Journal of the Society of Materials Science, Japan
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
Volume 52, Issue 8
Displaying 1-22 of 22 articles from this issue
  • 2003 Volume 52 Issue 8 Pages 3
    Published: 2003
    Released on J-STAGE: June 03, 2009
    JOURNAL FREE ACCESS
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  • Jia XIE, Qing-Qing NI, Masaharu IWAMOTO
    2003 Volume 52 Issue 8 Pages 884-890
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The higher-order shear deformation theory, which has the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surface, was employed for the buckling analysis of asymmetrical angle-ply laminates subjected to shear loading. It should be pointed out that the pb-2 Ritz functions, which consist of the product of a basic function and a two dimensional polynomial function, was introduced to represent an arbitrary edge condition, and thus the proposed analysis could obviate the tedious task of searching the displacement function to meet various edge supports. It was found that the buckling load in general asymmetrical laminates under normal shear loading was quite different from that under inverse shear loading, while there was not difference in anti-symmetric laminates. Furthermore, According to the analysis, the effect of boundary conditions, aspect ratios of the plate, lamination angle and the modulus of elasticity on buckling load and buckling mode were made clear. It was shown that the present method could be used to analyze the buckling behavior of almost laminated composite plates.
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  • Effect of Adhesive Film on the Load Dispersion
    Masatoshi MIKI, Tsutao KATAYAMA, Hidetake YAMAMOTO
    2003 Volume 52 Issue 8 Pages 891-896
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    In order to propose a new movement of the composite material design, the load dispersion of the solid-air composites caused by the hydrostatic pressures is investigated by applying numerical analysis. To simplify the evaluation of the load dispersion, the admissible stress field is supposed, where each stress field of closed cell is independent and that two different fields being in both sides of a cell wall satisfy the equilibrium of forces through the cell wall. The non-linear deformation under indentation was incrementally simulated by using the finite element formulation based on displacement method. The effect of adhesive film on the load dispersion is considered in the numerical model. It was shown that the assumption of admissible stress field on the interfacial load transmission is useful in evaluating the static load dispersion because the numerical results were well in agreement with the experimental ones. And it was clarified that a few structural design parameters become effective for the load dispersion.
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  • Evaluating Function of the Static Load Dispersion
    Masatoshi MIKI, Tsutao KATAYAMA, Hidetake YAMAMOTO
    2003 Volume 52 Issue 8 Pages 897-902
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The solid-air composites has been proposed to make a new movement of the composite material design. The estimating method of the internal hydrostatic pressure distribution has already been formulated by applying numerical analysis considering the interfacial load transmission. The purpose of the present study is to apply an experimental planning method to the internal hydrostatic distributions calculated by inputting the structural design factors as design variables to the FE model, and to investigate the simplification of the optimum design of the solid-air composites. In this optimization, it was supposed that the static load dispersion of the solid-air composites was able to be evaluated by using the internal hydrostatic pressure distribution. Consequently, the reasonable optimum solution by controlling the distribution of the hydrostatic pressure was obtained under the conditions of the static indentation and the simple support.
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  • Hideki SEMBOKUYA, Fumihiro SHIRAISHI, Masatoshi KUBOUCHI, Ken TSUDA
    2003 Volume 52 Issue 8 Pages 903-908
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    An epoxy resin cured with acid anhydride has good resistance to acid solution and an epoxy resin cured with amine has poor resistance. Two types of ground fillers were made from these two types of epoxy resins. Four kinds of recycled materials composed of two types of fillers and two types of matrix resins were prepared. The corrosion behaviors of the four kinds of particle filled epoxy resins (and other two types of neat resins) in sulfuric acid solution were investigated. In case the matrix was an epoxy resin cured with acid anhydride, flexural strength after immersion test in sulfuric acid solution normalized by that in pure water did not decrease for the neat epoxy resin and the recycled material filled with particles of epoxy resin cured with acid anhydride. With respect to the recycled material filled with particles of epoxy resin cured with amine, the normalized flexural strength decreased by degradation of exposed filler on the surface of specimen. On the other hand, in case the matrix was an epoxy resin cured with amine, the weight and thickness noticeably increased by immersing in sulfuric acid solution for the neat epoxy resin, the recycled material filled with particles of epoxy resin cured with acid anhydride and the recycled material filled with particles of epoxy resin cured with amine. For the three kinds of materials, the retention of flexural strength of dried specimens increased immediately after immersion tests started and then decreased. Sulfuric acid penetrated into all materials as results of X-ray elemental analysis. There was no distinct difference in decrease of strength of three kinds of materials and penetration of sulfuric acid into them.
