JSME International Journal Series A Solid Mechanics and Material Engineering
Online ISSN : 1347-5363
Print ISSN : 1344-7912
ISSN-L : 1344-7912
Volume 46 , Issue 3
Special Issue on Recent Advances in Materials and Processing
Showing 1-50 articles out of 55 articles from the selected issue
PAPERS
  • Kin-ichi MATSUYAMA
    2003 Volume 46 Issue 3 Pages 192-195
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    A new working style assisted with various computer technologies is reviewed in this article for improving the planing stage and manufacturing stage in welding and joining engineering. A new production system fully supported with some computer systems are introduced at the first section, and specified each relevant systems to planning and the manufacturing stages, separately. The systems have been developed with many computer simulation codes, co-simulation tools, AI tools, and many types of sensing and capturing tools of the welding state data, which can be used in the high current fields. Finally, some typical research results relating to this CAWS are summarized to show the current state of researches including recurrent model of Neural networks, hybrid simulation, and an example of professional skill database.
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  • Teruie TAKEMASU, Tatsuo OZAKI, Ryoichi MATSUNAGA
    2003 Volume 46 Issue 3 Pages 196-201
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The purpose of this study is to examine a practical application of a finish rolling process using a screw-shaped tool to consolidate the surface layer of sintered Fe alloy gears and to improve the tooth profile accuracy and the load carrying capacity simultaneously. These objectives are almost attained in the previous works except the crowning in tooth trace direction, which is the essential matter for gears in automotive transmissions. In this paper, a numerical control finish rolling machine is developed to enable the crowning process. In this new apparatus, the amount of radial feed of the tool is synchronized with the axial feed of the workpiece to put a specified crowning on the rolled gear teeth. A simple calculation method is proposed to decide the rolling orbit for crowning. The crowning profiles predicted in the analysis agree well with the experimental ones. Gears with a good tooth profile and a good surface finish can be obtained.
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  • Taewon KIM, Yasuo SUGA, Takashi KOIKE
    2003 Volume 46 Issue 3 Pages 202-207
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    TIG arc welding and laser welding are used widely in the world. However, these welding processes have some advantages and problems respectively. In order to improve problems and make use of advantages of the arc welding and the laser welding processes, hybrid welding process combined the TIG arc with the YAG laser was studied. Especially, the suitable welding conditions for thin steel plate welding were investigated to obtain sound weld with beautiful surface and back beads but without weld defects. As a result, it was confirmed that the shot position of the laser beam is very important to obtain sound welds in hybrid welding. Therefore, a new intelligent system to monitor the welding area using vision sensor is constructed. Furthermore, control system to shot the laser beam to a selected position in molten pool, which is formed by TIG arc, is constructed. As a result of welding experiments using these systems, it is confirmed that the hybrid welding process and the control system are effective on the stable welding of thin stainless steel plates.
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  • Akio SUZUMURA, Yohei INAGAKI, Toshi-Taka IKESHOJI, Yasuhiro UENO
    2003 Volume 46 Issue 3 Pages 208-212
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Braze Pressure Welding (BPW) with high frequency induction heating has been invented as the new joining method for welding general steel pipes for on-site piping without the danger of fire and the dispersion in the joint properties due to welder's skill. In the BPW, a brazing filler is interlaid between the mating surfaces to be joined. The filler melts by heating up to joining temperature, then the welding pressure discharges it from the joining interface. At the same time, the base metals are pressure-welded to each other, and that the discharged liquid filler forms fillets around the joining area. The fillets have the effects both on relaxing the stress concentration at the joint and on increasing the joining area, which contributes to the strengthening of joint. Experimentally it was revealed that the BPW joints had superior properties to brazed or pressure-welded joints by microscopy, EDS analysis, and tensile test of joints. The effect of the fillet on relaxing the stress concentration at the joint area was also confirmed by finite element analysis.
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  • Naoto OHTAKE, Xudong YANG, Toshihisa KURODA, Yukinori NAKAMURA, Yoshim ...
    2003 Volume 46 Issue 3 Pages 213-217
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In order to improve the wear resistance of stainless steel extrusion dies, the mechanical properties of diamond-like carbon (DLC) films deposited on SUS630 (17-4PH) substrates have been investigated. It was clearly shown that wear resistance of the dies was significantly improved when high-voltage pulse pretreatment was applied before DLC deposition by DC plasma CVD. The DLC film showed good wear resistance against cordierite clay in an extrusion experiment. Furthermore, in order to strengthen the adhesion between the DLC film and the substrate which were deposited, TiCN films was fabricated as a buffer layer between DLC and SUS630 substrates. It was found that DLC film with high adhesion strength was prepared at relatively low CH4 gas pressure of 6Pa.
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  • Zhengyi JIANG, Kiet Ahn TIEU
    2003 Volume 46 Issue 3 Pages 218-223
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In this paper, the rolling of thin strip is simulated by a 3-D rigid plastic finite element method (FEM), which considers friction variation models. The calculated rolling pressure, spread and forward slip, taking into account a suitable friction variation model in the roll bite, are in good agreement with the experimental values. Based on the FE simulation, the calculated strip velocity at the exit of roll bite is obtained, and the effect of the friction variation on the shape and flatness of strip is presented, the characteristic of the snaking of strip is also described in this paper.
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  • Yong-Taek IM, Seong-Hoon KANG, Jae-Seung CHEON, Soo-Young KIM
    2003 Volume 46 Issue 3 Pages 224-229
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In the tip test based on backward extrusion, the distance of the radial tip from the external side surface of the workpiece deformed has a linear relationship with the maximum forming load measured. In this study, finite element analyses were carried out to calibrate the relationship between this radial tip distance and the shear friction factor. It has been found that this relationship is in linear such that the simple measurement of this radial tip distance can be used to effectively predict the shear friction factor. Also, the friction conditions at the punch and lower die were examined. It was found that the shear friction factor at the lower die is about 60 and 75% of the one at the punch with and without a centering groove used, respectively. However, the predicted values of shear friction factors were similar regardless of the type of centering groove used.
