MF研究者総覧

研究者データベース

詳細
高橋　航圭(タカハシ　コウスケ)
工学研究院　機械・宇宙航空工学部門　機械材料システム
准教授
researchmap個人ページ
Last Updated :2024/05/09

基本情報

所属

  • 工学研究院　機械・宇宙航空工学部門　機械材料システム

職名

  • 准教授

学位

  • カリフォルニア大学ロサンゼルス校
  • Ph.D. in mechanical engineering

ホームページURL

J-Global ID

研究キーワード

  • 材料強度学   破壊力学   接着・接合   複合材料   

研究分野

  • ナノテク・材料 / 複合材料、界面
  • ものづくり技術（機械・電気電子・化学工学） / 材料力学、機械材料

担当教育組織

職歴

  • 2016年03月 - 現在 北海道大学 准教授
  • 2011年07月 - 2016年02月 東京工業大学 助教

学歴

  • 2008年09月 - 2011年06月   カリフォルニア大学ロサンゼルス校   機械工学専攻
  • 2006年04月 - 2008年03月   東京工業大学大学院   理工学研究科機械物理工学専攻
  • 2000年04月 - 2006年03月   東京工業大学   工学部機械宇宙学科

所属学協会

  • 日本接着学会   日本複合材料学会   日本材料学会   日本機械学会   

研究活動情報

論文

  • Kosuke Takahashi, Zhantong Sun, Takuma Kikuzawa, Kounosuke Shimamura, Sourabh Jagrat, Nao Fujimura, Takashi Nakamura
    Advanced Composite Materials 1 - 17 2023年11月20日 [査読有り][通常論文]
  • 舩木 優大, 藤村 奈央, 中村 孝, 髙橋 航圭, 和島 達希
    日本金属学会誌 87 11 305 - 308 2023年11月01日 [査読有り][通常論文]
  • Gaoge Xue, Takashi Nakamura, Nao Fujimura, Kosuke Takahashi, Hiroyuki Oguma, Akihisa Takeuchi, Masayuki Uesugi, Kentaro Uesugi
    International Journal of Fatigue 170 107571 - 107571 2023年05月
  • Masako Yamada, Kosuke Takahashi, Nao Fujimura, Takashi Nakamura
    Engineering Fracture Mechanics 271 2022年08月 [査読有り]
     
    The peel tests of pressure-sensitive adhesive (PSA) tapes were conducted to clarify the effect of the peel velocity, peel angle, and tape thickness. We focused on the viscoelastic deformation of the PSA layer and its relationship with the adhesion energy. It was found that, at a sufficiently low strain rate of the PSA layer, the adhesion energy has a threshold value of debonding. In addition, the increase of adhesion energy from the threshold value is proportional to the maximum stretch of the PSA layer and follows a power law relationship with the strain rate. The general relationship between the adhesion energy and the strain of PSA layer, independent from the peel angle and tape thickness, was established.
  • Kosuke Takahashi, Ryosuke Shoya, Takuma Matsuo, Wataru Sato, Takashi Nakamura, Akihisa Takeuchi, Masayuki Uesugi, Kentaro Uesugi
    Scientific Reports 12 1 2022年05月 [査読有り]
     
    The initial stage of fatigue failure has not been thoroughly clarified for carbon fiber reinforced plastics (CFRPs). Although the initiation of fatigue cracks has been regarded to be interfacial debonding between the carbon fiber and polymer matrix, their detection among numerous carbon fibers, whose diameter is only 7 µm, is extremely difficult. In this study, a single carbon fiber was transversely embedded in a dumbbell-shaped epoxy sample to focus on the interfacial debonding and was observed using synchrotron radiation (SR) X-ray computed tomography (CT). A tabletop fatigue testing machine driven by a piezoelectric actuator was developed to apply static and cyclic loads along the beamline. SR X-ray multiscale CT imaging was conducted by switching between an absorption-contrast projection method (micro-CT) and a phase-contrast imaging-type X-ray microscopic CT (nano-CT). The carbon fiber was entirely captured by micro-CT and then magnified at both ends on the free surfaces. Nano-CT clearly visualized the interfacial debonding under 30 MPa static tensile load and the implication of the coalescence of nano-voids along the interface under 50 MPa. Under cyclic loads, the interfacial debonding gradually progressed under a 8–40 MPa sinusoidal stress after 10,000 cycles, whereas it did not propagate under a stress below 30 MPa.
  • Gaoge Xue, Takashi Nakamura, Nao Fujimura, Kosuke Takahashi, Hiroyuki Oguma, Akihisa Takeuchi, Masayuki Uesugi, Kentaro Uesugi
    Engineering Fracture Mechanics 263 108308 - 108308 2022年03月 [査読有り]
  • Gaoge Xue, Yuta Tomoda, Takashi Nakamura, Nao Fujimura, Kosuke Takahashi, Fumiyoshi Yoshinaka, Akihisa Takeuchi, Masayuki Uesugi, Kentaro Uesugi
    Fatigue and Fracture of Engineering Materials and Structures 2022年 [査読有り]
     
    Two types of synchrotron radiation computed tomography (SR-CT)—projection CT (micro-CT) and phase-contrast imaging CT (nano-CT)—were used to observe internal fatigue cracks in (α + β) Ti-6Al-4V alloy. Micro-CT detected cracks in the specimen at ~1 μm spatial resolution, and the nano-CT provided magnified images at ~200 nm spatial resolution. The crack initiation sites were clarified as the α-phase for both the surface and internal cracks; however, their opening behaviors differed. A sharp crack tip was observed in the surface crack, and the crack tip opening displacement (CTOD) increased with an increase in the applied load. By contrast, a blunted crack tip, similar to that of a crack in a vacuum, was observed for the internal crack, and its CTOD remained almost constant regardless of the applied load. These phenomena are likely to explain the different behaviors of surface and internal cracks, particularly the slower growth rate of internal cracks, which leads to a longer fatigue life in the very high cycle fatigue regime.
  • Kosuke Takahashi, Futoshi Yanai, Kazuaki Inaba, Kikuo Kishimoto, Yuichi Kozone, Toshio Sugizaki
    Langmuir 37 39 11457 - 11464 2021年10月05日 [査読有り][通常論文]
  • Ryosuke SHOYA, Takuma MATSUO, Kosuke TAKAHASHI, Nao FUJIMURA, Takashi NAKAMURA
    Journal of the Japan Society for Composite Materials 47 5 186 - 193 2021年09月15日
  • 放射光 X線ナノ CT を用いたその場引張・疲労試験による炭素繊維－エポキシ樹脂の界面はく離検出
    勝谷亮介, 松尾拓磨, 髙橋航圭, 藤村奈央, 中村孝
    日本複合材料学会誌 47 5 186 - 193 2021年09月 [査読有り][通常論文]
  • Gaoge Xue, Takashi Nakamura, Nao Fujimura, Kosuke Takahashi, Hiroyuki Oguma
    Applied Sciences 11 1 131 - 131 2020年12月25日 [査読有り][通常論文]
     
    Uniaxial fatigue tests were conducted for a β titanium alloy Ti-22V-4Al up to a very high cycle fatigue (VHCF) regime. The initiation and propagation processes of the internal fatigue cracks were investigated using 3D fractographic analysis. Multiple facets were observed at the crack initiation site. Three facet initiation models were proposed based on the surface appearances and the 3D facet bonding patterns of the multiple facets, and the major facet was determined to be the true crack initiation site. Using the size of the major facet, a Tanaka–Akiniwa model, which can determine the material constants for the Paris law using only conventional fatigue tests, was applied to reveal the propagation process of the internal cracks. A reverse fatigue life prediction was also conducted to evaluate the accuracy of the material constants obtained using the Tanaka–Akiniwa model. When the facet initiation models were applied, the predictions showed less deviation and better agreement than when the facet initiation process was not considered. The findings of this study indicate that the formation of multiple facets in β titanium alloys is sequential rather than simultaneous.
  • Sae Obata, Kosuke Takahashi, Kazuaki Inaba
    Composite Structures 253 112787 - 112787 2020年08月 [査読有り]
  • Kosuke Takahashi, Ryuto Oda, Kazuaki Inaba, Kikuo Kishimoto
    Soft Matter 16 28 6493 - 6500 2020年06月 [査読有り]
     

    Scaling effect of adhesion force at detachment was clarified by a probe-tack test using a glass sphere at mm-scale and an AFM cantilever.

  • Nao Fujimura, Koyo Ooga, Kosuke Takahashi, Takashi Nakamura, Tatsuki Wajima
    MECHANICAL ENGINEERING JOURNAL 7 4 2020年 
    A machined material has a work-hardened layer at its surface. In this study, a surface modification technique, the scanning cyclic press (SCP), was applied to machined specimens of magnesium alloy, AZ31, to investigate whether SCP can improve its fatigue properties regardless of the surface finish. During the SCP process, a vibrating indenter reciprocally scanned the specimen's surface, and it applied cyclical low-compressive loadings to the surface for 8 x 10(6) cycles. After applying SCP, the surfaces of the specimens were observed using a laser scanning microscope, and the surface roughness was measured. The surface observation and surface roughness measurement showed that the changes in the surface state after applying SCP were relatively small and the surface roughness after applying SCP was more homogenous than before applying SCP. Uniaxial push-pull fatigue tests were conducted for SCP-treated specimens and untreated specimens. The test results showed that the fatigue life of SCP-treated specimens was longer than that of untreated specimens. To clarify the reason for the improvement effect, the fracture surfaces were observed using a scanning electron microscope (SEM). The SEM observation showed that the fracture morphology was different between the SCP-treated specimen and the untreated specimen. In the SCP-treated specimen, fatigue fracture origins were sub-surface, while the untreated specimen fractured at the surface. These results suggest that SCP could improve the fatigue properties of AZ31 regardless of the surface finish of the specimen before SCP.
  • Kosuke Takahashi, Takahiro Matsuo, Kazuaki Inaba, Kikuo Kishimoto
    Journal of Microelectromechanical Systems 28 4 685 - 694 2019年08月 [査読有り]
  • 高橋 航圭, 深澤 大志, 和久井 航太, TRIAWAN Farid, 因幡 和晃, 岸本 喜久雄, 橋村 徹
    日本機械学会論文集 84 865 18 - 00137-18-00137 一般社団法人 日本機械学会 2018年09月 [査読有り][通常論文]
     
