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Takeo Chinen, Tosiya Takahasi, Teiko Okazaki, Yasufumi Furuya
Article type: Article
Session ID: J0405-4-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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We developed (Fe_<0.80>Ga_<0.15>Al_<0.05>)_<98.5>C_<1.5> [at.%] alloy which has high strength (more over 600MPa), but magnetostriction decreased to 40-50 ppm. Because A2 phase changes to Ll_2 phase (Fe_3GaC_<0.5>) by carbon addition. Ll_2 (Fe_3GaC_<0.05> or Fe_3Ga) is known for decreasing magnetostriction. The purpose of this study is to enhance the alloy which has equal amount of magnetostriction of Galfenol alloy (>100ppm)) and mechanical strength over 600MPa. Therefore we thought it is necessity to restrain the dramatic decrease of the A2 phase (aFe-(Ga,Al)) which has large magnetostriction effect. In this study, we developed the alloy which restrain the generation of Ll_2 phase by the addition of small amounts of carbon (C = 0.0, 0.5, 1.0 at.%), and investigated influence on magnetostriction and mechanical strength by the addition of small amounts of carbon.
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Kun'ichi MIYAZAWA, Kayoko HOTTA, Jun FUJII, Tokushi KIZUKA, Mami ...
Article type: Article
Session ID: J0405-5-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Short C_<60> nanowhiskers with similar lengths and diameters were successfully synthesized by the liquid-liquid interfacial precipitation method. Those fullerene nanofibers will be applicable to fabricate composite plastics with uniformly dispersed fillers with an excellent recyclability.
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Hiroyuki MIKI, Takanori TAKENO, Toshiyuki TAKAGI
Article type: Article
Session ID: J0405-5-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Partly-polished CVD diamond film shows low friction without lubricant. For that reason, this material is expected as a new sliding material. In this research, the diamond films with different surface roughness were prepared, and the friction wear tests were done in the environment which controlled humidity. When the surface roughness was low, friction coefficient dropped with the fall of relative humidity. On the other hand, when surface roughness was high, it turned out that a friction coefficient becomes high with humidity reduced. This paper discusses the origin of the difference in the value of these friction coefficients.
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K. Mizuuchi, K. Inoue, Y. Agari, M. Sugioka, Y. Morisada, M. Tanaka, T ...
Article type: Article
Session ID: J0405-5-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in solid-liquid coexistent state by Spark Plasma Sintering (SPS) process from the mixture of diamond and pure Al powders and that of diamond and 5056-type Al-Mg alloy powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated at 813K for 2.1 ks in SPS process. No reaction at the interface between the diamond particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the diamond-Al composite fabricated was 97% or higher in a volume fraction range of diamond between 25 and 45.5%. Thermal conductivity of the diamond-Al composite containing 45.5 vol.% diamond reached 403W/mK, approximately 76% the theoretical thermal conductivity estimated using Maxwell-Eucken's equation.
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Shihomi ABE, Wataru NAKAO
Article type: Article
Session ID: J0405-5-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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An increase in speed of self-crack healing of Al_2O_3/SiC composite by SiC nano-sizing was attempted. Self-crack healing of ceramics is induced by the high-temperature oxidation of SiC. The surface energy of SiC particles is increased by nano sizing of SiC, and the reaction rate of SiC oxidation increase. Two Al_2O_3/18 vol. % SiC, which average grain sizes composed SiC were 20-150 nm and more less than 10 nm were prepared in the present study. SiC oxidation temperature was measured by differential thermal analysis. Also self-crack healing behavior was investigated. SiC nano sizing was found to be able to accelerate the reaction rate of SiC oxidation. It was, however, found that excess SiC nano sizing made disadvantage to heal the introduced crack completely at any temperature.
