Journal of the Society of Materials Science, Japan
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
Volume 53 , Issue 1
Showing 1-24 articles out of 24 articles from the selected issue
  • Tatsuaki NISHIGATA, Kazuhiko NISHIDA, Katsuji KURAMOCHI
    2004 Volume 53 Issue 1 Pages 1-4
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Soil nailing is a typical method for earth reinforcement that is widely applicable to both natural and cut slopes. Basically, it is considered to increase slope stability through the tensile force resistance generated in the reinforcement materials. On the other hand, the restraint effect in reinforced zone is effective for reinforced slope stability under the condition that small allowable deformation is adopted. In this study, the mechanism of restraint effect for reinforcement bar in granular soil is investigated by experiment of base friction model and numerical analysis of distinct element method.
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  • Tomio TAMANO, Kazuhiko NISHIDA, Bimal SHRESTHA, Masanobu KANAOKA, Hiro ...
    2004 Volume 53 Issue 1 Pages 5-8
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Japanese Castle masonry walls constructed from the end of sixteen century to the middle of seventeen century hold a historical heritage in the construction culture and are famous worldwide for their uniqueness with mortar-less construction. Present investigations on these walls have shown bulging at various locations and the engineering evaluation on the wall stability needs to be urgently required. Based on this viewpoint, this paper presents the FEM analysis results on the stability and deformation behavior with parametric analyses on Osaka Castle masonry wall. It is found that the cobble plays a significant role in reducing the stresses of stone wall and that the masonry wall structure ratio adds stability by the arching effect action on the masonry wall.
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  • Mamoru FUJII, Masashi KAWAMURA, Masahito TAMURA, Kazuhiro WATANABE, Ei ...
    2004 Volume 53 Issue 1 Pages 9-12
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    The present report concerns the results of experiments on evaluation methods of quality of soil-cement column by deep mixing method. Six improved soil columns in sandy ground and four improved soil columns in loam ground were prepared with different number of remolding respectively. And three kinds of quality evaluation methods were examined for these columns. These evaluation index were variation of resistivity, coefficient of variation of resistivity, coefficient of variation of unconfined compressive strength. We have developed a resistivity method capable of evaluating the quality variations of improved ground immediately after the construction by the axial resistivity changes of cone sensors pressed in the hardening body. At least 100kg/m3 of binder content is necessary to determine resistivity of improved body. The resistivity measuring cones have the Schlumberger type-4 electrode resistivity meter, 25mm in diameter and 200mm in length. Resistivity meter was penetrated into improved column. Applying current at every 50 to 100mm advance, electrical potential was determined. From results of these experiments, we found the existence of correlation between various kinds of evaluation index and blade rotation number. Especially, variation of resistivity and the coefficient of variation of the compressive strength of improved body became small when the blade rotation number increased. Further more, we could show the appreciate blade rotation number for these ground based on these results.
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  • Daisuke KATSUKI, Yukio NAKATA, Masayuki HYODO, Norimasa YOSHIMOTO, Hid ...
    2004 Volume 53 Issue 1 Pages 13-16
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    In order to clarify the effect of structural bonding on shearing property of the bonded granular materials, a series of tests was carried out. The splitting strength and unconfined compression strength of the bonded materials were examined and used as the index representing a degree of bonding. Isotropic compression test in which maximum stress of 40MPa was applied and triaxial compression test under a wide range of confining pressures were performed on both bonded and non-bonded materials. For the bonded materials the bonding had hardly any effect on the residual stress state in spite that the peak strength markedly increased with increasing cement content. The extra shearing resistance from the residual stress state increased with increasing strain increment ratio at peak. For the bonded materials the dilatancy component of shearing resistance seemed to result from overriding of the particle agglomerate. The strain increment ratio at peak was assessed using the splitting strength as well as the unconfined compression strength. The dilatancy component for the bonded materials markedly decreased as confining pressure increases.