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  • Ning FANG
    2003 Volume 46 Issue 3 Pages 230-236
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The modeling of face milling operations has been traditionally focused on using flat-faced tools with an assumption of perfectly straight chip formation. However, curled chip formation is a common phenomenon in practical milling operations, and it has a profound effect on machining performances. A new analytical model that takes into account the chip curling effect in milling operations is proposed in this paper. It is shown that chip morphology and machining parameters, such as the chip up-curl radius, the chip thickness, and the tool-chip contact length, simultaneously change with varying undeformed chip thickness during each tooth cycle. The proposed model is validated through milling tests. Good agreement between theory and experiments has been reached. A comparison of the average resultant force among three types of commercially available tool inserts is made to demonstrate the effect of tool insert chip-groove geometry on milling performances.
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  • Noriatsu HARIYAMA, Shin-ichi MATSUOKA
    2003 Volume 46 Issue 3 Pages 237-241
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This study experimentally examines the effects of changes in flow velocity at the die cavity during extrusion and investigates the mechanism of their occurrence. The die has two cavities of different diameters. One of the cavity serves as the velocity standard cavity and has a fixed diameter (D1=6.0mm), while the other cavity serves as the velocity comparison cavity and had different diameter (D2=6.0, 7.3, 8.5, and 10.4mm). Flow velocity at die cavities during extrusion is evaluated by the average flow velocity (D1; V1, D2; V2) calculated by the extrusion time and the extruded profile length for every 10mm of ram stroke. And changes in flow velocity are evaluated by flow velocity ratio (V2/V1). As a result, the flow velocity ratio (V2/V1) change occurs during the initial and end stages of the extrusion process due to the change of metal flow within the container.
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  • Ayako OHGUCHI, Eiji YUASA, Katsuyoshi KONDOH
    2003 Volume 46 Issue 3 Pages 242-246
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    To produce magnesium alloy with ultra fine-grain size, powder mixtures, which aluminum powder was added with various contents to turning chips of AZ31 alloy, were mechanically alloyed for various milling times. Micro-structural changes of the mechanically alloyed powder with milling were investigated. Super-saturated solid solutions of the magnesium phase with crystalline size of nanometer scale are formed in the Mg-12mol%Al and 30mol%Al powder mixtures mechanically alloyed for long milling time and, especially, it forms the eutectic structure together with Mg17Al12 in the Mg-30mol%Al powder. In the case of the Mg-40mol%Al and 61.5mol%Al powders, formation of the intermetallic compounds yields by the mechanical alloying for shorter milling time, and these crystals become to amorphous phase after the prolonged milling time. The harnesses of particles in the powder mechanically alloyed increase with forming of the super saturated solid solution or the intermetallic compound and their refining.
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  • Hiroshi MURAMATSU, Katsuyoshi KONDOH, Eiji YUASA, Tatsuhiko AIZAWA
    2003 Volume 46 Issue 3 Pages 247-250
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The mechanical properties of the Mg2Si/Mg composites solid-state synthesized from the mixed Mg-Si powders have been investigated. The macro-hardness (HRE) and the tensile strength of the composites increase with increasing the Si content and decreasing the Si size. The particle size of the synthesized Mg2Si depends on the initial Si size; the mechanical properties of the Mg2Si/Mg composite are remarkably improved by using fine Si particles or by decreasing the grain size of Mg matrix grains when the powder mixture was prepared via bulk mechanical alloying process.
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  • Venkataraman SHANKAR, Li LU, Man On LAI
    2003 Volume 46 Issue 3 Pages 251-254
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The mechanochemical reaction of TiO2 and Mg via mechanical alloying of Mg, TiO2 and Al has been investigated. Reduction of TiO2 is evident from substantial formation of MgO. Weakening of Mg and TiO2 diffraction peaks along with broadening suggests refinement in grain size. Mechanically milled powder shows completion of reaction upon subsequent heat treatment while the reaction of the unmilled powder is still incomplete. Analysis suggests that the milled powder undergoes self-propagation while unmilled powder does not.
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  • Hideki KAKISAWA, Kazumi MINAGAWA, Susumu TAKAMORI, Yoshiaki OSAWA, Koh ...
    2003 Volume 46 Issue 3 Pages 255-259
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The strengthening mechanism of Fe-Cu alloy from rapidly solidified powder was investigated. The powder microstructure was changed by annealing. The as-atomized and annealed powders were consolidated by groove rolling at a warm temperature in order to avoid recrystallization and to maintain the powder microstructure. Copper was precipitated in the ferrite matrix and at the primary powder boundaries in all of the consolidated samples; the precipitation was coarser in the samples from the annealed powders. The results of the tensile testing showed strengthening occurred by the addition of copper in all the samples; the magnitude of the strengthening was larger in the samples from the as-atomized powder. The minute and uniform copper distribution in the samples from the as-atomized powder resulted in a greater strengthening effect.
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  • Kazumi MINAGAWA, Yunzhong LIU, Hideki KAKISAWA, Kohmei HALADA
    2003 Volume 46 Issue 3 Pages 260-264
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Hybrid Atomization is a recently developed powder-making process that combines effectively free-fall gas atomization and centrifugal atomization. This technique can produce very fine spherical powders with mean diameters of around 10 micrometers, and in high yields. The present report discusses the concept and basic principles of hybrid atomization. Process experiments were carried out and the optimal processing conditions were obtained. The results show that the influences of processing parameters and optimum conditions differ greatly between the proposed and the conventional atomization processes. A new correlation of atomization equation applicable to hybrid atomization is proposed and discussed.
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  • Roman NOWAK, Timo MANNINEN, Chunliang LI, Kari HEISKANEN, Simo-Pekka H ...