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Taisuke SHIMIZU, Wataru NAKAO
Article type: Article
Session ID: J0405-5-5
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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A new methodology to improve thermal shock resistance of ceramics which utilizes self-crack-healing was proposed. Ceramics are anticipated to use as high-temperature materials, because they have higher refractoriness compared to metal materials. However ceramics have low thermal conductivity and low fracture toughness, therefore thermal shock and thermal fatigue could be critical fracture pattern. In the present study, it is attempted that the thermal shock resistance is improved by healing surface cracks which are initiation of the crack propagation due to thermal stress. Mullite containing 15 vol. % SiC particles composite which has excellent self-crack-healing ability was used for the present study. From the results, the surface cracks introduced by thermal shock avoided the crack healed zone, the critical temperature difference could be improved by healing the surface cracks, and the surface cracks introduced by thermal shock could be healed. Thus the thermal shock resistance of ceramics could be improved by using self-crack-healing. Furthermore these results imply self-crack-healing has the longer thermal fatigue lifetime ability.
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Satoshi KISHIMOTO, Toru SHIMIZU, Fuxing YIN
Article type: Article
Session ID: J0405-6-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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A metallic closed cellular material containing polymer has been fabricated. Metallic closed cellular materials containing polymer were then fabricated. The compressive tests were carried out to measure the mechanical properties of these materials. The results showed that these metallic closed cellular materials have different strength among the specimens that containing different polymers.
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Mitsuhiro KIBE, Hiroshi ASANUMA
Article type: Article
Session ID: J0405-6-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This paper describes the effect of humidity on the shape of the active laminate. The active laminate 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 unidirectional GFRP prepreg as an insulator between them and copper foils as electrodes. The hollow channels were formed in the GFRP layer. In this study, it was found that the curvature of the active laminate is increased by moisture absorption and this increase is enhanced by formation of the hollow channels in the GFRP layer.
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Tomohiro SUZUKI, Mitsuhiro KIBE, Hiroshi ASANUMA
Article type: Article
Session ID: J0405-6-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This paper describes the evaluation of heating and cooling characteristics of the active laminate having hollow channels. 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 unidirectional GFRP prepreg as an insulator between them and copper foils as electrodes. The hollow channels were formed in the GFRP layer. Firstly, the effects of formation of the hollow channels on the time for air cooling and forced cooling, that is, air-flow cooling and water-flow cooling, were investigated. The cooling rate of the active laminate having one hollow channel was improved with increasing its volume fraction up to 0.9, and it was greatly improved by water-flow cooling. Secondly, the effect of the hollow channels on the time constant for heating was examined, and it was clarified that the time constant is not significantly affected by them.
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Jun KUNIKATA, Tetsuro YANASEKO, Hiroshi ASANUMA
Article type: Article
Session ID: J0405-6-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This paper presents fabrication of an aluminum-based piezoelectric composite using hollow piezoelectric ceramic fiber. As the piezoelectric ceramic fiber is very fragile, the interphase forming/bonding (IF/B) method proposed by Asanuma was applied for embedding it in an aluminum matrix without losing its functions, and also forming an internal electrode inside the hollow fiber by filling the Al-Cu alloy produced during the IF/B process. In order to clarify the forming process of the internal electrode, the effects of hot-pressing condition and process on forming rate of the electrode were investigated. According to the results, most of the electrode is found to be composed of the Al-Cu alloy produced during the holding of the hot-pressing at 873 K. The filling rate in the hollow with the produced Al-Cu alloy attained to almost 100 % at around the hot-pressing period of 3.0 ks.
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Toshihiro OHTANI, Hiroyuki YAGI, Tsubasa SATO, Fuxing YIN
Article type: Article
Session ID: J0406-1-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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We studied the ultrasonic characterization in a high damping alloy, called M2052, which is the manganese-based alloy containing copper, nickel and iron with electromagnetic acoustic resonance (EMAR). We measured free vibration resonance frequencies and attenuation coefficients at room temperature with EMAR. EMAR is a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). The measurement of attenuation coefficient is inherently free from any energy loss, resulting in pure attenuation in a metal sample. The ultrasonic characterizations, especially, ultrasonic attenuation, of M2052s served several kind of heat treatment are discussed
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Kouzo MATSUMOTO, Yusaku FUJITA, Tetsuya KAWAMOTO, Hirotsugu OGI, Masah ...