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  • Noriyo HORIKAWA, Takayuki KUSAKA, Nobuaki TAKAGI, Hironori NAMIKI, Mas ...
    2003 Volume 52 Issue 8 Pages 909-915
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Retrofitting methods for RC beams were proposed in the present work. Tensioned carbon fiber sheets were employed to improve the bending strength of the RC beams for both live and dead loads. A novel tensioning device was developed to apply the tensile stress to the carbon fiber sheets and to prevent the interfacial debonding between the carbon fiber sheets and RC beam. Experimental results showed that the proposed device could apply by far higher tensile stress to the carbon fiber sheets than the conventional methods. As a result, the bending strength of the beams retrofitted by the present method was higher than that of the beams retrofitted by the conventional methods. Especially, the critical load at the crack initiation in the concrete increased about 3.8 times comparing with that of the original RC beam and about 1.6 times comparing with that of the RC beams retrofitted by the conventional methods by using the present method.
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  • Shinji OCHI, Hitoshi TAKAGI, Hideyuki TANAKA
    2003 Volume 52 Issue 8 Pages 916-921
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    This paper deals with the tensile properties of Manila hemp fabric reinforced cross-ply “green” composites. The composites were made from woven Manila hemp fibers as the reinforcement and starch-based emulsion-type biodegradable polymer as the matrix. Experimental results showed that their flexural strength increased with increasing the fiber content. However, the tensile strength increased with the fiber content until nearly 50 mass% and leveled off thereafter. We found from the result of tensile tests that maximum tensile force of 0° ply sheets decreased with increasing the fiber content. This dependence on the fiber content is due to the decrease in the fiber strength caused by fiber's damages introduced during hot-pressing. In order to avoid the damage of fibers aligned in loading direction, fiber sheets were produced by using hemp fibers for warp and cotton threads for weft. As a result of using the cotton weft, the tensile strength of cross-ply “green” composites increased from 153MPa to 188MPa.
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  • Takaomi INADA, Akira TODOROKI
    2003 Volume 52 Issue 8 Pages 922-926
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Authors have developed an electric resistance change method for monitoring delaminations of CFRP laminates. The method employs reinforcement fibers as sensors, and the electrodes are co-cured. In the present study, the cocured electrodes are adopted as sensors for monitoring of degree of cure. The present study proposes a new method for monitoring of the degree of cure without embedding or attaching sensors on the basis of the electrical capacitance change. Applying alternating current during curing process between the electrodes provides dielectric properties of CFRP composites. As same as the conventional dielectric sensors for cure monitoring, the degree of cure of composites is monitored by means of measuring the dielectric constant of the composites here. The dielectric constant of the epoxy resin changes as the change of the frequency of the applied alternating current. Using the dependency of the applied alternating current of the dielectric constants, the degree of cure is directly measured without curve fitting and without cumbersome measurements with DSC. The proposed method is applied to a single ply CFRP and a multi-ply CFRP laminate here. As a result, the method shows excellent estimations of the degree of cure without additional sensors.
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  • Teisuke SATO, Tatsuo BESSHI, Takuo NAGAMACHI, Tatsuya KATO, Jyunji TAM ...
    2003 Volume 52 Issue 8 Pages 927-931
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    By using molten wax colloidal process with graphite powders as combustible pore-forming agents, a method for controlling the porosity and pore size of porous hydroxapatite ceramics has been developed. Porous hydroxyapatite with unidirectionally aligned continuous pores were fabricated by multistage extrusion of green billets. Starting billet of this multistage extrusion was made from stacking hydoxyapatite green disks of outer diameter 50mm and inner diameter 25mm filled with 100% graphite green disks of 25mm. In order to make the porous matrix, the mixture of hyroxyapatite and graphite was used instead of hydroxyapatite. By the primary extrusion, hexagonal rods with the graphite in the central part were extruded. These extruded hexagonal rods were bundled to make composite billets for the next stage extrusion. This process was repeated for several stages. Finally, the extruded rods of proper stage were sintered. Size of the continuous pore can be controlled by total extrusion ratio. The pore diameter obtained in the present work was from 350μm to 8μm. The porosity can be controlled by the billet structure. The mean flexural strength of the porous hydroxyapatite ceramics obtained in this work was from 32MPa to 56MPa.
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  • Masahito MOCHIZUKI, Masaru KOHARA, Hiroshi SHIMANUKI, Yukito HAGIWARA, ...
