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 37, Issue 6
Displaying 1-4 of 4 articles from this issue
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Research paper
  • Fatigue Property and Mechanism of Unidirectional Jute Spun Yarn Reinforced PLA
    Hideaki KATOGI, Yoshinobu SHIMAMURA, Keiichiro TOHGO, Tomoyuki FUJII
    2011 Volume 37 Issue 6 Pages 203-208
    Published: 2011
    Released on J-STAGE: April 05, 2012
    DOIhttps://doi.org/10.6089/jscm.37.203
    JOURNAL FREE ACCESS
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    Natural fiber reinforced plastics have been expected as alternative materials of glass fiber reinforced composites. The fatigue properties of natural fiber reinforced plastics are, however, not always well known. In this study, uniaxial tensile fatigue tests of unidirectional jute spun yarn reinforced polylactic acid (PLA) were conducted in order to clarify the fatigue strength and its mechanism. The fatigue strength decreased with increasing the number of cycles. The fatigue strength at 106 cycles was 55% of the ultimate strength. The fatigue failure of composite specimens was probably caused by the breakage of the jute filaments of spun yarn at the tips of fatigue cracks in PLA. This implies that the fatigue strength of the composite was strongly affected by the fatigue property of PLA.
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  • Predicting FRP Erosion Using an Optical Fiber Sensor
    Limin BAO, Kenichi AKAHANE, Jian SHI, Kiyoshi KEMMOCHI
    2011 Volume 37 Issue 6 Pages 209-215
    Published: 2011
    Released on J-STAGE: April 05, 2012
    DOIhttps://doi.org/10.6089/jscm.37.209
    JOURNAL FREE ACCESS
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    A system that detects FRP erosion automatically is important. To achieve such a system, an FRP erosion detecting sensor using on optical fiber was proposed in this study. The relationship between the erosion characteristics of optical fiber alone and the attenuation of light was investigated, and it was found that such relationship can be applied in an erosion-detecting sensor. The sensor feasibility was confirmed by investigating the erosion characteristics of FRP with optical fiber embedded and conducting tests to detect abrasion based on the light attenuation. Four point bending tests were conducted on an FRP laminated plate with embedded optical fiber, and the mechanical characteristics of the plate were examined. The results indicated that the embedding optical fiber did not degrade the FRP rupture strength. The proposed erosion monitoring system effectively predicts FRP erosion.
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  • Investigation of the Interfacial Failure Criterion at Glass Fiber/Epoxy Matrix by the Cruciform Specimen Method Considering the Debonding Initiation Location
    Akihiro KASHIMA, Jun KOYANAGI, Shinji OGIHARA
    2011 Volume 37 Issue 6 Pages 216-225
    Published: 2011
    Released on J-STAGE: April 05, 2012
    DOIhttps://doi.org/10.6089/jscm.37.216
    JOURNAL FREE ACCESS
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    This paper evaluates interfacial failure criterion under combined stress state and precise location along the fiber circumference of interfacial failure (debonding) initiation at glass fiber fiber/epoxy interface by the cruciform specimen method. The effects of both thermal residual stress occurred during specimen preparation and inelastic stress-strain constitutive relationship of matrix resin on the evaluation of interfacial failure criterion are considered. The interfacial stresses distribute along with fiber circumference. In this study, the location of interfacial failure initiation is specified and the interfacial failure criterion is evaluated. By changing the cruciform arm angle (the angle between the fiber and the loading directions), various combined stress states are obtained which make it possible to evaluate the interfacial failure criterion. Both the quadratic and parabolic criteria are assumed and discussed.
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  • Electrical Resistance Characteristics in Wet CFRP Cross-Ply Laminates with Matrix Cracking
    Keiji OGI, Takaaki TANAKA
    2011 Volume 37 Issue 6 Pages 226-233
    Published: 2011
    Released on J-STAGE: April 05, 2012
    DOIhttps://doi.org/10.6089/jscm.37.226
    JOURNAL FREE ACCESS
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    This paper presents electrical resistance change due to moisture in a CFRP cross-ply laminate with and without matrix cracking. First, the electrical resistance change was measured for wet unidirectional and cross-ply laminates at room temperature and below the freezing point. Next, an equivalent circuit model was proposed for the cross-ply laminate, taking the resistance change ascribed to matrix cracking into account. It was found that resistance characteristics of the intact cross-ply laminate were similar to those of the longitudinal ply. Resistance properties of the wet cross-ply laminate with matrix cracking were dominated by those of the longitudinal ply, while the resistance change of the dry cracked cross-ply laminate was affected by the matrix crack resistance. The resistance of the dry cracked laminate decreases below the freezing point. Contrarily, the resistance of the wet cracked laminate increases below the freezing point.
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