著者

上田 政人 平賀 淳人 西村 哲

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.37, no.3, pp.103-110, 2011 (Released:2012-02-25)

参考文献数

23

被引用文献数

4 4

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Micro-buckling characteristic of a carbon mono-fiber in matrix was studied. A fiber was modeled in matrix as a column on elastic foundation. Buckling stress of the fiber was calculated incorporating the initial fiber misalignment and non-linearity of the matrix. The effect of bending on compressive stress was also taken into considered to estimate failure initiation at fiber surface. Two processes of ultimate fiber failure were considered. First one is a compressive fracture at fiber surface due to compression and bending. Second one is a matrix-yielding initiated unstable fiber deformation. Compression test of a carbon fiber in matrix was performed by means of a four point bending test. Electrical resistance of the carbon fiber was measured during the compression test to recognize initiation of the compressive fracture. Fiber breaks at two adjacent locations were observed, which was caused by micro-buckling of the fiber. Apparent compressive strength of the fiber was measured in the experiment. Actual compressive strength of the fiber was predicted from the apparent compressive strength. Correlation between compressive strengths based on the elastic foundation model and the kink band model was discussed.

著者

渡辺 圭子 日下 貴之 北條 正樹 福岡 俊康 石橋 正康

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.34, no.6, pp.226-232, 2008 (Released:2010-07-15)

参考文献数

22

被引用文献数

1 1

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The crack propagation behavior of CFRP laminates reinforced with Zanchor was experimentally investigated to find out the toughening mechanism under the mode II loading. The Zanchor is a novel technique of out-of-plane reinforcement to improve the interlaminar strength by entangling in-plane fibers in the through-thickness direction using special needles. Experimental result demonstrated that the effect of Zanchor process was remarkable for the improvement of mode II interlaminar fracture toughness of composite materials, where the fracture toughness proportionally increased with the Zanchor density. Moreover, broken traces of the fiber bundles oriented to the through-thickness direction were observed, whereas no fiber bridgings. Therefore, it was revealed that the key factor of the increase in mode II fracture toughness would be the breaking energy of fiber bundles, which was different from that under mode I loading.

著者

坂田 憲泰 岸谷 直美 邉 吾一

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.37, no.3, pp.111-118, 2011 (Released:2012-02-25)

参考文献数

5

被引用文献数

1

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Isogrid structures have a higher specific strength and stiffness, they are composed of triangular grid stiffeners and a face layer. One of features in isogrid structures is the offset part which is effective for avoiding stress concentration at the cross points of grid stiffeners. These structures are being mainly used for aerospace applications. In order to produce a metal isogrid cylindrical shell, a majority of thick metal plate is milled to produce the isogrid panel and then its both ends are welded to each other. Therefore, unstable behaviors of isogrid structures are generally observed in the joint parts. However, the CFRP isogrid cylindrical shell can be simultaneously fabricated the parts of shell and grid with a filament winding method. In this study, a molding of isogrid CFRP cylindrical shells is proposed and their compression tests are also conducted to investigate the stiffening effects of isogrid CFRP cylindrical shell. Furthermore, the results of the compression tests are compared with numerical ones obtained by FEM.

著者

小田原 晶子 佐藤 ひろゆき 杉江 朋彦 森迫 清貴 塩野 剛司 北島 佐紀人 仲井 朝美 濱田 泰以

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.35, no.1, pp.27-32, 2009 (Released:2010-11-30)

参考文献数

4

被引用文献数

3 2

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There are many traditional technologies that have much knowledge to fabricate products in Japan. Such a knowledge is so-called technical intuitions and sensitivities. The craftsmen apply the technique for regenerating some traditional products and we defined the knowledge as “implicit knowledge.” The concept of this study is to scientifically analyze the implicit knowledge of those technologies. Here, the implicit knowledge would be traced from the contemporary view point. Thus, the knowledge can be applied to the modern technology which is adaptable to the market requirements. Finally the traditional technology retailed with the advanced technology many create a new technology. Kyokabe is one of Japanese clay wall for the traditional architectures. The clay wall consists of clay, sand and straws. Straws obviously play a reinforcement, thus Kyokabe can be treated as a composite material. Straws are immersed in the mixture of clay, sand and water for some period of time. The implicit knowledge which Plasterers (masters of Kyokabe) have acquired is that increase in the straws quantity results in increase in compressive strength and increase in the time improves workability in drawing. In this study, the implicit knowledge is scientifically resolved. The effects of the quantity and the immersion time on the compressive properties and workability of Kyokabe were also investigated.

著者

島村 佳伸 麦島 新 轟 章

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.34, no.4, pp.133-140, 2008 (Released:2010-06-15)

参考文献数

15

被引用文献数

1

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Moisture absorption affects mechanical properties of CFRP, thus monitoring of moisture absorption ration in CFRP is useful to assess the structural integrity. Besides, health monitoring of CFRP by using an electrical resistance change method has been investigated recently. In order to apply the electrical resistance change method to composite components in service, it is important to understand the effect of moisture absorption on the electrical resistance change. We have reported that the electrical impedance of CFRP increases not only in the transverse direction but also in the fiber. In order to investigate the effect of deformation constraint on the electrical impedance increase in the fiber direction, the electrical impedance changes of constrained and unconstrained CFRP specimens are measured at constant temperature and humidity. The results show that the electrical impedance change of the constrained specimen is much smaller than that of the unconstrained. The experimental results indicate that swelling in the transverse direction affects the electrical impedance in the fiber direction. The mechanism of electrical impedance change is discussed by using finite element analysis. The analytical results show that discrete contacts between carbon fibers and electrodes cause the electrical impedance change.

著者

Xavier Chapeleau Monssef Drissi-habti 冨山 禎仁

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.36, no.1, pp.25-30, 2010 (Released:2011-02-25)

参考文献数

30

被引用文献数

1 1