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  • Toshiaki SANEMATSU, Satoru MOCHIDA, Shumpei TANAKA, Tetsushi KANDA
    2004 Volume 53 Issue 1 Pages 17-20
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    This study focused on strength properties of fiber-reinforced soil cement (hereafter FRSC), which contained PVA (polyvinyl alcohol) fiber with 14μm diameter, 8mm length, and 0.6% volume fraction. We conducted two series of experiments, mixing tests with different soil cement matrix mix proportions, and execution tests of FRSC column. As the result of material strength tests for laboratory mixed samples, improvement in tensile strength was the most significant: about four times higher than that of plain soil cement (hereafter SC). And modulus of rupture of FRSC also increased 2-3 times above those of SC. Execution test was conducted at loamy ground, using the machine for Soil Mixing Wall Method, and material strength tests of sampling specimen were carried out. Direction dependence of modulus of rupture was found, but executed FRSC column had approximately high-performance ductility close to that of laboratory mixed samples.
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  • Kohei SAWA, Seishi TOMOHISA
    2004 Volume 53 Issue 1 Pages 21-24
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    The purpose of this study is to make clear the possibility of the utilization of muddy soil mixed with incinerated ash or iron/steel slag as an additive. The muddy soil used is dredged soil reclaimed from a river. The strength properties of the dredged soil mixed with various incinerated ashes and so on are tested using the CBR test or cone penetration test. This is in order to be able to use the treated soil as construction material for super embankments and as subgrade material on roads.
    As a result, in the case where incinerated ashes are used as an additive, the treated soil mixed with incinerated ash gains high strength due to a reduction in the water content. When fluidized bed combustion coal fly ash is used as an additive, an increase in the strength of the treated soil was observed during aging, and it gives the greatest strength in comparison with other incinerated ashes. Furthermore, in order to gain high strength, it is more effective to decrease the water content of the dredged soil.
    In the case where iron/steel slag is used as an additive, the treated soil mixed with slag, with a maximum grain size of 20mm, passes the material standard for grain size distribution of super embankments. The greater the mixing rate of slag, the lower the water content and the higher CBR of the treated soil. The CBR of the treated soil mixed with a lot of fine-grain slag becomes high at a low mixing rate. By contrast, the CBR with a lot of coarse-grain slag becomes high at a high mixing rate.
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  • Mikio YAMADA, Katsuya TANIGUCHI, Mitsushi OKUMURA, Hiroaki SANO
    2004 Volume 53 Issue 1 Pages 25-28
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    In the oyster producing district, the shells are being crushed to maintain the capacity of dump yard. Though the crushed oyster shell has been diverted to feed, manure and soil conditioner from a past, the shell pieces are possible to also use as the construction materials.
    The purpose of present study is to verify the usefulness of crushed oyster shell as subgrade materials by executing improvement of existing road. The construction work was carried out in March, 2002 and the widening subgrade (70m in length, 3.5m in width and 0.35m in thickness) containing crushed oyster shell was built under three mixing conditions. The surface treatment was immediately paved over the base course after base materials were compacted. Allowing passage of vehicles, we have recently investigated the deflection shape of road surface by using “falling weight deflectometer” (FWD). According to the relationship between the load and the detected deflections, the maximum deflection at loading point tended to decrease with an increase in service time. Particularly, CBR value estimated from the deflection (D1500) has exceeded an object level of improvement for section including the almost dried shell pieces. These results show that the crushed oyster shell can be effectively utilized as subgrade materials.
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  • Keiichi KATSUSE, Hiroyoshi HORIKAWA, Kohji ITABASHI, Noriaki UCHIDA, N ...
    2004 Volume 53 Issue 1 Pages 29-32
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    As the population of cows and cattles kept in Hokkaido district amounts to 1.3 million, or one-third of that in Japan, the dairy facilities like paddocks and paths easily turn to muddy with their large amount of feces and urine. In order to keep the facilities clean, the ground is required to be paved, so that we aimed to develop a new paving material suitable for dairy facilities, as low-cost, non-slipping and cold-resistant, and also aimed as well to utilize the lime cake from sugar-manufacturing process for the paving material. It has been believed that the lime cake is difficult to be solidified with cement, therefore such things are examined in this investigation, as (a) mixing fine aggregate like volcanic ash with the lime cake, and (b) reducing sucrose in lime cake by fermentation. The paving material developed in this investigation (abbreviated Lime Cake Pavement to LCP) has been tested for the paddock and working yard at a dairy farm. After passing 2 winter seasons, the LCP is kept in use without serious problems.
