材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
57 巻 , 5 号
選択された号の論文の15件中1~15を表示しています
特集 複合材料
論文
  • 高野 直樹, 浅井 光輝, 黄田 尚宏, 橋本 和信
    2008 年 57 巻 5 号 p. 423-429
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    This paper presents a three-dimensional morphology analysis technique by means of TEM tomography and finite element modeling of nano particle dispersed composite materials. The target material system in this paper is natural rubber reinforced by carbon black (CB) nano-particles. The average diameter of CB ranges from 30 to 122nm. The main feature of this paper is that the interphase named sticky hard layer between CB and free rubber is considered in detail. The Young's modulus was estimated by pulse nuclear magnetic resonance (NMR), and the thickness was obtained by measuring the volume content and moreover considering the agglomeration of CB nano-particles. The Young's modulus of the sticky hard layer was 5 to 30times larger than that of free rubber. The relative thickness of the sticky hard layer divided by the CB diameter was found to be very influential on the overall properties of the composites, because its percolation forms the load carrying path in the composites as demonstrated by finite element analysis. These results have been supposed to be the major reason to explain the nano-particle size effect on the overall properties, which have never been understood by the classical rule of mixture.
  • 田中 和人, 鎌田 浩史, 片山 傳生, 山本 英毅
    2008 年 57 巻 5 号 p. 430-435
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    This research purpose is to learn mechanical hybrid construction of the bone tissues and to apply their design theory for development of the new composite materials adapting themselves to the mechanical designs in the next generation. As for the new composites from the biomimetic design for load dispersion properties of the cancellous bone, the solid-fluid composites have been proposed in the previous researches, where in order to apply the approximation of nonviscous body for the beginning of analyses, the solid-air composites were introduced for the solid-fluid composition of the cancellous bone by using aluminum honeycomb core as a solid component and air as an internal fluid one. In the present research, from the viewpoint of bio-kinematics, deformation state and the reaction force distribution of the solid-air composites were measured under kinetic indentation tests, and the load dispersion properties were evaluated by comparison with the experimental results under static indentation tests. It was concluded that the internal nonviscous flow had a great effect on kinetic load dispersion properties of the solid-air composites because both the deformation state and the reaction force distribution of aluminum honeycomb core were independent of the indentation speed under this loading condition. The experimental results were verified by dynamic solid-fluid coupling analyses applying a finite element model.
  • 邉 吾一, 角倉 浩平, 美浦 一葉
    2008 年 57 巻 5 号 p. 436-441
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    This paper proposes two new joining methods of CFRP pipes without both of a mechanical joint and an adhesive joint. In the two joining methods, the some region of resin is removed from the edge of CFRP pipe in order to obtain the exposed carbon fibers. In the first method, the exposed fibers are divided to two bundles and they are wounded perpendicularly to the center of another pipe. In the second method, two CFRP pipes having more ten bundles of exposed fibers at their edges are faced to each other. Then, the bundles in one pipe are enlaced to the bundles of another pipe with a pair and carbon roving is wound around those enlaced bundles. After resin is impregnated into the enlaced parts of two methods and is stiffened under room temperature, the CFRP pipes jointed perpendicularly or in series are obtained. These joints are called as T-style joint and I-style joint, respectively. The manufacturing processes of the T-style and I-style joints are explained here and their mechanical strengths are evaluated in the tensile and bending tests The FEM analyses are executed and are compared with the results of experiments.
  • 二村 道也, 三宅 卓志, 藤吉 俊希, 福澤 瞬, 大野 信忠
    2008 年 57 巻 5 号 p. 442-447
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    The axial stresses of the fiber in single carbon fiber/epoxy resin model composites under change of surroundings, e.g., temperature and water, have been measured by micro-Raman spectroscopy. The specimens were soaked in hot air, water and hot water, and returned to the beginning state to cause cyclic changes of temperature and water absorption : (1) heating and cooling at atmospheric environment, (2) immersing in the water of the room temperature and drying, and (3) immersing in the hot water of 80°C and drying at the room temperature. In the case of (1) and (2), the fiber axial stresses after the cyclic change of the surroundings recover almost the same before the heating or the immersion. On the other hand, the fiber axial stress after the drying is more compressive than that before the hygrothermal exposure in the case of (3). Hygrothermal effects on the residual stress are discussed based on fiber stresses caused at elevated temperature over the glass transition temperature of the epoxy resin.
