著者

藤田 和宏 永井 英幹 岩下 哲雄

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.5, pp.461-466, 2022-05-15 (Released:2022-05-20)

参考文献数

19

---

Carbon fiber is a brittle material and its tensile strength is strongly influenced by defects, which are often assessed by the shape parameter of the Weibull distribution. Therefore, the shorter the gauge length is, the higher the tensile strength is. The usual tensile test is conducted with a gauge length of 25 mm and the tensile strength at short gauge is derived using Weibull distribution. However, it is reported that the shape parameter changes when the gauge length is less than 1mm. The objective of this work is to attempt to evaluate the short gauge tensile strength of carbon fiber in tests under optical microscope observation. The shorter the gauge length was, the more test results of fiber separation from adhesive or fiber breakage in adhesive were observed. It is found that the test of short gauge of 0.2 mm requires careful specimen preparation to avoid shear stress due to misalignment of fiber and loading axes. Weibull shape parameters of the tensile strengths at the gauges from 50mm to 1mm were almost the same as the usual tensile test. However, the values for the 0.5 mm and 0.2 mm gauges were higher than those for the longer gauges.

著者

藤川 拓朗 Timothy Newson Aly Ahmed Muhammad Safdar

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.1, pp.41-46, 2022-01-15 (Released:2022-01-20)

参考文献数

15

---

According to the mission scenario of the International Space Exploration Collaboration Group (ISECG), a "Mars sample return plan" is underway to bring the soil of Mars back to Earth by 2030. In the near future, in order to efficiently perform various operations on Mars (filling, excavation, sampling, ground improvement, etc.), pre-simulation on Earth will be important. Therefore, there is an urgent need to develop an appropriate simulated soil and to understand its material and mechanical properties. Based on this background, the authors are investigating the physical and basic mechanical properties of Mojave Mars Simulant soil (MMS-1), which has been reported as a simulated soil for Mars. This study focused on the particle shape of MMS-1 and was conducted to investigate the effect of particle shape on shear strength and volume change. As a result, it was revealed that MMS-1 has a higher shear strength than Toyoura sand and has a clear peak as the relative density increases. Moreover, MMS-1 is a material that causes volume expansion during shearing even for low stress and density states compared with artificial soil, and it was revealed that this is due to the angularity of the MMS-1 particles.

著者

吉岡 洋明 山下 章

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.58, no.7, pp.649-656, 2009-07-15 (Released:2009-07-18)

参考文献数

15

被引用文献数

5 5

著者

和田 八三久

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.21, no.223, pp.253-259, 1972-04-15 (Released:2009-06-03)

参考文献数

38

著者

関口 秀夫 小畠 耕二 鳥阪 泰憲

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.38, no.435, pp.1458-1464, 1989-12-15 (Released:2009-06-03)

参考文献数

30

著者

財満 鎭雄

出版者

公益社団法人 日本材料学会

雑誌

材料試験 (ISSN:03727971)

巻号頁・発行日

vol.5, no.37, pp.584-586, 1956-10-15 (Released:2009-05-26)

参考文献数

4

被引用文献数

1 1

---

The measuring error of the depression has a large influence upon the hardness which is calculated by the area of depression.The author studied the surface indented by Brinel, Vickers and Knoop depressions using Ogoshi Surface Roughness Tester, and found that for the same metal the piling-up was almost constant regardless of the applied weight and the measuring error, i. e. the error of hardness, differs with the metal. It was also found that there was a slight piling-up in the diagonal of Vickers depression but no piling up in the major diagonal of Knoop depression.

著者

柄澤 秀親 柴﨑 広樹 糸日谷 剛 山下 慎一郎 新井 和吉

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.70, no.12, pp.896-903, 2021-12-15 (Released:2021-12-20)

参考文献数

15

---

Sand erosion is a phenomenon in which the collision of solid particles erodes a material surface. The rate of sand erosion is higher in carbon fiber reinforced plastics (CFRP) than in metallic materials. Therefore, CFRP requires a light and protective coating material. Herein, to improve the erosion resistance of CFRP, five polyurethane coated CFRPs with different glass transition temperatures were investigated at elevated temperatures, and a prediction formula of the erosion rate at the elevated temperatures was established. Furthermore, computational fluid dynamics was used to predict the surface temperature and erosion rate of fan exit guide vane (FEGV) when polyurethane coating was applied, and the coating thickness for FEGV in the erosion environment was estimated based on these predictions.