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  • Daisuke KIMURA, Masashi KUROSAKI
    2004 Volume 53 Issue 1 Pages 33-36
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Recently, the process of ground improvement has been expanded. Although the sand compaction pile method is the most commonly used ground improvement method, it has some drawbacks, such as the large vibration and noise during use in construction. Thus, our company developed the KS-EGG method that can render the sand compaction pile method quieter without the use of a vibratory hammer. The machine for the KS-EGG method consists of a casing pipe with an installed leaning head. To compact and to enlarge the piling materials are carried out by rotating the leaning head and moving the casing pipe up and down. The mechanism of this method is to compact the ground by pressing the pile materials to the horizontal direction using the leaning head. The levels of vibration and noise of this method are lower than those of the commonly used sand compaction pile method, and recycled materials, such as glass sands and crushed stones, can be efficiently used as piling materials. Thus, this is a new environmentally friendly method. It has also been proved by tests that the ground strength after improvement is as good as that obtained by the sand compaction pile method. The KS-EGG method was successfully carried out ten times between April 2001 and March 2003. In this report, we describe this new construction method.
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  • Masaaki KIYAMA, Akihiko OSHIMA, Shoji HIGASHI, Kenji HARADA, Shigehiro ...
    2004 Volume 53 Issue 1 Pages 37-40
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    In Osaka City the vertical drain method has been used to promote consolidation and settlement of clay soils (alluvial clay and dredged clay layers), and two new techniques have been developed, based on the principle of reducing neutral stress, with the specific purpose of reducing the volume of dredged soils. One technique combines the dewatering method with the newly developed plastic board drain by floating (PDF) method, and the other combines the PDF method with a vacuum consolidation method in which dredged clay is used as a sealing material over the top of horizontal drains.
    This paper gives an outline of the latter technique (accelerated consolidation method combining vacuum consolidation and PDF methods) and its major feature, and the results of field observations obtained from test and actual implementations. Actual settlement after implementation, taken from the field observations, conformed closely with calculated values, confirming that this technique promotes settlement at landfill sites where landfill is ongoing, in other words they are extremely effective as methods to reduce the volume of dredged clay soils. Furthermore the passage volume and capacity of water through drain materials are also studied.
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  • Mitsushi OKUMURA, Mikio YAMADA, Hiroaki SANO, Haruyoshi MAEKAWA
    2004 Volume 53 Issue 1 Pages 41-44
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Recently, the acid sedimentary soft rock that caused a collapse of the cutting ground has appeared in the surface with the road construction and the estate development. The acid soil at construction, however, must be effectively utilized as the land reclamation.
    The purposes of this study are to verify the importance of the biochemical oxidation of pyrite in the weathering process and to investigate the optimum pH condition for faster oxidation than in nature. First, pH, sulfate content and pyrite remaining in the acid soil that collected in the field were measured. When the ratio of pyrite remaining in the soil was less than 70 percents, pH was also lowered with the decrease in the pyrite remaining. Then, samples that added the commercial pyrite or sulfur powder were sterilized by the autoclave in order to clarify the biochemical characteristics of the acid sedimentary soft rock in the weathering. The result showed that sulfate ion was detected only in non-sterilized samples at pH below 3.5. On the other hand, sulfur powder was hardly converted at pH above 2.5. Therefore, it was confirmed that ferrous iron oxidation, given as Fe2++1/4O2+H+Fe3++1/2H2O was the most important process in the biochemical oxidation of pyrite and its optimum pH was 2.5-3.5.