  • 山下 耕司, 岡部 朋永
    2008 年 57 巻 5 号 p. 448-453
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    In order to improve the fracture strain of fiber reinforced ceramic composites, it is necessary to understand how the fiber/matrix interface affects the fracture strain of the composite. Therefore, in this paper, FEM simulation using a cohesive zone model was applied to the issue. To discuss the realistic situation, we examined the influence of the fiber flaw on the fracture strain at first. Two cases were delt with : the flaw is considered in one case, not considered in the other case. The result shows that if there is the flaw in the fiber, it caused the stress concentration and invoked fiber break. This result suggests that the fracture strain will be overestimated if the flaw is not considered. Secondly, Sigma-fiber-reinforced glass-matrix composite was considered and how the fiber/matrix interface affects the fracture strain and fracture behavior was examined. Of particular note is that the stress concentration at the tip of interfacial deboding may invoke fiber break. As a result, it is necessary for the composite not only to form multiple-crack state but also to have weak interface enough for the stress concentration at the tip not to invoke fiber break.
  • 田辺 克典, 松尾 貴則, Alexandre GOMES, 合田 公一, 大木 順司
    2008 年 57 巻 5 号 p. 454-460
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Plant-based natural fibers have a large variation in cross-sectional area. Even in a single fiber the cross-sectional area varies along the fiber-axis. In addition, the shape of the cross-section is not circle, but rather close to an ellipse. Therefore the fiber strength often results in under- or over-estimation. It was observed from cross-sectional micrographs of a curaua fiber green composite that real fiber cross-sectional areas indicated a strong correlation with fiber cross-sectional areas assumed as an ellipse. Based on such correlation, therefore, the present study proposes a new method of determining approximately fiber cross-sectional areas. The validity of the proposed method is shown through elliptical areas calculated from two projection widths, which are measured from two orthogonal directions of single curaua fibers. Moreover, a new probabilistic distribution function based on Weibull theory was created to explain the effect of variation in cross-sectional area along the fiber axis on fiber strength. This function is characterized to decide the statistical properties of fiber strength through a parameter, R, of variation in cross-sectional area.
  • 高木 均, 興津 嘉人
    2008 年 57 巻 5 号 p. 461-466
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Japanese timber bamboo (Madake) was hot-pressed in order to obtain increased mechanical properties, such as flexural strength, flexural modulus and impact strength. The hot-pressing conditions were varied in the following range: temperature, room temperature to 220°C : pressure, 5 to 100MPa. The flexural strength, compressive strength and Izod impact strength increased with increasing molding temperature up to 160°C, showing the maximum peak values, but thereafter decreased. The effect of molding pressure on the mechanical properties was also examined. Densification at both vascular bundles and parenchyma cells region was achieved at the molding pressure of 50MPa.
論文
  • 武田 武信, 水上 貴博
    2008 年 57 巻 5 号 p. 467-473
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Multiaxial stress tests were carried out on thin-walled cylindrical specimens of the A2024BE-T6 alloy aged at 120°C for 1 hr and the A2024BE-O alloy fully annealed at 495°C for 1hr. The shear strength of these alloys is much lower than the tensile one, and the equi-strain surfaces in the tension-torsion stress field lie within Tresca's criterion. Planar anisotropy was determined from two types of multiaxial stress tests by means of the combined loading of axial load, internal pressure and torsion, referred to as “off-axis tension test” and “off-axis torsion test”. The degree of anisotropy is expressed by using two different measures : one is the proof stress and the other is the angle deviation between the directions of the principal stress (or principal shear stress) and principal strain increment (or principal shear strain increment). The A2024BE-T6 alloy exhibits more severe anisotropy than the A2024BE-O alloy and both alloys reveal more severe anisotropy in off-axis tension test than in off-axis torsion test. The plastic deformation behavior can be analyzed precisely by the constitutive equation derived from the anisotropic yield function, hardening law and associated flow rule.
