日本複合材料学会誌
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
44 巻, 5 号
選択された号の論文の5件中1~5を表示しています
研究論文
  • 山田 湧太, 佐藤 優成, 斉藤 博嗣, 金原 勲
    2018 年 44 巻 5 号 p. 159-165
    発行日: 2018/09/15
    公開日: 2019/09/14
    ジャーナル フリー

    The interfacial failure, debonding, is considered one of the initial cracks in laminate, and propagates on a larger scale of failure, such as transverse cracks and delamination. Therefore, interfacial tensile strength should be evaluated correctly as an important parameter for application in analytical studies. There are some researches focusing on the evaluation of fiber-reinforced thermosetting composites; however, to the best of our knowledge, there have been few reports on interfacial properties of thermoplastic composites. The aim of this study was to evaluate the interfacial tensile strength at the CF/PC interface by a novel measurement method. Single-fiber pure shear (SFPS) test was performed on single-fiber-embedded specimens. Debonding was observed and the interfacial tensile strength was calculated to be 36.5±2.21 MPa. Therefore, we concluded that the SFPS test would be the most reliable method because its standard deviation was much smaller than that of conventional methods like the cruciform test and the transverse test. However, more experimental research is needed to enhance data reliability.

  • 桝田 剛, 影山 和郎, 松尾 剛, 金井 誠
    2018 年 44 巻 5 号 p. 166-172
    発行日: 2018/09/15
    公開日: 2019/09/14
    ジャーナル フリー

    This study focuses on the processing of prepregs and the mechanical properties of composites prepared using the prepregs, revealing certain crucial process requirements. To the best of our knowledge, studies correlating the prepreg manufacturing process and the mechanical properties of composites prepared using the prepregs have not been reported. Normally, carbon fiber reinforced thermoplastic (CFRTP) is prepared using the resin film infusion process. However, we used the melt impregnation method to manufacture unidirectional polypropylene prepregs to achieve efficient impregnation of carbon fiber bundles. This method merely requires an extruder to infuse the melt resin, making it possible to control different degrees of acid modification of polypropylene and the process temperature to investigate the composite properties. As a result, we could optimize the process parameters and the temperature conditions to manufacture unidirectional carbon fiber prepregs and successfully prepare good composite laminates with excellent carbon fiber distribution and low void content (below 1.0%).

  • 金崎 真人, 北口 尚紀, 西川 雅章, 北條 正樹
    2018 年 44 巻 5 号 p. 173-182
    発行日: 2018/09/15
    公開日: 2019/09/14
    ジャーナル フリー

    In this study, the viscosity of unidirectional CFRTP laminates near the melting point was evaluated to discuss the relationship between the thermal fusion conditions and the flow of fiber and matrix. The laminates were regarded as a fluid flowing in a direction perpendicular to the fiber. The microscopic flow of the fiber and matrix near the melting point was observed during a parallel plate compression test. Based on this observation, viscosity and flow properties were evaluated by the finite element method. The results of the parallel plate compression test showed that the test conditions and the decrease in the thickness of the laminates are related to the apparent viscosity of the unidirectional plate. In addition, cracks in the direction of the maximum shear stress were detected via in situ observation near the melting point of the matrix. The occurrence of this phenomenon depended on the apparent viscosity of the unidirectional laminates and it was found that no cracks occurred when the apparent maximum viscosity of the unidirectional laminates was lower than a certain threshold.

  • 黄木 景二, 堤 三佳, 水上 孝一, 松谷 浩明, 佐藤 成道
    2018 年 44 巻 5 号 p. 183-194
    発行日: 2018/09/15
    公開日: 2019/09/14
    ジャーナル フリー

    In this study, the effect of the degree of cure (DOC) on the relaxation modulus of thermosetting resin in carbon fiber-reinforced plastics (CFRPs) was investigated. First, the storage and loss moduli of epoxy resin for several levels of DOC after gelation were measured by dynamic mechanical analysis (DMA). Second, a shift factor was empirically obtained as a Boltzmann function of the inverse of temperature and a linear function of the DOC from the master curves for the storage and loss moduli. Third, the relaxation modulus, based on a generalized Maxwell model, was expressed by a Prony-series expansion to analyze the effect of the DOC on the viscoelastic properties, such as the relaxation spectrum. Finally, the glass transition temperature and loss tangent peak temperature measured by differential scanning calorimetry (DSC) and DMA, respectively, were compared to discuss the dependence of the DOC and loading frequency on those temperatures.

  • 古澤 佳樹, 杉本 大輝, 斉藤 博嗣, 田中 基嗣, 金崎 真人, 金原 勲
    2018 年 44 巻 5 号 p. 195-202
    発行日: 2018/09/15
    公開日: 2019/09/14
    ジャーナル フリー

    The interlaminar fracture toughness of composite laminates has been evaluated mainly for unidirectional or cross-ply laminates. However, it is difficult to estimate the realistic interlaminar fracture toughness and failure process for quasi-isotropic or angle-ply carbon fiber reinforced plastic (CFRP) laminates consisting of different fiber orientation angles. In this study, we focused on the effects of fiber orientation angle on the interlaminar fracture toughness. The static mode II interlaminar fracture toughness was measured for three types of CFRP laminates which interlaminar orientations consisted of 0º/45º, ±22.5º and 0º/0º layers, respectively. The results were evaluated both experimentally and analytically. Both the (0º/45º) laminates and the (±22.5º) laminates showed almost the same energy release rate as the unidirectional laminate. On the other hand, the difference in fracture mechanism between the (0º/45º) laminate and the (±22.5º) laminate was revealed in the fracture surface observation. In addition, the morphology of delamination propagation between the 0º and 45º-oriented layers resembled the fan-shaped pattern induced by out-of-plain impact in quasi-isotropic laminates. Therefore, the characteristic initiation and propagation mechanisms of impact-induced interlaminar failure in quasi-isotropic laminates is presented by an experimental evaluation of interlaminar fracture toughness for the (0º/45º) laminates.

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