    <p>Weld-joint has been atracting attention to assemble structures of dissimilar metals, particularly in automobile industry. However, the application of weld-joint to steel and aluminum plates is still limited due to uncertainty of the fatigue strength. Fatigue strength of weld-joint is rather complicated to evaluate because both effects of stress concentration at the edge and formation of intermetallic compounds along the interface should be considered carefully. This study focused on finding the key factor that determines the fatigue strength of steel-aluminum brazing joint by considering the variation of strength along interface. The welded part of single lap joint was partially removed by a wire-cut electric discharge machine to investigate the influence of length and location of interface on fatigue strength. When the applied load was relatively low it was found that the numbers of cycles to failure were found to be similar, even though the lengths of interface were different due to partial removal. Furthermore, observation on the fracture surface indicated that early stage of crack propagation showed similar topography regardless of the partial removal of weld part. These results clarified that the number of cycles to failure was mainly consumed at the early stage. Finite element analysis was then conducted to investigate the stress component affecting the fatigue strength. As a result, principal stresses were maximum at the fracture initiation site in all the specimens. Therefore, we concluded that fatigue life of weld-joint is dominant in the early stage of crack propagation, which is characterized by the principal stress.</p>
  • 藤村 奈央, 西塚 祐斗, 髙橋 航圭, 中村 孝
    日本機械学会論文集 84 864 18 - 00206-18-00206 一般社団法人 日本機械学会 2018年 [査読有り][通常論文]
     
    <p>To quantitatively investigate the cause of the changes in arithmetic mean roughness <i>R<sub>a</sub></i> of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on slip bands was conducted on SUS316NG. During the loading, the specimen's surface topography was regularly measured using a laser microscope. The topography was then characterized by frequency analysis to identify the surface reliefs due to persistent slip bands (PSBs), and their heights were measured. The heights increased with the usage factor (<i>UF</i>). The amount of the increase with respect to <i>UF</i> increased with the strain range. These tendencies are similar to those for <i>R<sub>a</sub></i>. A comparison between <i>R<sub>a</sub></i> and the heights of surface reliefs caused by PSBs showed that the values were strongly correlated. The number of PSBs formed on the surface was estimated from the area ratio of PSBs. The area ratio increased with <i>UF</i>, which is similar to the relationship for <i>R<sub>a</sub></i>. A comparison between <i>R<sub>a</sub></i> and the area ratio showed that these values were also strongly correlated. The product of the height due to PSBs and the area ratio was calculated and it was compared with <i>R<sub>a</sub></i>. As a result, the product was in good agreement with <i>R<sub>a</sub></i>. Consequently, the surface texture parameter <i>R<sub>a</sub></i> represent both the change in the height and the number of surface reliefs due to PSBs.</p>
  • HIBI Masaharu, TRIAWAN Farid, INABA Kazuaki, TAKAHASHI Kosuke, KISHIMOTO Kikuo, HAYABUSA Keisuke, NAKAMOTO Hiroaki
    Mechanical Engineering Journal 5 1 17 - 00151-17-00151 一般社団法人 日本機械学会 2018年 [査読有り][通常論文]
     
    <p>In turbomachinery, such as turbine, pump, and valve, components damage caused by collapsing cavitation bubbles has been a critical issue that needs a proper solution. For this reason, investigation on the cavitation erosion behavior of materials as well as the life prediction techniques has been extensively conducted. Moreover, a number of repairing techniques, such as by a surface coating of polymeric materials, has been established. However, in real operation, cavitation is actually not the only load acquired by the components. Other external loads, such as centrifugal force and hydraulic pressure, may also affect the generation of damage. Therefore, its effect on the lifetime needs to be considered carefully. In this paper, the behavior of cavitation damage of epoxy resin specimens subjected to uniaxial tensile loading is reported. A self-developed testing device was used to conduct a cavitation test based on ASTM G32 while at the same time exerting a constant uniaxial tensile load to the specimen. Using this device, various levels of tensile stress effect on the cavitation damage was examined. As a result, besides erosion damage, we revealed that the specimens demonstrated fracture when a certain tensile load was applied. Furthermore, as the tensile load was increased, the time to fracture was shortened significantly, indicating the pronounced effect of tensile stress on the damage formation. The crack growth mechanism was then analyzed by fractography. The result indicated that the crack propagation under a mixed condition of cavitation and tensile loads was most likely driven by the combination of creep deformation and fatigue-like crack growth. Finally, a mathematical relationship between tensile stress and cavitation damage life was proposed. The relationship is important to enhancing the existing theory of cavitation damage evaluation in e.g. turbomachinery application.</p>
  • Nao Fujimura, Takashi Nakamura, Kosuke Takahashi
    12TH INTERNATIONAL FATIGUE CONGRESS (FATIGUE 2018) 165 2018年 [査読有り]
     
    To quantitatively investigate the cause of the changes in arithmetic mean roughness R-a and arithmetic mean waviness W-a of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on persistent slip bands (PSBs) and crystal grain deformations was conducted on SU5316NG. During the fatigue tests, the specimen's surface topography was regularly measured using a laser microscope. The surface topographies were analysed by frequency analysis to separate the surface relief due to PSBs from that due to grain deformation. The height caused by PSBs and that by grain deformation were measured respectively. As a result, both of the heights rose with the increase of usage factor (UF). The amount of increase in the heights with respect to UF increased with strain range. The trend of development of both heights was similar with the trend of R-a. and W-a. A comparison between R-a and the height caused by PSBs showed that these values strongly correlated with each other. A comparison between W-a and the height caused by grain deformation also showed that these values strongly correlated with each other. Consequently, the surface texture parameters R-a. and W-a represent the changes in the heights of surface reliefs due to PSBs and grain deformation.
  • 藤村 奈央, 中村 孝, 髙橋 航圭, 和島 達希
    材料試験 66 12 906 - 912 公益社団法人 日本材料学会 2017年12月01日 [査読有り][通常論文]
     
    <p>A new surface modification technique, scanning cyclic press (SCP), was developed. SCP scans a metal surface with a vibrating indenter under precise loading control based on servo fatigue testing machine and can apply a variable cyclically compressive load. This study applied SCP to magnesium alloy AZ31 to investigate the effect on fatigue properties. After applying SCP, the surfaces of specimens were observed by using a laser scanning microscope and uniaxial push-pull fatigue tests were conducted. As a result, surface roughness of SCP-treated specimens slightly increased; however, the fatigue life became longer than that of untreated specimens. To clarify the reason for the improvement effect, fracture surfaces of the specimens were investigated in detail on the basis of SEM observation. SEM observation showed differences between the fracture surfaces of the untreated and SCP-treated specimens. The origin of fracture was at the surface in the untreated specimen. In the SCP-treated specimen, however, the fracture origins were sub-surface and a band-like layer just beneath the surface was observed on fracture surface, whereas the layer did not exist on that of untreated specimen. The surface hardness of SCP-treated specimen increased to almost twice as much after applying SCP. The result suggests that SCP modified surface layer of specimen and this layer suppressed crack initiation from surface.</p>
  • Tomohisa Kojima, Kazuaki Inaba, Kosuke Takahashi, Farid Triawan, Kikuo Kishimoto
    Journal of Pressure Vessel Technology 139 3 031308  2017年06月 [査読有り][通常論文]
     
    A theoretical model for wave propagation across solid-fluid interfaces with fluid-structure interaction (FSI) was explored by conducting experiments. Although many studies have been conducted on solid-solid and fluid-fluid interfaces, the mechanism of wave propagation across solid-fluid interfaces has not been well examined. Consequently, our aim is to clarify the mechanism of wave propagation across a solid-fluid interface with the movement of the interface and develop a theoretical model to explain this phenomenon. In the experiments conducted, a free-falling steel projectile was used to impact a solid buffer placed immediately above the surface of water within a polycarbonate (PC) tube. Two different buffers (aluminum and polycarbonate) were used to examine the relation between wave propagation across the interface of the buffer and water and the interface movement. With the experimental results, we confirmed that the peak value of the interface pressure can be predicted via acoustic theory based on the assumption that projectile and buffer behave as an elastic body with local deformation by wave propagation. On the other hand, it was revealed that the average profile of the interface pressure can be predicted with the momentum conservation between the projectile and the buffer assumed to be rigid and momentum increase of fluid. The momentum transmitted to the fluid gradually increases as the wave propagates and causes a gradual decrease in the interface pressure. The amount of momentum was estimated via the wave speed in the fluid-filled tube by taking into account the coupling of the fluid and the tube.
  • Bentang Arief Budiman, Kosuke Takahashi, Kazuaki Inaba, Kikuo Kishimoto
    COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING 90 211 - 217 2016年11月 [査読有り][通常論文]
     
    This paper presents a measurement technique of interfacial strength considering non-rigid bonding on a fiber/matrix interface modeled as a cohesive surface. By focusing on the stress concentration near a fiber crack obtained from a single-fiber fragmentation test, the stress contours in matrix observed by photoelasticity can be related to the interfacial strength by defining a characteristic length. An equation expressing the relationship between the characteristic length on the stress contour and the interfacial strength was derived, and validated using finite element analysis. The primary advantage of proposed measurement technique is that only a single fiber crack, which usually occurs within elastic deformation of matrix, is required for the evaluation of interfacial strength, whereas saturated fiber fragmentation is necessary in the conventional method. Herein, a sample application was demonstrated using a single carbon fiber and epoxy specimen, and an average interfacial strength of 23.8 MPa was successfully obtained. (C) 2016 Elsevier Ltd. All rights reserved.
  • Kosuke Takahashi, Yuichiro Yamagata, Kazuaki Inaba, Kikuo Kishimoto, Shiori Tomioka, Toshio Sugizaki
    LANGMUIR 32 14 3525 - 3531 2016年04月 [査読有り][通常論文]
     
    The adhesive force generated by a small short-term pressure, called tack, is measured by a probe tack test on pressure-sensitive adhesives (PSAs); the maximum force is evaluated by cavity growth at the interface between the PSA layer and the probe surface. As the PSA layer becomes thinner, it is more difficult to measure the tack with a cylindrical probe because of the uneven contact resulting from misalignment. A spherical probe is preferable to obtain reproducible contact on 5 the PSA layer, but the contact area should be taken into account if the contact pressure affects the tack performance. Tack was measured on PSAs with various thicknesses in different contact areas to clarify their effect. The results showed that a larger contact area on a thinner PSA generated higher adhesive stress with larger strain. It was found that the maximum adhesive stress was not affected by the contact pressure, but it was strongly correlated to the contact radius divided by the PSA thickness. In addition, a video microscope observation showed that, in all of the experimental cases, the adhesive stress always reached the maximum when cavities were generated at the interface between the PSA and probe surface. Therefore, the criterion of cavity growth was introduced for the evaluation of the maximum adhesive stress. As a result, the experimental results, even at different release rates, were in good agreement with the estimation by considering the effect of confining a thin layer. Furthermore, the theoretical estimation indicated the ultimate value, which was not dependent upon the PSA thickness or contact area. It was defined as a material property, referred to as the "ultimate tack strength" of PSAs.
  • 森重直樹, 森重直樹, 高橋航圭, 因幡和晃, 岸本喜久雄
    日本機械学会論文集(Web) 82 841 ROMBUNNO.16‐00194(J‐STAGE) - 00194-16-00194 一般社団法人 日本機械学会 2016年 [査読有り][通常論文]
     

    The dynamic buckling tests using cylindrical tubes with and without internal pellets were carried out to investigate the impact behavior. Various materials of cylindrical tubes and pellets were used to examine the buckling mode and the maximum loads at several impact velocities. In the case of low Young's modulus and low yield strength pellets, the influence of pellets was small because of the small load share of pellets, so the "W" shape of deformation shapes and the maximum impact loads were almost the same of those of empty tubes. On the other hand, the tubes with high Young's modulus and high yield strength pellets indicated different behaviors compared to the empty tubes because of the large load share of pellets. At low impact velocity, pellets with high yield strength caused the strengthening effect and increased the lateral stiffness for tubes. As a result, the pellets led to increase of impact load, decrease of deformation and change of buckling mode to the "S" shape. At high velocity, the strengthening effect of pellets made the tubes stiffer, but led to fracture by the constraint effect of pellets on plastic deformation. The deformation of tubes was compared to Euler's equation, and it was confirmed that the Euler's equation could be applied at the low impact velocity. However, it was not effective for the high velocity impact because of local deformation at the impact side. FEM analyses will be conducted to clarify the deformation shape, maximum load and the mechanism of fracture at high impact velocity as a further study.

