日本複合材料学会誌
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
32 巻, 6 号
選択された号の論文の5件中1~5を表示しています
  • 「NEDOプロジェクト1」:ハイサイクルー体成形の概説
    山口 晃司
    2006 年 32 巻 6 号 p. 231-236
    発行日: 2006/11/15
    公開日: 2009/08/11
    ジャーナル フリー
  • 末益 博志, 前田 雄介, 並木 文春, 稲木 秀介
    2006 年 32 巻 6 号 p. 237-243
    発行日: 2006/11/15
    公開日: 2009/08/11
    ジャーナル フリー
    In the present study, damage problems of a cryogenic CFRP tank with an aluminum alloy liner developed for the space vehicle is discussed through results from a three dimensional finite element analysis, which is subjected to not only internal pressure but also high thermal stresses due to cryogenic temperature. The interfacial stress distribution around the area of the thickness change of the liner in the cylindrical portion of the tank is studied since the broad debonding between the CFRP layer and the aluminum liner was observed along the thick liner area after the low temperature exposure and the internal pressure test. The thick portion of the liner was designed to make welding easy and to reduce the thermal effect on the Al alloy during welding. The magnitude of the interfacial stress is found to become sufficiently large to cause debonding at the different portion in thickness unless the size and dimensions of that portion is well designed. The yielding of the liner may cause even higher interfacial stress. The instability of the debonding crack is evaluated through the energy release rate obtained based on the elastic theory using the virtual crack closure technique.
  • 岩堀 豊, 石川 隆司, 渡辺 直行, 伊藤 光, 林 洋一
    2006 年 32 巻 6 号 p. 244-253
    発行日: 2006/11/15
    公開日: 2009/08/11
    ジャーナル フリー
    Experimental investigations of interlaminar strength for Kevlar(R) stitched CFRP laminates were carried out. The used Kevlar(R) thread thicknesses are 400d (denier), 600d, 800d, 1, 000d and 1, 200d. The stitched carbon fiber (CF) preforms were cured with RTM (resin transfer molding) technique. Stitching types employed to CF dry preform (T300 and T700) are a modified lock stitch (MLS) which has the stitch inter-locking position on the CFRP laminate surface and a lock stitch (LS) which has the inter-locking position in the CFRP laminate where an industrial sewing machine was used. Test specimens containing a single stitching thread were cut from the stitched CFRP laminates. The test specimens were loaded to the out-of-plane direction by a screw driven testing machine. Load-displacement curves were obtained and sectional observations for broken test specimens were executed. Maximum tension load and consumption energy for the single stitchthread specimens were measured. A trend would be found that MLS cases show larger maximum load and consumption energy than those of LS cases for each stitch thread thickness. The maximum load of the test specimen increases with stitch thread thickness. On the other hand, the consumption energy of 1, 000d is the highest among all the stitch thread thickness specimens. The reason why the 1, 000d MLS case shows the highest energy is an intense pull-out phenomenon. It is revealed that the maximum load and consumption energy of the stitched CFRP laminates was governed by an inter-locking position of stitching in the CFRP laminates. It is also suggested that the allowable strength and load distribution along the stitch thread affects the breaking position of the stitch thread in the CFRP laminates. A similarity is unveiled in the relationship between the values of G1 by double cantilever beam (DCB) tests and failure modes of stitching threads and in the relationship between the value of consumption energy by the present tests and failure modes of stitching threads.
  • 竹内 ふみ, 河井 昌道, 張 剣奇, 松田 哲也
    2006 年 32 巻 6 号 p. 254-261
    発行日: 2006/11/15
    公開日: 2009/08/11
    ジャーナル フリー
    The present paper focuses on experimental verification of the ply-by-ply basis inelastic analysis of multidirectional laminates. First of all, rate-dependence of the tensile behavior of balanced symmetric cross-ply laminates of T800H/epoxy under off-axis loading conditions at 100°C is examined. Uniaxial tension tests are performed on plain coupon specimens with various fiber orientations (θ=0, 5, 15, 45, and 90°) at two different strain rates (1.0%/min and 0.01%/min). The off-axis stress-strain curves exhibit marked nonlinearly for all off-axis fiber orientations except for the fiber directions θ=0 and 90°, regardless of the strain rates. The strain rate has appreciable influences on the off-axis flow stress in the regime of nonlinear response as well as on the off-axis elastic modulus in the regime of linear response. The macromechanical model based on a ply viscoplasticity model and the classical laminated plate theory is applied to the rate-dependent off-axis nonlinear behavior of the cross-ply CFRP laminates. The material constants involved by the ply viscoplasticity model are identified on the basis of the experimental results on the unidirectional laminate of the same carbon/epoxy system. It is suggested that good agreements between the predicted and the observed results can be obtained by taking into account the fiber rotation induced by deformation and rate-dependence of the moduli.
  • 八田 博志
    2006 年 32 巻 6 号 p. 263
    発行日: 2006/11/15
    公開日: 2009/08/11
    ジャーナル フリー
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