Researcher basic information

• Ph.D. in mechanical Engineering, University of California, Los Angeles
• Ph.D. in mechanical engineering

• https://researchmap.jp/kosuke?lang=en

• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201301066833554621
• https://mfm.eng.hokudai.ac.jp/
• https://mfm.eng.hokudai.ac.jp/index-en.html

• C-2867-2015

• 201301066833554621

• Strength of materials
• Fracture mechanics
• Adhesion
• Composite materials

• Nanotechnology/Materials, Composite materials and interfaces
• Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering), Mechanics of materials and materials

• Bachelor's degree program, School of Engineering
• Master's degree program, Graduate School of Engineering
• Doctoral (PhD) degree program, Graduate School of Engineering

Research activity information

• May 2025, 公益社団法人 日本材料学会, -
  Full-life growth behavior of a naturally initiated internal fatigue crack in beta titanium alloy via in situ synchrotron radiation multiscale tomography
  Gaoge Xue;Takashi Nakamura;Nao Fujimura;Kosuke Takahashi;Hiroyuki Oguma;Akihisa Takeuchi;Masayuki Uesugi;Kentaro Uesugi
• Jun. 2023, 一般社団法人日本複合材料学会, 論文賞
  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
• Jun. 2022, 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
  高橋航圭
• May 2019, 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
  高橋 航圭
• Apr. 2017, 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
  高橋 航圭
• Nov. 2015, 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
  高橋 航圭
• Mar. 2014, 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
  高橋 航圭