    2003 Volume 46 Issue 3 Pages 265-271
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This work clarifies the origin of anomalous surface deformation reflected by peculiar surface patterns around indentation impressions on various crystallographic planes of sapphire. The three-dimensional finite element simulation (3D-FEM) of nanoindentation in Al2O3 crystal allowed the authors to localize the regions in which various kinds of twinning and slip are most prone to be activated. The work provides a novel approach to the “hardness anisotropy”, which was modeled so far using a modified uniaxial-stress approximation of this essentially 3D, non-isotropic contact problem. The calculated results enabled the authors to unravel the asymmetric surface deformation detected on prismatic planes by the high-resolution microscopy, which cannot be explained using simple crystallographic considerations.
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  • Cheng LIU, Sanjiwan BHOLE, Derek NORTHWOOD
    2003 Volume 46 Issue 3 Pages 272-277
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The room temperature creep behavior is investigated for a commercial SAE 4340 steel containing small amounts of ferrite. Significant creep deformation occurs at stress levels below 1/3 σ0.2 (The yield strength at 0.2% offset strain). Small amounts of ferrite (0% to 4%) have no influence on the hardness and yield strength. However, these small amounts of ferrite play an important role in controlling the creep resistance. The presence of any ferrite leads to a reduction in the creep resistance. The creep deformation at room temperature increases with an increase in the amount of ferrite. The effects of ferrite morphology and an inhomogeneous microstructure on the creep resistance are discussed.
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  • Toshifumi KAKIUCHI, Tadashi SHIOYA, Katsuhiko SATOH, Koji FUJIMOTO
    2003 Volume 46 Issue 3 Pages 278-282
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The fracture modes are classified into two categories; ductile fracture and brittle fracture. This paper presents the study on the relationship between the fracture mode and the fractality of the fracture surface. Using iron and steel changing the carbon contents, the three-point bending fracture experiments were conducted. The critical stress intensity factor KIC was calculated as the macroscopic parameter. Furthermore, from the microscopic viewpoint, the fractality of the fracture surface was investigated using the surface profile curve obtained by the laser focus displacement meter, comparing with the SEM photographs of the fracture surface as the microscopic observation. The fractality of fracture surface depends on the fracture mode, which is explained by the facture mechanism. The final purpose of this study is to identify the fracture mode by quantifying the fracture surface using the concept of fractality.
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  • Koji FUJIMOTO, Katsuhiko SATOH, Tadashi SHIOYA, Naoki SEKI, Kazuhide F ...
    2003 Volume 46 Issue 3 Pages 283-289
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The degradation of materials exposed in LEO (low earth orbit) is one of the most important problems in space technology because the predominant component of the atmosphere in LEO is AO (atomic oxygen) which degrades some kinds of materials. This paper presents an experimental simulation on the ground for the degradation of carbon-based materials. In the experiment, AO produced at a plasma torch is accelerated fluid-dynamically with working gas. Graphite, C/C (carbon/carbon) composite and Si-C. C.(silicon impregnated C/C composite) were used as the target materials. The mass loss per unit area depends strongly on the temperature of the material surface. The eroded surfaces of materials were observed with SEM (scanning electron microscope) and laser focus displacement meter. In case of C/C composite, the matrix region erodes more than carbon fiber. The mass loss of Si-C. C. is less than that of corresponding C/C composite and only the C/C region erodes deeply with almost no erosion in Si and SiC regions. In order to investigate the degradation caused by the impact of AO, numerical simulation was also conducted for graphite using MD (molecular dynamics) method.
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  • Hiroshi HATTA, Tatsuji AOI, Itaru KAWAHARA, Yasuo KOGO, Ichiro SHIOTA
    2003 Volume 46 Issue 3 Pages 290-296
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In order to identify ruling mechanisms of tensile fracture of Carbon/Carbon composites (C/Cs), tensile tests were carried out for various C/Cs as functions of the density, heat treatment temperature, and interfacial strength between fiber and matrix. Three processing routes of preformed yarn, resin char, and HIP processes were adopted to densify C/Cs. These C/Cs were finally heat-treated at temperatures from 2273K to 3300K. The interfacial strength between fiber and matrix was varied by the selection of processing routes. As a result, two ruling failure mechanisms were identified. At density lower than 1.6g/cm3, the tensile fracture was controlled by stress transfer capability from the matrix to reinforcing fibers. However, at higher density than 1.6g/cm3, tensile strength was primarily governed by the interfacial strength between the matrix and fibers. Thus the latter mechanism is nearly same as ceramic matrix composites.
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  • Masanobu KUBOTA, Sotaro NIHO, Chu SAKAE, Yoshiyuki KONDO
    2003 Volume 46 Issue 3 Pages 297-302
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Axles are one of the most important components in railway vehicles with regard to safety, since a fail-safe design is not available. The problems of fretting fatigue crack initiation in a press-fitted axle have not been completely solved even though up-to-date fatigue design methods are employed. The objective of the present study is to clarify the effect of understress on fretting fatigue crack initiation behavior in the press-fitted axle. Most of the stress amplitude given to the axle in service is smaller than the fretting fatigue limit based on the stress to initiate cracks under a constant load σwf1. Rotating bending fatigue tests were performed using a 40mm-diameter press-fitted axle assembly. Two-step variable stresses consisting of σwf1 and half or one-third of σwf1 were used in the experiment. Crack initiation life was defined as the number of cycles when a fretting fatigue crack, which is longer than 30µm, was found using a metallurgical microscope. Fretting fatigue cracks were initiated even when the variable stress did not contain the stress above the fretting fatigue crack initiation limit. The crack initiation life varied from 4.0×107 to 1.2×108 depending on the stress frequency ratio nL/nH. The sum of the number of cycles of higher stress at crack initiation NH was much smaller than the number of cycles to initiate cracks estimated from the modified Miner's rule. The value of the modified Miner's damage ranged from 0.013 to 0.185. To clarify the effect of variable amplitude on the fretting fatigue crack initiation, a comprehensive investigation related to relative slip, tangential force and fretting wear is necessary.