Article type: Article
Session ID: J0406-1-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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We developed the picosecond ultrasound spectroscopy for measuring mechanical resonance frequencies of sub-terahertz frequencies in nanostructures, including ultrathin films and nanowires. It uses the pump-probe technique with ultrafast light pulses for generation and detection of picosecond ultrasound vibrations. The mechanical responses are applied to the detection of proteins in liquid through the antigen-antibody reaction. 20 nm Pt thin films and 100 nm SiN thin films were used as the oscillators. Staphylococcus aureus protein A and anti-human immunoglobulin G (hIgG) antibody were used as the receptor proteins and they were immobilized on the oscillator surfaces. hIgG molecules were then detected in the homebuilt flow injections system.
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Kenichi TANIGAKI, Hirotsugu OGI, Masahiko HIRAO, Kazuhito MATSUKAWA, H ...
Article type: Article
Session ID: J0406-1-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The concentration and size of oxygen precipitations in Si wafers which called bulk microdefects (BMD) affect the electrical and mechanical properties of devices. Recent device miniaturization requires the evaluation of BMDs with a nondestructive manner. In this study, we propose to inspect those nano-defects from the stiffness change at local regions of Si wafers measured by ultrahigh-frequency acoustic waves. Brillouin oscillations provide the stiffness showing high sensitivity to thin defects such as BMDs. Application of an ultrafast light pulse to the specimen generates the acoustic phonon pulse. We then irradiate the specimen with the time-delayed light pulse. which is diffracted by the phonon pulse, and its reflectivity change shows oscillations. This oscillation frequency gives the longitudinal-wave velocity, from which the elastic stiffness is obtained. Our results indicate that the nano-defects decrease the out-of-plane elastic constant of the Si wafer, confirming that this methodology can be a powerful tool for quantitative evaluation of BMDs.
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Yasuhiro KAMADA, Nobutomo NAKAMURA, Hirotsugu OGI, Hiroaki KIKUCHI, Sa ...
Article type: Article
Session ID: J0406-1-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Ultrasonic characteristics of neutron-irradiated reactor pressure vessel (RPV) steels and model alloys were investigated by resonant ultrasound spectroscopy (RUS). Specimens were neutron-irradiated at the Japan Materials Testing Reactor at 290℃ up to a fast neutron fluence of 5×10^<23> n/m^2 (E>1MeV), and isochronal annealed at temperature ranges from 360℃ to 570℃ at 70K interval for 30 min. Both Vickers hardness and RUS measurements were carried out after each post-irradiation annealing (PIA). The effects of irradiation on elastic constants are discussed.
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Shigehiko CHIGUSA, Yasuhiro KAMADA, Toshihiro OHTANI, Hiroaki KIKUCHI, ...
Article type: Article
Session ID: J0406-1-5
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The purpose of this study is to investigate the elastic properties of thermally aged Fe-Cu model alloys by the electromagnetic acoustic resonance (EMAR) method and to clarify the underlying mechanism. Fe-lwt.%Cu alloys, in supersaturated Cu solid solution, were prepared. The specimens were isothermally aged at 773K up to 10^4 min and isochronally aged for 30 min up to 973K. Resonant ultrasound spectra were obtained in both aging procedures. The aging time dependence of resonance frequencies of isothermally aged specimens, which relates to the elastic constants, showed an increasing behavior. This is different from the peaking trend of the hardness and attributable to the increase of the elastic constant due to Cu solute depletion in the matrix during the precipitation process. This study suggests the possible application of the EMAR method for nondestructive characterization of the matrix state of irradiated RPV steels.