• Enhancement of strength and durability in single-lap joints using thin double-sided tape
  Ashwani Kumar Devisharan; Xuan Ngoc Chau Ho; Kounosuke Shimamura; Kosuke Takahashi
  International Journal of Solids and Structures, Sep. 2026, [Peer-reviewed], [Last author, Corresponding author]
  English, Scientific journal
• Mechanism of room-temperature nitriding in pure titanium by the scanning cyclic press
  Yuta Funaki; Kosuke Takahashi; Tatsuki Wajima; Takashi Nakamura
  Materialia, May 2026
  Scientific journal
• Quantitative analysis of interface crack propagation along a single carbon fiber under off-axis cyclic loading using nanoscopic three-dimensional imaging
  Naoya Matsuda; Kosuke Takahashi
  Composites Science and Technology, Mar. 2026
  Scientific journal
• Adhesion testing of dysphagia diets for the quantitative evaluation of swallowing
  Kosuke Takahashi; Ryo Yoshida; Kohei Ohie; Satomi Kumagai; Yuji Tasaka
  Food Hydrocolloids, Mar. 2026
  Scientific journal
• Carbon-Fiber Interface Crack Extraction Using Machine-Learning Denoising of Low-dose X-ray CT
  西口諒真; 松田尚也; 矢田楓; 高橋航圭
  日本複合材料学会誌, 52, 1, 22, 29, 2026, [Peer-reviewed], [Last author, Corresponding author]
  Scientific journal
• Viscous dissipative energy density as a general adhesion characteristic of adhesive tape
  Kosuke Takahashi; Masako Yamada; Tatsuya Sasaki; Takashi Nakamura
  Soft Matter, Royal Society of Chemistry (RSC), Jul. 2025, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal, The adhesion energy (G_c) divided by the maximum elongation of the PSA layer (a_f), which is defined as the viscous dissipative energy density, and the strain rate has a linear relationship on a logarithmic scale, independent of the tape thickness.
• Influence of irradiation with synchrotron radiation X-ray on Nano-Scale CT for carbon fibers and epoxy matrix
  Kosuke Takahashi; Takuma Matsuo; Katsuma Wakabayashi; Akihisa Takeuchi; Masayuki Uesugi; Kentaro Uesugi; Takashi Nakamura
  Composites Part A: Applied Science and Manufacturing, 198, 109060, 109060, Elsevier BV, May 2025, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal, 30964622
• Decreasing propagation rate of interfacial debonding between a single carbon fiber and epoxy matrix under cyclic loading
  Kosuke Takahashi; Takuma Matsuo; Wataru Sato; Takashi Nakamura
  Composites Science and Technology, 258, 10 Nov. 2024, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• In situ analysis of three-dimensional microcrack propagation in cross-ply laminates using synchrotron radiation X-ray computed tomography
  Kosuke Takahashi; Ryuto Higashiyama; Gaoge Xue; Takashi Nakamura
  Composites Science and Technology, 258, 10 Nov. 2024, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Effect of Porosity Distribution of Cement Paste on the Change in Splitting Tensile Strength because of Aggregate Incorporation
  Riki Nagao; Kosuke Takahashi; Kota Ohyama; Masato Tsujino
  日本複合材料学会誌, 50, 5, 11, 18, 15 Sep. 2024, [Peer-reviewed], [Corresponding author], [Domestic magazines]
  Japanese, Scientific journal
• Toughened single-lap joints by composite bondline of adhesive and double-sided tape
  Kosuke Takahashi; Zhantong Sun; Takuma Kikuzawa; Kounosuke Shimamura; Sourabh Jagrat; Nao Fujimura; Takashi Nakamura
  Advanced Composite Materials, 1, 17, Informa UK Limited, 20 Nov. 2023, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal, 30964513
• Room-Temperature-Nitriding of Pure Titanium Using Scanning Cyclic Press in a Nitrogen Environment
  Yuta Funaki; Nao Fujimura; Takashi Nakamura; Kosuke Takahashi; Tatsuki Wajima
  Journal of the Japan Institute of Metals and Materials, 87, 11, 305, 308, Japan Institute of Metals, 01 Nov. 2023, [Peer-reviewed]
  Japanese, Scientific journal
• Full-life growth behavior of a naturally initiated internal fatigue crack in beta titanium alloy via in situ synchrotron radiation multiscale tomography
  Gaoge Xue; Takashi Nakamura; Nao Fujimura; Kosuke Takahashi; Hiroyuki Oguma; Akihisa Takeuchi; Masayuki Uesugi; Kentaro Uesugi
  International Journal of Fatigue, 170, 107571, 107571, Elsevier BV, May 2023, [Peer-reviewed]
  Scientific journal
• Fatigue Life Distribution Analysis of α+β Titanium Alloy Based on the Initiation and Propagation Behaviors of Small Internal Cracks
  Hironori MORISHITA; Takashi NAKAMURA; Nao FUJIMURA; Kosuke TAKAHASHI
  Journal of the Society of Materials Science, Japan, 71, 12, 997, 1004, Society of Materials Science, Japan, 15 Dec. 2022, [Peer-reviewed]
  Japanese, Scientific journal
• Generalized characteristics of peel tests independent of peel angle and tape thickness
  Masako Yamada; Kosuke Takahashi; Nao Fujimura; Takashi Nakamura
  Engineering Fracture Mechanics, 271, Aug. 2022, [Peer-reviewed], [Corresponding author]
  Scientific journal
• X-ray nanoimaging of a transversely embedded carbon fiber in epoxy matrix under static and cyclic loads
  Kosuke Takahashi; Ryosuke Shoya; Takuma Matsuo; Wataru Sato; Takashi Nakamura; Akihisa Takeuchi; Masayuki Uesugi; Kentaro Uesugi
  Scientific Reports, 12, 1, May 2022, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Initiation and propagation of small fatigue crack in beta titanium alloy observed through synchrotron radiation multiscale computed tomography
  Gaoge Xue; Takashi Nakamura; Nao Fujimura; Kosuke Takahashi; Hiroyuki Oguma; Akihisa Takeuchi; Masayuki Uesugi; Kentaro Uesugi