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  • (Degradation Properties of GFRP Caused by Water Absorption)
    Hiroyuki KAWADA, Akira KOBIKI
    2003 Volume 46 Issue 3 Pages 303-307
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Recently the crack propagation properties of GFRP on the stress corrosion cracking (S. C.C) are investigated, and the threshold stress intensity factor KICC is verified in some environmental solution. From the investigation, it was found that GFRP reinforced by C-glass fiber has a superior acid resistance. However the microscopic crack propagation mechanisms caused by the material corrosion are not verified, and the microscopic mechanisms are necessary to assure the durability. Therefore the degradation mechanisms of the inner fiber and the matrix and the fiber/matrix interface should be quantified. In this study, the degradation of the fiber strength and the fiber/matrix interfacial shear strength are investigated using a single fiber composite previously immersed into environmental solutions, distilled water and acid solution. The effects of solution diffusion into the matrix resin on the fiber strength and the interfacial shear strength have been evaluated as a function of immersion time by fragmentation test in the room air. It is found that the diffusion of distilled water influences the degradation earlier than the acid solution. And the diffusion behavior is confirmed by Fickian diffusion analysis. The calculated concentration distribution showed that the water concentration around the fiber is saturated much earlier than the saturation of the acid ion due to the lower diffusion coefficient. Furthermore the crack propagation mechanisms are discussed based on the degradation estimated by the fragmentation test.
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  • Takashi YOKOYAMA
    2003 Volume 46 Issue 3 Pages 308-315
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The tensile strength and energy absorption for dissimilar metal friction welds between 6061 Al alloy and Type 304 stainless steel at high rates of loading are determined using the split Hopkinson bar. Cylindrical tensile specimens machined from as-welded butt joints of 13 mm in diameter are used in both static and impact tests. Friction welding is conducted using a brake type friction welding machine under two different welding conditions. The effects of the welding conditions and loading rate on the joint tensile properties are examined. Results show that the joint tensile properties are greatly affected by the welding parameters, and are slightly enhanced with increasing loading rate. Macroscopic observations reveal that the tensile fracture modes in the butt joint specimens vary with loading rate, depending on the welding conditions. Microhardness profiles across the weld interface are measured to investigate the extent of the heat-affected zone (HAZ). The slight enhancement of the joint tensile properties with increasing loading rate is due to the strain-rate dependence of the thermally-softened 6061 Al alloy base material.
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  • Masaaki ITABASHI
    2003 Volume 46 Issue 3 Pages 316-321
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In order to design thin-walled impact-resistant structure, for example, an automotive body, dynamic behavior of thin plate is essential. So far, except for laminated composite materials, high velocity tensile test of thin plate specimen did not attract impact researchers' and engineers' attention very much. In this paper, the previous thin plate specimen assembly for the one bar method was improved. The one bar method has been utilized for cylindrical specimens of various solid materials and is known as an effective high velocity tensile testing technique. Unfortunately, the previous assembly introduced a tremendous initial peak on stress-strain curves, even for aluminum alloys. With a new specimen assembly, stress-strain curves for IF (Interstitial-atom Free) steel and 7075-T6 aluminum alloy obtained by the one bar method were almost equivalent to those obtained by the tensile version of the split Hopkinson pressure bar method.
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  • Kinya OGAWA
    2003 Volume 46 Issue 3 Pages 322-327
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Since titanium and aluminum alloys are the most promising structural materials for the high velocity vehicles, the impact tensile strength of the materials is presently investigated. Three kinds of aging treatments on the beta-titanium alloy and two on the 6061 aluminum alloy were performed, and the tensile deformation behaviors were identified in the wide range of the temperature and the strain rate. The stress-strain relations of the titanium alloy significantly depend on the temperature and the strain rate investigated. Thermally activated process concept was applied to explain the experimental results, and the stress-strain relations at high strain rates were well understood with taking account of adiabatic heating effect. In the case of the aluminum alloy, the temperature and the strain rate effects are significant only in the low temperature range. Both for the alloys investigated, the stress-strain curves depend on the microstructures, while the temperature and the strain rate effects are almost independent of the different aging treatments.
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  • Takayuki KUSAKA
    2003 Volume 46 Issue 3 Pages 328-334
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Novel experimental methods were proposed to easily and precisely evaluate the mode I, II and I+II fracture toughness of polymer matrix composite laminates under low-velocity impact loading. A ramped incident stress wave was applied to suppress the flexural vibration of the specimen. A strain-based formula was employed to improve the accuracy of evaluation of the dynamic energy release rate. The validity of the proposed method was confirmed by the results of finite element analyses and dynamic experiments. The effects of loading rate and mode mixture on the interlaminar fracture behavior of carbon-fiber/epoxy composite laminates were investigated over a very wide range of loading rate from static to impact. The macroscopic fracture toughness clearly showed loading rate dependence regardless of mode ratio, and consequently the mixed mode fracture criterion varied with loading rate. The microscopic fracture morphology also showed loading rate dependence; cohesive fracture of matrix resin itself was a dominant fracture mechanism at higher loading rate, whereas debonding of fiber/matrix interface was a dominant fracture mechanism at lower loading rate.
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  • Yukio MIYASHITA, Yu SASAKI, Tomoaki KUROISHI, Takanori WATANABE, Jin-Q ...
    2003 Volume 46 Issue 3 Pages 335-340
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Scratch tests were carried out on TiC and TiN coatings which had been deposited by PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) techniques. The critical load Lc was detected by the acoustic emission method (AE) and also by the frictional force curve. The critical load corresponded to the load at which local delamination of coating was observed on the scratch track. A study the scratch tracks induced in a coating during the scratch test revealed that fine cracks, which propagated parallel to the scratch track, were created before local delamination occurred. Other cracks, which propagated perpendicular to the scratch direction, were observed to form in the scratch track at the critical load. Localized delamination also occurred at the edge of scratch track at Lc. The stress distribution at the interface was estimated by FEM (Finite Element Method) analysis. From both the experimental and analytical results, it was found that local delamination occurred at a critical shear stress at the interface between coating and substrate. Since the shear stress at the interface decreased with decreasing tangential force, the critical load Lc increased with decreasing of tangential force. Indentation tests without tangential force was also carried out. The critical load was higher in the indentation test compared to that in scratch test. However, the critical shear stresses at the interface for both scratch and indentation tests coincided with each other. It was concluded that the adhesive strength between coating and substrate is a function of the critical interfacial shear stress.