  • 米津 明生, 中山 朝之, 小川 武史
    2008 年 57 巻 5 号 p. 474-480
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    This paper discussed the fracture mechanism of diamond like carbon (DLC) film subjected to contact loading. The DLC films with over 10μm thick were deposited onto stainless steel (SUS304) by Radio Frequency (RF) plasma-based ion implantation method with different applied voltage of –20, –15 and –10kV. Rockwell indentation tests with simultaneous monitoring of acoustic emission (AE) and corrosion potential fluctuation (CPF) techniques were applied to the DLC films to clarify the mechanism of contact fracture. The DLC films were found to produce two types of crack morphology. One is general ring crack produced by tensile stress developed around contact area of indenter under loading process. The other indicated spiral crack morphology. This crack was found to be produced under unloading process detected by AE and CPF analyses, which could determine the indentation force, Fu, at the onset of spiral crack. The values of Fu are strongly dependent on the maximum indentation force and coating process. Finite element analysis suggested that the DLC deformed plasticaly prior to the tensile fracture under loading process. Due to this plastic strain, the film buckling occurred under unloading process and resulted in the delamination and the spiral crack. Rockwell indentation method with AE and CPF monitoring system could determine the onset of film fracture, which enabled us to discuss the detailed fracture mechanism.
  • 川原村 敏幸, 西中 浩之, 藤田 静雄
    2008 年 57 巻 5 号 p. 481-487
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    The mist CVD method, previously named as mist deposition or spray pyrolysis, is an environmental friendly and cost-effective technology for the deposition of thin oxide films. The mist CVD method features the liquid solution of constituent elements as source materials, which is atomized to form the mist of aerosol particles. The mists are then transferred by a carrier gas to the reaction area to the deposition of thin films. This does not need vacuum systems because it is operated at atmospheric conditions. Furthermore various material solutions are chosen for the source, including innocuous and nonpoisonous ones. Therefore, this method possesses advantages of safety, cost-effective, light load to the environment, harmless to the human, and multiplicity of applying to a lot of materials.
    In order to make smoother films on large substrates in this technology, it is important to obtain the uniform flow of mists and carrier gas. We have developed two kind of new methods. One of them is named as fine channel mist chemical vapor deposition (FCM-CVD) method which has a fine channel and collisional mixing to obtain uniform flow of mists and carrier gas. The other is named as linear source mist (LSM-) CVD method which is a technique for specializing in a continuous process. With using FCM-CVD, we fabricated ZnO thin films and succeed to obtain the homogeneous thin films on the 100mm square glass substrate whose deviation rate was ±0.45% at 40mm2.
    In this study, we report the effect of “fine channel” and “collisional mixing” on mist CVD method from view points of theorem, simulation, experience, and so on.
  • 中村 守正, 三浦 健一, 松岡 敬, 平山 朋子
    2008 年 57 巻 5 号 p. 488-494
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Effects of deposition conditions for residual stress in DLC films consisted of a–C:H layer and Cr/C inclined interlayer were studied. Residual stresses in upper and lower film were calculated respectively by our developed Stoney's equation in order to apply double layer film. a–C:H layer and Cr/C inclined interlayer were prepared by UBM sputtering onto SUS304 substrate as a function of process parameters : substrate bias voltage, deposition temperature, gas mixture ratio [CH4]/{[Ar]+[CH4]}, and total gas pressure. Applying a bias voltage to a substrate brought a rapid increase in the compressive stress of a–C:H layer. However, over –300V voltage brought a slightly decrease in the compressive stress. Compressive stress in a–C:H layer increased with deposition temperature under 501K, and decreased over 501K. An increase of gas mixture ratio brought a gradual decrease of compressive stress. Compressive stress in a–C:H layer decreased with total gas pressure. Meanwhile, deposition conditions brought different changes of residual stress in Cr/C inclined interlayer from that in a–C:H layer. Compressive stresses in a–C:H layer were compared with N/S ratio obtained by Raman spectrum, which seemed to indicate hydrogen contents in the films. In group of films having small compressive stresses, compressive stresses in a–C:H layer approximately decreased with increase of N/S ratio. And in group of films having large compressive stresses, Ar ion assist affected to rapid increase of compressive stress in a–C:H layer deposited as a function over –100V substrate bias voltage and under total gas pressure 0.25Pa. Higher substrate temperature at the end of deposition over approximately 530K brought a decrease of compressive stress in a–C:H layer.