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Nobutomo NAKAMURA, Yosuke KAKE, Hirotsugu OGI, Masahiko HIRAO
Article type: Article
Session ID: J0406-1-6
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Elastic stiffness of ultrathin films is studied by the pump-probe technique using the femtosecond light pulse. This method generates the longitudinal sub-terahertz ultrasonics by the irradiation of the specimen with the femtosecond light pulse, and they are preferentially detected by the probing pulse. When the film thickness is relatively small, longitudinal standing waves are generated in the thickness direction. For the thicker films, the sub-terahertz longitudinal-wave pulses are generated near the film surface, propagate in the thickness direction, and reflect at the interface between the film and substrate. By measuring the resonance frequencies and round-trip time, the elastic stiffness is determined. In this study, it is found that the elastic stiffness of polycrystalline Pt films on MgO substrates shows the relationship with the residual strain. The change ratio is significantly large and it is confirmed that the conventional acoustoelasticity cannot explain it quantitatively.
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Kazuyuki NAKAHATA, Sohichi HIROSE
Article type: Article
Session ID: J0406-2-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The ultrasonic testing (UT) for an austenitic steel with welds is difficult due to the acoustic anisotropy and local heterogeneity. The ultrasonic wave in the austenitic steel is skewed along crystallographic directions and scattered by weld boundaries. For reliable UT, a straightforward simulation tool to predict the wave propagation is desired. Here a combined method of elasto-dynamic finite integration technique (EFIT) and digital image processing is developed as a wave simulation tool for UT. In our simulation, a picture of the surface of the steel bar with a V-groove weld is scanned and fed into the image based EFIT modeling. An example of a two dimensional simulation of a phased array UT in an austenitic steel bar is demonstrated.
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Hironori TOHMYOH, AKANDA Md. Abdus Salam, Masumi SAKA
Article type: Article
Session ID: J0406-2-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This study describes the sensitivity of acoustic microscopy for detecting three-dimensional defects in a Si structure. A number of nanometer height circular gaps with diameters ranging from 5 to 1000 μm were successfully embedded in Si disks by a direct bonding technique, and these were tested with different conditions of acoustic imaging. The sensitivity of gap detection is found to be dependent the three-dimensional features of the embedded defects, their positions, and the intensity of ultrasound applied to the gaps. The acoustical interaction with nanometer gaps is interpreted by a simple mechanical model.
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Hiroyuki WAKI, Satoshi KUBO, Hirotsugu OGI
Article type: Article
Session ID: J0406-2-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Heat resistant coatings have been used in gas turbine blades and combustors. Three points supported resonance ultrasound spectroscopy (RUS) method was expanded to high temperature measurement in order to clarify the high temperature elastic moduli of heat resistant coating. Resonance spectrum was measured up to 1073K by the equipment with induction heating and remote sensing by laser-Doppler interferometry, which was originally developed. It was found from the measurement of atmospheric plasma sprayed CoNiCrAlY coating as follows: (1) The Poisson's ratio was high if the spraying powder was large. (2) The Poisson's ratio scarcely changed by thermal treatment differently from Young's modulus.
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Hideo CHO, Yasushi TAMURA, Takeshi YASUI, Takuma MATSUO
Article type: Article
Session ID: J0406-2-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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We simultaneously monitored active corrosion under the insulation by using acoustic emission technique and humidity measurement. AE was produced by rust fracture induced by progression of corrosion. Humidity measurement was carried out with hydrophilic polymer coated plastic fiber. As optical index of the polymer depends on the humidity, transmitting light energy was changed by outside humidity. The sensor could be used to measure humidity of 65 to 95 %RH at 70℃. We monitored active corrosion under the insulation under wetting and drying cycle. Most AE signals were produced by the drying process in each cycle. Source locations of AE signals agreed well with corrosion area.
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Yudai TAKAYAMA, Takahiro SASAKI, Tubasa KANERURA, Takuma MATUO, Hideo ...
Article type: Article
Session ID: J0406-2-5
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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We developed a highly sensitive and stable optical fiber AE monitoring system equipped with two functions which compensated the phase and polarization differences between object and reference beams. The phase control was achieved by changing the length of the reference fiber with PZT actuaior glued on the reference fiber to compensate low frequency vibration. Additionally, we simultaneously controlled the polarization of the object beam to coincide polarization of object beam with that of reference beam by a polarization controller. We applied the developed system to monitor AE while welding two steel plates. As the result, we succeed in detecting AE during welding and cooling process.
