Journal of the Japan Society for Composite Materials
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
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Volume 16, Issue 5
Displaying 1-8 of 8 articles from this issue
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  • [title in Japanese]
    Atsushi SUMIDA
    1990 Volume 16 Issue 5 Pages 173-180
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.173
    JOURNAL FREE ACCESS
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  • Fractography of Carbon Fiber Unidirectionally Reinforced Epoxy Composites in Mode of Transverse Tension
    Y. SAWADA, T. HONZYO, Y. NAKANISHI
    1990 Volume 16 Issue 5 Pages 181-187
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.181
    JOURNAL FREE ACCESS
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    Transverse tensile fracture surfaces of carbon fiber unidirectionally reinforced epoxy composites (CFRP) were examined by a scanning electron microscopy, in order to understand micromechanics of the failure at the interface. The tensile tests were carried out in two directions. One was transverse in prepreg sheets plane (Y direction), and the other was perpendicular to the prepreg sheets plane (Z direction). It was observed that many parts of the fiber/matrix interface were fractured in the fracture surfaces of the CFRP using unsurface treated carbon fiber. But in contrast, in the fracture surfaces of the CFRP using surface treated carbonized fiber, the failure was largely occured in the matrix. The effect of sizing of the fiber on the fractography could not be detected. In the transverse tensile fracture surface of Y direction, the row of 'cusps' at resin fracture surface near broken fiber was observed. On the other hand, the fracture surface of Z direction was more flattish than that of Y direction. And areas of 'river' and 'scarp' parts in the fracture surface of Z direction were larger than that of Y direction. The transverse tensile strength of Y direction was 30-40% higher than that of Z direction. These differences in Y and Z directions are considered to be due mainly to the anisotropy of fiber misorientation angle and the difference of the surface condition of the specimens.
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  • Fabrication and Transverse Tensile Properties of Unidirectional Carbon Fiber/PEEK Composites Utilizing Commingled Yarn and Cowoven Cloth
    K. TAKAHASHI, T. HISAYAMA, K. HARAKAWA, K. NAKAJIMA
    1990 Volume 16 Issue 5 Pages 188-195
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.188
    JOURNAL FREE ACCESS
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    Three types of unidirectional carbon fiber/PEEK composites are fabricated from : (a) prepreg sheet, (b) plain weave cloth ; warp : commingled yarn (1800 d) of carbon fiber with PEEK fiber, weft : PEEK yarn (70 d), (c) 5-shaft sateen weave cloth ; warp : carbon yarn (1800 d), weft : PEEK yarn (900 d). The transverse tensile properties are measured and compared with the theoretical predictions based on the perfect adhesion and interfacial slippage models. The transverse Young's moduli of the composites fabricated from (a) and (b) are in good agreement with the theoretical values based on the perfect adhesion model at the fiber/matrix interface. On the other hand, Young's modulus of the composite from (c) rather coincides with the prediction by the interfacial slippage model. The wettability and the interfacial adhesion between the carbon fiber and the PEEK resin are also investigated by the SEM observation of the fracture surface.
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  • Strength Optimization of Laminated Composites under Multiple Loading
    H. FUKUNAGA
    1990 Volume 16 Issue 5 Pages 196-203
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.196
    JOURNAL FREE ACCESS
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    The present paper deals with the strength optimization of laminated composites under multiple loading based upon a mathematical programming method. A method using the transformed design variables with respect to the layer angles is proposed. In order to reduce the nonlinearity between the strength constraints and the layer angles, cos 2θ or sin 2θ is used as the design variable instead of using d directly. It is shown through several numerical examples that the present method gives reliable optimal results which are less sensitive to initial values used in the optimization.
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  • Sonic Modulus in Fiber-axis Direction of Carbon Fibers
    E. HAYAKAWA, M. SHIOYA, A. TAKAKU
    1990 Volume 16 Issue 5 Pages 204-210
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.204
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    For a series of polyacrylonitrile (PAN) -based carbon fibers, measurements of sonic modulus in fiber-axis direction have been carried out on tows and on carbon fiber-epoxy resin composite strands. It has been obtained that the sonic modulus of composite strands, Es, c, can be represented by a rule of mixture, Es, c=Es, f υf +Es, m(1-υf), where Es, f and Es, m are sonic moduli of fiber and matrix, and Uf is fiber fractional volume. From this, it results that the measurement of sonic modulus of composite strands can be applied as a convenient method for determining the fractional volume of fiber in composite strands if the sonic moduli of fiber and matrix are known in advance. The variation of sonic modulus of carbon fibers with applied stress has been also investigated. The relation between the modulus Ef of carbon fibers and the applied stress c at small stresses can be represented as Ef=[1-(2S111/S11)σ]/S11 where S11 is the initial compliance. The factor 2S111/S11 has shown almost a constant value for a variety of PAN-based carbon fibers. The relations between the parameters representing the dependence of the sonic modulus on the applied stress and the fiber-structural parameters are shown.
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  • Preparation of SiC Whisker/Silica Glass Composites by the Sol-gel Method
    H. UNUMA, Y. SUZUKI, S. OGATA, T. YAMAMOTO
    1990 Volume 16 Issue 5 Pages 211-214
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.211
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    SiC whisker (SiCw)/silica glass composites were prepared from tetramethylorthosilicate, silica fine powder and SiCw by the sol-gel method. An optimum condition for the gel preparation and the following HIP sintering was investigated. Employment of the optimum sol composition and aging of the resultant gel made it possible to obtain crack-free SiCw/SiO2 gel in which SiCw was dispersed homogeneously. HIP sintering under the condition of 1, 000°C, 30 MPa, 2 h was optimum since the crystallization of the glass matrix to cristobalite could be avoided. Theoretically dense composites were obtained up to 15 vol % SiCw. A maximum fracture toughness of 2.3 MPa m1/2 was obtained.
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  • [title in Japanese]
    Akira KOBAYASHI, Nobuo TAKEDA, Takashi ISHIKAWA, Yutaka KAGAWA
    1990 Volume 16 Issue 5 Pages 215-218
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.215
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese]
    1990 Volume 16 Issue 5 Pages 218a
    Published: September 15, 1990
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.16.218a
    JOURNAL FREE ACCESS
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