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  • Yukio MIYASHITA, Yoshihiro YOSHIMURA, Jin-Quan XU, Makoto HORIKOSHI, Y ...
    2003 Volume 46 Issue 3 Pages 341-347
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Rolling contact fatigue tests of sintered alloy were carried out under two cylinder contacts. Damage of the specimen was detected by using acceleration sensor before occurrence of final failure, namely spalling failure. In order to study the damage process of contact fatigue of sintered alloy, surfaces and cross sections of the specimens were observed after contact fatigue test. Damage on the specimen surface such as pitting mode of failure was not observed, while subsurface crack initiation and propagation were dominantly observed. Subsurface crack length increased with increasing number of cycles. Crack initiation and propagation in the subsurface of the specimen will be followed by a spalling mode of fracture. Stress distribution near the contact region was estimated by FEM (Finite Element Method) analysis. The location of the maximum shear stress range estimated by FEM analysis coincided with the depth of the crack initiation point observed in experiment. The position at the maximum shear stress range approaches to the specimen surface with an increase in tangential force. Subsurface crack growth behavior was controlled by the shear stress intensity factor range, ΔKII.
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  • Teppei KAWAKAMI, Satoshi KOBAYASHI, Shuichi WAKAYAMA
    2003 Volume 46 Issue 3 Pages 348-352
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The effect of simulated body environment on mechanical properties and fracture behavior of bioceramics were investigated. Alumina ceramics, which is a typical bioinert ceramics, was used. Four-point bending tests were carried out in air, refined water and the simulated body fluid in order to investigate the dependence of microfracture process on environments. The microfracture process during the bending tests was evaluated by an acoustic emission technique. Rapidly increasing point of cumulative AE energy was observed before the final unstable fracture. It was understood that the stress at AE increasing point, σC, corresponds to the maincrack formation stress in the previous work. These test environments affected σC more strongly than bending strength, σB. Consequently, it was suggested that the critical stress, σC, is available as an evaluation parameter, which is essential as the yield strength in metals, for bioceramics.
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  • Kazuki ENOMOTO, Toshiyuki YASUHARA, Naoto OHTAKE, Kazunori KATO
    2003 Volume 46 Issue 3 Pages 353-358
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Vapor grown carbon fiber (VGCF) is a kind of carbon nanotube (CNT), which has outstanding properties such as high mechanical strength and high electrical conductivity. In this study, injection molding properties of polystyrene (PS) filled with VGCF and evaluation of mechanical and electrical properties are discussed in comparison with composites in which conventional carbon fillers were filled. As a result, volume resistivity of VGCF/PS composites dropped significantly between VGCF concentration of 3 and 4vol.%. Resistivity of the composites filled with VGCF was 1.2×102Ω·cm when VGCF concentration was 11.6vol.%. The resistivity was significantly lower than that of composites which were filled with conventional carbon fillers. The elastic modulus slightly increases with increasing VGCF concentration, whereas the tensile strength slightly decreases in the VGCF concentration in the range from 0 to 12vol.%.
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  • Susumu KUMAGAI, Yasuhide SHINDO, Katsumi HORIGUCHI, Tomo TAKEDA
    2003 Volume 46 Issue 3 Pages 359-364
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In order to evaluate the mechanical properties of T800H/3633 CFRP woven laminates for cryogenic tankage in RLV, tensile and in-plane shear tests were performed at room temperature, liquid nitrogen temperature (77K) and liquid helium temperature (4K). The tensile tests were conducted in accordance with ASTM D 3039 and JIS K 7073. Tensile strength and modulus were evaluated for both the warp and fill directions. A problem was encountered with obtaining acceptable failure of the specimens. We could not achieve failure in the test section. This problem was avoided by using dogbone shaped specimens. A two-dimensional finite element analysis was also used to study the stress distributions within the specimens and to interpret the experimental measurements. The in-plane shear modulus and shear strength were measured by tensile tests on the ±45° specimens (ASTM D 3518 and JIS K 7079). The effects of temperature on the stress-strain responses in tension and in-plane shear are examined. Fracture topography of specimens is also investigated and interpreted.
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  • Kazunari YOSHIDA, Somchai NORASETHASOPON, Tetsuo SHINOHARA, Ryuta IDO
    2003 Volume 46 Issue 3 Pages 365-370
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    By means of the finite element analysis (FEA), this study analyzed wire breaks that occurred in the drawing fine wires containing flaws on the wire surface, inclusion and void. The deformation behavior of an inclusion was examined, in which the inclusion's location is assumed to be on the center axis of the wire, and the cause of wire breaks and their prevention method were clarified. It was found that an inclusion diameter/wire diameter ratio of 0.4 or higher increases the likelihood of wire breaks occurring. When the inclusion is not assumed to be in the center axis of the wire, it was also found that necking and wire breaks appear more frequently. FEA showed that a flaw grows with each processing step, when a small circumferential flaw is placed on the wire rod surface, and eventually becomes a surface defect, which is called a check mark in practice.
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  • Tsunehisa MIKI, Norio TAKAKURA, Takashi IIZUKA, Katsuhiko YAMAGUCHI, K ...
    2003 Volume 46 Issue 3 Pages 371-377
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Extrusion tests of mixed wood powders of cryptomeria with the Japanese cypress are carried out at various temperatures in order to confirm the possibility of near net shape forming of wood powders. Effects of extrusion temperature, extrusion ratio, moisture content and particle size of the mixed wood powders on the flow characteristics, bending strength, hardness and bulk density of extruded products are discussed. The experimental results show that the fluidity of the mixed powders and the bending strength and bulk density of extruded products increase with increasing temperature and moisture content of powders. However, when the extrusion temperature is too high, the bending strength and bulk density of extruded products tend to decrease due to bubbles generated in the extruded product.
