材料システム
Online ISSN : 2435-9734
Print ISSN : 0286-6013
26 巻
選択された号の論文の14件中1~14を表示しています
  • 中田 政之
    2008 年 26 巻 p. 1-2
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
  • 宮野 靖
    2008 年 26 巻 p. 3-4
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
  • 荒尾 与史彦, 小柳 潤, 川田 宏之, 八田 博志
    2008 年 26 巻 p. 5-16
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    Fiber reinforced plastics (FRPs) have low thermal expansion and high specific stiffness compared to other structure materials. By applying FRPs to the structural material of precise machines such as antenna and mirror, not only the mechanical performance but also the functionality will be improved drastically. In spite of its excellent properties, the study in dimensional stability of FRPs isn't well discussed. In order to apply FRPs for such materials, we must discuss the long-term dimensional stability of FRPs. Dominant factors affecting the time-dependent deformation of FRPs are moisture absorption, viscoelastic behavior, shrinkages caused by chemical reactions and physical aging. The effects of these factors on dimensional stability are small, so we must discuss these factors in high accuracy. In this paper, conventional articles relating above the three factors in FRPs are cited wholly and main issues to be solved are clarified. The requirement of the dimensional stability was first discussed, and corresponding applications are then introduced. Second, moisture absorption behavior and the concept of CME (Coefficient of Moisture Expansion) are presented and the prediction of viscoelastic deformation is thirdly summarized. Finally, the effects of chemical shrinkage and physical aging against micro-deformation of FRPs are mentioned.
  • 新保 實, 中野 晋, 三沢 章博, 福村 功昌
    2008 年 26 巻 p. 17-22
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    This study has examined the foaming process of a silicone rubber which is a type of crosslinked polymer that uses an environment-friendly physical blowing agent. Since crosslinking progresses in a silicone rubber over time and as temperature increases, it is extremely difficult to mold foams that have the required cell size. Here, the degree of vulcanization of a silicone rubber was controlled by the plasticity, and it groped for the foaming process based on this plasticity. And the microstructure and mechanical properties of a silicone rubber that has been foamed by using this process have been evaluated. As a result of this, the following has been found. 1) The degree of crosslinking that varies with time and temperature has been evaluated by using plasticity, and a physical foaming process based on this plasticity has been proposed. 2) The plasticity of a silicone rubber can be adjusted by means of temperature and time, the time-temperature equivalent law holding between these, and the shift factors take on an Arrhenius's type behavior. 3) It has been found that there exists an optimum range of plasticity for obtaining a foamed silicone rubber of the desired cell size, and foaming control can be achieved by using the process proposed in 1) above. 4) By changing the plasticity before foaming by employing the proposed foaming process, a foamed silicone rubber has successfully been obtained which has a cell size of several micrometers and a hardness that represents tactile impressions as human body.
  • 福島 学, 吉澤 友一
    2008 年 26 巻 p. 23-28
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    Porous alumina membrane supports with submicrometer pores, sintered at 1300-1400℃, were prepared by using milled raw powders with various periods (0-7days), the press molding of 40MPa and with or without further cold isostatic pressing of 100MPa (CIP). The relationship between processing factors, pore size and microstructure was examined. Varying the sintering temperature, the press condition and the period of mill were found to be effective for controlling pore size and porosity. The porosities of the membrane supports sintered at 1400℃ showed 13.45%, which could be controlled by the particle size of raw powder and the packing density of green body. The pore size and particle size increased with increased sintering temperature. These were found to be closely correlated with the formation of developed neck area and the grain coarsening during sintering. However, even when sintered at 1400℃, the pore sizes of supports from 3days and no.milled powders showed the fine sizes of 0.34 and 0.51μm, respectively.