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Yoshihiro MIZUTANI, Sota SUGIMOTO, Akira TODOROKI, Ryosuke MATSUZAKI
Article type: Article
Session ID: J0406-2-6
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This study examined the applicability of acoustic emission testing (AT) for the impact damage evaluation of CFRP pressure vessels. AE signals were detected during pressurization tests of CFRP pressure vessels before and after an impact test. The impact test of 15-J energy was conducted by using a drop-weight impact tester. Before the impact test, a few AE signals were detected during the pressurization test. After the impact test, however, a large number of AE signals were detected during the pressurization test. From these results, it is assumed that AT can be used for the impact damage evaluation of CFRP pressure vessels. In addition, the dominant frequencies of AE signals were changed after the impact test. So there is a possibility that impact damage could be also detected by analyzing the frequency of AE signals.
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Manabu TAKAHASHI, Ikuo IHARA
Article type: Article
Session ID: J0406-3-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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An ultrasonic method has been applied to internal temperature measurements of heated materials during casting process. The principle of the method is based on the temperature dependence of the velocity of ultrasonic wave propagating through a material. An inverse analysis coupled with a finite difference calculation is used to determine a one-dimensional temperature distribution. In this work, an attempt to monitor both temperatures of a solidifying alloy and a die during casting process has been made. A low melting-point alloy is employed as the melt. Ultrasonic pulse-echo measurements are performed and the changes in the transit times of the reflected echoes through the die and the alloy are continuously acquired, and then the temperature distributions inside the die and the alloy have been estimated during the casting process.
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Hiroyuki YAMADA, Manabu TAKAHASHI, Ikuo IHARA
Article type: Article
Session ID: J0406-3-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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A new ultrasonic method for measuring two-dimensional temperature distribution on a material surface is presented. The method provides non-contact measurements of surface temperature. The principle of the method is based on surface acoustic wave (SAW) measurements using a laser-ultrasonic technique and its two-dimensional scanning on a material surface. The surface temperature distribution is basically determined by an effective method consisting of SAW measurements and an inverse analysis coupled with a one-dimensional finite difference calculation. The ultrasonic method has been applied to the surface temperature measurement of an steel plate whose single side is being heated. The surface temperature distributions determined by the ultrasonic method almost agree with those measured using an infrared camera.
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Koichiro Kawashima, Ryusuke Imanishi
Article type: Article
Session ID: J0406-3-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The sizing of IGSSC in Ni-based alloy weld by the conventional UT technique is very difficult because the backscattered echoes from the coarse grain boundaries often hide the echo from IGSSC. Then, the validity of the higher harmonic imaging technique is demonstrated for detecting and sizing IGSCC in Ni-based alloy weld. The IGSCC was imaged by the normal and oblique incidence techniques. The higher harmonic images of the IGSSC show higher contrast and spatial resolution than those with the conventional UT.
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Yoshio ARAI, Daiki KAWAMOTO, Wakako ARAKI
Article type: Article
Session ID: J0406-3-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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A new method is proposed to detect a tilted planar flaw on the back surface of a plate using the interference of ultrasonic waves. Parameters for flaw evaluation are developed and examined through experimental results for artificial flaws. The existence of the flaw and its height are estimated by parameter B_h, which shows the first amplitude of the interference fringe. The effect of tilt angle of the flaw on parameter B_α, which indicates the amount of asymmetry of the interference fringe along the direction normal to the flaw, is investigated. Flaw with a tilt angle of 60 deg from the normal direction of the inspection surface having 1 mm length can be detected using the present method.
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Kyoji HOMMA, Makoto TAKAHASHI, Hiroki YOSHIDA, Michihito AOKI, Takuji ...