  Engineering Fracture Mechanics, 263, 108308, 108308, Elsevier BV, Mar. 2022, [Peer-reviewed]
  Scientific journal
• Detection of small internal fatigue cracks in Ti-6Al-4V via synchrotron radiation nanocomputed tomography
  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, [Peer-reviewed]
  Scientific journal
• Sticking Effect of a Tackifier on the Fibrillation of Acrylic Pressure-Sensitive Adhesives
  Takahashi, K.; Yanai, F.; Inaba, K.; Kishimoto, K.; Kozone, Y.; Sugizaki, T.
  Langmuir, 37, 39, 11457, 11464, American Chemical Society ({ACS}), 05 Oct. 2021, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• 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
  Ryosuke SHOYA; Takuma MATSUO; Kosuke TAKAHASHI; Nao FUJIMURA; Takashi NAKAMURA
  日本複合材料学会誌, 47, 5, 186, 193, 15 Sep. 2021, [Peer-reviewed], [Corresponding author], [Domestic magazines]
  Japanese, Scientific journal
• Initiation and Propagation Processes of Internal Fatigue Cracks in β Titanium Alloy Based on Fractographic Analysis
  Gaoge Xue; Takashi Nakamura; Nao Fujimura; Kosuke Takahashi; Hiroyuki Oguma
  Applied Sciences, 11, 1, 131, 131, 25 Dec. 2020, [Peer-reviewed]
  English, Scientific journal
• Laminate design for a tapered FRP structure with ply drop-off based on yielding of resin pockets
  Sae Obata; Kosuke Takahashi; Kazuaki Inaba
  Composite Structures, 253, 112787, 112787, Elsevier {BV}, Dec. 2020, [Peer-reviewed], [Corresponding author]
  English, Scientific journal
• Scaling effect on the detachment of pressure-sensitive adhesives through fibrillation characterized by a probe-tack test
  Takahashi, K.; Oda, R.; Inaba, K.; Kishimoto, K.
  Soft Matter, 16, 28, 6493, 6500, Royal Society of Chemistry ({RSC}), Jun. 2020, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press
  Nao Fujimura; Koyo Ooga; Kosuke Takahashi; Takashi Nakamura; Tatsuki Wajima
  MECHANICAL ENGINEERING JOURNAL, 7, 4, 2020, [Peer-reviewed]
  English, Scientific journal
• Bending Deformation of Multiple Aligned Plates Toward Coalescence Induced by Capillarity
  Takahashi, K.; Matsuo, T.; Inaba, K.; Kishimoto, K.
  Journal of Microelectromechanical Systems, 28, 4, 685, 694, Institute of Electrical and Electronics Engineers ({IEEE}), Aug. 2019, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Study of the primary factor in the fatigue strength of steel-aluminium brazing joint by partial machining of joint parts
  TAKAHASHI Kosuke; FUKAZAWA Hiroshi; WAKUI Kouta; TRIAWAN Farid; INABA Kazuaki; KISHIMOTO Kikuo; HASHIMURA Toru
  Transactions of the JSME (in Japanese), 84, 865, 18, 00137-18-00137, 一般社団法人 日本機械学会, Sep. 2018, [Peer-reviewed], [Lead author, Corresponding author], [Domestic magazines]
  Japanese, Scientific journal, <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>
• Changing mechanism of surface topography in low-cycle fatigue of austenitic stainless steel
  FUJIMURA Nao; NISHIZUKA Yuto; TAKAHASHI Kosuke; NAKAMURA Takashi
  Transactions of the JSME (in Japanese), 84, 864, 18, 00206-18-00206, 一般社団法人 日本機械学会, 2018, [Peer-reviewed], [Domestic magazines]
  Japanese, Scientific journal, <p>To quantitatively investigate the cause of the changes in arithmetic mean roughness <i>R_a</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_a</i>. A comparison between <i>R_a</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_a</i>. A comparison between <i>R_a</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_a</i>. As a result, the product was in good agreement with <i>R_a</i>. Consequently, the surface texture parameter <i>R_a</i> represent both the change in the height and the number of surface reliefs due to PSBs.</p>
• Cavitation damage of epoxy resin subjected to uniaxial tensile loading
  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, [Peer-reviewed]
  English, Scientific journal, <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>
• Surface modification of magnesium AZ31 by using scanning cyclic press and the improvement effect on fatigue properties
  Nao Fujimura; Takashi Nakamura; Kosuke Takahashi; Tatsuki Wajima
  Zairyo/Journal of the Society of Materials Science, Japan, 66, 12, 906, 912, Society of Materials Science Japan, 01 Dec. 2017, [Peer-reviewed]
  Japanese, Scientific journal
• Dynamics of Wave Propagation Across Solid-Fluid Movable Interface in Fluid-Structure Interaction
  Tomohisa Kojima; Kazuaki Inaba; Kosuke Takahashi; Farid Triawan; Kikuo Kishimoto
  JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME, 139, 3, 031308, Jun. 2017, [Peer-reviewed]
  English, Scientific journal
• Evaluation of interfacial strength between fiber and matrix based on cohesive zone modeling
  Bentang Arief Budiman; Kosuke Takahashi; Kazuaki Inaba; Kikuo Kishimoto
  COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, 90, 211, 217, Nov. 2016, [Peer-reviewed], [Corresponding author]
  English, Scientific journal
• Characterization of Tack Strength Based on Cavity-Growth Criterion
  Kosuke Takahashi; Yuichiro Yamagata; Kazuaki Inaba; Kikuo Kishimoto; Shiori Tomioka; Toshio Sugizaki
  LANGMUIR, 32, 14, 3525, 3531, Apr. 2016, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Study on impact behavior for cylindrical tubes with and without pellets
  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, The Japan Society of Mechanical Engineers, 2016, [Peer-reviewed]
  Japanese, Scientific journal,