    2003 Volume 52 Issue 8 Pages 932-938
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    It is important to study effects of microstructure on the characteristics of fracture in steels with microscopic heterogeneity. Crack initiation and propagation behaviors are of course dominant to the characteristics of fracture, and they are studied in two kind of ferrite/martensite dual-phase steels with the same micro-hardness in each microscopic phase. Three-point bending tests are performed to two kind of dual-phase steels, one has 30% volume fraction of ferrite and 70% of martensite (Ferrite 30% steel), and the other is Ferrite 70% steel. Brittle cracks are mainly initiated in the ferrite phase near the fatigue precrack tip in the center of specimen thickness by bending load, regardless of the difference of the volume fraction of microstructure. It is considered that not only the volume fraction of microstructure but also the stress-strain field due to microscopic heterogeneity affects crack generation. Crack mainly propagates along ferritic phase with connection to initial microcracks, and it is little influence on microscopic heterogeneity. Propagated crack width expands in proportion with the increase of CTOD value.
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  • Masahito MOCHIZUKI, Masaru KOHARA, Hiroshi SHIMANUKI, Yukito HAGIWARA, ...
    2003 Volume 52 Issue 8 Pages 939-945
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Numerical analysis is conducted in order to study the effects of microscopic heterogeneous morphology on crack generation in ferrite/martensite dual-phase steels. The macro-model of three-point bending specimen and the micro-model of heterogeneitic phases are connected with a boundary condition in the analysis. Stress distribution near fatigue precrack tip in the three-point bending specimen is calculated by the macro-model, and the stress-ratio of the triaxiality is used for the boundary condition of the micro-model. Microscopic unit cell is modeled by considering the strength heterogeneity between ferrite and martensite phases in a ferrite/martensite dual-phase steel. The relation between the characteristics of stress distribution and the heterogeneitic morphology are clarified from the numerical analysis, and the location of crack generation is investigated. The heterogeneitic morphology in the micromodel and CTOD in the macro-model are related by using the both results of the analytical models. The effects of the heterogeneitic morphology on crack generation are discussed.
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  • Toshio SAKUMA, Makoto YAMADA, Uichi IWATA, Yasuo OCHI, Maho HOSOGI, Na ...
    2003 Volume 52 Issue 8 Pages 946-951
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The effects of maximum strain, testing temperature and shape memory treatment temperature on superelasticity characteristics in Ti-Ni alloy wires were investigated. The isothermal cyclic tensile tests were carried out at temperatures of 343, 353 and 363K. Specimens were Ti-50.6at%Ni, annealed at 623, 673, 723 and 773K for 3.6ks after cold drawing with 34% reduction. The results show that the changes in the critical stress for inducing martensite, the dissipated strain energy and residual strain are significant in early cycles, but become insignificant after 20 cycles. The degradation of the critical stress for inducing martensite and the dissipated strain energy increase with increasing testing temperature and shape memory treatment temperature. However, these changes are insensitive to maximum strain. Furthermore, in order to clarify the effects of maximum strain, testing temperature and shape memory treatment temperature on the degradation of materials functions, the residual martensite volume fraction subjected to slip deformation was evaluated by a two-phase model consisting of the parent phase and the martensitic phase connected in series. Increase in residual strain against the residual martensite volume fraction becomes larger as shape memory treatment temperature increases. The residual martensite volume fraction represents the changes in the critical stress for inducing martensite and the dissipated strain energy with number of cycles, maximum strain, testing temperature and shape memory treatment temperature. Based on these results it can be stated that the residual martensite volume fraction subjected to slip deformation is capable of representing the effects of cyclic deformation, maximum strain, testing temperature and shape memory treatment temperature on the degradation of materials functions.
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  • Naoki TAKANO, Masaru ZAKO, Yoshihiro OKUNO
    2003 Volume 52 Issue 8 Pages 952-957
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    In the last decade, a multi-scale computational method using the asymptotic homogenization method with the help of the finite element method has been intensively studied and applied to various advanced materials such as fiber reinforced composite materials and porous materials. It enables us to analyze the overall behaviors of structures considering the microscopic heterogeneity, where there is a large gap between the macro-scale and the micro-scale within the framework of continuum mechanics. However, no literature can be found that studied the joint or laminated members of heterogeneous dissimilar materials with interface crack. Due to the non-periodic condition at the interface and the existence of crack, the homogenized material modeling is of no use. Hence, an enhanced finite element mesh superposition method is employed to solve the two-scale problem. Two independent meshes, i. e., the global mesh and the local mesh, are used. The global mesh represents the joint or laminated members from the macroscopic viewpoint using the homogenized model. The local mesh is used to consider the heterogeneous microstructure of the material as well as the crack and superimposed onto the global mesh. The formulation, numerical accuracy and effectiveness of the proposed multi-scale method are presented in this paper.