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  • Masashi KAMON, Toru INUI, Kazunori SASAKI
    2004 Volume 53 Issue 1 Pages 45-48
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Several leaching tests were carried out for the stabilized/solidified sludge to evaluate the release of inorganic contaminants. The main objective is to examine the effect of seawater attack on the heavy metal leaching from the monolithic materials stabilized/solidified with the Portland or slag cement. Batch leaching tests were used to determine the basic leaching characteristics of contaminated sludge and cement-based materials. Dynamic tank leaching tests on monolithic materials (with and without crushing) were conducted to determine the rate of heavy metal release as a function of leaching time with the different solvents (distilled water and seawater). The concentrations of zinc released from the contaminated sludge during the tank leaching test were significantly influenced by pH of solutions. The use of seawater as the solvent reduced the alkali leaching from the cement-based materials and influenced the pH of leaching solutions (pH 8-9). In response to decreasing pH, the amount of released Zn decreased, since the solubility of Zn under pH 8-9 is lower than under the strong alkaline condition. However, in the cases with seawater as the leaching solvent, Zn release was gradually increased as a function of leaching time. In addition, stabilization/solidification (S/S) with the Portland cement achieved the immobilization of Zn more effectively than the S/S with the slag cement.
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  • Yoshikazu MIWA, Munenori KASEBE, Koichi GODA, Junji OHGI, Satoshi NAGA ...
    2004 Volume 53 Issue 1 Pages 50-56
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Chemically different fiber surface properties were created by electrolytic oxidation on continuous carbon fibers with uneven and smooth surfaces, in order to clarify the effect of bond strength between the fiber and matrix on the mechanical properties of unidirectional carbon fiber reinforced plastics (CFRP). It was proven from a fiber fragmentation test, using single fiber composites embedded in epoxy, that interfacial shear strength (IFSS) increases with an increase in ratio of oxygen to carbon (O/C) on the fiber surface. The result of the tensile tests of CFRP specimens with the different fiber surface properties showed that an appropriate IFSS not only increases tensile strength, but decreases coefficient of variation in tensile strength. It was discussed based on the previously reported simulation results that such an optimal IFSS should be given by the only value. Furthemore, using the same CFRP specimens, relation between IFSS and fatigue life was experimentally investigated.
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  • Hiroaki TANAKA
    2004 Volume 53 Issue 1 Pages 57-63
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    A new probabilistic model describing the fatigue crack growth with retardation due to random overloads is developed. First, a crack growth equation is formulated based upon the Elber law, where a concept of retardation factor is introduced to quantify the retardation effect. Next, a new approach is discussed for describing the temporal variation of the retardation factor by the use of a system of differential equations. The validity of the obtained crack growth model is then shown by comparing with experimental results by McMaster et. al. Next, the discussion is made on an extension of the proposed crack growth model to a probabilistic model, in which the overload process is mathematically modeled as a compound Poisson process to describe the random property associated with loading times as well as stress of overloads. The proposed probabilistic model takes a form of a system of random differential equations of Itô type driven by the compound Poisson process. Finally, numerical demonstration is carried out for generating crack growth samples based upon the proposed model.
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  • Keisuke OKITA, Nagatoshi OKABE, Maho HOSOGI, Toshio SAKUMA, Kiyoshi YA ...
    2004 Volume 53 Issue 1 Pages 64-69
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    For the purpose of applying a shape memory alloy ring to combining two separated pipes, the way to exchange the reverse transformation properties of uni-axial stress for those of multi-axial stress was proposed by modeling σ-ε behaviors not only in the process of loading and unloading but also in the process of heating for using to make a FEM analysis. Using the new idea way, the behaviors of deformation recovery and pressure against inserted pipe in the process of ring diameter enlarging and heating for combining two separated pipes were clarified considering the effects of ring diameter enlarging rate and ring thickness. From the viewpoint of saving SMA material cost as well as improving efficiency of ring diameter enlarging works, it was clarified that optimum thickness of ring is about 3mm to 5mm.
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  • Hiroshi YOSHIZU, Masayoshi YAMAZAKI, Kohmei HALADA, Mitsutane FUJITA, ...