  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.

• Wetting-induced attraction of thin plates due to capillary flow
  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, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal,

  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.

• 粘着剤の非線形粘弾性を考慮したはく離強度評価
  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, [Peer-reviewed], [Lead author, Corresponding author]
  Japanese, Scientific journal, 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.
• Instant electrode fabrication on carbon-fiber-reinforced plastic structures using metal nano-ink via flash light sintering for smart sensing
  Kosuke Takahashi; Kensuke Namiki; Takahiro Fujimura; Eun-Beom Jeon; Hak-Sung Kim
  COMPOSITES PART B-ENGINEERING, 76, 167, 173, Jul. 2015, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• A new method of evaluating interfacial properties of a fiber/matrix composite
  Bentang Arief Budiman; Kosuke Takahashi; Kazuaki Inaba; Kikuo Kishimoto
  JOURNAL OF COMPOSITE MATERIALS, 49, 4, 465, 475, Feb. 2015, [Peer-reviewed], [Corresponding author]
  English, Scientific journal
• An investigation of contact resistance between carbon fiber/epoxy composite laminate and printed silver electrode for damage monitoring
  Eun-Beom Jeon; Takahiro Fujimura; Kosuke Takahashi; Hak-Sung Kim
  COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING, 66, 193, 200, Nov. 2014, [Peer-reviewed]
  English, Scientific journal
• Interaction of Serum Proteins with Hemodialysis Membrane: Comparison with De-adhesion Process of AFM Probe from Adhesive Tapes
  Rehana Afrin; Atsushi Ikai; Kosuke Takahashi; Kazuaki Inaba; Kikuo Kishimoto
  MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 603, 1, 157, 164, Nov. 2014, [Peer-reviewed]
  English, Scientific journal
• Evaluation of Contact Resistance between Carbon Fiber/Epoxy Composite Laminate and Printed Silver Electrode for Damage Monitoring
  Eun-Beom Jeon; Kosuke Takahashi; Hak-Sung Kim
  Journal of the Korean Society for Nondestructive Testing, 34, 5, 377, 383, The Korean Society of Nondestructive Testing, 30 Oct. 2014, [Peer-reviewed]
  Korean, Scientific journal
• Supercritical CO2 generator using bubble collapse by water hammer
  Hiroyuki Ushifusa; Kazuaki Inaba; Kosuke Takahashi; Kikuo Kishimoto
  JOURNAL OF SUPERCRITICAL FLUIDS, 94, 174, 181, Oct. 2014, [Peer-reviewed]
  English, Scientific journal
• Transient phenomena in wave propagation around a large suspended particle in a water-filled tube
  Tatsuro Hori; Kazuaki Inaba; Kosuke Takahashi; Kikuo Kishimoto
  Applied Mechanics and Materials, 566, 431, 436, Trans Tech Publications Ltd, 2014, [Peer-reviewed]
  English, International conference proceedings
• Filtering effects of periodic structure in water hammer
  Minoru Nagai; Kazuaki Inaba; Kosuke Takahashi; Kikuo Kishimoto
  Applied Mechanics and Materials, 566, 50, 55, Trans Tech Publications Ltd, 2014, [Peer-reviewed]
  English, International conference proceedings
• 機械・構造物補修用コーティング材料の耐キャビテーション評価
  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, [Peer-reviewed], [Lead author, Corresponding author]
  Japanese, 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.
• Evaluation of capillary-induced deformation of thin plates due to liquid column formation
  Kosuke Takahashi; Seiji Sugita; Shuzo Oshima; Kazuaki Inaba; Kikuo Kishimoto
  Applied Physics Letters, 103, 4, 043113, AIP Publishing, 22 Jul. 2013, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• A Modeling of Cerebral Blood Flow Changes due to Head Motion for fNIRS
  Takahashi, K.; Tanaka, T.; Nara, H.; Kaneko, S.; Inoue, M.; Shimizu, S.; Kojima, S.
  International Journal of Optomechatronics, 7, 2, 2013
  Scientific journal
• Tack performance of pressure-sensitive adhesive tapes under tensile loading
  Kosuke Takahashi; Masashi Shimizu; Kazuaki Inaba; Kikuo Kishimoto; Yoichi Inao; Toshio Sugizaki
  International Journal of Adhesion and Adhesives, 45, 90, 97, Elsevier, 2013, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Towards practical application of electrical resistance change measurement for damage monitoring using an addressable conducting network
  Kosuke Takahashi; H. Thomas Hahn
  STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL, 11, 3, 367, 377, May 2012, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Autonomic thermal management of graphite fiber/epoxy composite structures using an addressable conducting network
  Kosuke Takahashi; H. Thomas Hahn
  COMPOSITES PART B-ENGINEERING, 43, 3, 833, 840, Apr. 2012, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Investigation of temperature dependency of electrical resistance changes for structural management of graphite/polymer composite
  Kosuke Takahashi; H. Thomas Hahn
  JOURNAL OF COMPOSITE MATERIALS, 45, 25, 2603, 2611, Dec. 2011, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Multiple healing effect of thermally activated self-healing composites based on Diels-Alder reaction
  Jong Se Park; Thomas Darlington; Anthony F. Starr; Kosuke Takahashi; Joseph Riendeau; H. Thomas Hahn
  COMPOSITES SCIENCE AND TECHNOLOGY, 70, 15, 2154, 2159, Dec. 2010, [Peer-reviewed]
  English, Scientific journal
• An addressable conducting network for autonomic structural health management of composite structures
  Kosuke Takahashi; Jong Se Park; H. Thomas Hahn
  SMART MATERIALS & STRUCTURES, 19, 10, 105023, Oct. 2010, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Simultaneous Measurement of Multiple Electrical Resistance Changes with Strain of CFRP
  TAKAHASHI Kosuke; TODOROKI Akira; MATSUZAKI Ryosuke
  JSMME, 4, 4, 557, 567, The Japan Society of Mechanical Engineers, 2010, [Peer-reviewed], [Lead author]
  English, 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.
• Electrical Resistance Change Measurement with Elevated Temperature due to Joule Heating for the Detection of Delamination in Graphite/Epoxy Composites
  Takahashi Kosuke; Todoroki Akira; Matsuzaki Ryosuke
  Journal of Environment and Engineering, 5, 1, 15, 26, The Japan Society of Mechanical Engineers, 2010, [Peer-reviewed], [Lead author]
  English, 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.
• Delamination detection in CFRP plates using statistical analysis of change in temperature characteristic of resistance
  Yoshiro Suzuki; Akira Todoroki; Kosuke Takahashi; Yoshihiro Mizutani; Ryosuke Matsuzaki
  Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A, 76, 767, 961, 967, Japan Society of Mechanical Engineers, 2010, [Peer-reviewed]
  Japanese, Scientific journal
• Towards Development of a Self-Healing Composite using a Mendable Polymer and Resistive Heating
  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, Dec. 2008, [Peer-reviewed]
  English, Scientific journal
• Time-synchronized wireless strain and damage measurements at multiple locations in CFRP laminate using oscillating frequency changes and spectral analysis
  Ryosuke Matsuzaki; Akira Todoroki; Kosuke Takahashi
  SMART MATERIALS & STRUCTURES, 17, 5, 055001, Oct. 2008, [Peer-reviewed]
  English, Scientific journal
• CFRP のひずみに伴う電気抵抗変化の多点同時測定
  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, [Peer-reviewed], [Lead author]
  Japanese, 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.
• ジュール発熱による電気抵抗変化を利用した CFRP 構造物の層間はく離検知
  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, [Peer-reviewed], [Lead author]
  Japanese, 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.
• Statistical damage detection of laminated CFRP beam using electrical resistance change method
  Kosuke Takahashi; Akira Todoroki; Yoshinobu Shimamura; Atsushi Iwasaki
  PROGRESSES IN FRACTURE AND STRENGTH OF MATERIALS AND STRUCTURES, 1-4, 353-358, 1330, +, 2007, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Time-synchronized Wireless Strain and Damage Measurements at Multiple Locations in CFRP Laminate Using Oscillating Frequency Changes and Spectral Analysis
  MATSUZAKI Ryosuke; TODOROKI Akira; TAKAHASHI Kosuke
  Transactions of the Japan Society of Mechanical Engineers Series B, 73, 724, 1904, 1911, The Japan Society of Mechanical Engineers, 25 Dec. 2006, [Peer-reviewed]
  Japanese, 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.