  • Kosuke TAKAHASHI, Takahiro MATSUO, Masakazu FURUTA, Shuzo OSHIMA, Kazuaki INABA, Kikuo KISHIMOTO
    Mechanical Engineering Letters 2 0 16 - 00227-16-00227 Japan Society of Mechanical Engineers 2016年 [査読有り][通常論文]
     

    Wetting-induced attraction are widely observed in microstructures where liquid flows along solid surfaces. Unexpected bending or collapse occurs if wetting-induced forces are neglected in the structural design, such as high aspect ratio pillars in the process of wet-etching. In this study, a simple experiment is designed to capture the evolving deformation of a cantilever beam due to capillary flow. A pair of polymer plates fixed at one end with a small gap is submerged into liquid, so that capillary rise between the plates and their attraction can be simultaneously observed. The plate dimension is sub-millimeter scale, which is rather large in observation of capillarity, in order to clearly capture deformation process of the plates until their contacts. Different types of liquids are prepared to investigate the influence of wettability, surface tension, and viscosity. Velocity of capillary flow is also considered by changing submergence rate of the plate. The experimental results of plate deflection are compared to analytical estimation obtained from an equation of motion for capillary rise and an equilibrium between capillary attraction and elastic force of plate. This estimation corresponded well with experimental results regardless of liquid types. In addition, the relationship between plate deflection and material constants is derived in a non-dimensional form. Therefore, plate deformation due to wetting-induced attraction, considering velocity of capillary flow, became predictable only from dimension of plates and material constants.

  • 高橋 航圭, 熊谷, 理 勝山, 優一郎, 因幡, 和晃, 岸本, 喜久雄, 山田, 幹典谷中, 雅顕
    日本機械学会論文集 82 833 The Japan Society of Mechanical Engineers 2016年 [査読有り][通常論文]
     
    Peel test is widely used to evaluate interfacial strength of adhesive tape. The interface strength is usually obtained by subtracting energy consumed for plastic deformation of substrate film from external work for peeling. Deformation of substrate results from interface strength generated in adhesive layer, whose mechanical property is regarded as elastic when substrate is thick enough. It is also convenient to calculate deformation of substrate with assuming elastic behavior of adhesive layer. However, substrates thinner than 100 μm may be affected by viscoelastic property of adhesive layer since thickness of adhesive layer is no longer negligible. It is indispensable to investigate the influence of viscoelastic behavior of adhesive layer on evaluating interface strength of particularly thin adhesive film. In this study, 90° peel test was conducted and the interface strength was evaluated by modifying conventional elastic model to consider viscoelastic behavior of adhesive layer. Stress in adhesive layer caused from displacement of substrate is a function of strain and strain rate, and the corresponding deformation of substrate was computed by finite element method. The shape of substrate deformation was compared with one obtained from conventional elastic model in terms of thickness of substrate and peel speed. The interface strength was also obtained from directly observing peel shape using high speed camera to validate the proposed model. As a result, it was found that the substrate shapes were similar regardless of models when substrate was thick, but proposed model more accurately reflected the influence of peel speed in the thin substrate.
  • Kosuke Takahashi, Kensuke Namiki, Takahiro Fujimura, Eun-Beom Jeon, Hak-Sung Kim
    COMPOSITES PART B-ENGINEERING 76 167 - 173 2015年07月 [査読有り][通常論文]
     
    The electrical-resistance-change method (ERCM) is a potential smart-sensing technique for carbon-fiber-reinforced plastic (CFRP) structures. However, a practical way to fabricate electrodes on CFRP structures, such as ink-jet printing with metal nano-inks, is necessary to reduce the time required for the process. As metal nano-inks can be sintered in a few milliseconds under ambient conditions using white-flash-light irradiation from a xenon lamp, the parameters of flash-light sintering such as light energy, duration, and number of pulses were investigated. The light intensity, which is the light energy divided by duration, was found to be an indicator of whether low electrical resistance was attained along with strong adhesion to the CFRP plate. The contact resistance between the electrode and CFRP plate was also examined in a tensile test to confirm the durability. The electrode sintered by flash light with the properly selected parameters exhibited high quality and strain monitoring capability. (C) 2015 Elsevier Ltd. All rights reserved.
  • Bentang Arief Budiman, Kosuke Takahashi, Kazuaki Inaba, Kikuo Kishimoto
    JOURNAL OF COMPOSITE MATERIALS 49 4 465 - 475 2015年02月 [査読有り][通常論文]
     
    Interfacial debonding frequently initiates composite failure in a fiber/matrix composite. A single-fiber fragmentation test and its modifications can be used to evaluate interfacial properties. However, they still have accuracy problems due to fiber impurities and friction work. This paper presents a new method of evaluating interfacial properties using a stress contour of composite matrix. A single-fiber fragmentation test model was developed to simulate the stress contour. The interface was modeled as a cohesive zone model. Four characteristic lengths on the stress contour were found after conducting simulations with many interfacial properties values. The stress contour was then captured from the single-fiber fragmentation test employing a photo-elasticity technique and the four characteristic lengths were measured. Iteration in simulation involved changing interfacial properties until corresponding characteristic lengths from experiment and simulation were obtained. The results were compared with those obtained with existing methods and found to be reasonable.
  • Eun-Beom Jeon, Takahiro Fujimura, Kosuke Takahashi, Hak-Sung Kim
    COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING 66 193 - 200 2014年11月 [査読有り][通常論文]
     
    An addressable conducting network (ACN) enables the structural condition to be monitored by the electrical resistance between electrodes on surface of CFRP (carbon fiber reinforced polymer) structure. To improve the reliability of ACN for damage detection, the contact resistance between the electrodes and CFRP laminates needs to be minimized. In this paper, the silver nanoparticles electrodes were fabricated via printed electronics techniques on CFRP composite. The contact resistance between the silver electrodes and CFRP was measured with respect to various fabrication conditions such as the sintering temperature of silver nanoink and the surface roughness of CFRP laminates. The interfaces between silver electrode and carbon fibers were observed using scanning electron microscope (SEM). From the study, it was found that the lowest contact resistance of 0.3664 Omega could be achieved when the sintering temperature of the silver nanoink and surface roughness were 120 degrees C and 230 nm, respectively. (C) 2014 Elsevier Ltd. All rights reserved.
  • Rehana Afrin, Atsushi Ikai, Kosuke Takahashi, Kazuaki Inaba, Kikuo Kishimoto
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 603 1 157 - 164 2014年11月 [査読有り][通常論文]
     
    Adhesive properties of several serum proteins to the hemodialysis membrane surface previously studied by atomic force microscopy were compared with a more general case of adhesion/de-adhesion process of adhesive tapes and films. The three different tapes and film samples showed de-adhesion curves with different level of tack and flow properties. The two types of de-adhesion force curves of serum albumin from the hemodialysis membrane can be explained in terms of the difference in the physical process of de-adhesion and in a general perspective of self-cohesive force of the adhesives.
  • Hiroyuki Ushifusa, Kazuaki Inaba, Kosuke Takahashi, Kikuo Kishimoto
    JOURNAL OF SUPERCRITICAL FLUIDS 94 174 - 181 2014年10月 [査読有り][通常論文]
     
    We have developed a new apparatus to dynamically generate supercritical CO2 (scCO(2)) bubbles in water using a water hammer facility by efficiently concentrating water energy. We measured the internal and external pressures of a CO2 bubble covered with a rubber membrane using pressure transducers, and observed the bubble's oscillations by a high-speed video camera. We evaluated the maximum duration of the scCO(2) for conditions 60 mu s in experiments. We performed numerical simulations using the Rayleigh-Plesset equation by substituting the experimental external pressure profiles of the bubble and confirmed that numerical results agreed with the experimental internal pressure. Moreover, in the minimum external pressure condition where we experimentally achieved the condition of scCO(2) in the bubble for 16 mu s by water hammer, we obtained the maximum duration of scCO(2) conditions up to 55 mu s numerical simulations assuming isotropic compression. (C) 2014 Elsevier B.V. All rights reserved.
  • 高橋航圭, 新井大輔, 因幡和晃
    ターボ機械 42 12 767 - 776 日本工業出版 2014年 [査読有り][通常論文]
     
    Structural repair by polymer coating has been recently attracted attention to pumps in water plants because of its simplicity.The performance of coating material is simply evaluated by cavitation resistance, but it should be considered under loadingcondition for application to existing structures. In this study, damage of coating material due to cavitation is observedwith various loading conditions. Epoxy resin is selected as coating material on aluminum base. First, tensile and shear testsof the coating material is conducted with different way of coating angles to obtain fracture stresses. Second, a conventionalcavitation erosion test is modified using a tensile jig developed to conduct a tension-cavitation test. As a result, the tensioncavitationtest resulted in much severer damage in short time than conventional cavitation erosion test even though the stresson the coating material is more than 10 times smaller than the fracture stresses.
  • Kosuke Takahashi, Seiji Sugita, Shuzo Oshima, Kazuaki Inaba, Kikuo Kishimoto
    Applied Physics Letters 103 4 043113  2013年07月22日 [査読有り][通常論文]
     
    Deformation induced by capillarity is quantitatively evaluated in this study. A pair of polymer plates, fixed at one end and immersed in liquid, bends because of capillary forces from a liquid column formed between the plates. Bending proceeds to either contact or collapse the plates if their gap spacing becomes smaller than 2/3 of the initial plate separation, regardless of plate dimensions. This phenomenon is theoretically validated by proposing a dimensionless number, which is derived from a balance of surface energy, potential energy of a liquid, and strain energy of a plate. © 2013 AIP Publishing LLC.
  • Kosuke Takahashi, Masashi Shimizu, Kazuaki Inaba, Kikuo Kishimoto, Yoichi Inao, Toshio Sugizaki
    International Journal of Adhesion and Adhesives 45 90 - 97 2013年 [査読有り][通常論文]
     
