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 31, Issue 5
Displaying 1-4 of 4 articles from this issue
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  • [title in Japanese]
    Keiichiro TOHGO
    2005 Volume 31 Issue 5 Pages 205-213
    Published: September 15, 2005
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.31.205
    JOURNAL FREE ACCESS
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  • DSC Analyses of Absorbed Water in Polyamide 6- and Epoxy-Carbon Fiber Model Composites
    Makoto KAWAGOE, Minoru NABATA, Atsuyuki ISHISAKA, Kazuaki SANADA
    2005 Volume 31 Issue 5 Pages 214-219
    Published: September 15, 2005
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.31.214
    JOURNAL FREE ACCESS
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    The mobility of water molecules existing in polyamide 6- and epoxy-carbon fiber model composites was discussed in comparison with that in each neat polymer specimen. The water mobility was evaluated by a differential scanning calorimetry (DSC), under the process of which the watercontaining specimens weresubjected to cooling from 25°C to -70°C and subsequent reversed heating to 25°C at 2°C/min, and a freezing (crystallization) and a melting behavior of water were analyzed. The absorbed water in PA6 exists as a non-freezing bound water, probably due to the strong interaction with amide group, while in the composite specimen a freezable bound water and a water with greater mobility like a free water are clearly detected. The water in EP resin mainly behaves as a freezable bound water, and the introducing the carbon fibers results in an increase in the mobility nearly equal to the free water. These DSC results suggest that for the model composites there exist some heterogeneous region and/or defects accumelated under very weak interaction with the water molecules.
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  • Proposal of New Test Method of Open Hole Compression (OHC) and Results of Round Robin Tests for Standardization
    Takashi ISHIKAWA, Yasumasa HAMAGUCHI, Naoya SHIKATA, Goichi BEN, Kazur ...
    2005 Volume 31 Issue 5 Pages 220-229
    Published: September 15, 2005
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.31.220
    JOURNAL FREE ACCESS
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    Open Hole Compression (OHC) tests sometimes provide most critical strength data in CF/epoxy compositesstructural design. The current de facto standard method, SACMA SRM 3R-94, exhibits some drawbacks such as utilization of very long specimen and complicated fixtures. A new substitute method, NAL-III, was proposed based on modified ASTM D 695 type fixture with the same size window as SACMA. The other maintained point is a ratio of the hole diameter to the specimen width, 1/6. The first step was an examination of this new test method for four types of carbon/epoxy composites. A comparison of OHC strengths obtained by SACMA andNAL-III methods shows almost identical results. Based on this knowledge, round robin tests by nine organizations were conducted for the establishment of Japan Industrial Standard, JIS. The results confirmthat NAL-III provides less scattered and identical average OHC strengths as SACMA. For some portion of these tests, in-situ observation of failure process using a fiber optic microscope was conducted and someimportant features of mechanics to failure were recognized. Fiber micro-buckling in 0-lamina induced at rather low loads is the most probable trigger of delamination onsets. The final phase of the failure is controlled by delamination propagation transverse to the compression load, which is quite similar tocompression-after-impact (CAI) tests. This failure mechanism implies no effect of the specimen length onthe OHC strengths.
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  • Improving Tensile Behavior of Dry Carbon Fiber Sheets
    Zhishen WU, Kentaro IWASHITA, Keiji HAYASHI, Tetsuo HIGUCHI, Shinkichi ...
    2005 Volume 31 Issue 5 Pages 230-237
    Published: September 15, 2005
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.31.230
    JOURNAL FREE ACCESS
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    The purpose of this study is to improve tensile behavior of no-impregnated (dry) carbon fiber sheets. First, tensile tests of dry carbon fiber sheets with different spans are carried out and it is confirmedthat the tensile strength is only about 30-40% of that of carbon fiber reinforced polymer (CFRP) sheets. Then, two countermeasures by means of partial impregnation with epoxy resin and hybridization with PBO (Poly-para-phenylene-benzo-bis-oxazole) fiber sheets which present high performance in energy absorption are examined to improve the tensile strength of dry carbon fiber sheets. Through a series of experiments, it is realized that the tensile strength ratios of dry carbon fiber sheets with a combination of the two countermeasures to CFRP sheets can be enhanced into 60-70%.
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