著者

中川 雄策 玉村 建雄 根本 正

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.21, no.231, pp.1099-1105, 1972-12-15 (Released:2009-06-03)

参考文献数

9

被引用文献数

1 2

---

The residual stresses in quenched, tempered and isothermally treated steels were investigated by the X-ray method.The materials used were plain carbon steels containing 0.08%∼1.03% carbon and Ni-Cr and Cr-Mo low alloy steels. Test specimens were 50×50×20(mm) plates and 25φ×100(mm) round bars. They were quenched in water or oil from 800°C∼1000°C and tempered at several temperatures between 100°C∼800°C. Ni-Cr low alloy steel specimens were martempered at 200°C or austempered at 400°C.Residual stresses were determined by Sin2ψ method, using Cr-Kα radiation.The experimental results are as follows;(1) The surface residual stresses and residual stress distribution of these specimens were affected mainly by the hardenability of steels. The surface residual stresses of the plain carbon steel specimens quenched in water were compressive, while those of the low alloy steel specimens were tensile.(2) The surface residual stresses of the specimens quenched in water or oil decrease with the increase in tempering temperature. Particularly, in case of tempering above 400°C, the surface residual stresses were very small.(3) In the 0.85% carbon steel specimen quenched in water, large compressive stress was found just beneath the surface.(4) At the surface of the Ni-Cr steel specimens quenched in water or oil, the residual stresses were 55∼58kg/mm2 on tensile side, while those martempered at 200°C for 4 hours and those austempered at 400°C for 4 hours showed the residual stresses of 6.4kg/mm2 on tensile side and 20.8kg/mm2 on compressive side, respectively.In the Ni-Cr steel with high hardenability, isothermal treatment was effective in lowering the residual stress.

著者

菅野 蓑作

出版者

公益社団法人 日本材料学会

雑誌

材料試験 (ISSN:03727971)

巻号頁・発行日

vol.10, no.98, pp.850-854, 1961-11-15 (Released:2009-05-26)

参考文献数

20

被引用文献数

1 1

著者

野村 泰稔 矢子 嗣人 服部 洋 中山 正純

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.3, pp.296-302, 2022-03-15 (Released:2022-03-20)

参考文献数

9

---

In industrial, agricultural, and chemical plants, rotating machinery is the most regularly used and important equipment, and its troubles and failures have a significant impact on production and quality. Therefore, the development of technology for detecting abnormalities and diagnosing the soundness of rotating machinery has been an important topic of study for many years. Recently, anomaly detection using unsupervised learning methods of machine learning has been studied in various fields. In this study, we attempted to develop an unsupervised anomaly detection method that does not require damage data in advance. Using a Variational Autoencoder (VAE), which is one of the machine learning techniques, we conducted an anomaly detection experiment through vibration experiments simulating some typical damages of rotating machines and investigated whether the system can recognize situations different from normal appropriately.

著者

小林 英男

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.27, no.299, pp.711-720, 1978-08-15 (Released:2009-06-03)

参考文献数

57

著者

道浦 大祐 中原 佳夫 宇野 和行 田中 一郎

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.65, no.9, pp.652-655, 2016-09-15 (Released:2016-09-20)

参考文献数

12

被引用文献数

1 1

---

We improved the carrier mobility of the pentacene thin film transistors (TFT), which were fabricated with polysilsesquioxane (PSQ) gate dielectric layers, from 0.082 to 0.31 cm2V-1s-1 by treating the PSQ surface with ultra-violet irradiation (UV)/O3 and 1,1,1,3,3,3-hexamethyldisilazane (HMDS). It was found that the PSQ layers were flattened by the UV/O3 treatment, and the PSQ surface became hydrophilic at the same time because the organic functional groups on the PSQ surface were changed to hydroxyl groups. The grains of the pentacene films deposited on the UV/O3-treated PSQ surfaces were found to be as large as a few microns. However, the carrier mobility of the pentacene TFTs was not so much improved as expected from the largely grown pentacene grains probably because the hydroxyl groups scattered the charged carriers. In addition, the off-current of the pentacene TFTs increased by 4 orders of magnitude. It is thus considered that the hydroxyl groups also worked as hopping sites for the increased off-current which flew without the gate voltage. On the other hand, the carrier mobility of the pentacene TFTs fabricated with the PSQ dielectric layers of which surfaces were treated with UV/O3 and HMDS became ~4 times larger than that without any surface treatment of the PSQ layers, and also the off-current decreased by 3 orders of magnitude because the hydroxyl groups were changed with silyl groups by the HMDS treatment.

著者

中山 英明 田中 道七 山元 茂 村田 隆行

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.41, no.466, pp.1040-1046, 1992-07-15 (Released:2009-06-03)