    An important property of adhesive tapes is their tack performance, which relates to the adhesive force generated by a small short-term pressure on the tapes. Tack performance declines when an adhesive tape experiences tensile loading, but this influence has not been characterized well, especially for thin adhesive tapes. A testing apparatus is developed to quantitatively evaluate the influence of applied tensile loading on the tack performance of various thicknesses adhesive tapes. The apparatus allows microscopic observation of the adhered area during separation. The separation force of 15 μm and 5 μm thick adhesive tapes exhibit ductile behavior, while that of 1 μm thick adhesive exhibits brittle behavior. These separation behaviors relate to the generation of cavities in the adhesive, whose expansion is affected by adhesive thickness. Microscopic images show that the adhered area becomes smaller with increasing tensile loadings. The unified separation energy is defined and calculated for adhesive tapes, to simultaneously evaluate the tack performance for different adhesive thicknesses and applied tensile loadings. The separation energy decreases with increasing tensile loading, but the separation energy per unit area remains largely constant, regardless of the applied tension. The effect of separation speed on separation behavior is investigated, with a change from ductile to brittle separation observed with increasing separation speed. Separation speed is also reflected in the unified separation energy. © 2013 Elsevier Ltd. All rights reserved.
  • Kosuke Takahashi, H. Thomas Hahn
    STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL 11 3 367 - 377 2012年05月 [査読有り][通常論文]
     
    This article considers the practical use of electrical resistance change method (ERCM) for damage detection in graphite/polymer composites. ERCM utilizes the high electrical conductivity of graphite fibers in the composites and can detect damage by change in electrical resistance. Since the effectiveness of ERCM has been shown extensively in the literature, it is now necessary to consider how to apply ERCM into existing structures. For practical use of ERCM, a new concept of an addressable conducting network (ACN) has been proposed, which consists of two sets of conducting lines normal to each other. One set of lines resides on the top surface of the laminate and the other resides on the bottom surface. Damage can be detected by monitoring resistance change between two lines across the laminate thickness. In this article, composite panels with several sets of conducting lines are locally loaded by a static indentation test and examined to monitor the distribution of electrical resistance changes. Monitoring the changes in resistance successfully indicated the damage occurrence, but it is sometimes difficult to pinpoint the damage location due to the resistance changes caused by compressive deformation. To improve the sensitivity of ACN to damage, the relationship between damage location and electrical conductivity was investigated using a design of experiments. The changes in resistance with various damage locations and electrical conductivities were acquired from finite element analysis, and the results suggested several ways to optimize damage detection. Depending on the damage tolerance of target structure, spacing of conducting lines and the electrical conductivities can be preferably selected toward practical application of ACN.
  • Kosuke Takahashi, H. Thomas Hahn
    COMPOSITES PART B-ENGINEERING 43 3 833 - 840 2012年04月 [査読有り][通常論文]
     
    This paper aims to develop an autonomic thermal management system of graphite fiber/polymer composite structures using their electrical property. A number of copper tapes are integrated on top and bottom surfaces of a composite plate, and through the thickness resistances between these tapes are measured on a hotplate for temperature monitoring. The resistance at warmer area successfully reflected the temperature distribution taken by an IR imaging camera. The same copper tapes are subsequently used for generating resistive heat by supplying a large amount of current. The effective heat generation is investigated by a finite element analysis, showing that the temperature of a laminate can be controlled by adjusting the conductivity in the fiber and thickness directions. (C) 2012 Elsevier Ltd. All rights reserved.
  • Kosuke Takahashi, H. Thomas Hahn
    JOURNAL OF COMPOSITE MATERIALS 45 25 2603 - 2611 2011年12月 [査読有り][通常論文]
     
    This article investigates the dependency of electrical resistance on temperature for graphite/polymer composites. The electrical resistance change of a unidirectional laminate is measured with elevated temperature in the fiber, transverse and through-thickness directions. Because of the properties of graphite fibers, the electrical resistance decreases as temperature increases in any direction. The activation energy is calculated from an Arrhenius plot to evaluate the difference among the different directions. The activation energy is the lowest in the fiber direction due to the high electrical conductivity of graphite fibers. Since electric current flows thorough the contacts between neighboring graphite fibers, similar activation energies are required in the transverse and through-thickness directions, indicating transversely isotropic properties. These characteristics will be used to establish the relationship between electrical resistance outputs and structural conditions, and will be eventually applied to an in-service structural management system using addressable conducting network, which is a grid arrangement of conducting lines on a composite panel.
  • Jong Se Park, Thomas Darlington, Anthony F. Starr, Kosuke Takahashi, Joseph Riendeau, H. Thomas Hahn
    COMPOSITES SCIENCE AND TECHNOLOGY 70 15 2154 - 2159 2010年12月 [査読有り][通常論文]
     
    Self-healing composites using a thermally mendable polymer bis-maleimide tetrafuran (2MEP4F) based on Diels-Alder reaction and electrical resistive heating were fabricated using a vacuum assisted injection molding method Delaminations were induced using short span three point bending on composite coupons The induced damage and permanent deformation of the composite coupons were observed using X ray micro-tomography The same procedure was repeated to confirm multiple healings after electrical resistive heating and healing efficiency of the samples was determined The permanent deformations and induced delaminations were repaired after the heating process which is due to both healing and shape memory effects The multiple healing ability and shape memory effect of the fabricated composite combined with electrical resistive heating realizes a noble self-healing composite (C) 2010 Elsevier Ltd All rights reserved
  • Kosuke Takahashi, Jong Se Park, H. Thomas Hahn
    SMART MATERIALS & STRUCTURES 19 10 105023  2010年10月 [査読有り][通常論文]
     
    The electrical resistance change method (ERCM) has long been an area of interest as an in-service health monitoring system. To apply the ERCM to existing structures, a new concept, the addressable conducting network (ACN), is proposed for autonomic structural health management of graphite/polymer composites. The ACN consists of two sets of conducting lines normal to each other, where one set resides on the top surface of the laminate and the other on the bottom surface. Damage can be detected by monitoring the resistance change 'through the laminate thickness' between two lines. By using a thermally mendable polymer as the matrix, the same conducting lines can be used to supply the electric current needed for resistive heating, thereby allowing the detected damage to be healed. As shown experimentally, the electrical resistance change method using an ACN distinguishes between laminates made of properly and improperly cured prepreg as well as revealing damage generated during three-point bending tests. Finite element analysis was performed to examine the feasibility of the ACN and indicated that the damage can be easily located from the spatial distribution of resistance changes and that the damaged area can be locally heated by supplying a large amount of current to selected conducting lines.
  • TAKAHASHI Kosuke, TODOROKI Akira, MATSUZAKI Ryosuke
    Journal of Solid Mechanics and Materials Engineering 4 4 557 - 567 The Japan Society of Mechanical Engineers 2010年 
    Strain monitoring of CFRP structure by measuring electrical resistance change has attracted attention over the years. High electrical conductivity of carbon fibers enables to measure the strain by making electrodes on the structure's surface and using bridge circuit as conventional strain gauge. Electrical resistance change method, however, is difficult to specify the gauge length because electric current is applied directly to the structure, and the current path depends on the stacking sequences, fiber volume fraction, and electrode's location. It is also difficult to measure the electrical resistance changes at different parts simultaneously because the outputs may interfere with each other due to overlapping of current paths inside the structure. In this study, three electrodes are connected to each bridge circuit to prevent electrical interference when the electrical resistance changes are measured simultaneously, whereas electrical resistance measurements normally use two electrodes. The proposed method puts ground electrodes every other so that current path could be limited between the ground electrodes. Only the strain between ground electrodes affects the electrical resistance output, and it makes simultaneous measurements at different position possible.
  • Takahashi Kosuke, Todoroki Akira, Matsuzaki Ryosuke
    Transactions of the Japan Society of Mechanical Engineers Series A 74 748 1573 - 1579 一般社団法人日本機械学会 2010年 [査読有り][通常論文]
     
    Strain monitoring of CFRP structure by measuring electrical resistance change has attracted attention over the years. High electrical conductivity of carbon fibers enables to measure the strain by making electrodes on the structure's surface and using bridge circuit as conventional strain gauge. Electrical resistance change method, however, is difficult to specify the gauge length because electric current is applied directly to the structure, and the current path depends on the stacking sequences, fiber volume fraction, and electrode's location. It is also difficult to measure the electrical resistance changes at different parts simultaneously because the outputs may interfere with each other due to overlapping of current paths inside the structure. In this study, three electrodes are connected to each bridge circuit to prevent electrical interference when the electrical resistance changes are measured simultaneously, whereas electrical resistance measurements normally use two electrodes. The proposed method puts ground electrodes every other so that current path could be limited between the ground electrodes. Only the strain between ground electrodes affects the electrical resistance output, and it makes simultaneous measurements at different position possible.
  • Takahashi Kosuke, Todoroki Akira, Matsuzaki Ryosuke
    Journal of Environment and Engineering 5 1 15 - 26 The Japan Society of Mechanical Engineers 2010年 [査読有り][通常論文]
     
    Delamination cracks in a graphite/epoxy composite change the thermal expansion properties in the damaged regions. We detect this change by measuring the electrical resistance in the affected areas while heating. The proposed damage detection method is effective even when a damaged electrode is used, in contrast to the traditional method, which requires highly reliable electrodes to prevent an increase of the inherent electrical resistance. The proposed damage detection method is thus feasible for a variety of environments that might cause the degradation of the electrode. Heating of the composite is performed by Joule heating of the graphite fibers rather than general heating using an outside heat source. Graphite fibers, due to their high electrical conductivity, are used not only as the damage sensor but also as the heat source. The influences of delamination and electrode defects on a heated cross-ply beam are examined by simulation. The electrical resistance change after Joule heating is also experimentally measured. As a result, we proved that delamination detection is possible even with a damaged electrode.
  • 鈴木良郎, 轟章, 高橋航圭, 水谷義弘, 松崎亮介
    日本機械学會論文集. A 編 76 767 961 - 967 一般社団法人日本機械学会 2010年 [査読有り][通常論文]
     
    The previous study employs delamination detection in CFRP laminates using electrical resistance change. To prevent electrical resistance changes caused by damages of electrical contact at electrodes, a new method using temperature characteristic of resistance is developed here. CFRP laminates are heated up by applying electric currents through the electrodes mounted on the surface of the CFRP plates. When the delamination occurs, the electrical resistance change caused by the temperature rising becomes different from that of other intact parts. A statistical analysis method discriminates the changes. The electrical resistance changes caused by the damage of electrodes do not affect the temperature characteristic of the measured resistance. The present study employs the new method for the delamination detection of quasi-isotropic-plied CFRP plates. The detection limit of the method is experimentally investigated, and the effect of electrode damage on the diagnosis is discussed here.
  • Jong Se Park, Kosuke Takahashi, Zhanhu Guo, Ying Wang, Ed Bolanos, Christine Hamann-Schaffner, Erin Murphy, Fred Wudl, H. Thomas Hahn
    JOURNAL OF COMPOSITE MATERIALS 42 26 2869 - 2881 2008年12月 [査読有り][通常論文]
     