• 振動圧縮負荷による純チタン表層の常温窒化現象とその要因
  舩木優大; 中村孝; 髙橋航圭; 和島達希, 熱処理, 65, 2, 75, 78, May 2025, [Peer-reviewed], [Invited]
  Japanese, Introduction scientific journal
• Nondestructive Observation of Small Internal Cracks in Gigacycle Fatigue of Titanium Alloys
  Takashi Nakamura; Fumiyoshi Yoshinaka; Gaoge Xue; Nao Fujimura; Kosuke Takahashi, Materia Japan, 63, 11, 770, 775, 01 Nov. 2024
  Japan Institute of Metals
• Detection of Fatigue Crack along Nano-Interface for Realizing Composites with Superlong Fatigue-Life,複合材料の超長寿命化に向けたナノ界面の疲労き裂検出
  Takahashi, K., Zairyo Journal of the Society of Materials Science Japan, 73, 8, 663, 668, Aug. 2024, [Invited], [Lead author, Corresponding author]
  Japanese, Introduction scientific journal, 30964622
• Studying Abroad for a Ph. D. Degree
  TAKAHASHI Kosuke, Journal of the Society of Materials Science, Japan, 72, 2, 150, 15 Feb. 2023
  The Society of Materials Science, Japan, Japanese
• Approaches Based on Strength of Materials for Adhesion Strength Considering Thickness of PSA Layer and Backing
  Kosuke Takahashi, Journal of the Adhesion Society of Japan, 46, 4, 125, 132, 2020, [Invited], [Lead author, Corresponding author]
  Japanese, Introduction scientific journal
• ぬれが及ぼす微細構造体における吸着力・接着力の評価と課題
  高橋航圭; 因幡和晃; 岸本喜久雄, 日本接着学会誌, 50, 7, 235, 242, Jul. 2014, [Invited], [Lead author, Corresponding author]
  The Adhesion Society of Japan, Japanese, Introduction scientific journal
• スマートストラクチャ(6)セルフヒーリングコンポジット
  高橋 航圭; Hahn H. Thomas, 強化プラスチックス, 55, 9, 340, 345, Sep. 2009, [Invited], [Lead author, Corresponding author]
  強化プラスチック協会, Japanese, Introduction scientific journal

• 接着・接合の支配要因と最適化技術
  18 粘着テープのバルク特性に着目したはく離強度評価
  S&T出版, Feb. 2021, 9784907002848, xiii, 271p, 図版[4]p, Japanese, [Contributor]