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  • Yoshiyuki KOJIMA, Toshihiro ASAKURA, Kazuyuki YOSHIKAWA, Yoshiyuki SHI ...
    2003 Volume 52 Issue 8 Pages 958-965
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    To establish an adequate evaluative method of existing tunnel deformation behaviors due to ground surface excavation above the tunnels, case studies of 23 tunnels' field measurement data and numerical parametric analyses using two dimensional FEM have been conducted. To sum up the contents; 1) Cracking of tunnel lining are roughly found in cases of the final/initial overburden ratio h/H<0.2-0.3 (h: final overburden, H: initial overburden). 2) Tunnel deformation behaviors consist mainly of B/2 (h+D) (B: excavation width, D: tunnel diameter), lining rigidity, ground rigidity, contact condition between ground and tunnel lining, and ground initial stress K0.
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  • Junji NAGATA, Yukitaka MURAKAMI
    2003 Volume 52 Issue 8 Pages 966-973
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The mechanism of fatigue failure in the ultra-high cycle regime was studied using a bearing steel, JIS SUJ2 (SAE52100). In the case of tension-compression fatigue testing, the S-N curve for high strength steels consisted of a single straight line in contrast to the dual S-N curve observed in rotating bending. The effect of internal hydrogen trapped by nonmetallic inclusions on high cycle fatigue behavior has been discussed by Murakami et al. In order to investigate further the influence of hydrogen trapped by various types of inclusions, four materials of different chemical compositions were prepared. Those specimens having a longer fatigue life had a particular morphology designated as ODA (Optically Dark Area) surrounding the inclusion at the fracture origin. In order to investigate the growth of ODA with cycling, fatigue tests involving multi-step loading were carried out, and the appearance of the ODA was compared with that of specimens tested under a constant amplitude loading. A specimen which endured N=2×108 under a stress was fractured by tensile test at -190°C. The fracture origin in this tensile test was at a subsurface, nonmetallic inclusion. If the fatigue test had not been interrupted, the potential fatigue life of the specimen was estimated from the size of the inclusion and the ODA using the √area parameter model. The model was also used to estimate the fatigue limit in the ultra-high cycle range. The condition for the critical size of ODA for the start of conventional fatigue crack growth was analyzed using fracture mechanics. The critical stress intensity factor range ΔKODA for the critical size of the ODA can be correlated with the threshold stress intensity factor range ΔKth expressed by the √area parameter model for small cracks. A fatigue design method for ultra-high fatigue life regime was proposed based upon the growth behavior of the ODA, the statistics of extremes of inclusions, and the √area parameter model.
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  • Seiji KANAMORI, Tetsuya TAGAWA, Takashi MIYATA
    2003 Volume 52 Issue 8 Pages 974-980
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Constraint effect on the ductility and the fracture toughness of Al-alloys were investigated to examine a modelling of the fracture toughness and to confirm the applicability of unique parameter fracture mechanics to the mircovoid coalescence type of fracture. Stress triaxiality effect on the ductility was investigated in notched round bar specimens. Toughness testing was performed for three points bend and CT specimens with different thickness and notch depth ratio. Stress triaxiality effect on the ductility is significant in low strength materials. The fracture toughness, JIC of high strength Al-alloys, 7075-T6 is varied with the specimen thickness even in the specimens that satisfies the prescription on the size requirements for plane strain condition in the toughness testing method, ASTM E1820. Morphology of the fracture surface composed with the dimple pattern and the intergranular fracture is closely related to the degradation in the toughness. Correlation between the toughness and the ductility in notched specimens demonstrates the validity of the characteristic distance model that describes the toughness in terms of the flow stress and the ductility of the materials.
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  • Tomokazu MASUDA, Toshiro KOBAYASHI, Hiroyuki TODA, Lei WANG
    2003 Volume 52 Issue 8 Pages 981-987
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The aim of the present study is to investigate strain rate dependency of Al-Mg alloys within a wide range of strain rates. Tensile tests of a wide range of strain rate are carried out using Instron universal, servo-hydraulic impact and split-Hopkinson bar testing machines. Also, strain rate sensitivity is evaluated by test of changing the strain rate. The SEM technique is used to analyze the fracture surface characteristics of deformed specimens. The negative strain rate dependency shows at strain rate region between 4.3×10-4 and 1.0×102s-1 for Al-Mg alloys. However, the extent of rate sensitivity over 1.0×102s-1, ultimate tensile strength increases with increasing strain rate. Although the shear dimple type fracture surface is mainly observed under static loading condition, normal type dimple fracture surface is found under high strain rate. The fracture behavior under the variation of strain rates is also discussed based on the results of the microstructure observation.