    Mendomers are a group of polymers that are mendable upon heating. Specifically, cracks in these polymers have been shown to heal themselves when heated close to the glass transition temperature. The main mechanism behind the healing is the thermally reversible Diels-Alder reaction, where a dicyclopentadiene unit in the polymer backbone breaks apart into two cyclopentadiene terminal groups, which then reunite upon heating. The present study investigates the feasibility of using a mendomer as a matrix for re-mending composites reinforced with graphite fibers. The graphite fibers are used as electrical conductors to provide the necessary heat to the polymer. Specimens were prepared by spreading a monomer, called mendomer, powder on a graphite/epoxy laminate substrate and curing in a vacuum oven. Microcracks were introduced by bending the substrate coupon, and the latter was heated by applying electric currents. The healing behavior was confirmed by disappearance of microcracks that were observed with an optical microscope and a scanning electron microscope (SEM).
  • Ryosuke Matsuzaki, Akira Todoroki, Kosuke Takahashi
    SMART MATERIALS & STRUCTURES 17 5 055001  2008年10月 [査読有り][通常論文]
     
    Wireless monitoring of the health of CFRP structures reduces the cost and time of inspections and can be usefully applied for continuous monitoring. In a previous study, we presented a wireless sensor for detection of internal delamination in a CFRP laminate. The method utilizes a simple electrical resistance change in CFRP and so monitors delamination at only one location. For monitoring of large-scale structures, however, many sensors have to be distributed to cover the structure. A major problem for using many sensors is time synchronization among sensors. To overcome the problem and enable strain/damage to be monitored at multiple locations with time synchronization, we develop a simple wireless strain/damage sensor that consists of a bridge circuit, voltage-controlled oscillator and amplifiers. Since the sensor does not need A/D conversion procedures or memory storing, there is no time delay. Each sensor has an original basic frequency that changes in accordance with the electrical resistance. The frequencies from the multiple sensors are transmitted to a receiver. Using a short-time maximum entropy method, the received waves are converted to multiple electrical resistance data. The proposed method is applied to CFRP laminates and oscillating frequencies are measured in real time. The results show that the system successfully measures applied strain and detects fiber breakage at multiple locations in CFRP laminates with time synchronization.
  • 高橋航圭, 轟章, 松崎亮介
    日本機械学会論文集 A 編 74 748 1573 - 1579 The Japan Society of Mechanical Engineers 2008年 [査読有り][通常論文]
     
    Strain monitoring of CFRP structure by measuring electrical resistance change has attracted attention over the years. High electrical conductivity of carbon fibers enables to measure the strain by making electrodes on the structure's surface and using bridge circuit as conventional strain gauge. Electrical resistance change method, however, is difficult to specify the gauge length because electric current is applied directly to the structure, and the current path depends on the stacking sequences, fiber volume fraction, and electrode's location. It is also difficult to measure the electrical resistance changes at different parts simultaneously because the outputs may interfere with each other due to overlapping of current paths inside the structure. In this study, three electrodes are connected to each bridge circuit to prevent electrical interference when the electrical resistance changes are measured simultaneously, whereas electrical resistance measurements normally use two electrodes. The proposed method puts ground electrodes every other so that current path could be limited between the ground electrodes. Only the strain between ground electrodes affects the electrical resistance output, and it makes simultaneous measurements at different position possible.
  • 高橋航圭, 轟章, 松崎亮介
    日本機械学会論文集 A 編 74 748 1565 - 1572 The Japan Society of Mechanical Engineers 2008年 [査読有り][通常論文]
     
    Delamination of CFRP structure is detected by means of electrical resistance change due to Joule heating in the present study. A CFRP beam is heated up by applying electric current through electrodes mounted on the surface. When the CFRP beam is heated up, the thermal expansion at the part with a delamination is different from that at the undamaged part, and the difference of the thermal expansion affects the electrical resistance change with elevated temperature because CFRP has piezoelectricity. The electrical resistance changes between the electrodes are measured using bridge circuits just like using conventional strain gauge. In addition, the effect of electrode's damage on the electrical resistance change is also considered because the quality of the electrode is important to identify delamination. Electrical resistance change due to Joule heating is measured using a cross-plied CFRP beam with a delamination and electrode's damage, and as a result, delamination detection is even possible with a damaged electrode.
  • Kosuke Takahashi, Akira Todoroki, Yoshinobu Shimamura, Atsushi Iwasaki
    PROGRESSES IN FRACTURE AND STRENGTH OF MATERIALS AND STRUCTURES, 1-4 353-358 1330 - + 2007年 [査読有り][通常論文]
     
    Statistical diagnosis using electrical resistance changes is performed to detect a delamination crack in a CFRP beam. This method enables to reduce data required for damage identification. First, a new measuring method of multiple electrical resistance changes is proposed to perform statistical diagnosis. The proposed method measures electrical resistance changes of multiple segments in a CFRP beam although electrical interference must be considered when multiple voltages are charged at once. Next, statistical diagnosis is performed on loading to the CFRP beam. A delamination crack is detected by the change of relative relationship between multiple electrical resistance changes due to damage occurring. As a result, the monitored states of the CFRP beam are diagnosed exactly by the proposed damage detection system.
  • 松崎 亮介, 轟 章, 高橋 航圭
    日本機械学会論文集. A編 = Transactions of the Japan Society of Mechanical Engineers. A 73 724 1904 - 1911 一般社団法人日本機械学会 2006年12月25日 
    Wireless health monitoring for CFRP structures reduces the cost and time of inspection and it can be useful for continuous monitoring. In the previous study, we presented a wireless sensor for detection of internal delamination in a CFRP laminate. The method utilizes a simple electric resistance change in CFRP, thus it monitors delamination at only one location. For monitoring of large-scale structures, however, many sensors have to be distributed to cover the structure. Major problem for using many sensors is the time synchronization among sensors. To overcome the problem and enable to monitor strain/damage at multiple locations with time synchronization, we develop wireless strain/damage sensor which simply consists of a bridge circuit, voltage controlled oscillator and amplifiers. Since the sensor does not need procedures of AD conversion or memory storing, the time delay does not take place. Each sensor has original basic frequency which changes due to the electric resistance, and the frequencies from multiple sensors are transmitted to a receiver. Using short-time maximum entropy method, received wave is converted to multiple electric resistance data at one time. The proposed method is applied to CFRP laminates and oscillating frequencies are measured in real-time. As the result, the system successfully measures the applied strain and detects fiber breakage at multiple locations in CFRP laminate with time synchronization.

書籍

講演・口頭発表等

  • Nao Fujimura, Takashi Nakamura, Kosuke Takahashi
    MATEC Web of Conferences 2018年05月 EDP Sciences
     
    To quantitatively investigate the cause of the changes in arithmetic mean roughness Ra and arithmetic mean waviness Wa of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on persistent slip bands (PSBs) and crystal grain deformations was conducted on SUS316NG. During the fatigue tests, the specimen's surface topography was regularly measured using a laser microscope. The surface topographies were analysed by frequency analysis to separate the surface relief due to PSBs from that due to grain deformation. The height caused by PSBs and that by grain deformation were measured respectively. As a result, both of the heights rose with the increase of usage factor (UF). The amount of increase in the heights with respect to UF increased with strain range. The trend of development of both heights was similar with the trend of Ra and Wa. A comparison between Ra and the height caused by PSBs showed that these values strongly correlated with each other. A comparison between Wa and the height caused by grain deformation also showed that these values strongly correlated with each other. Consequently, the surface texture parameters Ra and Wa represent the changes in the heights of surface reliefs due to PSBs and grain deformation.
  • WAVE PROPAGATION ACROSS THE INTERFACE OF FLUID-STRUCTURE INTERACTION WITH VARIOUS SURFACE CONDITIONS OF SOLID MEDIUM  [通常講演]
    Tomohisa Kojima, Kazuaki Inaba, Kosuke Takahashi
    PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE, 2016, VOL 4 2017年 AMER SOC MECHANICAL ENGINEERS
     
    This study aims to clarity the effect of surface conditions of solid on wave propagation at solid-fluid interface with fluid structure interaction. Although many studies have been done to develop the theoretical models of fluid-structure interaction caused by wave propagation, they do not take into account the surface conditions of the solid medium on the solid-fluid interface where interaction occurs. In this study, we experimentally investigated the wave propagation across the solid-fluid interface with several value of surface wettabilities and roughnesses of solid. We conducted an impact experiment with a free-falling projectile which hit the cylindrical solid buffer placed on top of the water surface within the elastic tube standing on the ground. During the experiments, cavitation bubbles were generated from the interface of the buffer and water That generation was inhibited according to the decrease of the value of the contact angle (improve of the wettability) of the buffer surface. The amplitude of transmitted pressure wave from the buffer to water become smaller than the theoretical value according to the decrease of the value of the contact angle on the buffer surface (the smallest value was 55% of the theoretical value). Concerning the surface roughness, the amplitude of transmitted pressure wave becomes smaller than the theoretical value according to the shape of the buffer surface become more different from flat surface (the smallest value was 75% of the theoretical value). These experimental results indicate that by taking into account the surface condition of the solid on the interface, more accurate model of fluid-structure interaction or ways to reduce the damage of structures by fluid-structure interaction would be proposed.
  • PS0031-450 水撃波伝播と管壁の連成振動メカニズムの実験的研究
    山口 大介, 増子 拓也, 因幡 和晃, 高橋 航圭, 岸本 喜久雄
    M&M材料力学カンファレンス 2015年11月 一般社団法人日本機械学会
     
    Water hammer is familiar phenomena in our life while this phenomena causes noises and failures of water plumbing. Previous studies of water hammer revealed that wave speeds were well predicted by a simple theory and pressure surges could be estimated with the speeds by experiments, numerical analysis, and analytic methods. However, the frontal wave shape of water hammer was neglected and its propagation mechanism was not discussed in the simplified theories. This study focus on the frontal mechanism to understand the structure and decrease the damage of the water hammer. In the present study, we visualize the frontal structures in experiments and numerical analysis as well as revealing strain signals of coupled tubes with pressure waves.
  • OS1519-461 固液連成界面における固体材料の表面状態が波動伝播へ及ぼす影響
    小島 朋久, 因幡 和晃, 高橋 航圭, 岸本 喜久雄
    M&M材料力学カンファレンス 2015年11月 一般社団法人日本機械学会
     
    Fluid-structure interaction is one of the most important phenomena to be clarified and controlled in many industrial fields. In some problems, interaction mechanism strongly depends on wave propagation across the interface of solid and fluid. Although many studies have been conducted about fluid-structure interaction, the mechanism of wave propagation across to the solid-fluid interface remains unclear. In this study, we investigated the effect of surface conditions such as surface roughness and wettability of solid materials to wave propagation across the interface. The results of the experiments indicated that due to the wettability of the solid surface, the intensity of the cavitation which appeared near the interface was changed and theoretical assumption of the interface continuity may not be valid under some conditions.
  • OS0414-326 逆解析を利用した気泡崩壊時のマイクロ・スケール衝撃力測定
    石井 智弥, 因幡 和晃, 高橋 航圭, 岸本 喜久雄
    M&M材料力学カンファレンス 2015年11月 一般社団法人日本機械学会
     
