材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
56 巻 , 11 号
選択された号の論文の16件中1~16を表示しています
論文
  • 木嶋 健
    2007 年 56 巻 11 号 p. 999-1004
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    FRP might be widely applied to infrastructures in coast areas, because it is a corrosion-resisting material. Joints such as adhesive joints and bolted joints are required in application of FRP to infrastructures. Pultruded FRP is desirably applied to infrastructures because its mass production could bring about lower cost. The purpose of this paper is to obtain the effect of clamping force on the strength of bolted joints in pultruded GFRP laminates through the experiment. The two types of bolted joints are focused, friction-type bolted joints and bonded-bolted joints. The strength of friction-type bolted joints increases with the clamping force. The failure mode is bearing failure for joints without clamping force and shear-out failure for joints with clamping force. The strength increase with clamping force is brought about by the increase of bearing strength and the friction between the specimen and the attached plate. The strength of bonded-bolted joints also increases with the clamping force. The failure mode is adhesive failure for adhesive used joints and bearing or shear-out failure for adhesive tape used joints, because adhesive tapes have lower strength than adhesives. The strength increase of adhesive used joints with clamping force is brought about by the increase of failure stress at the end of adhesives. On the other hand, the strength increase of adhesive tape used joints with clamping force is brought about by the increase of bearing strength.
  • 石田 拓也, 葛西 裕, 浦山 健治, 瀧川 敏算
    2007 年 56 巻 11 号 p. 1005-1009
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    Thermal and mechanical properties of Nafion membranes in the dry and swollen states have been examined. The results of differential scanning calorimetry (DSC) and dynamic viscoelasticity measurements give the glass transition temperature (Tg) of the membranes lying around 120°C, which is close to that of polytetrafluoroethylenes (PTFEs ; Tg∼115°C). This shows that Tg of the Nafion membranes stems from the relaxation of PTFE main chains of the Nafion membranes. Stress-strain curves of the dry membranes below Tg exhibit the yielding that originates from the failure of the glassy matrix, i. e., the PTFE domains in the membranes. The Nafion membranes swollen by water also show the yielding of the stress-strain curves, i.e., no plasticization effect takes place in the PTFE domains. This suggests that water is localized in hydrophilic domains in the Nafion films. A finite water flow is observed in the water permeability measurement using the static pressures. These results clearly indicate a bicontinuous microphase separated structure composed of hydrophobic and hydrophilic domains.
  • 鈴木 徹, 加賀谷 誠, 高橋 哲躬
    2007 年 56 巻 11 号 p. 1010-1015
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    The road surface repair material of cold hardening type was tested on the workability such as self-leveling, hardened properties and hardening time for opening the traffic. The flow test was suitable for testing on self-leveling characteristics and the allowable flow time for the characteristic was 4 to 10seconds and the handling time after mixing was 10minutes at 20degree Celsius. The properties of hardened repair material were almost the same as those of dense grade hot asphalt mixture. The rutting resistance was superior to dense grade hot asphalt mixture. Flexural property and strength of this road repair material were satisfactory for bonding on the existing road surface. The hardening time of this repair material could be evaluated by the durometer with semi-globular shape type of press needle and the hardness for opening the traffic was about 85 at 60minutes after finishing the repair work at 20degree Celsius.
  • Rafiquzzaman MD., 荒居 善雄, 土田 栄一郎
    2007 年 56 巻 11 号 p. 1016-1021
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    In this paper, fracture mechanisms under monotonic and cyclic load and its stress distribution of an aluminum cast alloy locally reinforced by SiC particles and Al2O3 whiskers are investigated experimentally and numerically. The material is monotonically and cyclically deformed to failure at room temperature. The fracture origin and the fracture path are investigated on the fracture surfaces. The fracture occurs in the reinforced part under both monotonic and cyclic loads. SEM analysis of the fracture surface shows that the fatigue fracture is controlled by the fracture of coarse Al2O3 whiskers. On the other hand the static fracture (monotonic loading) shows that the fracture mechanism is the combination of reinforcing particle fracture and interfacial debonding between reinforcing ceramics and matrix metal. The stress distributions around the boundary between the reinforced part and unreinforced part are calculated based on an inclusion array model considering the microscopic inhomogeneous effects. Both the experimental results and the finite element simulation results show that the critical location for fracture is changed by the external stress level which controls the local stress distribution through plastic constraint between reinforcing particle and matrix alloy.
  • 伊藤 義康, 須山 章子
    2007 年 56 巻 11 号 p. 1022-1027
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    A cold spray process has been developed for dense and clean and tightly bonded coatings in contract with other established thermal spray processes. The cold sprayed aluminum is particularly well suited for metallic coatings, such as electric conductor and corrosion resistance. However, the thermal and electrical properties of aluminum coatings formed by the cold spray have not always been clarified. Two kinds of free-standing aluminum specimens, which were formed by the cold spray process and an atmospheric plasma spray process, were machined from the thick coatings and were used for measuring the thermal conductivity, specific heat and electrical resistivity etc. The experimental results suggested that the porosity and oxide content had important effects on the thermal and electrical properties. Namely, high thermal conductivity and the low electrical resistivity of coatings could be obtained from the cold spray process, because of the low porosity and the low oxide content.