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  • Osamu TAKAGI, Kazuyuki YOGO, Masakuni OZAWA, Suguru SUZUKI
    2003 Volume 52 Issue 8 Pages 988-991
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    The influence of the added electrolyte KCl concentration was investigated on the dispersion of alumina particles in the alumina aqueous slurries. In the present work, the viscosities and the colloidal vibration potentials (CVP) were measured as a function of electrolyte KCl concentration in the range of 0 to 2000mmol·dm-3 at the fixed concentrations of alumina (10 mass%) and dispersant (0.5 mass%) in the aqueous slurries. The viscosities of all slurries decreased with increasing the shear rate, so called the shear-thinning behavior was shown, and this behavior became vivid in more than 200mmol·dm-3. The yield stresses obtained from the measured viscosities increased rapidly in more than 200mmol·dm-3, too. The CVPs approached to 0μV in more than 200mmol·dm-3 of electrolyte KCl concentration. The particle size distribution shifted to the larger radius side more than 200mmol·dm-3. From the results mentioned above, it is considered that the agglomeration occurred in more than 200mmol·dm-3 with electrolyte KCl concentrations in the present alumina aqueous slurry.
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  • Yaqin FU, Qing-Qing NI, Ken KURASHIKI, Masaharu IWAMOTO
    2003 Volume 52 Issue 8 Pages 992-997
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    PMMA/Silica hybrids were innovated by in-situ polymerization from methyl methacrylate and tetraethyl orthosilicate with hydroxypropyl acrylate as a coupling agent. The obtained PMMA/silica innovation materials were investigated from material structure, transparency and thermal/mechanical properties. The hardness, elasticity modulus, wear and thermal properties of the materials deeply depend on the situation with or without a catalyst. This was resulted from bond type formed during the hybridization. Based on FT-IR analysis, it was shown that the covalent bonds were formed between organic matrix and silica under an acid catalyst, while the covalent bonds and hydrogen bonds were formed if there was no catalyst. These results indicated that changing catalyst and the amount of silica could control the material properties and the inner structures.
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  • Kotokaze FURUSAWA, Naoki FURUMACHI, Koji TAKAHASI, Sinji SAITO, Kotoji ...
    2003 Volume 52 Issue 8 Pages 998-1005
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Three point bending specimen was made from mullite/SiC composite ceramics. A semi-elliptical surface crack of 75μm or 100μm in diameter (aspect ratio ≈0.9) was introduced on the specimen. Basic crack-healing behavior of the cracked-sample was studied systematically as a function of crack-healing temperature, time, environment and cyclic stress applied. Followings are main conclusion obtained; (1) Mullite/SiC composite ceramics are able to recover strength of cracked sample by heat treatment in air. (2) The recovery was caused by the crack-healing behavior, and the activation energy was evaluated as Q=413kJ/mol. (3) This sample was able to heal a crack even under cyclic stress at service temperature. This behavior was defined as in situ crack-healing. (4) The crack-healed sample from 1273K to 1473K exhibited same level bending strength to crack-healed sample at 1573K just at the healed temperature. This behavior was defined as in situ bending strength of in situ crack-healed sample.
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  • Yuzo OHNISHI, Takumi NAKAI, Meiji RYU, Satoshi NISHIYAMA
    2003 Volume 52 Issue 8 Pages 1006-1011
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
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    Because deformations are important indicators of the degree of stability during construction of rock structures, monitoring of deformation is a key element of observational method in tunnels. Monitoring can also help determine the depth of the loosened zone, movements on discontinuities, in-situ modulus, and other items that may be dealt with in design. We have studied the applicability of digital photogrammetry for monitoring of surface displacements in civil engineering. Digital Photogrammetry is the technique obtaining three dimensional coordinates of an object by means of digital photography. This photogrammetry has the advantage of measuring deformation of an object by some photos with easy measurements and excellent cost performance. Because the linearized equation to analyze the coordinates of object points has some rank defects due to no control points in tunnel, we present constrained least square estimation to measure the displacements without the incorporation of control point configuration. The results of experiments demonstrated that this measurement system could yield high accurate three dimensional coordinates of target points situated on an object. It is also shown that this digital photogrammetry can monitor the displacements of the tunnel accurately along with a capability of real-time measurement because of removal of human skills in measurement tasks.
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  • I: Geological Disposal of High-Level Radioactive Waste and Role of Rock Engineering
    Kozo SUGIHARA
    2003 Volume 52 Issue 8 Pages 1012-1017
    Published: August 15, 2003
    Released on J-STAGE: June 03, 2009
    JOURNAL FREE ACCESS
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