Article type: Article
Session ID: J0406-3-5
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Present paper suggests a new ultrasonic inspection technique to classify the defects occurred by casting of cast steel using the neural network. Reflected echo waves are hard to discriminate the defects by the way of wave observation because of receiving the strong effect of surface roughness. Learning and classification of neural network for the subject of both vacancy defect and gas defect were carried out to the reflected echo. Defects could be classified by specifying the ratio of defect and non-defect as well as the number of learning data.
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Hiroshi Yamamoto, Naoya Kawakami, Takahisa Maruyama, Hiroaki Yanagimot ...
Article type: Article
Session ID: J0406-3-6
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The semiconductor package in now a day has advanced 3-dimension structure with multi-layer silicon chip, and every layer is extremely thin. For example, the memory chip often has tens layers for large memory space and small size. So the advanced analysis technology for ultrasonic imaging system become important, and the development of the technology is needed instantly. In this paper, a pseudo-defect sample in a multi-layer package is prepared for experimental and theoretical analysis. It is noticed that the residual vibration component in later part of signal shows a little difference between the normal package and that with defect. The difference is considered to be caused by the defect. Two type image processing methods for making clear S/N of the small difference are discussed. (1) to abstract the difference in frequency domain, (2) to abstract the difference in time domain. The result shows even so only the simple signal processing method is used, the image of detect become more clear than before.
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Tetsuya MORISAKI, Zhongwei JIANG, Kazuhiro ODA, Koichi YOSHITSUGU
Article type: Article
Session ID: J0406-4-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Structures have the potential for a damage accumulation and unpredicted failure. In order to guarantee a stable service and prevent any fatal flaw, it is important to monitor the condition of them. On the other hand, it implies increasing the maintenance costs. From such a background, the concern with Low-Cost Structural Health Monitoring System has been growing. This report presents the development process of the not only low-cost but also small and on-site measurement device based on the pulse-echo method, which is consisted of a microcomputer, PZT, power supply and some cheap amplifiers and parts. The trial production was verified in experiments using steel plates that the crack can be characterized quantitatively. The result shows that the proposing device has enough capability for achieving the above object.
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Yasuhiro TANAKA, Toyokazu KOMATSU, Kenichi YOSHIDA, Hideo NISHINO
Article type: Article
Session ID: J0406-4-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This paper describes evaluation of obliquely stretching defect using guided waves propagating in pipes detections. Piezoelectric sensor ring having 16 sensor elements was used to generate and detect the T(0,1) mode guided waves. The inclination angles of the defects were set to be 0°, 20°, 40° and 60° to the axial direction of the pipes. In this paper, the signal amplitudes were shown as a function of the defect depth gradually increased in the experiments. The obtained results showed that the sensitivities of the defects were not so much different between the defects having 0°, 20°, 40° inclinations. Conversely, as for the 60° defect, sensitivity was a little bit poor and a unique phenomenon was observed comparing to the other defects.
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Toyokazu KOMATSU, Yasuhiro TANAKA, Kenichi YOSHIDA, Hideo NISHINO
Article type: Article
Session ID: J0406-4-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Evaluations of axially increasing defects have been carried out with guided waves in 50A pipes. A piezoelectric ring shaped sensor was used to generate and detect the guided waves. Two types (rectangular and round) of defect shapes were evaluated in the experiments. Obtained amplitude was not monotonically increased but was fluctuated with the increase of axial length of the defect. The mechanism of this phenomenon minutely discussed.
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Toshiro TANAKA, Shuichi MASUDA, Kenichi YOSHIDA, Hideo NISHINO
Article type: Article
Session ID: J0406-4-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Experimental investigation of mode conversions of a guided wave in a pipe through an elbow has been carried out. Based on the particle displacement of the guided wave modes, the mode conversions from the T(0,1) mode to circumferentially higher order modes, the T(1,1) and T(2,1) modes, were confirmed. The experiments were carried out with 8 sensor elements located circumferential positions to detect the modes. A simple signal processing method for preferential detection for each mode was shown.