    2004 Volume 53 Issue 1 Pages 70-75
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    This research aims at construction of the technology which can carry out sharing of the material databases built in domestic and overseas as common property. The existing material databases are built by an original concept and an original technique, and they are not premised on sharing. To predict life of materials with the material database, it is difficult to use the databases for cooperation and utilization on the analysis system which a user has. Then, we used the data description language XML (eXtensible Markup Language) on the Internet as a common description language of material database description, and tried life prediction of material. The method is to carry out XML description supposing the material property data from some material databases with a different data structure. And the material property data were used. The described material property data are creep rupture data. In life prediction of materials, those data required for analysis, such as the test temperature, test stress, and time to rupture were extracted from the creep rupture property described in XML with XML application. Consequently, 1) creep rupture data were structured in hierarchical order by XML, and it was used as alanguage of description. 2) Data required for analysis were extracted by the XML describing method and XML application. 3) In data analysis, individual data analysis or strength comparison with a different data structure was conducted. Therefore, the method of using XML can treat data with a different data structure, and XML utilization is a promised way as a technique for sharing of a material database.
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  • Hitoshi INOMO, Wataru SHIRAKI, Masahiro DOGAKI, Hiroshi ISHIKAWA
    2004 Volume 53 Issue 1 Pages 76-83
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    After the Hanshin-Awaji (Kobe) Earthquake occurred on January 17, 1995, the earthquake design codes of highway bridges were revised by the Japanese Association of Road Engineering. However, the revised edition of codes were performed within the conventional design paradigm. They are not written based on the general principle of the reliability design of the structure (ISO2394) adopted in Europe and America. In this paper, a load factors design format based on the reliability theory for steel rigid-frame piers at elastic limit states is proposed using the reliability evaluation results of the author's early papers. The load factors are calculated so that the steel piers are ensured the target reliability index βT at the elastic limit state. The steel rigid-frame piers are redesign by using proposed design format and the reliability indices of these piers are calculated to check the effectiveness of the proposed format.
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  • Juksanee VIRULSRI, Skinsuke SAKAI, Satoshi IZUMI
    2004 Volume 53 Issue 1 Pages 84-89
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    This paper presents a new index to evaluate the sensitivity of the variation in one objective value to the variation in the other in the multi-objective optimization framework. This index is named as Robustness index, RI and is applicable to determine the decision-making point in the multi-objective problem. The decision-making point determined by the conventional method does not necessarily satisfy the robustness of the solution. However, the point determined by RI satisfies the robustness since this index shows the property of sensitivity of solutions. In this paper, the application of RI to the decision-making process in the multi-objective optimization problem is shown according to the user' s requirement. The index is examined using a system in nuclear power plant and the effectiveness to the multi-objective problem is confirmed.
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  • Naohide TOMITA
    2004 Volume 53 Issue 1 Pages 91-94
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
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  • Tomoaki ISHIKURO, Shinichi MATSUOKA
    2004 Volume 53 Issue 1 Pages 95-100
    Published: January 15, 2004
    Released: June 03, 2009
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    In order to improve the alkali resistance of anodic oxide film of aluminum, anodized aluminum was autoclaved in 0 mass% and 0.1-10 mass% zinc acetate dihydrate (ZnAce) added in 0-100 mass% 1, 4-butanediol (BD) aqueous solution at 130°Cto 250°Cfor 4 houres. In result, over 150°Cand with the exception of 100 mass% BD, anodic oxide film was sealed by ZnAl2O4 spinel (ZAS) phase above 1 mass% ZnAce, and by complex phase with ZAS and pseud-boehmite between 0.1 and 1 mass% ZnAce, and by pseud-boehmite phase only without ZnAce. In the case of 100 mass% BD, ZAS or pseud-boehmite was not produced, then, it was thought that these phases were prepared through dissolve/precipitation reaction of anodic oxide film by contained water. By means of SEM observation of cross-section of film, the film was composed of three layers, outer dense layer and a middle layer and inner columnar layer, or two layers, outer dense layer and inner columnar layers. Alkali resistance time of this film in 10 mass% of NaOH aqueous solution by means of the electromotive force method (JIS H-8681-1) was 100-1000 times as long as the boiling water sealing film. The alkali resistance time increased with increasing of the dense layer thickness. From this result, it was thought that the effect of the ZAS phase sealing on alkali resistance was about 10-times bigger than the pseud-boehmite phase sealing, and, the effect of the complex phase sealing was 4-times bigger than the pseud-boehmite phase sealing.