  • 日向 秀樹, 近藤 直樹, 北 英紀, 岡野 宏昭, 菅井 淳, 土田 二朗
    2008 年 26 巻 p. 29-34
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    Reaction bonded and post-sintered silicon nitride ceramics was fabricated using ZrO2-MgAl2O4 as sintering additives. It was clarified that added ZrO2 was act as nitridation enhanced effect under MgAl2O4 coexistence during reaction bonding process, and nitridation of the silicon was also completed lower temperature than that of Silicon without ZrO2-MgAl2O4. The post-sintered specimen had a four-point bending strength of 850 MPa, which was obtained same fracture strength at same additive system prepared using high purity silicon nitride powder as a starting material.
  • 鈴木 寛
    2008 年 26 巻 p. 35-40
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    In this study, an equation for predicting width distribution of overlapping part of fibers observed under the surface of a short fiber reinforced composite in which fibers were random in 2D was formulated. It was assumed that the fiber direction distribution was random in a plane parallel to the composite surface. The overlapping width of one fiber was approximated to a rectangle with constant width w. The rectangles could be arbitrarly located between two edges of the fiber. Number of the rectangles located on the fiber could be expressed as a linear function of depth from the composite surface. When the width of overlapping part was between (n-1)w and nw (n= 1, 2, 3,…), the width distribution of the overlapping part were given by n-2 following equation of the width of the overlapping part. The distribution of width distribution of overlapping part of fibers could be expressed by an extremely simple equation.
  • 吉田 啓史郎, 青木 隆平
    2008 年 26 巻 p. 41-48
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    The single-ply triaxially woven fabric (TWF) constitutes of three sets of inter-woven carbon fiber yarns oriented in 0deg, +60deg and -60deg angles. The fabric is impregnated with epoxy resin to constitute single-ply TWF composite. The material system is utilized in various fields, including space applications due to its low apparent density and high flexibility together with the expected isotropy in stiffness, all of these characteristics resulting from its distinctive configuration. In the present study, the numerical simulation utilizing the beam network model in which yarns that constitute the woven fabric composite are modeled as beams and these beams are connected each other at crossover section of yarns is conducted to analyze the mechanical properties of this material system. The numerical results of the beam network model show good agreement with those of the conventional 3-D solid finite element model.
  • 荻原 慎二, 松田 勝博
    2008 年 26 巻 p. 49-54
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    Mode III interlaminar fracture toughness in CFRP is evaluated experimentally by using the Edge Crack Torsion (ECT)test. A material system used is T700S/2500 carbon/epoxy system. Laminate configuration is [90/(±45)3/(±45)3/90]S with a delamination introduced by a 25μm-thick kapton film at the mid-plane along one edge. The specimen size is 90mm long, 40mm wide, and 4.2mm thick. A natural crack is produced with a wedge from the film edge. The resulting crack lengths are from 8mm to 18mm. The film lengths were 0, 5, 10 and 15mm, respectively. Two data reduction schemes are used to calculate mode III interlaminar fracture toughness GIIIC at the maximum load and load at onset of nonlinearity. Soft X-ray radiograph is used to observe delamination propagation. Three-dimensional finite element analysis is performed to calculate the distribution of mode I, mode II, and mode III energy release rate along the delamination front. The validity of the experimental method is also discussed.
  • 斉藤 博嗣, 金原 勲
    2008 年 26 巻 p. 55-60
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    In this paper, the joint strength of lap jointed CFRP laminate manufactured by VARTM process was evaluated. Unlike the adhered joint, manufacturing of the lap joint with VARTM can be conducted in one-process, which means that the secondary processing like sanding and adhesion is unnecessary. Three types of joint configuration were adopted in this study ; single-lap, double-lap and scarf-lap joints. First, the effectiveness of one-process molding of single-lap joint was evaluated comparing with the adhered joint. The joint strength of one-process molded joint was about 80% higher than that of adhered joint. In one-process manufacturing, the joint strength of scarf-lap joint was about 100% higher than that of single-lap joint. Next, the stress condition in lap joint specimen was evaluated to discuss the fracture mechanism of joint structure with Finite element analysis. FEM results showed good agreement with experimental data. Finally, the energy release rate at the tip of lap surface was calculated by FEM in order to clarify the mechanism of the initiation of delamination.