• Application of Testing Method for the Adhesion Performance towards Quantitative Evaluation of Swallowing
  吉田稜生; 中村孝; 高橋航圭
  日本接着学会年次大会講演要旨集(CD-ROM), 2024
  2024 - 2024
• Fatigue Properties of Extruded Magnesium Alloy with Surface Modification Using Scanning Cyclic Press
  藤村奈央; 高橋航圭; 中村孝; 和島達希
  疲労シンポジウム講演論文集, 2024
  2024 - 2024
• Characteristics of the Internal Fatigue Crack Propagation in Beta Titanium Alloy
  XUE Gaoge; 藤村奈央; 高橋航圭; 中村孝
  疲労シンポジウム講演論文集, 2024
  2024 - 2024
• The Adhesion Behavior of Internal Fatigue Crack in (α+β) Ti-6Al-4V Under Cyclic Compressive Loading
  舩木優大; 増谷幸香; XUE Gaoge; 高橋航圭; 藤村奈央; 中村孝
  疲労シンポジウム講演論文集, 2024
  2024 - 2024
• Propagation Properties of Surface- and Internally-Initiated Small Fatigue Cracks in Precipitation-Hardened Stainless Steel SUS630
  上野竜史; XUE Gaoge; 舩木優大; 高橋航圭; 藤村奈央; 中村孝
  疲労シンポジウム講演論文集, 2024
  2024 - 2024
• Initiation and growth behaviors of small internal fatigue cracks in precipitation-hardened stainless steel SUS 630
  中村孝; 五十嵐元; 藤村奈央; 高橋航圭
  日本材料学会学術講演会講演論文集(CD-ROM), 2024
  2024 - 2024
• Effects of Number of Cyclic Loading in Scanning Cyclic Press on the Surface Modification of Magnesium Alloy
  ABE Suzuka; FUJIMURA Nao; OOGA Koyo; TAKAHASHI Kosuke; NAKAMURA Takashi; WAJIMA Tatsuki
  The Proceedings of Mechanical Engineering Congress, Japan, 2020, The Japan Society of Mechanical Engineers, Japanese
  2020 - 2020, A new surface modification technique, scanning cyclic press (SCP), was developed. SCP scans a metal surface with a vibrating indenter and refines the surface layer using cyclic compressive loading. This study applied SCP to the surface of magnesium alloy AZ31 under number of cyclic loading of 3.2×10⁵ and 8.0×10⁶ cycles to investigate the effect on surface structure. After applying SCP, the cross sections of specimens were observed by electron back scattering diffraction (EBSD) using SEM. As a result, a fine structure around 1－10 μm in grain size and a twin were formed in the surface layer of both specimens. The depth of these structures from the surface remained unchanged regardless of the number of cyclic loading. However, the surface structure under 8.0×10⁶ cycles was finer than that under 3.2×10⁵ cycles. This is likely caused by the increase of accumulated plastic strain during SCP process.
• A Study of Room-temperature-nitriding Process of Pure Titanium Using Scanning Cyclic Press under Controlled Atmosphere
  FUKUDA Tetsuya; KATONO Yutaka; FUJIMURA Nao; TAKAHASHI Kosuke; NAKAMURA Takashi; WAJIMA Tatsuki
  The Proceedings of Mechanical Engineering Congress, Japan, 2020, The Japan Society of Mechanical Engineers, Japanese
  2020 - 2020, A new surface modification technique, scanning cyclic press (SCP), was applied to commercially pure titanium (CP-Ti) in a nitrogen atmosphere at room temperature. During the SCP process, a vibrating indenter reciprocally scanned the specimen’s surface to apply cyclic low compressive load. In this study, a possibility of a room-temperature-nitriding technique using SCP was investigated. Before and after SCP, the surface and the cross-section of the specimens were observed using a laser microscope and scanning ion microscope (SIM), respectively. Then, elemental and composition analyses were conducted by using EPMA and XRD. As a result, a pale golden color, which is known as a characteristic of titanium nitride coating, appeared at the surface of SCP-treated specimen. The SIM observation of the cross-section showed that a nanocrystalline structure was created in the surface layer, and the nitrogen element was detected in the same layer. The XRD analysis showed a strong possibility to form titanium nitride at the surface of SCP-treated specimen. These results suggested that nitrogen element surrounding the specimen diffused into the microstructure beneath the surface and likely created titanium nitride during SCP even at room temperature.
• Damage Simulation of Mortar Materials by Multi-scale Analysis
  OHYAMA Kota; TAKAHASHI Kosuke; FUJIMURA Nao; NAKAMURA Takashi
  The Proceedings of Mechanical Engineering Congress, Japan, 2020, The Japan Society of Mechanical Engineers, Japanese
  2020 - 2020, In this study, multi-scale analysis was carried out by designing a porous cement paste model, and a mortar model using glass spheres as fine aggregates. The tensile simulation of porous cement paste model was conducted by RVE model that reflects the distribution of pore size in a cement specimen. It was shown that the elastic modulus and strength of cement have a linear relationship with porosity. The finite element model of cylindrical samples was then created to simulate the splitting tensile test. For the cylindrical mortar model, spatial variation of the physical properties due to the porosity distribution in cement was reflected. When cement had a distribution of physical properties, the strength of the cement model was similar to that of mortar model as it was observed from the experiment, whereas the strength of the cement model was higher by 20 % if uniform physical properties were used for cement matrix. It was confirmed that our simulation well corresponded to the experimental result of at the ages of 28 days. In addition, the decrease in the strength, which would be expected for further aging mortar, can be also modeled by the porous layer at glass-cement interface, representing the Interfacial Transition Zone.
• High-resolution non-destructive observation of microstructure in high strength metallic materials using synchrotron radiation micro/nano CT
  KON Yuma; NAKAMURA Takashi; FUJIMURA Nao; YOSHINAKA Fumiyoshi; TAKAHASHI Kosuke; TAKEUCHI Akihisa; UESUGI Masayuki; UESUGI Kentaro
  The Proceedings of the Materials and Mechanics Conference, 2019, The Japan Society of Mechanical Engineers, Japanese
  2019 - 2019, To investigate the initiation and propagation processes of internal fatigue crack in high strength metallic materials, high resolution and non-destructive observation technique was proposed. The opening and closing behaviors of fatigue cracks in Ti-6Al-4V, and the non-metallic inclusions in SNCM439, which are regarded as a potential crack initiation site, were observed by synchrotron radiation CT (SR-CT) at SPring-8. To ensure a sufficient X ray transmission, fatigue specimens with a small diameter were designed, and a tensile loading jig was newly developed to measure the CTOD during SR-CT. In Ti-6Al-4V, micro CT and nano CT with a resolution around 1 μm and 200 nm, respectively, were used to observe internal cracks. As a result, it was clarified that surface cracks and internal cracks showed different behaviors. The crack tip of surface cracks had a sharp shape and the CTOD was changed by the tensile load. On the other hand, the shape of crack tips of internal cracks was blunted, and the tensile load did not affect CTOD. This crack blunting was explained by the vacuum-like environment around the internal crack. In SNCM439, small non-metallic inclusions with the size around 8 μm in diameter were clearly observed. Accordingly, it is expected that we can observe the initiation and propagation of internal cracks in high strength steel by repeating fatigue tests and SR-CT alternately.
• Fatigue life estimation of subsurface cracks based on crack growth rates measured in a vacuum environment
  MODI Sourav Kumar; MEHENDIRATTA Paras; TSUKAGOSHI Takuma; NAKAMURA Takashi; FUJIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2019, The Japan Society of Mechanical Engineers, Japanese
