日本複合材料学会誌
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
35 巻, 4 号
選択された号の論文の4件中1~4を表示しています
研究論文
  • 山口 拓真, 岡部 朋永, 高坂 達郎
    2009 年 35 巻 4 号 p. 141-148
    発行日: 2009年
    公開日: 2010/12/18
    ジャーナル フリー
    Hybrid laminates made of polymer matrix composite plies with metal sheet are called fiber metal laminates (FML). In this study, a new numerical approach for the fatigue damage progress of the FML is presented. The layer-wise finite element with cohesive element are used to predict the fatigue damage progress of split, transverse crack and delamination. Four-node cohesive elements are introduced to express the 0° ply splitting and transverse crack. Eight-node cohesive elements are inserted to ply interfaces to represent the delamination. Then, the most important character of this model is that the proposed simulation introduces a damage-mechanics concept into the degradation process in cohesive elements in order to express the damage progress due to the cyclic loading. This enable us to address the complicated fatigue damage process observed in the FML. We applied this model to the Ti/GFRP laminates and compared the simulated results with the experimental data reported in the reference. We confirmed that this model could reproduce the fatigue damage process in the FML. The effects of parameters of cohesive element on Ti crack growth and delamination profile were also investigated. Ti crack growth rate was strongly associated with the delamination profile in the vicinity of the crack tip.
  • 西川 雅章, 岡部 朋永, 武田 展雄
    2009 年 35 巻 4 号 p. 149-156
    発行日: 2009年
    公開日: 2010/12/18
    ジャーナル フリー
    This paper investigated the damage transition mechanism between the fiber-breakage mode and the fiber-avoiding crack mode when the fiber-length is reduced in the unidirectional discontinuous carbon-fiber-reinforced-plastics (CFRP) composites. The critical fiber-length for the transition is a key parameter for the manufacturing of flexible and high-strength CFRP composites with thermoset resin, because below this limit, we cannot take full advantage of the superior strength properties of fibers. For this discussion, we presented a numerical model for the microscopic damage and fracture of unidirectional discontinuous fiber-reinforced plastics. The model addressed the microscopic damage generated in these composites; the matrix cracking with continuum damage mechanics model and the fiber breakage with the Weibull model for fiber strengths. With this numerical model, the damage transition behavior was discussed when the fiber length was varied. The comparison revealed that the length of discontinuous fibers in composites influences the formation and growth of the cluster of fiber-end damage, which causes the damage mode transition. Since the composite strength is significantly reduced below the critical fiber-length for the transition to fiber-avoiding crack mode, we should understand the damage mode transition appropriately with the analysis on the mechanism of the cluster growth of fiber-end damage.
  • 國澤 鉄也, 倪 慶清
    2009 年 35 巻 4 号 p. 157-164
    発行日: 2009年
    公開日: 2010/12/18
    ジャーナル フリー
    Grip performance and braking distance of a tire strongly depend on the frictional characteristics between the tread (the part which touches to the road surface) rubber and the road surface. To meet the complex needs of a tire, a polymer blend is commonly used and the fillers in the polymer blend may have a great influence on tire properties. In this paper, a bias dispersion state of carbon black (CB) in polymer blended rubber composites consisting of styrene butadiene rubber (SBR) and natural rubber (NR) was observed by scanning probe microscope (SPM). It was indicated that the SBR/CB interaction in rubber composite was stronger than that of the NR/CB interaction by measuring tensile strength in NR/SBR blended rubber composites. It was found that island patterns of SBR phase were formed in the polymer and more carbon blacks were segregated in SBR phase than in NR phase. Then a method to predict the distribution ratio of CB in SBR phase was proposed according to characteristic behavior of storage modulus in dynamic viscoelasticity. And the concentration of CB in SBR phase was estimated to be about twice as large as that in NR phase.
  • 平野 義鎭, 勝俣 慎吾, 岩堀 豊, 轟 章
    2009 年 35 巻 4 号 p. 165-174
    発行日: 2009年
    公開日: 2010/12/18
    ジャーナル フリー
    This paper examines the fundamental fracture behavior of CFRP laminate due to lightning strikes. In order to clarify the influence of lightning parameters and specimen size variations, the comparative results of performing artificial lightning strike testing on a series of laminated composite specimens has been explored. For the artificial lightning strike testing, the high-strength/middle-modulus graphite/epoxy composite of IM600/133 is selected as a typical aerospace grade material. The damage to the CFRP laminate was assessed by using visual inspection, ultrasonic inspection, micro X-ray inspection, and sectional observation. The test results clarified that the damage mode can be categorized into three different damage mode of fiber damaged area, resin deterioration area, and internal delaminations. And the damage progress is governed by the strong electrical and thermal orthotropic properties of CFRP laminates. As a result of damage size evaluation, it is confirmed that the lightning parameters which define impulse waveform show strong relationship with certain damage modes though the specimen size and thickness variation hardly affect damage size due to lightning strike.
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