材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
67 巻 , 8 号
選択された号の論文の11件中1~11を表示しています
資料
  • Hiroshi YOSHIHARA, Masahiro YOSHINOBU, Makoto MARUTA, Hiroshi USUKI
    2018 年 67 巻 8 号 p. 761-766
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    The tensile strength of a copy paper with a center notch was measured. During the test, the loading direction coincided with the cross direction (CD) or the machine direction (MD) of the paper sheet, and the configuration and dimension of the notch were varied. The relationship between the tensile strength and notch dimension was fitted using the following four theories: uniform stress criterion (USC), point stress criterion (PSC), average stress criterion (ASC), and fracture mechanics theory (FMT). Although the effect of loading direction was significant on the relationship between the tensile strength and notch dimension, the effect of notch configuration was not so significant. When the loading direction coincided with the CD of the paper, the PSC and ASC methods were superior to the other two methods for fitting the relationship. In contrast, the PSC and FMT methods were superior to the other two methods for fitting the relationship when the loading direction coincided with the MD.

論文
  • 田中 聡一, 杉野 秀明, 関 雅子, 三木 恒久, 梅村 研二, 金山 公三
    2018 年 67 巻 8 号 p. 767-772
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    The purpose of our study was to clarify the influence on wood color of relative humidity (RH) in conditioning, or process of evaporating water, of dye-aqueous solution impregnated wood. The cross-cut (RT) or quarter-sawn (LR) sample of hinoki (Chamaecyparis obtusa) was impregnated with a 0.1 mass% aqueous solution of patent blue VF (PB), and subsequently conditioned at several levels of RHs (40 °C) to reach to a constant mass. The conditioned samples were dried at 40 °C over phosphorus pentoxide in a vacuum and observed by microscope, and each parameters of the sample in L*a*b* color space were measured by color spectrometer. With the increase in RH, the values of L* and b* for the RT and LT surfaces of the RT and LT samples, respectively, increased and became closer to those for the untreated samples. This was considered to be caused by the decrease in the amount of PB on the surface of cell walls with increasing RH because of the increase in the diffusivity of PB into cell walls. In the RT cross section of LR sample, the area of the deeper color was concentrated into the center of the cross-section if the RH was high, which indicates the macroscopic diffusion of PB from the surface to the center in the sample.

  • 小林 孝一, 吉倉 淳平
    2018 年 67 巻 8 号 p. 773-780
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    The deterioration process of concrete structure usually possesses large uncertainty. Furthermore, the re-deterioration process after the repair suffers much greater uncertainty, resulting in a difficulty in verifying cost-benefit of repair. This study calculates LCC of RC structures that have deteriorated by chloride attack by simulating their deterioration and re-deterioration processes with a consideration on probability. Here, a patch repair and a cathodic protection were dealt with as repair methods to be investigated, and LCC with these repair methods were calculated by assuming their average expected lifetimes and their dispersions based on the results of investigations for the concrete structures. In carrying out the calculation, the effects of deterioration rate and water-cement ratio were also investigated. From this, the following results were obtained: Both the average and the standard deviation of the LCC of patching repair were larger than those of cathodic protection. In all the cases examined here, the LCC of pathing repair was five times as large as that of cathodic protection. While the deterioration rate by chloride attack largely affected the average of LCC, it less affected the standard deviation of LCC. The increase of water cement ratio raised the average of LCC. The influences of water cement ratio on the re-deterioration should be investigated in future. If the average and dispersion of the lifetimes can be determined based on the investigation on the structures, they may affect the LCC of the patch repair and the cathodic protection.

  • 倉橋 貴彦, 山際 健吾
    2018 年 67 巻 8 号 p. 781-788
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    In this paper, we present identification of order of singularity near interface edge of bonded structures using displacement value. In general, the adjoint variable and the direct differentiation methods are employed for the inverse analysis. However, the order of singularity is not explicitly included in the governing equation, and the methods of inverse analysis can not be directly applied to identify the order of singularity. Therefore, the finite element procedure using Akin's singular element is employed for the discretization of the governing equation, and the finite element equation including the order of singularity is used for the formulation of the identification problem based on the adjoint variable method. In this study, the order of singularity is identified by using displacement values. The order of singularity is frequently obtained based on the Bogy's methodology, but we present the identification method of the order of singularity based on the displacement values. Some numerical experiments and considerations are shown in this paper

  • 森井 隼, 佐藤 文夫, 鈴木 健太郎
    2018 年 67 巻 8 号 p. 789-794
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    It is important to understand the mechanical properties of the material used at the operating temperature for stable operation of a thermal power plant, and necessary to analyze the nanometer scale microstructure that governs the properties. We have performed microstructure characterization of KA-SUS304J1HTB austenitic steel from ultra-supercritical boiler tubes after 130,718 hour use whose designed steam condition was 873 K / 24.5 MPa. EPMA, EBSD and STEM observation revealed the presence of Cr-rich σ phase mainly at grain boundaries. Neither Cu nor Nb(C, N) are present as coherent nanometer-sized precipitates; their average size were 70 nm and 60 nm, respectively. We also confirmed the presence of MX type Nb carbonitrides of nearly 5 μm in size and Cu precipitates of nearly 1 μm around σ phase. The decrease of coherent Cu and Nb(C, N) precipitates will reduce matrix strengthening and the formation of σ phase will cause grain boundary embrittlement.