  • 荻原 慎二, 岡田 明久, 小林 訓史
    2008 年 26 巻 p. 61-66
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    In recent years, from necessity of eco-friendly materials, biodegradable plastics have been developed. These materials as substitutes of conventional plastics have attracted a lot of attention. However, many of them have lower mechanical properties than conventional engineering plastics. When considering their application as structural materials, reinforcing them with a natural fiber is one of reinforcing method without a loss of their biodegradability. On such natural fiber reinforced biodegradable plastic composites, only some combinations of fibers and matrices have been tried and the mechanical properties of them are not well known. In the present study, we use a bamboo fiber as the reinforcement and polybutylenesuccinate (PBS) as the matrix. We fabricate long fiber unidirectional composites with different fiber volume fraction. We conduct tensile tests which tensile direction is 0, 45, and 90 degree and evaluate the mechanical properties of these composites. We discuss the experimentally-obtained properties based on the mechanical properties of the constituent materials.
  • 小林 訓史, 坂本 和紀
    2008 年 26 巻 p. 67-78
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    In order to investigate hydrolysis behavior of bioresorbable plastic composites, β-tricalcium phosphate (β-TCP) /poly(l-lactide) (PLLA), long term immersion tests into phosphate buffered solution (PBS) with different pH were conducted. After the immersion tests, differential scanning calorimetry and tensile, bending and compressive tests were conducted on the specimen. The crystallinity of PLLA increased with increasing immersion period. The significant decrease in the mechanical properties of the specimens with 5.0wt% β-TCP contents were not observed after 24 weeks immersion into PBS with pH7.4, whereas significant decrease were observed for the specimen with 9.5 and 14.0wt% contents. For the immersion tests into PBS with pH6.4, the degradation was accelerated. The degradation in moduli was attributed to lower load capacity of β-TCP particles due to the bioresorption.
  • 生分解性樹脂による編物構造複合材料の開発
    田中 信生, 日和 千秋, 井元 俊之, 安達 泰治, 北條 正樹, 馬場 俊輔
    2008 年 26 巻 p. 79-88
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    Medical scaffolds made of novel tubular knitted fabric composites were developed for the regeneration of alveolar bones. These composite scaffolds were made of high strength PLLA(poly .L-lactide) fiber and two types of coating polymers, PCL(poly ε-caprolactone) and PLGA(poly(L-lactide-co-glycolide)). Axial tensile and radial compressive properties of composite scaffolds were much higher than those of fabric structure without coating. The effect of coating polymer on biodegradability was investigated in PBS(Phosphate buffer saline) solution. While mechanical properties of scaffolds with PCL coating were rather insensitive to PBS immersion, those with PLGA coating were much higher in strength at initial stage, and then showed rapid decrease. Then, we can control mechanical and biodegradable properties of composite scaffolds to meet wide range medical design demand.
  • マウス骨芽細胞様細胞による骨組織形成過程
    日和 千秋, 沖添 晃政, 中井 善一, 田中 信生, 安達 泰治, 北條 正樹, 馬場 俊輔
    2008 年 26 巻 p. 89-95
    発行日: 2008年
    公開日: 2021/02/17
    ジャーナル フリー
    We developed novel fabric structural composite scaffolds using a bioabsorbable polymer for a tissue regeneration of alveolar bone. This scaffold consists of the high strength polylactic acid (PLA) resin fiber fabric and the flexible ε-polycaprolactone (PCL) resin coat. The rigidity and yield strength of scaffold are increased owing to the bonding of fiber intersection by resin coat. In the aim of evaluation of cell proliferation and differentiation on scaffolds, mouse osteoblast-like cells (MC3T3-E1) were seeded onto the scaffolds and cultured in vitro for six weeks. The cells proliferated during the time in culture and formed a space-filling tissue between polymer fibers. Bone regenerative messenger ALP/DNA levels remained high compared with those one of culture dish. Mineralization of the deposited collagen on scaffold was initially observed at four weeks and subsequently increased. Similarly, rigidity and strength to the radial direction of scaffold increased. Culture of cell on scaffold led to formation of a bone tissue for six weeks.
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