    When cavitation occurs and bubbles collapses in fluid machinery, such as pumps, impact loading due to the bubble collapsing shortens the life time and decreases the performance. Recently, inspection of cavitation-erosion damage inside the pumps has been conducted by direct visual observations after stopping the operation temporarily. In this study, to realize damage monitoring remotely from outside of the machinery, impact load by spark-generated bubble collapse was estimated using inverse analysis. Impact experiments by spark-generated bubbles were conducted with aluminum plate and impact load and point were measured with AE sensors. The effect of impact point in measurement of impact load was confirmed by bubble collapses at different impact points.
  • OS0511-444 破壊形態を考慮したFe-Al異材接合継手の疲労寿命予測
    深澤 大志, 高橋 航圭, 因幡 和晃, 岸本 喜久雄, 橋村 徹
    M&M材料力学カンファレンス 2015年11月 一般社団法人日本機械学会
     
    Dissimilar material joint makes a machine light and efficient. Welding is widely used to connect dissimilar materials, but an intermetallic compound produced in the interface and stress specificity at interface end are concerned to decrease the joint strength. It is important to evaluate the strength of welded joint for designing machine and structure. In this study, single lap specimens with welding joint of Fe and Al plates were prepared for a tensile shear test and a fatigue test. Joint strength and interfacial strength were investigated by modifying shape of welding joint. Fracture analysis revealed the interface was brittleness destruction and the joint strength depends on the strength of the starting point of the destruction. Fatigue curve can be classified every destruction form by using the hotspot stress of the starting point of the destruction.
  • OS13-6 Image Processing Technique of Photoelastic Analysis for Evaluating Stress Transfer at Fiber/Matrix Interface(Interface,OS13 Micro- and meso-mechanics of composites,MICRO AND NANO MECHANICS)
    Budiman Bentang Arief, Takahashi Kosuke, Inaba Kazuaki, Kishimoto Kikuo
    Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2015年10月 一般社団法人日本機械学会
  • S0520302 マグネティックバーチャルチャネルの形成
    高橋 龍太朗, 大島 修造, 因幡 和晃, 高橋 航圭
    年次大会 : Mechanical Engineering Congress, Japan 2015年09月 一般社団法人日本機械学会
     
    Nonmagnetic fluid can be levitated if a very strong magnetic field is applied by a super-conducting magnet. This study suggests noncontact magnetic virtual channel (MVC) in the casting process of nonconductive materials such as glasses to enable the continuous casting in high quality. In this study, we model the MVC by using a magnetic fluid in a weak magnetic field. A rectangular coil is assumed as a source of the magnetic power. The magnetic field distribution of the rectangular coil was calculated and the distribution of the magnetic force is obtained. To confirm whether a liquid column is stable or not, stability analysis is carried out about a liquid film held by magnetic power. As a result, stability is confirmed and further analysis about the floating position and the cross sectional shape of the floating liquid is done. An experiment to let a nonmagnetic fluid float in magnetic fluid was conducted. Tests were done with distilled water and silicone oil and both liquids can be levitated. Observation suggests that the shape of the floating liquids vary according to the boundary tension. Therefore, this accords with the analysis results qualitatively.
  • S0520301 容器内二相液体の電磁加振に関する研究
    伊藤 怜, 大島 修造, 因幡 和晃, 高橋 航圭
    年次大会 : Mechanical Engineering Congress, Japan 2015年09月 一般社団法人日本機械学会
     
    In the field of steelmaking and refining, phosphorus is impurities. The steel is produced by removing reacted with slug to it. Improving the reaction speed of phosphorus contribute significantly to the reduction of steel making process and it can achievement by increase interfacial area between slug and metal. So the purpose of this research is to increase interfacial area efficiently by electromagnetic force (EMF) instead of inert gas. It revealed that it is possible to sloshing of the liquid metal by electromagnetic force in horizontal directions by numerical simulation and increasing the interfacial area during sloshing. Performs approximate analysis by linear theory for horizontal sloshing of the multiliquid-layer and compered with the numerical value. In addition, new vertical sloshing method that is locally applied electric field and magnetic field is devised.
  • Hiroyuki Ushifusa, Kazuaki Inaba, Konosuke Sugasawa, Kosuke Takahashi, Kikuo Kishimoto
    EFM14 - EXPERIMENTAL FLUID MECHANICS 2014 2015年 E D P SCIENCES
     
    A new experimental device was developed to observe and measure dynamical generations of supercritical CO2 in a chamber. Temperature and pressure were measured locally by thin thermocouple and pressure transducer. The Rayleigh scattering in the chamber was visualized by a high-speed video camera. Heating of the liquid CO2 was conducted by a ceramic heater from the upper or the lower side of the chamber. In the case of heating from the upper side, temperature profile was stable and generates scCO(2) slowly within a few seconds. On the other hand, in the case of heating from the lower side, scCO(2), was created faster within a second but natural convection and turbulence were observed. Numerical simulations of the scCO(2) creation in a chamber were also performed using the COMSOL Multiphysics with a program package for themophysical properties of CO2 called the PROPATH. It showed that scCO(2) creation in the heating from the upper side was stable due to the gas-like properties of the scCO(2) near the heater. In the case of heating from the lower side, density distribution depended on temperature distribution firstly but after natural convection grows, flow in the chamber became disturbed and the density distribution depended not only on temperature distribution but also on the density fluctuation caused by the convection vortexes. Same tendency was observed in experimental results.
  • Tomohisa Kojima, Kazuaki Inaba, Kosuke Takahashi
    PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE - 2015, VOL 5 2015年 AMER SOC MECHANICAL ENGINEERS
     
    This paper reports on investigations conducted with a view towards developing a theoretical model for wave propagation across solid-fluid interfaces with fluid-structure interaction. Although many studies have been conducted, the mechanism of wave propagation close to the solid-fluid interface remains unclear Consequently, our aim is to clarify the mechanism of wave propagation across the solid-fluid interface with fluid structure interaction and develop a theoretical model to explain this phenomenon. In experiments conducted to develop the theory, a free-falling steel projectile is used to impact the top of a solid buffer placed immediately above the surface of water within a polycarbonate tube. The stress waves created as a result of the impact.of the projectile propagated through the buffer and reached the interface of the buffer and water (fluid) in the tube. Two different buffers (polycarbonate and aluminum) were used to examine the interaction effects. The results of the experiments indicated that the amplitude of the interface pressure increased in accordance with the characteristic impedance of the solid medium. This cannot be explained by the classical theory of wave reflection and transmission. Thus, it is clear that on the solid-fluid interface with fluid-structure interaction, classical theories alone cannot precisely predict the generated pressure.
  • 動脈瘤を含む脳動脈分岐部まわりの応力の評価
    小田 健太郎, 大島 修造, 因幡 和晃, 高橋 航圭
    計算力学講演会講演論文集 2014年11月 一般社団法人日本機械学会
     
    Abstract A cerebral aneurysm is a disease in which part of the artery in the brain is enlarged in nodular and causes a subarachnoid hemorrhage when the aneurysm is ruptured. It brings pain to people and death. In this study, in order to compare the stress at the branch in the development process of the aneurysm, numerical simulation was performed using the aneurysm growth model. In the model without aneurysm, large circumferential stress and pressure were acting on the center of the branch. In the aneurysm growth model, the circumferential stress of about 1.5 times of a case without aneurysm was acting upon base of the aneurysm. Therefore we thought the local distention may be involved in the growth and development of cerebral aneurysm. Moreover, it must be necessary to investigate the growth and rupture mechanism of cerebral aneurysm by the simulation using the model of the large aneurysm under the various conditions of the branch vessel diameter ratio and branch angle.
  • OS1118 毛細管力によるピラーアレイ構造体凝集現象の評価
    古田 将一, 高橋 航圭, 因幡 和晃, 岸本 喜久雄
    M&M材料力学カンファレンス 2014年07月 一般社団法人日本機械学会
     
    Capillary induced forces are widely observed in fine structures where liquid flows along solid surfaces, such as wet-etching process in micro/nano-pillar fabrication. Undesirable bending or collapse of the structure occurs if they are improperly considered in the structural design. In this study, liquid column formation between aligned polymer plates is observed and the resulting capillary induced force causing the plate deformation is evaluated. The plate dimension is sub-millimeter scale, which is rather large in observation of capillarity, in order to clearly measure deformation process of the aligned plates until their contacts. When the plates are immersed into liquid from the fixed end, gap between plates becomes smaller due to liquid columns formed far from the end. It is found that the deformation of the plates proceeds more unstably as the number of plates increase, but their contact is initiated at the similar plate length into liquid.
  • OS0304 Fe-Al異材接合継手の強度評価
    深澤 大志, 三浦 靖史, 高橋 航圭, 因幡 和晃, 岸本 喜久雄, 橋村 徹
    M&M材料力学カンファレンス 2014年07月 一般社団法人日本機械学会
     
    Welding is widely used to connect dissimilar materials, but an intermetallic compound produced in the interface is concerned to decrease the joint strength. It is important to evaluate the strength of welded joint for designing machine and structure. In this study, single lap specimens with welding joint of Fe and Al plates were prepared for a tensile shear test and a fatigue test. Influence of rotation caused by tension and distribution of interfacial strength were investigated by modifying specimen length, number of tabs, and shape of welding joint. It was found that the rotation did not have significant influence on interfacial strength, but fracture behavior varied and indicated uneven strength distribution along interface.
  • Tatsuro Hori, Kazuaki Inaba, Kosuke Takahashi, Kikuo Kishimoto
    Applied Mechanics and Materials 2014年 Trans Tech Publications Ltd
     
    Our study focuses on the response of a water-filled polycarbonate tube under axial impact loading to the presence of a single large suspended particle. The particles, composed of steel, aluminum, and polycarbonate, were individually suspended by elastic string along the centerline of the tube. The impact of a free-fall piston initiated pressure waves in the water, called water hammer, and stress waves in the tube, especially at the level of the particle. Hoop strains were measured as impact responses their distribution indicated that the maximum strains occurred around the particle. These maximum strains are narrowly confined and independent of particle composition. From measurements, hoop strain above the level of the particle become larger with increasing particle mass. We propose a theoretical model that assumes the particle to be a rigid body, and estimate tube responses from the change in area due to the particle's presence rather than a dependence on particle material. With similar conditions as in experiments, numerical simulations, performed using the software AUTODYN, revealed that the particle motion initiated a reflected pressure wave and created another pressure wave underneath the particle. The transients propagating around the particle are independent of particle material, but composition does affect the attenuation of the reflected pressure wave above the particle. © (2014) Trans Tech Publications, Switzerland.
  • Minoru Nagai, Kazuaki Inaba, Kosuke Takahashi, Kikuo Kishimoto
    Applied Mechanics and Materials 2014年 Trans Tech Publications Ltd
     