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  • Noriyuki HISAMORI, Yuji MARUYAMA, Kenichi TAKAI
    2004 Volume 53 Issue 1 Pages 101-107
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Metals are by far the oldest materials used in surgical procedures. Titanium alloys are hoped to be used much more for applications as implant materials in the orthopedic and dental medical fields because of their mechanical properties, such as biocompatibility, corrosion resistance and specific strength compared with other metallic implant materials. The performance of any biomedical material is controlled by two characteristics, biofunctionality and biocompatibility. Biofunctionality defines the ability of the device to perform the required function, whereas biocompatibility determines the compatibility of the material with the body. This biocompatibility is improved by coating the surface in contact with living tissues with calcium phosphates, specially hydroxyapatite. Some of the new implants utilize titanium alloys substructure coated with a thin layer of calcium phosphates ceramics, hydroxyapatite, or the plasma spray technique. Hydroxyapatite coating are designed to produce a bioactive surface promoting bone growth and inducing a direct bond between the implant and the hard tissues. The titanium metal also forms the bone like apatite layer on its surface in simulated body fluid, when it has been previously treated with NaOH aqueous solution to form a sodium titanium hydro gel layer on its surface. In the present study, surface structural changes of Ti-6Al-4V alloys with the alkali treatments and mechanical property in simulated body fluid were investigated. Thus it is expected that alkali treated titanium alloys could also form the bone like apatite layer on its surface in the living body and bond to living bone through the apatite layer. Studies have demonstrated that the bone bonding ability of titanium alloys could be evaluated by testing the titanium alloys in a simulated body fluid. In test results of with apatite coating specimens extremely higher fracture strength, compared with monolithic Ti-6Al-4V alloys whose fracture strength was 60MPa·m1/2. For apatite coating Ti-6Al-4V alloys the general tendencies in the fracture strength depending upon apatite coating were understood as follows. With apatite coating Ti-6Al-4V alloys it is recognized that speculated that this tight bond might be attributed to a graded interface structure between the apatite layer and the substrates.
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  • Nobuaki OTSUKI, Shinichi MARUYAMA, Takahiro NISHIDA, Baccay Melito ALI ...
    2004 Volume 53 Issue 1 Pages 108-113
    Published: January 15, 2004
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    In view of the maintenance of reinforced concrete members, it is necessary to evaluate steel corrosion in concrete. In this study, the influence of temperature on the corrosion rate of the steel bar at a joint in carbonated concrete members was investigated.
    As a result of the laboratory test and the field test, the following conclusions were derived. First, it was experimentally and theoretically confirmed that the corrosion rate of the steel bar in carbonated concrete increased with temperature rising. Secondary, the corrosion rate of the steel bar in existing concrete member increased with temperature rising, and this tendency was similar to the result of laboratory test.
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  • Kisaragi YASHIRO, Tomohiro ITOH, Yoshihiro TOMITA
    2004 Volume 53 Issue 1 Pages 114-119
    Published: January 15, 2004
    Released: June 03, 2009
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    A nanoscopic specimen of amorphous polyethylene, involving 3, 542 random coil molecular chains composed of 500-1500 methylene monomers with about 2 million methylene groups, is subjected to uniaxial tension by means of molecular dynamics simulation. After showing a linear elastic relationship at the initial stage of εzz≤0.03 at εzz=5.0×1011/s, the material “yields” by elongating without stress increase up to the strain of 1.5, where strain hardening appears. Careful investigation on change in dihedral angle and morphology of all molecular chains reveals that the gauchetrans transition takes place during yielding, generating a new network-like structure composed of entangled molecular clusters and oriented chains bridging them. The strain hardening is caused by the directional orientation and stretching of molecular chains between entanglements in the nucleated structure.
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  • Noboru NAKAMURA
    2004 Volume 53 Issue 1 Pages 120-125
    Published: January 15, 2004
    Released: June 03, 2009
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