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  • Kazunari SHINAGAWA
    2003 Volume 46 Issue 3 Pages 378-383
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The internal stress of graded powder compacts during sintering is analyzed by using plate theory with shrinkage and warpage taken into consideration. Diagrams giving the in-plane stress on the surface of the compacts, produced by mismatch and bending, are presented as a function of sintering stress and viscosity. The diagrams show the contours of tension and compression as well as the direction of warpage for given multilayered substrate. When the viscosity of the top layer is smaller than that of the substrate, the shrinkage constrained by the substrate significantly influences the internal stress. In the opposite case, the bending stress dominates the stress condition. The tension/compression boundaries in the diagrams change according to the number and the thickness of the graded layers as well as the sintering stress and the viscosity.
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  • Masaaki KIMURA, Kenji SEO, Masahiro KUSAKA, Akiyoshi FUJI
    2003 Volume 46 Issue 3 Pages 384-390
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This report describes the observation result of joining phenomena in the friction stage, and an improvement of the conventional friction welding method with similar materials. The materials used were carbon steels and a brake type (direct drive) friction welding machine was used for joining. As the improving friction welding method, relative speed was instantaneously rendered to zero at the end of each friction time. The wear of both surfaces started at periphery portion (outer surface) of the joint and moved to center portion (center axis). Seizure and joining began at center portion and then extended toward periphery portion. The friction torque reached to initial peak torque when the welded interface was joined completely and upsetting of both base metals started. It was determined that friction welded joints with 100% joint efficiency and good bend ductility could be obtained by using only the friction stage up to initial peak torque and without the need for the forging (upsetting) stage. As a conclusion, friction welded joints made without using the forging stage has the same mechanical properties as those welded by the conventional friction welding process including that stage. The friction welding method without forging stage has the advantages of less burn-off (axial shortening) and less burr.
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  • Masahiro MURAMATSU, Yasuo SUGA, Kazuhiro MORI
    2003 Volume 46 Issue 3 Pages 391-397
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In order to obtain sound welded joints in the welding of horizontal fixed pipes, it is important to control the back bead width in the first pass. However, it is difficult to obtain optimum back bead width, because the proper welding conditions change with welding position. In this paper, in order to fully automatize the welding of fixed pipes, a new method is developed to control the back bead width with monitoring the shape and dimensions of the molten pool from the reverse side by autonomous mobile robot system. This robot has spherical shape so as to move in a complex route including curved pipe, elbow joint and so on. It has also a camera to observe inner surface of pipe and recognize a route in which the robot moves. The robot moves to welding point in the pipe, and monitors the reverse side shape of molten pool during welding. The host computer processes the images of molten pool acquired by the robot vision system, and calculates the optimum welding conditions to realize adaptive control of welding. As a result of the welding control experiments, the effectiveness of this system for the penetration control of fixed pipes is demonstrated.
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  • Hitoshi SOYAMA, Kei SASAKI, Dan ODHIAMBO, Masumi SAKA
    2003 Volume 46 Issue 3 Pages 398-402
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Cavitation Shotless Peening (CSP) is a new method of surface modification. Cavitation impacts induced by the collapse of cavitation bubbles produce compressive residual stress and work hardens the material surface. In the case of CSP, shots are not required and therefore we call it Cavitation Shotless Peening. In CSP, cavitation is induced by a submerged high-speed water jet, i. e., a cavitating jet, for which the intensity and region of cavitation impact can be controlled by parameters such as the upstream pressure and nozzle size. The authors have already shown that the lifetime of forging die treated by CSP can be extended by about 50% compared with non-peened forging die. In this paper, in order to make clear the mechanism by which the lifetime of forging die is increased, an alloy tool steel (JIS SKD61) was tested both in peened and non-peened conditions. Compressive residual stress was measured by an X-ray diffraction method. It was evident from a comparison between the non-peened specimen and the cavitation shotless peened specimen that CSP improved the mechanical properties of the forging die thus giving it a longer lifetime.
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  • Yoshiharu MUTOH, Jin-Quan XU, Yukio MIYASHITA, Gomez G. BERNARDO, Masa ...
    2003 Volume 46 Issue 3 Pages 403-408
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Failure of thermal barrier coating (TBC) layer, especially spalling of ceramic coating layer, results not only in degradation of thermal barrier properties but also in crucial damage to turbine components. The spalling of ceramic coating layer will follow the crack initiation and propagation along the interface between ceramic top-layer and metal bond-layer. In the present study, fatigue crack growth tests of TBCs with various porosities were carried out at room and elevated temperatures. It is found that an interface crack induced near a pre-introduced notch propagates along the interface under mixed mode condition, and its growth behavior can be well characterized by using the parameter ΔKi=Δ√(K12+K22), which corresponds to the energy release rate. It is also found that the crack propagation resistance decreases with increasing of the porosity of the top ceramic coating. The crack propagation resistance at elevated temperature becomes lower compared to that at room temperature.
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  • Mitsuhiko TAKA, Juhachi ODA, Masahiro TOMISAKA
    2003 Volume 46 Issue 3 Pages 409-414
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    In this paper, a new method to produce the functional continuum for the micro-devices is proposed. The method is a topological optimization technique based on the function of a continuum and is composed of three steps. First, an initial mechanism model, which conforms to the given function, is determined using the Evolutionary L System (ELS). The ELS is a technique to obtain the optimum plate-thickness distributions of material using L System with genetic algorithms. The obtained mechanism model is changed to a framed structure as rahmen model in the second step. The cross-section and length of members in the framed structure are optimized to maintain the original design requirement. In the final step, the framed structure is changed to the functional continuum using some well-known shape optimization techniques. This method is applied to the problem of functional continuum, which is to produce the micro-gripper of two fingers for the use in the medical fields. The micro-gripper is cut with YAG laser and the performance by the piezoelectric actuator is confirmed experimentally. From the results, it is obvious that the proposed method is very useful to produce the functional continuum.