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Shuichi MASUDA, Toshiro TANAKA, Kenichi YOSHIDA, Hideo NISHINO
Article type: Article
Session ID: J0406-4-5
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Sensitivity of defect detections using guided waves through elbow pipes has been experimentally evaluated. The T(0,1) mode guided wave was used for the evaluations. The sensor system was cramped on the straight part of the two straight parts welded to the both sides of elbow part. The artificial defects were introduced at the other straight part. To evaluate the sensitivities, artificial defects were gradually increased by 0.05 mm step. Many spurious signals were confirmed due to the welds and elbow. It was also confirmed that the sensitivity decreased to 1/3-1/4 compared to the straight pipes.
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Keiji OGURA, Akira SATOH, Kenichi YOSHIDA, Hideo NISHINO
Article type: Article
Session ID: J0406-4-6
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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A novel method called Multireflecting Guided wave Energy Trapping (MGET) Method has been developed for highly efficient defect detection in pipes and piping. In this method, sensitivity of defect detection is drastically improved, however its inspection area is restricted between the two reflectors placing on appropriate positions of pipe. When the guided wave is trapped and multireflected between the two reflectors, n combination of propagation paths having same path length are principally existed at n times multireflections. Therefore the defect signals were accumulated to be overlapped n times. Details of the principle and experimental demonstration are shown. The sensitivity of the MGET method was evaluated about 14 times larger than that of the conventional guided wave method.
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Dong-Yeul SONG, Kei Yoshii, Taito Izaki, Shinji Ogihara, Tsutomu Kasah ...
Article type: Article
Session ID: J0407-1-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Pull out specimen of single fiber bundle (diameter of about 50-70μm), which is bundled with filaments with diameter of about 12μm, was fabricated using different surface-treated silk fibers and biodegradable PBS(Polybutylene succinate) plastic, and interfacial strength between silk fiber and PBS matrix was evaluated using pull out specimens. Three types of surface treatment were the untreatment, the about 45% removal of the content of sericin covered on the silk fiber(fibrous) and the "ensui processing" of silk fiber. Unidirectional silk fiber/PBS composites and injection molded silk short fiber/PBS composites were fabricated, and their mechanical properties were investigated and characterized with regard to the surface treatment and content of fiber using these specimens. As a result, it is found that the mechanical properties of composites have a close relation with the change of the interfacial strength and the content of fiber.
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Hitoshi TAKAGI, Takehito Mori
Article type: Article
Session ID: J0407-1-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Formabilities and mechanical properties of resinless bamboo fiber green composites were experimentally investigated by changing molding conditions; temperature and pressure. The green composites composed of only bamboo fibers which obtained from a steam explosion method were fabricated by a hot-press method. The molding temperature has a much greater effect on the mechanical properties such as tensile property and bending property. Molding pressure has an insignificant effect on tensile and bending strength of green composites. Fracture elongation of the composites tends to decrease with rise of temperature above 140℃ due to the decreasing of the strength of single fiber bundle during hot-pressing.
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Kazuya Okubo, Toru Fujii, Shigeyuki Suzuki
Article type: Article
Session ID: J0407-1-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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This paper discussed the differences of elastic modulus of paper fabricated with the bamboo single fibers. The separated bamboo fibers were alkali treated after the extraction from Moso bamboo trees, in which their age was between 2 months to 4 years old, respectively. Specific elastic modulus and dimensions of single fibers according to the age of bamboo were investigated. The bamboo paper was processed with a heat press technique using the selected wet bamboo fibers after the filtration. Superior property on specific elastic modulus of the paper was obtained when the young Moso trees were selected for the material of paper. The result was introduced due to high aspect ratio of single fibers in which the number of connections would be increased between single fibers rather than due to improvement of specific modulus of single fibers according to high content of cellulose shown in young bamboo tree.
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Kenichi MATSUSHIGE, Masahiro ITO, Koichi GODA, Junji NODA, Kenji AOKI, ...