  • Yu-Chuan KAO, Takao UEDA, Chien-Kuo CHIU
    2018 年 67 巻 8 号 p. 795-802
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    As a conventional repair method for reinforced concrete (RC) structures deteriorated by the chloride attack, the patch repair has been applied widely. When the patch repair method is applied, the re-deterioration has been sometimes observed around the joint part of the substrate concrete and the repair material. One of the major deterioration mechanisms after the patch repair is the macro-cell corrosion caused by the remained chlorides in concrete or by the corrosive products like chloride ions (Cl-) supplied through the inadequate joint part. In this study, the effects of fly-ash-mixing and the dosage of LiNO2 in the patch repair materials on the basic properties of repair materials and on the chloride-induced steel corrosion due to the supply of Cl- ions around the interface between the substrate concrete and the repair material were investigated. As a result, the effective diffusion coefficients of Cl- obtained by using the joint specimens with polymer cement mortar (PCM) were larger than the cases of joint specimens with normal mortar. The PCM based patch repair materials showed the high resistance to Cl- penetration but in some cases, Cl- penetration into concrete near the joint surface between concrete and patch repair materials was promoted. On the other hand, the PCM containing both fly ash and LiNO2 showed a high protection effect against steel corrosion in the RC joint specimens and the macro-cell current around the joint face was also suppressed compared with the case of a general PCM.

  • Tomio IWASAKI
    2018 年 67 巻 8 号 p. 803-810
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    A technology for efficiently designing an appropriate metal material with strong adhesion to a ceramic material was developed by using a combination of an orthogonal array and a response-surface method, and it was applied to the interface adhesion between metals and an example ceramic, alumina (Al2O3) in nanoscale thin-film devices. In this optimum-design technology, at the first step, important factors that significantly influence the adhesion strength were selected from various factors that characterize metal materials by using an orthogonal array with molecular simulations. As a result, the short-side and long-side lattice constants a and b were selected from four metal-material factors (a, b, the electronegativity, E, and the surface energy density, S). At the second step, the adhesion strength was described as a function of the selected important factors by using a response-surface method. From this function, the ideally most appropriate values for a and b that made the adhesion strength maximum were obtained. The obtained optimum values for a and b agreed well with the lattice constants of the ceramic (alumina). At the third step, the most appropriate metal material whose lattice constants were close to the optimum values, which were the lattice constants of the ceramic (alumina), was selected by use of the molecular simulation results of lattice constants. As a result, a Pd alloy with Ni, whose lattice constants were almost the same as the optimum values, was selected as the most appropriate metal material with the strongest adhesion to the ceramic (alumina).

  • Lei YANG, Jie MEI, Shucai LI, Yujing JIANG, Kongling GUO, Bo ZHANG, We ...
    2018 年 67 巻 8 号 p. 811-818
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    A comprehensive understanding of the fracture’s effects on wave propagation is a necessary prerequisite for estimating the dynamic behavior of fractured rock masses. This study presents a series of ultrasonic experiments on the multifarious effects of open fractures on the propagation characteristics of waves, considering various geometric parameters of fractures. The results indicate that fractures disrupt the waveform and attenuates the wave amplitude and velocity. With the increase of fracture width, the amplitude of transmitted wave and the dominant frequency of transmitted wave decrease, while the transmit time of wave in the sample increases. An increasing fracture dip angle generally leads to the increase of wave amplitude and dominant frequency, while reduces the transmit time of wave. As the fracture spacing increases in the testing range, the wave amplitude increases, while the wave frequency exhibits an opposite tendency. Comparing with the experimental results in the cases of single and multiple fractures, it is confirmed that the attenuation effect and the low-pass effect of fractures on wave propagation are enhanced quickly with the increase of fracture number.

講座
  • 3.近年のFRP成形モニタリング技術とその応用
    高坂 達郎
    2018 年 67 巻 8 号 p. 819-825
    発行日: 2018/08/15
    公開日: 2018/08/20
    ジャーナル フリー

    In-situ monitoring methods of FRP (Fiber Reinforced Plastics) molding process have been developed in recent 20 years. The present paper describes the recent developments of dielectric/electrical measurement, ultrasonic measurement and optical fiber sensors for in-situ process monitoring of FRP. These sensors can be utilized for monitoring resin impregnation, cure and cooling process of FRP molding. The recent trends of the in-situ process monitoring are measurements of flow-front of liquid resin, degree-of-cure, curing shrinkage, complex stiffness, gelation and vitrification of matrix resin, and process-induced strain and dimensional accuracy of FRP parts. The measured information in FRP during molding process is used to create an accurate model for process simulation and optimize molding process parameters.

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