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  • Hatsuhiko USAMI, Kazuto OHASHI, Shinnya SASAKI, Junji SUGISHITA
    2003 Volume 46 Issue 3 Pages 415-418
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The present paper describes cracking behavior of brittle materials in sphere indentation experiment. Fused silica glass plates were used for the specimen. An electro-mechanical testing apparatus was applied for the experiment. A silicon nitride sphere was penetrated with various cross head speed in air at room temperature. Au coating was applied on the testing surface to avoid the effect of corrosion. The cracking behavior was observed continuously during the test by installing a CCD camera with a lens assembly behind the specimen and was recorded with a digital memory. Acoustic emission (AE) measurement was also connected for the evaluation. The indentation strength based on an elastic contact theory was calculated. Reliability of the fracture load determination by AE measurement and the effect of cross head speed on the cracking behavior were evaluated. Obtained results revealed that the control of cross head speed was important for the indentation strength measurement.
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  • Takahiro IYAMA, Takashi HOSHI, Kentaro ODANAKA, Yoshio FUJISHIRO, Moto ...
    2003 Volume 46 Issue 3 Pages 419-425
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper deals with a complex-shaped hat channel product, which combines a straight part with a curved part in the longitudinal direction. Twist in the longitudinal direction is the most typical and serious of all dimensional inaccuracies in the product. Influencing factors in twisting can be classified into in-plane residual stress and residual moment. At first, by varying forming conditions such as the blank holding force and the cushion force, the influence of the in-plane residual stress on twist of the shrink and the stretch flange are investigated. Contrary to expectation, the in-plane residual stress had almost no relation to twist. Subsequently, by slitting the flanges and the side wall to release the residual moment, the influence of the residual moment on twist was investigated. It was observed that the residual moment plays an important role on twist. Based on the above, certain regions of the die radius are varied to control residual moment. As a result, the twist was decreased experimentally.
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  • Jun-ichi OZAKI, Ken-ichi MANABE
    2003 Volume 46 Issue 3 Pages 426-431
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    Thermoforming of braided thermoplastic composite tubes was carried out in order to clarify the mechanism of the thermoforming process for pipe fittings such as T-shape fittings, cross fittings and two-branch fittings. The composite tube was made of a cowoven braid that consists of a carbon braid and polyamide resin, and 4-ply tubes with initial fiber orientations of 18° and 26° are used in the experiment. The branch is formed with not only the fisherman's net effect but also with moving yarns along the longitudinal direction in every forming process. The results show that the deformation behavior of the braid is very complex. Therefore, fiber orientation through forming is also greatly changed. Wall thickness at the branch decreases with increasing branch height. From these results, it is found that a fitting with complex shape can be produced by thermoforming. T-shape fittings, cross fittings and two-branch fittings are achieved by this process. It is confirmed that moving yarns along the longitudinal direction plays an important role in branch forming of pipe fittings.
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  • Takahiro OHASHI
    2003 Volume 46 Issue 3 Pages 432-436
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The author developed a die-life analyzer to be used in cooperation with independent databases of cold forging die life on the Internet. These Internet instance databases (written in HTML and XML and accessed using a “www” browser) are used by forging engineers as references in their forging process design. The die-life analyzer uses these databases as a knowledge base to predict and analyze forging die life, as well as the causes of short die life. The author considers die-life analysis as risk analysis of whether the life of a target tool will be shorter than the life of instances and developed a die-life analyzer using risk-tree networks and fuzzy linguistic risk calculation. The author subsequently investigated the causes of short life in order to create a risk analysis tree network. A certain cause, or a “parent node” in other word, is divided into more detailed causes called “daughter nodes.” The daughter nodes are connected to their parent nodes with weights, and the risk of the parent node is calculated as the average of daughter nodes' risks using the extension principle. Through this process, the risks, which cause die life to be shorter than for instances (that is, the risk rate of the top of all nodes), are calculated. Finally, the system predicts die life with interpolation using die life instances and the corresponding risks that shorten die life.
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  • Yozo HAMAGAMI, Naoyuki SEKINE, Masayuki NAKADA, Yasushi MIYANO
    2003 Volume 46 Issue 3 Pages 437-440
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The flexural fracture behavior of four kinds of CFRP laminates with the combination of heat-resistant thermosetting resin and PAN-based carbon fiber were investigated by three-point bending tests over a wide range of temperature and deflection rate. The flexural fracture behavior by the fractographs as well as the flexural strength strongly depend on the testing rate and temperature. The master curves for these strengths can be produced based on the time-temperature superposition principle. The time-temperature shift factor for the flexural strength of each laminates is quantitatively in good agreement with that for the stress-strain relation of the corresponding matrix resin. Therefore, it is cleared that the time and temperature dependence of flexural fracture behavior of heat-resistant CFRP laminates are mainly controlled by the viscoelastic behavior of matrix resin.
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  • Yoshitaka IWABUCHI
    2003 Volume 46 Issue 3 Pages 441-446
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper details the factors affecting mechanical properties of soft martensitic stainless steel castings that have lower carbon contents and increased nickel contents of up to 6% compared with normal martensitic stainless steel castings. The effect of alloying elements and impurities on the microstructural features and tempering characteristics was considered in detail, with special reference to reverted austenite and temper embrittlement. The mechanical properties were also investigated, and it was shown that the best combination of strength and toughness is obtained when tempered at around 900K. Addition of Mo was shown to improve toughness degradation due to slow cooling from the tempering temperature. Lowering P and S contents leads to superior toughness and fatigue properties. The threshold stress intensity range was shown to decrease with increasing stress ratio, depending on P content.
