxe&rdquo; image of specimens were distributed to 32 subjects using the repeated equal-division method. Color values (<i>Y, x</i> and <i>y</i>) of specimens were measured by the colorimeter. Local-area gloss <i>G</i> and spatial ratio of contrasts <i>C</i> were calculated using digital image analyses. <i>G</i> was the index of the local-area glossiness (highlight), and <i>C</i> was the index of the noticeability of wood grain figures. Calculation procedures for both indices were newly developed in this paper. The single correlation coefficient between a visual &ldquo;hard&rdquo; image and <i>Y</i> (lightness of specimen) was -0.91, and that between <i>G</i> was 0.83. Using visual &ldquo;hardness&rdquo; as a criterion variable and <i>Y</i> and <i>G</i> as predictor variables, a multiple regression analysis was performed. The multiple correlation coefficient was 0.931, the ratio of contribution was 86.7% (significant level 1%). Furthermore <i>C</i> was added to the regression model, above values were 0.942 and 88.8%, respectively (significant level 1%).

著者

工藤 清勝 岡本 剛

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.17, no.179, pp.656-666, 1968

被引用文献数

1

著者

林 知行

出版者

社団法人日本材料学会

雑誌

材料 = JOURNAL OF THE SOCIETY OF MATERIALS SCIENCE, JAPAN (ISSN:05145163)

巻号頁・発行日

vol.53, no.3, pp.345-350, 2004-03-15

参考文献数

19

被引用文献数

2

著者

中村 孝

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.55, no.4, pp.445-446, 2006-04-15

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筆者は2004年10月から2005年7月まで,カナダのアルバータ大学機械工学科で在外研究を行う機会を得た.アルバータ大学はアルバータ州の州都エドモントンにある学生数3万人以上の総合大学であり,世界45ヵ国170校と提携を結んでいる.特に,機械工学科は筆者の所属する北海道大学機械系専攻と実質的な交流を続けている.筆者は約10ヶ月の間,Advanced Composite Materials Engineering (ACME) Groupに在籍し,Fernand Ellyin教授とZihui Xia助教授の指導の下でCFRPの環境強度に関する研究に携わった.研究内容については,論文等で紹介する機会もあると思うので,本稿では印象に残った身の回りの出来事を綴ってみたい.

著者

大路 清嗣

出版者

社団法人日本材料学会

雑誌

材料試験 : journal of the Japan Society for Testing Materials (ISSN:03727971)

巻号頁・発行日

vol.8, no.74, 1959-11-15

著者

菊池 潮美

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.5, 1996-05-15

著者

中川 隆夫

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.304, pp.2-8, 1979-01-15

著者

山本 正

出版者

社団法人日本材料学会

雑誌

材料試験 : journal of the Japan Society for Testing Materials (ISSN:03727971)

巻号頁・発行日

vol.5, no.33, pp.346-351, 1956-06-15

著者

村瀬 勝彦 ジョーンズ ノーマン

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.42, no.483, pp.1420-1426, 1993-12-15

被引用文献数

5 6

---

Progressive plastic buckling appears in the axial symmetric behavion of circular tubes subjected to static loads or low velocity impacts,when the inertia effect is neglible.For high velocity impacrs in which imertia cannot be neglected,the studies.However,a series of impact tests on tubes by Florence et al.recorded thephenomenon of dynamic plastic buckling in which the deformation consists of many waves superposed on a uniform plastic deformation.This phenomenon was found for moderately thick circular tubes subjected to high velocity axial impacts.Ren et al. observed that dynami plastic buckling developed on thin circular tubed.Thus,the plastic buckling behavior for high velocity impact tests on circular tubes consist of both progressive plastic buckling and dynamic plastic buckling,but the deraied behavior is not clear yet.The purpose of this study is to clarify the characteristics for the transition process from progressive plastic buckling to dynamic plastic buckling.In particular,the following features are examined:(1) The comparison and consideration of various experimental methods used in the pervious impact test results.(2) The influence of end condition on the static buckling behavior of circular tubes.(3)The consideration of some impact test results.