  • 鳥居 太始之, 馬 東輝, 松葉 朗, 清水 憲一
    2007 年 56 巻 11 号 p. 1028-1034
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    As model specimens of surface film-bonded materials, pure copper films with the thickness of 100, 50, 30μm were bonded to the surface of steel base plate by epoxy resin bonding or by diffusion bonding. As a result of fracture surface observation for the fatigue crack initiation at the notch root, there was a tendency for the fracture surface morphology to show fracture with intergranular cracking for the epoxy-bonded copper film but shear type with transgranular cracking for the diffusion-bonded film, respectively. Moreover, many fatigue cracks with very few slips were caused only on the surface film at the multiple sites sufficiently away from the notch root on the epoxy-bonded films. In contrast, on the diffusion-bonded film, a fatigue crack with many slips was caused only at the notch root and propagated through the thickness including the base plate. Furthermore, some thin extrusion-like bulging could be observed partially along the fatigue crack on the epoxy-bonded film, while many pairs of “intrusion” and “extrusion” were observed predominantly at the slip band near the fatigue crack on the diffusion-bonded film as well as on the bulk metal specimens. The difference in fatigue damage behavior between the epoxy-bonded and diffusion-bonded films was discussed in terms of elastic displacement field propagated by wave into the films from the base plate subjected to cyclic deformation.
  • 上村 隆之, 土井 教史, 鹿島 和幸, 和暮 憲夫, 原 修一, 中原 勝也, 安藤 隆一, 幸 英昭
    2007 年 56 巻 11 号 p. 1035-1041
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    The rust layer formed on the weathering steels coated with a surface treatment promoting protective rust formation exposed at a coastal region containing 0.4mg/dm2/day of air-borne salt particles for 9 years has been investigated by means of X-ray diffraction, Raman spectroscopy, Electron probe micro-analysis and Mössbauer spectroscopy. In the surface treatment, Cr2(SO4)3 is contained to form the protective rust layer. Corrosion loss vs. time curve of surface treated weathering steels follows Y = AXB type function, where X is the exposure duration, Y is the corrosion loss, A and B are the constants. The surface of the treated weathering steels were covered with triple layers ; outer rust layer, surface treatment film and inner rust layer. The outer rust layer consisted of mainly β-FeOOH, and the inner one mainly α-FeOOH. Cr enrichment was observed in the inner rust layer. It can be said that the surface treatment works well to promote the formation of Cr-containing α-FeOOH layer formed on weathering steel.
  • 中澤 嘉明, 田村 憲司, 日下 貴之, 吉田 経尊, 北條 正樹
    2007 年 56 巻 11 号 p. 1042-1048
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    By using finite element analysis, effects of installing concave geometry in thin-walled octagonal shell members on plastic buckling behavior were studied to evolve a novel design method of the crash box for automobiles. Numerical results showed that the installation of concave geometry in thin-walled octagonal shell members enabled to shorten the wavelength of plastic buckling and consequently to improve the plastic buckling load. This buckling load became larger as the concave width and the concave depth increased. Moreover the installation of concave geometry changed the phases of plastic buckling between adjacent regions in the circumferential direction. A novel design scheme improving crash energy absorption of thin-walled polygonal shell members was also established on the basis of the above outcomes.
  • 舟木 克之, 鷹合 滋樹, 藤井 要, 佐々木 敏彦, 広瀬 幸雄
    2007 年 56 巻 11 号 p. 1049-1054
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    The in-situ measurement of phase stress under tensile deformation on an A6061 alloy reinforced with SiC whiskers (MMC) was performed using the X-ray diffraction technique. Phase stress in Al matrix was increased linearly up to 2800×10–6 in strain and then saturated immediately. On the other hand phase stress in SiC whiskers showed an unstable stress behavior. It was decreased at first because of the Poisson effect from Al matrix but reversed over 500×10–6 applied strain. The measured phase stress behavior in elastic region agreed with the calculations using micromechanics based on Eshelby/Mori-Tanaka model except for this unstable internal stress region. Facets were observed on the fatigue fracture surface and many clusters of the whisker existed beneath the fracture surface. These suggest a clustering deformation in the inside of MMC. Incidentally, each phase in the MMC under tensile deformation cause a strain level difference that arise from the difference of elastic constant between Al matrix and SiC phase. This quantity of plastic strain mismatch at the interface, Δεp was estimated by using micromechanics. The Δεp change under tensile deformation reflected internal fracture such as formation of micro voids or exfoliation of whiskers occurred at the interface.