参考文献数

26

被引用文献数

1

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Recently, reliability assessment on the micro-joining for electronic apparatus attracts major attention of engineers and researchers in this field. Failure problems of the micro-joining have to be investigated from an interdisciplinary point of view, for the failure phenomena are caused not only by a mechanical effect but also by a metallurgical and/or electrochemical effect. For example, construction of brittle intermetallic compounds at Au wire/Al pad interface of ball bonding is a problem of metallurgical aspect, and electro-migration induced between soldering parts on high density printed circuit board is problem of electrochemical aspect. Though there are several micro-joining methods such as thermo-compression, ultrasonic bonding, micro-soldering and so on, a majority of micro-joining applied in electronic apparatus is micro-soldering. Therefore, it is an urgent problem to establish a valid evaluation method for solder joint performance under service conditions. A typical problem on this point is the solder cracking induced by temperature cycling, depending on the mismatch of thermal expansion coefficients of structural elements. In order to clear the failure problem of solder joint, fatigue failure mechanism of solder itself must be systematized.The main purpose of the present study is to investigate the fatigue strength and strain behaviors of 60Sn/40Pb solder plate specimen under several repeated load conditions including impact load carried out at room temperature. And furthermore, room temperature creep tests were also carried out to discuss the correlation between cyclic fatigue and static fatigue of the solder.The results of this study revealed a clear dependence of the fatigue life on the stress patterns; the lower was the frequency of stress cycle the lower was the fatigue strength. And the strength in impact fatigue showed the highest value. Then, the evaluation from the viewpoint of cumulative loading time indicated that the fatigue life of the solder could be well estimated by the cumulative loading time regardless of the type of stress pattern. And furthermore, the relationship of the stress vs. the cumulative loading time in cyclic fatigue well coincided with the creep rupture curve.

著者

近藤 了嗣 山 活成

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.2, pp.159-166, 2022

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<p>A multi-scale analysis of elasto-plastic deformation and dislocation movement and accumulation of tri-crystalline models during cyclic deformation was performed. The accumulation of dislocations in geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs) was investigated in detail. Experimental observations have shown that fatigue life and fatigue crack propagation are also deteriorated when the material is subjected to overload or underload. However, in the microscopic and mesoscopic regions, where the effects of the crack tip shape change are not related to the size of the crack tip, a different phenomenon is essentially occurring. In this paper, the effects of overload and underload are investigated using a simple model without a crack. From the analysis results, it was found that the dislocation structure generated in the material subjected to overload or underload affects the subsequent deformation behavior. However, even though the absolute values are the same, the effects of overloading and underloading on the subsequent deformation are different, and underloading increases the non-uniformity of the subsequent deformation, which is on the dangerous side, while overloading decreases with increasing the number of repetitions. </p>

著者

佐藤 知広 久保田 敦斗 齋藤 賢一 藤 正督 高井 千加 瀬名 ハディ 宅間 正則 高橋 可昌

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.2, pp.167-174, 2022-02-15 (Released:2022-02-20)

参考文献数

14

被引用文献数

1

---

The industrial manufacturing methods for ceramics are powder mixing, molding, and firing. Ceramics are fired at a higher temperature than metal sintering. For this reason, in the ceramics manufacturing process, a large amount of energy is consumed, and a large amount of carbon dioxide is also emitted, especially in the firing process. Therefore, attention is focused on the non-firing solidification process of ceramics. In this method, after the molding process, there is a solidification process using a solvent instead of firing. In order to realize this solidification process, a grinding process is required to increase the activation energy of the surface of the raw ceramics particle. Therefore, in this study, we set up a molecular dynamics model that simulated grinding and calculated the activation of the silica surface. The grinding of the material surface was modified by the cylindrical indenter of LAMMPS, the material surface was constantly activated by passing multiple indenters continuously instead of a single indenter. As a result, a clear increase in energy was observed. It was suggested that continuous energy input is more effective than local energy input to the surface when reproducing surface activity. Furthermore, activation of the internal structure was observed as in the experiment. Adding water molecules in the relaxation calculation on the activated surface, binding through and without water molecules was observed. It was clarified that there are hydrogen bonds and siloxane bonds in this bond.

著者

奥田 博 伊藤 正治

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.32, no.358, pp.823-829, 1983-07-15 (Released:2009-06-03)

参考文献数

14

被引用文献数

3 3

著者

宮田 昇

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.37, no.415, pp.361-370, 1988-04-15 (Released:2009-06-03)

参考文献数

45

被引用文献数

4 4

著者

宮田 昇 神野 博

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.32, no.354, pp.340-346, 1983-03-15 (Released:2009-06-03)

参考文献数

47

被引用文献数

2 5

著者

西村 伊吹 松原 仁

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.1, pp.59-66, 2022

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<p>The soil improvement technique called as microbially induced carbonate precipitation (MICP) is recognized to be more environmentally friendly than traditional techniques using piles or cement milk. The soil particles bind by precipitating calcium carbonate on particles or in pores, depending on microbial activity. Although the binding structures such as active and inactive bonds have been numerically simulated from chemical-based modelling, the simulation of carbonate precipitation taking into account microbial growth has not been carried out. In addition, the relationship between the spatial precipitation pattern and improvement of mechanical properties remains ambiguous. In this study, a novel MICP simulation scheme dealing with microbial growth is proposed, and the impact of carbonate precipitation on the mechanical properties of the MICP-treated materials is discussed. In this scheme, a reaction-diffusion system and a homogenization method are used for microscale bacterial growth and for multiscale stress and strain analysis, respectively. The results of the calcium carbonate precipitation were 4.5 μmol/mm³ at 10.3 hour, which is slightly higher than the experimental data. Furthermore, the homogenization simulations indicated that soil stabilization could be attributed to the formation of a novel skeleton structure comprising soil particles and calcium carbonate-filled soil pores.</p>

著者

松原 仁

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.71, no.1, 2022