  2019 - 2019, In recent years, it has been revealed that in high strength steel, fracture occurs from non-metallic inclusions inside of the material in the very high cycle region. However, because of the difficulty in directly observing the internal fatigue process, its mechanism is still unknown. Subsequently efforts are being made for better understanding of fatigue crack initiation and propagation. In this study, we have tried to estimate life in this subsurface fatigue region using crack growth rates measured in a vacuum environment and compare it with actual life found out in subsurface fractures in fatigue test to better understand fatigue crack properties.
• Fatigue property improving effect of low carbon steel S25C by surface modification technique Scanning Cyclic Press
  TANNO Ryoko; FUJIMURA Nao; NAKAMURA Takashi; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2019, The Japan Society of Mechanical Engineers, Japanese
  2019 - 2019, In this study, we applied a new surface modification technique, scanning cyclic press (SCP) to machined specimens of low carbon steel S25C. In the SCP process, a vibrating indenter scans the metal surface and cyclically applies a variable low compressive load to modify the microstructure at the surface. During applying the SCP, the processing parameters, such as the scanning speed, the amount of compressive load and the number of cyclic loading, were changed to investigate the effects on the microstructure and the fatigue property. After applying the SCP, the surface roughness of specimens became smaller than that before. To clarify the changes in the microstructure beneath the surface of the SCP-treated specimens, the cross-section was created using focused ion beam technique. Scanning ion microscopic observations showed the microstructure refinement at the surface layer. The microstructure refinement was promoted with increasing the scanning speed, and the surface hardness also increased. Additionally, at the higher compressive load and the larger number of cyclic loading, finer microstructure was observed at the surface layer above the modified microstructure. This result suggested that the microstructure refinement is promoted by increasing the amount and the number of compressive loading. Fatigue test results showed that the fatigue lives of the SCP-treated specimens were 2 to 50 times longer than that of non-treated specimens.
• Changing Mechanisms of Surface Relief and the Damage Evaluation of Low Cycle Fatigued Austenitic Stainless Steel
  Nao Fujimura; Takashi Nakamura; Kosuke Takahashi
  MATEC Web of Conferences, 25 May 2018, EDP Sciences, English
  25 May 2018 - 25 May 2018
• Effects of vacuum environment on the fatigue crack growth properties of high strength steel-Behavior of small crack by ΔK-increasing test-
  ISHIHARA Risa; MEHENDIRATTA Paras; NAKAMURA Takashi; FUJIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2018, The Japan Society of Mechanical Engineers, Japanese
  2018 - 2018, In recent years, it has been revealed that in high strength steel, fracture occurs from non-metallic inclusions inside of the material in the very high cycle region. However, because of the difficulty in directly observing the internal fatigue process, its mechanism is largely unknown. In this study, we try to clarify the internal fatigue process on the basis that the environment around an internal crack is like a vacuum environment. Also, it has been reported that the effect of vacuum environment is more prominent in the initial stages of crack propagation. This suggests that targeting the crack propagation process of small cracks, like that with the same size as a small defect, would shed light on the controlling factors in the internal fatigue process. Thus, we conducted ΔK-increasing tests in air and in vacuum using specimens with a small artificial defect on its surface. As a result, fatigue crack propagation rates in vacuum were lower than that in air. Also, when compared with the results of long cracks, the crack propagation rates in both environments were much higher. However, after eliminating the effect of crack closure for the results of long crack, the crack propagation rates in both environments matched.
• Effects of vacuum environment on the fatigue crack growth properties of high strength steel- behavior of long crack by ΔK decrease test
  MEHENDIRATTA Paras; ISHIHARA Risa; NAKAMURA Takashi; FUJIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2018, The Japan Society of Mechanical Engineers, Japanese
  2018 - 2018, Sub-surface fractures are known as a characteristic fatigue mode of high strength steel in the very high cycle region. To reveal the mechanism of sub-surface fractures, ΔK-decreasing tests were conducted in high vacuum and air environments based on the idea that sub-surface cracks are exposed to a vacuum-like environment. As a result, fatigue crack growth rates in high vacuum were slower than those in air. In high vacuum, fatigue crack growth still took place at a considerably low rate around 10^-13 m/cycle, and the effective threshold stress intensity factor rage (ΔK_eff) in high vacuum lower to that in air. Unlike in air environment, negligible effects of oxide-induced crack closure in vacuum was considered as the reason for the results. The behavior of fatigue crack growth properties in high vacuum well explained the characteristics of sub-surface crack growths in very high cycle regime.
• Evaluation of healing characteristics of a mendable polymer with FEM
  HASEGAWA Ryo; TAKAHASHI Kosuke; FUJIMURA Nao; NAKAMURA Takashi
  The Proceedings of the Materials and processing conference, 2018, The Japan Society of Mechanical Engineers, Japanese
  2018 - 2018
• Adhesively bonded joint strengthened by double-sided adhesive tape
  KIKUZAWA Takuma; TAKAHASHI Kosuke; FUJIMURA Nao; NAKAMURA Takashi
  The Proceedings of the Materials and processing conference, 2018, The Japan Society of Mechanical Engineers, Japanese
  2018 - 2018
• Observation of fatigue crack initiation process in Ti-22V-4Al
  KASHIMA Shota; TAKANASHI Kei; YOSHINAKA Fumiyoshi; NAKAMURA Takashi; FUJIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2017, The Japan Society of Mechanical Engineers, Japanese
  2017 - 2017, It is generally reported on titanium alloys that crack initiation occurs from a small flat plane called the “facet”. Thus, it is important to investigate facet formation processes in revealing the fatigue characteristics of titanium alloy. In the present work, β type titanium alloy Ti-22V-4Al was investigated in order to elucidate the fatigue crack initiation process. An axial load fatigue test was carried out with an etched specimen in order to examine the positional relationship between the microstructure and crack initiation site (in the grain or at the grain boundary). After the fatigue test, the fracture surface and the specimen surface were observed by using a scanning electron microscope. From the fracture surface observation, four crack propagation traces were observed on the fracture surface. When focusing on the crack initiation site, it was revealed that each crack initiated from a facet. Then, the facet angle was measured as the angle between the loading direction and the normal to the facet plane, which revealed that the shear stress largely contributed to crack initiation. The result of the specimen surface observation demonstrated that crack initiation occurred in β phase without α precipitate rather than at the β grain boundary. Therefore, in this sample material, crack initiated in β phase mainly by the shear stress.
• Fatigue crack initiation and propagation properties of Ti-22V-4Al