  • 粕谷 平和, 牧 繁夫, 辻本 真之, 根本 圭一
    2007 年 56 巻 11 号 p. 1055-1060
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    Because of their high specific strength and stiffness, fiber-reinforced plastics have used as structural members in various fields, and hence analysis of thin laminated structures is important. The postbuckling behaviors of thin laminated curved plates under uniaxial compressive loads have been discussed by many researchers. However, they become unstable with further loading and the secondary buckling which occurs accompanying snapping-through to higher-order deflection pattern has not yet been clarified. In this paper, cross-ply laminated curved plates under biaxial compressive loads which are simply supported along four edges is considered as an example. By a proposed method based on the second variation of total potential energy to judge the stability of postbuckling equilibrium state, the inevitability of secondary buckling is proved analytically and the effects of various factors on the secondary buckling values are clarified.
  • 君島 健之, 長岡 誠一, 中山 公彦, 小林 茂広
    2007 年 56 巻 11 号 p. 1061-1067
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    Some problems are pointed out about the examination method of evaluating the alkali reactivity of aggregate. For example, by the mortar bar method of JIS without supply of alkali from the exterior, and the method immersed in the NaOH solution defined by ASTM and the method immersed in saturation NaCl solution (Denmark method), the judgment result changes with kinds of aggregate. Then, in order to acquire broad knowledge about the factor influenced on an examination result in this research, the influence affect the result which alkali content of cement depends on the various examination methods was considered. Consequently, it became clear that the grades influenced alkali content and the kind and the amount of reactant mineral in aggregate by the examination method differ. Especially, a result, which supports indication that it is necessary to examine whether the Denmark method for having an advantage, like that it can judge for a short period of time and a judgment result becomes clear can apply to the aggregate of our country, was brought.
  • 下川 智嗣, 平本 知之, 喜成 年泰, 新宅 救徳
    2007 年 56 巻 11 号 p. 1068-1075
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    Atomic simulations of shear deformation of aluminum and coppernanocrystalline models are performed to determine the influences ofdefect plane energies on defect structures in nanocrystallinemetals. In aluminum models with high stacking fault energy, deformation twins can be observed in the case of the specific crystalorientation which is the same one as that expected analytically. Inthis case, extrinsic stacking faults always form in the early stage ofthe formation of intrinsic stacking faults. It is also observed thatnew crystal slip generates in an extended stacking fault in anothercrystal orientation in aluminum. In order to clarify the appearancemechanism of these defects in aluminum, we use the dislocation theoryand nudged elastic band method, and necessary conditions to formdeformation twin in aluminum are discussed.
  • 丸屋 英二, 坂井 悦郎, 萩原 清市, 大門 正機
    2007 年 56 巻 11 号 p. 1076-1080
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    The evaluating test for adiabatic temperature rise in concrete is not adequate for daily quality control because it requires considerable labor. In order to establish a convenient method for the evaluation of adiabatic temperature rise using about 30mL of mortar sample only, we produced an adiabatic calorimeter experimentally. In this paper, the accuracy and the applicability of this equipment is investigated. Values of adiabatic temperature rise measured using this equipment were found to correspond to those obtained using existing equipment, by the correction of heat capacity of a sample container. Clear differences were observed between mortar samples with different blending conditions. These results suggest that the quality control of cement and preparatory experiments could be practiced reasonably by using this adiabatic calorimeter.
  • 小川 和彦, 岡部 敏弘, 小川 誠
    2007 年 56 巻 11 号 p. 1081-1086
    発行日: 2007年
    公開日: 2007/11/22
    ジャーナル フリー
    The term woodceramics is the generic name for carbon materials made of plant originated materials impregnated with phenol and carbonized under reduced pressure of 200 to 2000°C. The inside of woodceramics is porous and they exhibit various properties when the carbonaization temperature is changed. Currently, woodceramics are attracting attention as materials used for humidity sensors, electromagnetic shielding materials, far-infrared heaters and various gas sensors. As such, woodceramics have many characteristics. However, they are stiff, brittle, difficult to process and they tend to crack or chip during processing. Moreover, woodceramics have a tendency to increase in hardness as the carbonaization temperature rises and their processing characteristics differ according to the carbonaization temperature. In our experiment, we used woodceramics, which were made from MDF produced at carbonaization temperatures between 500 and 1200°C, to study the processing characteristics when a blade is used at different carbonaization temperatures. The following are the results. (1) The cutting force is proportional to the carbonaization temperature. (2) Woodceramics carbonized at high temperatures above 1000°C have a tendency to chip more than WCS fired at low temperatures between 500 and 650°C. (3) The continuous-type #300 wheel is best for cutting woodceramics. (4) The surface roughness of woodceramics does not depend on the processing speed at carbonaization temperatures above 1000°C. However, the surface roughness of woodceramics carbonized at temperatures below 800°C greatly depends on the processing speed.
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