著者

林田 建世 福本 博明 山口 明

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.22, no.243, pp.1104-1109, 1973-12-15

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The stationary viscoelastic properties of general purpose polystyrene (GPPS) and high impact polystyrene (HIPS) melts were measured by means of a screwless extruder. Since the cone rim pressure was not equal to the atmospheric pressure, some theoretical considerations were necessary to derive an approximate relation for calculating the first normal stress difference from the profile of Weissenberg's pressure and the value of pressure at the cone rim. Measurements of Weissenberg's pressure were performed in a stationary state which occur-red at 7〜10 min after the starting of the rotor and continued for about 5 min. The first normal stress difference observed for low density polyethylene (M.I.=2.0, 190℃) showed a fairly good agreement with the literature values. The first normal stress difference for GPPS was slightly greater than that for HIPS at the same shear rate. Some flow properties were measured with an extruder-type rheometer according to both Bagley's and the pressure gradient methods, which gave the same results. The apparent viscosity of HIPS was somewhat greater than that of GPPS at the same shear rate. The rigidity, calculated from the first normal stress difference and the apparent viscosity for HIPS, was considerably higher than that for GPPS at the same shear rate. The correlation between the Weissenberg effect data and the exit pressure data was also examined.

著者

鄭 強 荒木 修 瀧川 敏算 高橋 雅興 升田 利史郎

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.45, no.12, pp.1284-1289, 1996-12-15

参考文献数

23

被引用文献数

2

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Mixtures of Poly (metyl methacrylate) (PMMA) and poly (α-methylstyrene-co-acrilonitrile) (αMSAN) exhibit a LCST type of phase behavior. Dynamic rheological properties of PMMA / αMSAN blends of various compositions were measured at temperatures below, near, and above the phase-separation temperature. The time-temperature superposition was tried to obtain the master curves of G′ and G″ at 160℃. The time-temperature superposition principle failed above a certain temperature due to a phase separation. The "breakdown" temperature is close to the cloud temperature T_c of the blend samples. Comparison of log G′ vs. log G″ relation between the two components and the blends was made. The results show that the slopes of log G′ vs. log G″ plots in the terminal region are dependent on the composition of the blends. The rheological measurements have been found to be useful for characterizing the phase-separation of PMMA / αMSAN blends.

著者

矢野 武夫

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

長嶋 晋一

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.358, pp.705-715, 1983-07-15

被引用文献数

2 1

著者

中井 博 北田 俊行 穐山 正幸 三田村 武 小林 剛 島本 明

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.48, no.6, pp.623-628, 1999-06-15

参考文献数

7

被引用文献数

1

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Investigated in this paper is a new hybrid cable-wire consisting of outer new Fiber Reinforced Plastic(FRP)and a steel wire as a core. First of all, a design method of cross section of the new hybrid cable-wire is proposed on the basis of the safety factors of 1.7, 3.0 and 1.1 against the yield limit state of the core steel wire, the ultimate limit state of the hybrid wire and the hazard state corresponding to the breaking of the outer FRP by accidents from standpoint of fail safe, respectively. Next, the mechanical properties of carbon-steel hybrid wires are dealt with, which consist of outer CFRP containing parallel carbon fibers and a core steel wire, and are dimensioned by the design method and produced by a method called the pultrusion method for trial. Results of a static tensile test, bending test, lateral pressure test and fatigue test prove the possibility of their application to structural cables and the necessity of further study for developing reliable anchorage systems of hybrid cables. A corrosion test emphasizes the importance of investigation on countermeasures against galvanic corrosion of carbon-steel hybrid wires.

著者

山口 章三郎 大柳 康 辻川 洋三郎 高橋 義男

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.23, no.250, pp.588-592, 1974-07-15

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The effects of dimensions and supporting conditions on the compressive strength and deformation of polyvinylchloride pipes under external pressure were discussed. The following four kinds of pipe supporting conditions were used; (A) compression between two steel plates, (B) compression between a steel plate and a concave wooden block, (C) compression between two concave wooden blocks, and (D) compression between two concave hard rubber supporters. The main results obtained are as follows. (1) The relation between the compressive strength P and the dimensions of PVC pipe is given by the following formula, similar to the mid load bending for a both end flxed straight beam with a rectangular section; P=(4σ_b・l・t^2)/(3・Dm)・c_1 (a) where, l, t and D_m are the length, thickness and diameter of pipe, respectively, c_1 the correction coefficient according to pipe supporting conditions, and σ_b the bending stress in kg/mm^2. The value of correction coefficient c_1 was 0.81〜1.35 for A-method, 1.35 for B-method, 8.0 for C-method and 2.3 for D-method, respectively. (2) The deflection δ under elastic deformation is given by the following formula; δ=(P・D_m^3)/(8E・l・t^3)c_2 (b) where, E is Young's modulus in kg/mm^2 of pipe material, and c_2 the correction coefficient similar to c_1. The value of c_2 was 2.22 for A-method. (3) It seems reasonable, therefore, that the theory of straight beam may be applied to the compressive strength and deflection of plastics-pipe under external pressure by using the correction coefficient c_1 or c_2.