巻号一覧
39 巻 (2013)
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39 巻, 6 号
選択された号の論文の4件中1～4を表示しています
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研究論文
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呉 智深, 吉清 一洋, 岩下 健太郎2013 年 39 巻 6 号 p. 212-220
発行日: 2013年
公開日: 2015/02/11
ジャーナル フリーIn the previous study, the authors proposed hybrid FRP sheets consisting of several types of fibers with various specific properties and investigated their mechanical properties. The observed stress drop due to the gradual rupture of higher modulus, higher strength and/or higher ductility fibers is a concern and should be controlled. It was experimentally confirmed that integrated performance, including tensile strength, stiffness, and ductility could be thoroughly realized through appropriately hybridizing high modulus fibers, high strength fibers, and high ductility fibers for which the stress drop can be controlled within a required range. In this study, a control index for controlling the stress drop is first designed. Through a quantitative investigation with an experimental program, the relationships between the control index and stress drop are identified for different hybridizations including high modulus-high strength hybrid fibers sheet, high strength-high ductility hybrid fibers sheet and high modulus-high ductility hybrid fibers sheet.抄録全体を表示PDF形式でダウンロード (2288K) -
山下 慎一郎, 大澤 勇, 松尾 剛, 張 昕, 髙橋 淳2013 年 39 巻 6 号 p. 221-230
発行日: 2013年
公開日: 2015/02/11
ジャーナル フリーNovel CFRTPs (carbon fiber reinforced thermoplastics) for mass production automobile have been developed in Japanese METI-NEDO project (2008-2012 fy). These CFRTPs have not only high mechanical properties, but also high cycle moldability and high recyclability. To perform reliable structural design for the CFRTP, we discussed if the use of conventional test method is applicable or not. Because shear modulus of the matrix of CFRTP is sometimes low, out-of-plane shear modulus of CFRTP would be lower than that of CFRTS (carbon fiber reinforced thermosetting resin), so conventional bending test standard may not be applicable to CFRTP. Hence this paper proposes a simple method to estimate accurate Young’s modulus and out-of-plane shear modulus by three point bending tests with small specimen. Three point bending tests are performed with changing the span length for the same specimen, the results of apparent flexural modulus are plotted, y-intercept and gradient are calculated by least squares method, and Young’s modulus and out-of-plane shear modulus are calculated based on a theory. It was found that Young’s modulus of CF/PP was accurately estimated by the method proposed in this study and underestimated by JIS standard. In addition, out-of-plane shear modulus was also able to be estimated by this method.抄録全体を表示PDF形式でダウンロード (2571K) -
安部 展弘, 青木 隆平, 小林 やよい2013 年 39 巻 6 号 p. 231-239
発行日: 2013年
公開日: 2015/02/11
ジャーナル フリーThe popularity of woven fabric composites (WFC) has increased recently in the aerospace industries due to their lightweight property, low thermal expansion and high flexibility. Several researches related to mechanical properties of these materials have been carried out, but those focused on fatigue characteristic of these materials are very limited in author’s knowledge. In this study, a simple original experimental device for pure bending fatigue tests is developed, and bending fatigue characteristic of WFC is investigated experimentally in detail using this device. Bending fatigue tests are conducted to acquire trends of S-N diagrams. Fatigue of WFC exhibits similar tendency as metals, and damage accumulation by bending fatigue is verified. Also, a stress distribution in the unit cell of tri-axially woven fabric composites (TWFC) under bending deformation is analyzed by finite element method (FEM) analysis to detect where a fatigue failure would initiate in TWFC for different levels of curvature. These results show that the maximum tensile and compressive stresses are located at the overlapping section of yarns. This means the possibility of bending fatigue failure is the highest at that area. Overall experimental results correspond to these analytical predictions.抄録全体を表示PDF形式でダウンロード (5809K) -
小笠原 俊夫, 仲本 兼悟, 津田 皓正, 小川 武史, 文 淑英, 島村 佳伸, 井上 翼2013 年 39 巻 6 号 p. 240-247
発行日: 2013年
公開日: 2015/02/11
ジャーナル フリーThis study examined the mechanical properties of aligned multi-walled carbon nanotube (CNT)/epoxy composites processed using a hot-melt prepreg method. Vertically aligned ultra-long CNT arrays (forest) were synthesized using chemical vapor deposition with high growth rate, and were converted to horizontally aligned CNT sheets by pulling them out. An aligned CNT/epoxy prepreg was fabricated using hot-melting with B-stage cured epoxy resin film. High quality composite film specimens were produced. Tensile tests were conducted to evaluate the mechanical properties. The resultant composites exhibit high Young’s modulus and tensile strength. For example, the maximum elastic modulus and ultimate tensile strength of a CNT (32.8 vol.%)/epoxy composite were 89 GPa and 239 MPa. These values were, respectively, 36 and 5 times higher than those of the epoxy resin. CNT orientation angle distribution was quantitatively examined. Mori-Tanaka theory was adopted to estimate the elastic moduli of the composites. The estimated Young’s modulus of CNT was 680 GPa. The numerical calculation results suggested that the Young’s moduli of unidirectional CNT composites (32 vol.%) and 2-D randomly oriented CNT composites (35 vol.%) are almost equal to those of unidirectional and quasi-isotropic CFRP laminates.抄録全体を表示PDF形式でダウンロード (3243K)
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