Article type: Article
Session ID: J0407-1-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The purpose of this study is to develop a natural fiber reinforced polymer matrix composite with high strength and stiffness, in order to apply biomass resources for practical use. A MAPP-included polypropylene resin was used as a matrix of the composite, and extruded with 5 and 10 wt% ramie short fibers. In this extrusion the composites were fabricated as a thin sheet, and treated with cyclic loading application to increase the strength and stiffness of the reinforcement. The results show that the composites were improved in tensile strength and Young's modulus after the treatment. Especially, Young's modulus of the composites increases 52% higher at 90° direction after bi-axial cyclic loading treatment. Through this treatment the composites are also improved in strength at bi-axial directions.
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Kenichi TAKEMURA
Article type: Article
Session ID: J0407-2-1
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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In this study, molding condition and tensile properties of jute fiber reinforced composite were examined. Before tensile test, specimens have an offset twist. As a result, following results are obtained. In the case of jute fiber, the effect of twist deformation to tensile strength is not great. As the molding temperature increases, the strength of the composite increases. The reason is the crystallization in the matrix. When the molding temperature is so high, fiber has degradation, and the strength of the composite decreases. As the degree of twist increases, the strength decreases due to the delamination.
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Tomoyuki MINENO, Toru SAWAI, Takashi HAYAMI, Mitushi OMASA, Noriyasu H ...
Article type: Article
Session ID: J0407-2-2
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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Extrusion experiments for pruned branches from fruit tree and Japanese cedar thinning were conducted at a uniform press speed. The results obtained in the present study are as follows. (1) The formability in extrusion process is significantly affected by the forming temperature and moisture contents of samples. The molding defects are observed at a forming temperature below 120 degree C for the moisture content of 17%. It is considered that the expansion of moldings is due to the residual free water. (2) The dynamic equilibrium load decreases with increasing forming temperature and moisture content. The temperature for the thermo-fluid phenomena of wood powder depends on tree species. It is found that the forming temperature for the branches of Japanese apricot and persimmon is lower than that for Japanese cedar.
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Haruhiro INO, Lixia JIN, Teruo KIMURA
Article type: Article
Session ID: J0407-2-3
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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The utilization renewable resource "biomass" becomes more important in recent society. Silk fiber is one kind of natural material and which possess high tensile strength and remarkable elongation property. Although silk is expensive material, many waste silk are discharged as mill ends in silk textile factory. Therefore the recycling of waste silk contributes efficient utilization of natural resource and it lower cost of material. To make fibroin compact, silk fibroin was dissolved in neutral salt solution and dried to make powder. In addition, to enhance mechanical strength of fibroin compact, silk fabric was inserted into fibroin compact to make all-fibroin composite. Herein, degummed silk fiber was dissolved by CaCl_2/ethanol/water solution and dialyzed in distilled water and was freeze-dried to obtain fibroin powder. Silk fabric and fibroin powder were laminated alternatively and were moisturized. They were hot-pressed in mold at 80℃ 0.5 hour and then at 150℃ 2.5 hour. Thus all-silk fibroin composite was obtained. Tensile strength of composite was measured and dependency on molding conditions and fiber content was considered.
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Yoshihito OZAWA, Tokio KIKUCHI, Masayoshi WATANABE, Koichi YABUKI
Article type: Article
Session ID: J0407-2-4
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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In this paper, the fabrication method and mechanical and wear properties of Carbon/Carbon composites from Bacterial Cellulose (BC) Form/Polymer composites is investigated. The effects of material properties and configurations on the properties of BC composites were discussed, and three dimensional micro structure for strengthening in BC composite was also considered. A fabrication method of Carbon/Carbon composites with BC form, in which BC microfibril network of three dimensional structure of nano-scale and their bonding conditions remain, was developed. The experimental results of wear characteristics were shown for the nano-Carbon/Carbon composites from BC. Wear tests of the composites were conducted under dry sliding condition. The coefficient of wear took the low values of 0.17-0.18 during the tests. It reveals that the composites have excellent wear property in comparison with silicon nitride ceramics and the diamond-like carbon (DLC).
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Article type: Appendix
Pages
App4-
Published: September 12, 2009
Released on J-STAGE: August 01, 2017
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