    In this study, we conducted water hammer experiments in the tube which was periodically supported by various numbers of clamps, named periodic structure, initiated by a projectile impact. The parts of the polycarbonate (PC) tube supported by 1-7 steel clamps make the tube stiffer and heavier than the original PC tube and are expected to cause a filtering effect of the frontal frequency components in the water hammer. According to our experimental observations, we confirmed that higher frequency components more than 1 kHz in the wave front were attenuated and the peak strains in circumferential direction of the tube were decreased 20% from the original PC tube. Moreover, we conducted numerical simulations of the water hammer wave similar to the experimental setup. Numerical results also revealed that frontal peak is attenuated 22% through periodic structure. © (2014) Trans Tech Publications, Switzerland.
  • TRANSIENT BEHAVIOR OF WATER HAMMER IN A TWO-PIPE SYSTEM  [通常講演]
    Kazuaki Inaba, Masaya Kamijukkoku, Kosuke Takahashi, Kikuo Kishimoto
    PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE - 2013, VOL 4: FLUID-STRUCTURE INTERACTION 2014年 AMER SOC MECHANICAL ENGINEERS
     
    We experimentally investigated the propagation behavior of pressure waves in fluid coupled with elastic stress waves in tubes across a straight junction of two different tubes with different diameters and materials, named discontinuity. We measured wave speeds of water hammers upstream and downstream of the discontinuity and the transmission and reflection ratios of water hammer pressures at the discontinuity. To obtain the ratios, strain gages were attached at constant intervals in the hoop direction and the axial direction. Strain signals were converted into pressure histories and used to obtain the ratios. It is confirmed that propagation speeds upstream and downstream of the discontinuity can be estimated by the Korteweg wave speed. Furthermore, the impact responses of tubes in the hoop direction can be evaluated by characteristic impedance with an area change. However, we found that the axial strains due to the area change from the larger diameter tube to the smaller diameter tube were clearly different from values evaluated by the Poisson coupling. It is confirmed that when the tube cross-sectional area suddenly decreases by half at the straight junction of two tubes, the reflected pressure loading in the axial direction can cause the axial peak strain that is 0.6 times as large as the hoop peak strain.
  • OS1703 粘着剤のはく離変形挙動の観察によるタック強度評価
    山縣 勇一朗, 高橋 航圭, 因幡 和晃, 岸本 喜久雄, 稲男 洋一, 杉崎 俊夫
    M&M材料力学カンファレンス 2013年10月 一般社団法人日本機械学会
     
    A tack is important physical property for pressure-sensitive adhesive that shows instantaneous adhesiveness. Recently, thinner adhesive has been developed and often applied in industry while the occurrence and the mechanism of the tack have not been clarified yet. It is known that as adhesive is thinner than 5μm, the tack becomes much weaker. To improve and develop the thin but strong adhesive it is necessary to observe the peeling phenomena of the adhesive. In this study, the aim is to investigate the effect of the adhesive's thickness on peeling behaviors and tack strengths with probe tack tests. We confirmed that as adhesive is thicker, peel force becomes larger but the rate of increase of peel force becomes lower and the amount of adhesive deformation becomes larger. We observed the displacement of fine particles mixed in adhesive. As result, as the particles reaches deeply from the surface of the adhesive to its inside, the displacement of the particles becomes smaller and the movement of the particles isn't seen at 25 μm from the surface.
  • OS0925 濡れによる液架橋形成が及ぼす平板の変形評価
    高橋 航圭, 杉田 精司, 因幡 和晃, 岸本 喜久雄
    M&M材料力学カンファレンス 2013年10月 一般社団法人日本機械学会
     
    In a design of fine structures, characteristic phenomena such as surface forces, which are usually negligible in a macroscopic scale, need to be taken into consideration. When a liquid exists between solid surfaces, a liquid column can form in accordance with the balance of their surface energies, called capillarity. In this study, deformation induced by capillarity is quantitatively evaluated. A pair of polymer plates fixed at one end and immersed in liquid, bends because of capillary forces from a liquid column formed between the plates. Although capillary-induced deformation is usually observed at the micro/nano scales, the dimensions of the prepared plate specimens are on the order of millimeters because the larger scale makes observation of the evolving deformation easier. Experimental results indicate that bending proceeds to either contact or collapse the plates if their gap spacing becomes smaller than 2/3 of the initial plate separation, regardless of plate dimensions. This phenomenon is theoretically validated by proposing a dimensionless number, which is derived from a balance of surface energy, potential energy of a liquid, and strain energy of a plate.
  • OS1005 複合矩形管における水撃波動伝播
    武田 健吾, 因幡 和晃, 高橋 航圭, 岸本 喜久雄
    M&M材料力学カンファレンス 2013年10月 一般社団法人日本機械学会
     
    Water hammer occurs in a pipe when water flow is suddenly stopped. There are pipes having the square or rectangular cross sectional shape rather than the circular shape: micro channel, gutter, and so on. Moreover, a part of the walls is often composed by different material or different wall thickness. To reveal pressure wave propagation in such a channel, we examined water hammer phenomenon and measured wave speeds in rectangular tubes with different wall materials and thicknesses. We newly proposed theoretical wave speeds based on the classical theory and the junction conditions of two walls: fixed, simply supported, and mixed. We confirmed that theoretical predictions agreed with experimental wave speeds.
  • 補修材料に対する界面強度評価手法の確立
    早房敬祐, 中本浩章, 岸本喜久雄, 新井大輔, 因幡和晃, 高橋航圭
    日本材料学会学術講演会講演論文集 2013年
  • OS1212 スティックスリップはく離の発生に及ぼす被着体の剛性の影響
    熊谷 理, 高橋 航圭, 因幡 和晃, 岸本 喜久雄, 山田 幹典, 谷中 雅顕
    M&M材料力学カンファレンス 2012年09月 一般社団法人日本機械学会
     
    The use of thin-film technology has rapidly expanded. Multilayer structures composed of thin film with specific properties are used in many fields, for example liquid crystal displays and solar cells. In a multi-layer structure, the interface between films has the lowest strength, thus the interface strength between film and adhesive is important for designing products and improving interface strength. Peeling test is used widely as a method to measure the interface strength. In that test, stick-slip phenomenon sometimes occurs in particular conditions, and it is difficult to evaluate the interface strength if that happens. Therefore the research about stick-slip behavior in peeling test is important to establish the method measuring the interface strength appropriately. This paper focuses on the relation between adherend stiffness and stick-slip phenomenon, and clarifies the effect of adherend stiffness on stick-slip phenomenon.
  • OS1208 樹脂系補修材料の剥離強度試験およびその評価方法の検討
    中本 浩章, 早房 敬祐, 能見 基彦, 岸本 喜久雄, 因幡 和晃, 高橋 航圭, 新井 大輔
    M&M材料力学カンファレンス 2012年09月 一般社団法人日本機械学会
     
    Repair composites has high stiffness and flexible workability. Therefore, they have been used as efficient repair material for surface damages including cracks and erosions. Catalog parameters such as stiffness, water resistance, chemical resistance, and delamination strength. However, catalog delamination strength for lining-application has not been well clarified. In this study, we examined tensile test using particle-reinforced composite material bonded on tensile test pieces. Delamination strength was evaluated by nominal strain and effect of material and surface condition of tensile specimen.
  • OS0508 表面凹凸化による円管の圧壊特性向上
    川北 純, 合田 峻広, 高橋 航圭, 因幡 和晃, 岸本 喜久雄, 橋村 徹
    M&M材料力学カンファレンス 2012年09月 一般社団法人日本機械学会
     
    Structural members of automobiles are required to improve collision safety and reduce weight for the purpose of lower fuel consumption. Therefore a thin-walled cylinder which has excellent energy absorption efficiency and lightweight is used for the shock absorber of structural members. This cylinder absorbs impact energy in the continuous plastic buckling distortion caused by axial impact loading. However the load histories of the axial crushing of the cylinder repeat the periodic variation with the local buckling. That is causing the decrease of energy absorption efficiency. For this reason, the design which suppresses variation of load lead to improved energy absorption efficiency. The purpose of this study is to develop members improved the stability of load. We examined the optimal cross-sectional shape of the cylinder to reduce the load variation with FEM analysis.
  • OS0113 ピラーアレイの変形に及ぼす液体架橋による表面張力の影響
    杉田 精司, 高橋 航圭, 因幡 和晃, 岸本 喜久雄
    M&M材料力学カンファレンス 2012年09月 一般社団法人日本機械学会
     
    Structural interaction between solids and liquids are seen in various industrial fields, such as MEMS fabrication. A droplet between solid surfaces forms a liquid bridge, which provides a resistive or a desorption force due to surface tension. These forces can be ignored in large scale structures, but they show significant influence in micro scale. Since the deformation caused by liquid bridge has not been sufficiently studied, it is necessary to quantitatively evaluate these forces. In this study, two pillars that were aligned in parallel were prepared and the deformation caused by a liquid bridge was observed with different types of liquid. It is confirmed that the spacing between two pillars were getting closer and eventually attached with each other when silicone oil was used as liquid. But water did not cause any change in two pillars. The evaluation of the pillar deformation was conducted using a cantilever model, considering Laplace pressure and surface tension as drive forces. As a result, it was found that Laplace pressure has more significant influence than surface tension.
  • 早房 敬祐, 中本 浩章, 岸本 喜久雄, 新井 大輔, 因幡 和晃, 高橋 航圭
    学術講演会講演論文集 2012年 日本材料学会
  • PS06 抵抗温度特性利用の電気抵抗変化法によるCFRPの統計的損傷診断(ポスターセッション)
    鈴木 良郎, 轟 章, 高橋 航圭, 水谷 義弘, 松崎 亮介
    M&M材料力学カンファレンス 2009年07月 一般社団法人日本機械学会
     
    The present study employs the delamination detection in CFRP laminates using electrical resistance changes. Although the method detects the delamination without expensive sensors, the electrical resistance changes only due to electrode's damage make a wrong diagnosis. A delamination detection using statistical analysis of temperature characteristic of resistance changes is developed. CFRP laminates are heated up by applying electric currents through the electrodes mounted on the surface of the structure. When the delamination occurs, the electrical resistance change due to elevated temperature becomes different from that of the other intact parts. A statistical analysis method detects the change. The electrical resistance changes due to electrode's damage don't affect the temperature characteristic of resistance. The present study employs the new method for the delamination detection of cross-plied CFRP beams. In this study, the method is applied for quasi-isotropic CFRP plates. The detection limit of the method is investigated, and the effect of electrode's damage on the diagnosis is discussed.
  • P006 電気抵抗変化の温度依存性を利用したCFRPの統計的損傷検知(フェロー賞表彰対象ポスターセッション)
    高橋 航圭, 轟 章, 島村 佳伸, 岩崎 篤, 松崎 亮介
    M&M材料力学カンファレンス 2007年10月 一般社団法人日本機械学会
     