  • 中村 省三, 川端 拓也, 福井 雄, 吉見 健二
    2008 年 57 巻 5 号 p. 495-501
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    A simplified evaluation equation that handily predicts the warp deformation behavior arising when the thermal load was provided to a viscoelastic laminated beam consisted of epoxy resin and steel was proposed, and validity of the equation was verified through comparison with not only exact solution based on linear viscoelastic theory but experimental values. The proposed simplified evaluation equation is composed of the glass transition temperature, the rubber transition temperature, the elastic modulus and the linear thermal expansion coefficient of the component material. It this study, it was clarified that the warp deformation behavior of the viscoelastic laminated beam could be predicted handily by using proposed simplified evaluation equation which was divided elastic modulus into three regions such as glassy state, leathery state and rubbery state.
  • 平石 陽一, 宮里 心一, 海野 統彦, 藤本 一男
    2008 年 57 巻 5 号 p. 502-508
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Recently, the investigation of the corrosion rate at the existing reinforced concrete was temporally evaluated only by the microcell corrosion rate using the polarization resistance method. That is, to appropriately evaluate the durability of the existing reinforced concrete, it is necessary to construct the check system that continuously measures not only the microcell corrosion rate but also the macrocell corrosion rate. From the above backgrounds, the objective of this study is to propose the method monitoring the macrocell corrosion rate at the existing reinforced concrete. Therefore, the technique for monitoring the macrocell corrosion rate by the non-destructive test is proposed using the specimen. Also, it is applied to the pier with a crack and the road bridge with a joint. As a result, the macrocell corrosion rate at the existing reinforced concrete can be continuously measured in all seasons. In this method, the Cupper boards etc. are set on the existing reinforced concrete, and the polarization resistance, the concrete resistance and the potential are measured in the arbitrary time. These measured values are substituted for the simulated electric circuit model of the macrocell in the reinforced concrete, and the macrocell corrosion rate is calculated. Especially, this method has the merit that can be used continuously for more than a year under the chloride environment.
  • 吉岡 慧, 吉田 和隆, 吉武 勇, 浜田 純夫, 北原 敦志
    2008 年 57 巻 5 号 p. 509-514
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    There is a large demand in consumption of fly ash due to current increase of coal power plants. Fly ash in concrete as admixture contributes to decrease heat of hydration. The larger amount of fly ash is in concrete, the lower heat of hydration is generated in the early age. This is caused by substitution of fly ash for cement, which implies that less cement is mixed in the concrete. Present paper describes adiabatic temperatures of the high volume fly ash concrete. The estimated adiabatic temperature in the concrete standard specification evaluates a little higher for amounts less than 200kg/m3 of cement in concrete, and an equation of adiabatic temperature for these amounts of cement is herein proposed.
  • 岩原 廣彦, 佐々木 勝教, 山中 稔, 増田 拓朗, 森 邦夫
    2008 年 57 巻 5 号 p. 515-522
    発行日: 2008年
    公開日: 2008/05/20
    ジャーナル フリー
    Many researches already concluded that concrete which contains fly ash usually possesses higher rates of pozzolanic reactions with increasing pore sizes of 0.1μm or less. When a pozzolanic reaction evolves, densification of CSH hydrates also starts. This densification process is high in 0.003–0.01μm size of pore and low in 0.01–0.05μm size of pore. The technology described in this paper is related to the microstructure change in granulated foundation materials, which contain primarily fly ash mixed with small amounts of cement. The authors developed a special mixer that can be used to prepare granular foundation materials from mixing of water, fly ash, and cement. This kind of foundation material has many similarities with natural foundation materials like sand and crushed stone, and it can be produced by a single process of mixing in a short time.
    Similar to the fly ash concrete, the granulated foundation material chiefly composed of fly ash and a small amount of cement contains many pores of sizes 0.1μm or less. Experiments also concluded that when hydrated lime was added into the granulated foundation material to prevent leaching of heavy metals and other substances, CSH hydrates developed in pores of size 0.1μm or less and the material consisted of approximately 50% of the total pore space.
    The authors also used an electron probe microscope analysis (EPMA) and measured pore size distribution after addition of hydrated lime to the granulated foundation material. It made easier to understand the changes in micro-structure and to explore the causes behind the development of different microstructures in the granulated foundation material after addition of hydrated lime.
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