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  • Satoshi KISHIMOTO, Zhenlun SONG, Norio SHINYA
    2003 Volume 46 Issue 3 Pages 447-451
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    A metallic closed cellular material containing organic materials for smart systems has been developed. Polymer powder particles coated with a nickel-phosphorus alloy layer using electroless plating were pressed into green pellets and sintered at high temperatures in a vacuum. A metallic closed cellular material containing organic materials was then fabricated. The compressive, damping and ultrasonic tests were carried out to measure the mechanical, damping and ultrasonic properties of this material, respectively. The results showed that this material had different stress-strain curves among the specimens of different cell thickness, each stress-strain curve had a long plateau region, and the sintering temperatures of the specimens affected the compressive strength of each specimen. The internal friction and ultrasonic attenuation coefficients of this material were shown to be very large. These results indicate that this metallic closed cellular material can be utilized as a material for energy-absorbing and passive-damping systems.
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  • Akiyoshi KOBAYASHI, Michihide MACHIDA, Shigeo HUKAYA, Masatoshi SUZUKI
    2003 Volume 46 Issue 3 Pages 452-459
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The possibility of joining composite materials, conventional steel and lighter aluminum alloy, is tested using friction welding that preserves the natural environment greatly. The friction welding of aluminum alloy, Al-Mg (A5056), and carbon steel (S45C) are done under various experimental conditions and the friction welding characteristics are examined. The mechanical property (tensile strength) of the welded specimen has enough strength under the friction welding conditions of 1000rpm, the friction pressure of above 20MPa, the friction time of less than 1 second and a quite high upset pressure near the plastic flow pressure of A5056. The macroscopic and microscopic interface structures are also examined in relation to the friction welding conditions in order to clarify the joining mechanism of the interface between different materials by the friction welding. Moreover, the heat quantity during friction welding that relates closely to the generation of the inter-metallic compound and the joining mechanism is also examined. The amount of upset that relates closely to the mechanical properties of the welded specimen is also examined.
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  • Katsuhiro MAEKAWA, Tomohiro NISHII, Terutake HAYASHI, Hideo AKABANE, M ...
    2003 Volume 46 Issue 3 Pages 460-466
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    The present paper describes the application of Kansei Engineering to the physical design of engineering products as well as its realization by laser sintering. We have investigated the affective information that might be included in three-dimensional objects such as a ceramic bowl for the tea ceremony. First, an X-ray CT apparatus is utilized to retrieve surface data from the teabowl, and then a frequency analysis is carried out after noise has been filtered. The surface fluctuation is characterized by a power spectrum that is in inverse proportion to the wave number f in circumference. Second, we consider how to realize the surface with a 1/f fluctuation on a computer screen using a 3D CAD model. The fluctuation is applied to a reference shape assuming that the outer surface has a spiral flow line on which unevenness is superimposed. Finally, the selective laser sintering method has been applied to the fabrication of 1/f fluctuation objects. Nylon powder is sintered layer by layer using a CO2 laser to form an artificial teabowl with complicated surface contours.
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  • Hisanori FUJIEDA, Naoyuki SEKINE, Masayuki NAKADA, Yasushi MIYANO, Aki ...
    2003 Volume 46 Issue 3 Pages 467-472
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper is concerned with the influence of water absorption on the time-temperature dependent flexural strength of CFRP laminates. The CFRP laminates were prepared under three conditions of “Dry”, “Wet”, and “Wet+Dry”. The “Dry” laminates were obtained by holding the cured laminates in the oven at 150°C for 2 hours, the “Wet” laminates were obtained by soaking the “Dry” laminates in hot water at 95°C for 12, 24 and 48hours, and the “Wet+Dry” laminates were obtained by dehydrating the “Wet” laminates in the oven at 150°C for 2 hours. The constant strain rate (CSR) bending tests at various strain rates and temperatures as well as the creep test at various temperatures were carried out for these three kinds of laminates. The time-temperature dependence of flexural CSR strength and creep compliance of these laminates were obtained and the influence of water absorption on these strength and creep compliance were discussed. As results, the master-master curves of CSR strength as well as creep compliance were constructed based on the time-temperature-water absorption superposition principle.
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  • Hiroshi ASANUMA, Genji HAKODA, Takeshi MOCHIZUKI
    2003 Volume 46 Issue 3 Pages 473-477
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper describes fabrication of an active metal-matrix composite working at elevated temperatures. To realize this material, a SiC fiber reinforced nickel layer was laminated on a unreinforced nickel one with an aluminum insert. Fabrication condition of this material was examined and the most appropriate one, that is, hot-pressing temperature of 993K, pressure of 27MPa and time of 4.8ks in a low vacuum of 1×102Pa using a 0.1mm thick insert was obtained in the experimental range. Curvature of the composite monotonously changes with increasing temperature up to and higher than 1200K. A cyclic heating was also performed on the composite by increasing the maximum temperature from 373K up to 1273K in 100K steps, and it was found that its curvature change has no hysteresis up to 673K, and has hystereses but is reproducible at 773K and 873K, and is no longer reproducible when heated up to 973K and above.
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  • Hiroshi ASANUMA, Osamu HAGA, Junichiro OHIRA, Kyosuke TAKEMOTO, Masata ...
    2003 Volume 46 Issue 3 Pages 478-483
    Published: 2003
    Released: June 25, 2004
    JOURNALS FREE ACCESS
    This paper describes fabrication and evaluation of the active laminate. It was made by hot-pressing of an aluminum plate as a high CTE material, a unidirectional CFRP prepreg as a low CTE material and an electric resistance heater, a KFRP prepreg as a low CTE material and an insulator between them, and copper foils as electrodes. In this study, fabricating conditions and performances such as curvature change and output force were examined. Under optimized fabricating conditions, it became clear that 1) the curvature of the active laminate linearly changes as a function of temperature, between room temperature and its hot pressing temperature without hysteresis by electric resistance heating of carbon fiber in the CFRP layer and cooling, and 2) the output force against a fixed punch almost linearly increases with increasing temperature during heating from 313K up to around the glass transition temperature of the epoxy matrix.
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