    The damage detection system of CFRP structures by making use of electrical resistance changes due to elevated temperature is performed. CFRP is heated up by applying electric currents through the electrodes mounted on the surface of the structure. When the delamination occurs, the electrical resistance change due to elevated temperature becomes different from that of the other intact parts. In this study, therefore, the electrical resistance changes are measured at the multiple segments on a CFRP beam simultaneously, and the damage is detected from the change of relative relationship between the measurements. A set of electrical resistance changes is related with each other by means of a response surface, which changes when delamination cracks occur. The similarity of the response surfaces is evaluated by F statistics. These damage detection systems are applied to detect a delamination in cross-plied CFRP beam and the delamination is successfully identified.
  • Statistical damage detection of laminated CFRP beam using electrical resistance change method  [通常講演]
    Kosuke Takahashi, Akira Todoroki, Yoshinobu Shimamura, Atsushi Iwasaki
    PROGRESSES IN FRACTURE AND STRENGTH OF MATERIALS AND STRUCTURES, 1-4 2007年 TRANS TECH PUBLICATIONS LTD
     
    Statistical diagnosis using electrical resistance changes is performed to detect a delamination crack in a CFRP beam. This method enables to reduce data required for damage identification. First, a new measuring method of multiple electrical resistance changes is proposed to perform statistical diagnosis. The proposed method measures electrical resistance changes of multiple segments in a CFRP beam although electrical interference must be considered when multiple voltages are charged at once. Next, statistical diagnosis is performed on loading to the CFRP beam. A delamination crack is detected by the change of relative relationship between multiple electrical resistance changes due to damage occurring. As a result, the monitored states of the CFRP beam are diagnosed exactly by the proposed damage detection system.
  • 轟 章, 高橋 航圭, 岩崎 篤
    埼玉ブロック大会(講演会)講演論文集 2005年 日本機械学会関東支部

その他活動・業績

受賞

  • 2022年06月 日本複合材料学会 林賞
     強化繊維の表面・界面を介した変形・強度評価手法の構築 
    受賞者: 高橋航圭
  • 2019年05月 日本接着学会 進歩賞
     キャビティ膨張とフィブリル伸張に基づくはく離強度の粘着剤・基材厚さ依存性に関する考察 
    受賞者: 高橋 航圭
  • 2017年04月 日本機械学会 日本機械学会奨励賞（研究）
     微細構造体の表面エネルギーに起因する吸着力・接着力の評価に関する研究 
    受賞者: 高橋 航圭
  • 2015年11月 日本機械学会材料力学部門 M&M若手シンポジウム2015 優秀講演表彰
     毛細管現象の吸着力による平板の変形過程 
    受賞者: 高橋 航圭
  • 2014年03月 日本機械学会材料力学部門 M&M 2013材料力学カンファレンス 優秀講演表彰
     濡れによる液架橋形成が及ぼす平板の変形評価 
    受賞者: 高橋 航圭

共同研究・競争的資金等の研究課題

  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2021年04月 -2024年03月 
    代表者 : 高橋 航圭
     
    本研究では，力と変形量の関係に基づく材料力学的な観点から，粘着テープの粘着界面におけるはく離メカニズムを明らかにし，それに基づく汎用的かつ簡便なはく離強度評価指標の確立を目的とする．はく離力が，粘着剤層と被着体の間の界面力，粘着剤層の伸縮，テープ基材の曲げ変形に起因する点に着目し，はく離力におけるこれらの寄与を個別に評価する独自手法に取り組む． これまでに，粘着剤層で消費されたはく離エネルギーと粘着剤層のひずみ速度に着目して実験を行った．テープ材料・テープ厚さ・はく離速度・はく離角度を変えたピール試験とプローブタック試験を行い，両者の関係を調べた．結果，ピール試験，プローブタック試験ともに定常的な界面はく離を示し、ひずみ速度が0.01から100 1/sの広い範囲で，それぞれから得たはく離エネルギーとひずみ速度の関係は同等となり，両対数軸上における直線関係を見出すことができた． この直線関係は，既往の研究成果から粘弾性のべき乗則に基づく結果であることを確認し，はく離過程における粘着剤層の伸縮過程と関連付けることができた．また，粘着剤層が薄い場合には，はく離界面でキャビティが生じやすく，これによってはく離に要する外部仕事が小さくなることも明らかとなった．今後は，はく離過程におけるキャビティの発生有無をはく離領域における粘着剤層内の応力分布と関連付け，破壊力学的な観点から粘着界面のはく離現象にアプローチする．
  • ナノ界面の疲労損傷検出と抑制による複合材料の超長寿命化技術
    科学技術振興機構：戦略的創造研究推進事業 個人型研究(さきがけ)
    研究期間 : 2020年11月 -2024年03月
  • 科学技術振興機構：研究成果最適展開支援プログラム(A-STEP) トライアウト
    研究期間 : 2020年11月 -2022年03月
  • 日本学術振興会：科学研究費助成事業 若手研究
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 高橋 航圭
     
    今年度は、粘着剤のはく離試験の高精度化に向けて、試験機の整備に注力した。まず、はく離角度可変のピール試験機を導入し、高倍率マイクロスコープと併用することで、粘着剤のはく離力と変形の同時測定ができるようになった。さらに、万能試験機を応用してプローブタック試験を行うため、粘着テープの冶具と支持台、ならびに円柱と球状のプローブを作成した。これら試験機の性能を確認するため、試料として同種のモノマーを異なる重合度で合成したゴム系の粘着剤を用意し、厚さ25um、50umのPET基材に塗工して試験を行った。同種のモノマーであることから被着材へのぬれ性は同等で、異なる重合度によって変形抵抗の違いを狙ったサンプルである。 ピール試験の結果、厚さ50umのPET基材の場合には、重合度の違いに関わらずはく離荷重は同程度であった。厚さが25umのPET基材の場合、どちらの粘着剤もはく離荷重は増加したが、重合度の小さい粘着剤の方が大きなはく離荷重を示した。PET基材が薄くなることで、はく離時の粘着剤のひずみ速度が大きくなるため、重合度の低下に伴う粘性効果の増大によりはく離荷重が大きくなったと考えられる。プローブタック試験は、測定精度向上のために検討を続けている段階であるが、マイクロスコープの観察結果からはく離過程におけるキャビティの生成に違いを確認することができている。 また、はく離シミュレーションによる妥当性の検証に向け、ピール試験の有限要素モデルを作成し、粘着剤の粘弾性を考慮したはく離解析が行えるようになった。
  • 日本学術振興会：科学研究費助成事業 若手研究(B)
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 高橋 航圭
     
    本研究では，固体表面のぬれ性に着目し，液面に浮かべたフィルムの中央部を引き上げることで円筒状の立体構造を形成する方法を提案した．様々な寸法のプラスチックフィルム，ゴムシートで実験を行った結果，適切な寸法を選択することで，円筒状構造が形成可能であることを示した．また，液体とフィルムの物性値，寸法を用いて，形成される円筒状構造の解析解ならびに形成に必要なフィルム厚さの条件を導出することができた．さらに，グラフェンシートからも円筒状構造が形成可能なことを，シミュレーションにより示した．
  • Evaluation of tack strength by criterion of cavity generation
    公益財団法人村田学術振興財団：研究者海外派遣援助
    研究期間 : 2016年09月 -2016年09月
  • 動的荷重下における繊維強化複合材料の繊維/樹脂界面特性評価に関する研究
    みずほ学術振興財団：第56回工学研究助成
    研究期間 : 2013年04月 -2015年03月 
    代表者 : 高橋 航圭
  • 損傷検知・修復機能を有する複合材料構造物の開発
    日本学術振興会：二国間交流事業（韓国との共同研究）
    研究期間 : 2012年07月 -2014年06月 
    代表者 : 高橋 航圭
  • 液体のぬれが及ぼす構造体変形現象のマクロスケール観察による定式化と無次元数を用いたマイクロ・ナノデバイスへの適用性に関する研究
    公益財団法人マツダ財団：第29回（2013年度）マツダ研究助成
    研究期間 : 2013年04月 -2014年03月 
    代表者 : 高橋 航圭
  • 日本学術振興会：科学研究費助成事業 特別研究員奨励費
    研究期間 : 2008年 -2008年 
    代表者 : 高橋 航圭

教育活動情報

主要な担当授業

  • 高分子材料工学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 高分子材料、高分子基複合材料、エラストマー、粘弾性、材料の破損則、接着
  • 高分子材料工学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 高分子材料、高分子基複合材料、エラストマー、粘弾性、材料の破損則、接着
  • 国際交流Ⅱ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 国際本部
    キーワード : 高分子材料、高分子基複合材料、エラストマー、粘弾性、材料の破損則、接着
  • 材料強度学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 材料強度、延性破壊、脆性破壊、降伏、破壊、時間依存型破壊
  • 計算工学Ａ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 数値計算、有限要素法、材料力学
  • 科学・技術の世界（1単位）
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : インド、言語、文化、科学技術、生活、インフラ
  • 機械工学概論
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 機械工学，材料，機械力学，熱，流体，エネルギー

大学運営

委員歴

  • 2022年06月 - 現在   日本接着学会   コンテンツ委員会委員
  • 2022年04月 - 現在   日本複合材料学会   日本複合材料学会誌編集委員
  • 2022年04月 - 現在   日本機械学会   材料力学部門幹事幹事
  • 2021年04月 - 現在   日本機械学会   RC294分科会委員
  • 2020年06月 - 2022年06月   日本接着学会   国際交流委員会委員
  • 2019年04月 - 2021年03月   日本複合材料学会   東北・北海道支部 商議員
  • 2019年04月 - 2021年03月   日本機械学会   RC287分科会委員
  • 2019年04月 - 2021年03月   日本材料学会   破壊力学部門 北海道地区幹事
  • 2019年04月 - 2020年03月   日本機械学会 材料力学部門   広報委員会委員長
  • 2018年04月 - 2020年03月   日本機械学会   RC278分科会 委員
  • 2018年04月 - 2020年03月   日本機械学会材料力学部門   シンポジウム実行委員会（M&M 若手シンポジウム 2019）委員
  • 2017年05月 - 2019年03月   日本溶接協会   FQA3小委員会 中立委員
  • 2016年04月 - 2019年03月   日本機械学会 機械材料・材料加工部門   運営委員会委員
  • 2017年04月 - 2018年03月   日本機械学会材料力学部門   M&M2017材料力学カンファレンス実行委員会 委員
  • 2017年04月 - 2018年03月   日本複合材料学会   代議員
  • 2016年04月 - 2018年03月   日本機械学会   RC271分科会 委員
  • 2016年04月 - 2017年03月   日本機械学会材料力学部門   シンポジウム実行委員会（2016 M&M International Symposium for Young Researchers）委員

その他

  • 2013年04月 - 9999年  船井情報科学振興財団 奨学事業選考委員 
    海外大学への留学を目指す積極的で意欲ある優秀な学生に授業料、生活費などの奨学金を支給することにより、若者の留学意欲を高め、広い視野をもった人材の育成に貢献する活動です。

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