  TAKANASHI Kei; KASHIMA Shota; YOSHINAKA Fumiyoshi; NAKAMURA Takashi; FUJIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2017, The Japan Society of Mechanical Engineers, Japanese
  2017 - 2017, To investigate the fatigue crack initiation and propagation properties of Ti-22V-4Al, uniaxial fatigue tests and surface observation were carried out. As a result of surface observation, the crack initiation life of each crack was clarified. The cracks initiated at N = 2000 to 8000 cycles. Based on the crack initiation life of each crack, the tendency of crack initiation was investigated using probability paper. As a result, it was shown that the crack initiation life follows the lognormal distribution. Based on the crack propagation observation results, the relationship between the crack growth rate da/dN and the stress intensity factor range ΔK was investigated. As a result, in the small ΔK region, the dispersions of each crack was large. However, with the increase in ΔK, the dispersions became smaller and showed a certain width. Comparing with the same material with different heat treatment samples, da/dN-ΔK relations in large ΔK regions show similar value. So it suggests that crack propagation resistance may not be affected by the precipitation amount of α phase in this material.
• Effect of Scanning Cyclic Press on Fatigue Properties of AZ31
  OGA Koyo; FUJIMURA Nao; NAKAMURA Takashi; TAKAHASHI Kosuke; WAJIMA Tatsuki
  The Proceedings of the Materials and Mechanics Conference, 2017, The Japan Society of Mechanical Engineers, Japanese
  2017 - 2017, Magnesium alloy is the lightest metal among all practical metals and recognized as a promising material; however, it has a limited use because of the poor fatigue properties. In this study, a new surface modification technique, scanning cyclic press (SCP), was applied to magnesium alloy AZ31 to improve its fatigue properties. SCP scans a metal surface with a vibrating indenter under precise loading control based on a servo testing machine and can apply a variable cyclically compressive load. The surface observation on AZ31 specimens showed an increase in surface roughness of SCP-treated specimens. However, the fatigue life of SCP-treated specimens clearly increased. Microstructure of a cross section of SCP-treated specimen was observed using an optical microscope. A fine mesh-patterned region was formed beneath the surface to a depth of 50 μm. The fracture surface observation showed that the fracture origin of SCP-treated specimens located in subsurface site whereas that of untreated specimens was at the surface of the specimen. The observation also showed a band-like layer just beneath surface in SCP-treated specimen which did not exist in the untreated specimen. The layer corresponded to the mesh-patterned region. The results suggested that SCP changed the surface microstructure of magnesium alloy and suppressed crack initiation from the specimen's surface.
• Changing Mechanisms of Surface Topography and the Damage Assessment in Low Cycle Fatigued SUS316NG
  FUJIMURA Nao; NISHIZUKA Yuto; NAKAMURA Takashi; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2017, The Japan Society of Mechanical Engineers, Japanese
  2017 - 2017, 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 slip bands and 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 obtained were analyzed by frequency analysis to separate the surface relief due to persistent slip bands (PSBs) from that due to crystal grain deformation. The height caused by PSBs and that by crystal grain deformation were measured respectively. As a result, the both heights developed 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 crystal 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 crystal grain deformation.
• WAVE PROPAGATION ACROSS THE INTERFACE OF FLUID-STRUCTURE INTERACTION WITH VARIOUS SURFACE CONDITIONS OF SOLID MEDIUM
  Tomohisa Kojima; Kazuaki Inaba; Kosuke Takahashi
  PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE, 2016, VOL 4, 2017, English
  2017 - 2017
• Measurement and evaluation of fracture toughness in the thickness direction of polyimide film
  NAGUMO Yoshinori; SAKAMOTO Yusuke; NAKAMURA Takashi; FUZIMURA Nao; TAKAHASHI Kosuke
  The Proceedings of the Materials and Mechanics Conference, 2016, The Japan Society of Mechanical Engineers, Japanese
  2016 - 2016, Polyimide (PI) film with a surface small defect subjected to tensile load is fractured by the crack propagation from the defect in the film thickness direction. However, the evaluation method of fracture toughness in this type of fracture hasn’t yet been established. In this paper, SENT tests were carried out using 125 μm-thick PI films with a surface pre-crack having different depths from 10 μm to 60 μm, and fracture processes focusing on crack opening and crack extension were observed with a color 3D laser scanning microscope. Based on the results, fracture toughnesses J_in in the direction of film thickness were calculated by using two different equations for SENT specimen. As a result, J_in values were clarified to have a slight dependency on pre-crack depth. The differences between J_in values calculated by the two equations were considered small, and fracture toughness was in the range from 0.4 to 1 kJ/m².
• PS0031-450 Experimental Study on Mechanism of Water Hammer Propagation and Coupled Tube Wall Vibration
  YAMAGUCHI Daisuke; MASUKO Takuya; INABA Kazuaki; TAKAHASHI Kousuke; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 21 Nov. 2015, The Japan Society of Mechanical Engineers, Japanese
  21 Nov. 2015 - 21 Nov. 2015, 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 Effect of Surface Condition of Solid Materials on Wave propagation at Solid-Fluid Interface with Fluid-Structure Interaction
  KOJIMA Tomohisa; INABA Kazuaki; TAKAHASHI Kosuke; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 21 Nov. 2015, The Japan Society of Mechanical Engineers, Japanese
  21 Nov. 2015 - 21 Nov. 2015, 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 Measurements of micro-scale impact loads due to bubble collapses using inverse analysis
  ISHII Tomoya; INABA Kazuaki; TAKAHASHI Kosuke; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 21 Nov. 2015, The Japan Society of Mechanical Engineers, Japanese
  21 Nov. 2015 - 21 Nov. 2015, 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 Fatigue life prediction of Steel-Aluminum welded joint considering the fracture form
  FUKAZAWA Hiroshi; TAKAHASHI Kousuke; INABA Kazuaki; KISHIMOTO Kikuo; HASHIMURA Toru
  M&M材料力学カンファレンス, 21 Nov. 2015, The Japan Society of Mechanical Engineers, Japanese
  21 Nov. 2015 - 21 Nov. 2015, 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, 04 Oct. 2015, The Japan Society of Mechanical Engineers, English
  04 Oct. 2015 - 04 Oct. 2015
• S0520302 Formation of magnetic virtual channel
  TAKAHASHI Ryutaro; OHSIMA Shuzo; INABA Kazuaki; TAKAHASHI Kosuke
  Mechanical Engineering Congress, Japan, 13 Sep. 2015, The Japan Society of Mechanical Engineers, Japanese
  13 Sep. 2015 - 13 Sep. 2015, 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 Electromagnetic Sloshing of Bilayer Liquids in Converter
  ITO Satoshi; OSHIMA Shuzo; INABA Kazuaki; TAKAHASHI Kosuke
  Mechanical Engineering Congress, Japan, 13 Sep. 2015, The Japan Society of Mechanical Engineers, Japanese
  13 Sep. 2015 - 13 Sep. 2015, 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.
• Measurement and visualization of supercrtcal CO2 in dynamic phase transition
  Hiroyuki Ushifusa; Kazuaki Inaba; Konosuke Sugasawa; Kosuke Takahashi; Kikuo Kishimoto
  EFM14 - EXPERIMENTAL FLUID MECHANICS 2014, 2015, English
  2015 - 2015
• WAVE PROPAGATION ACROSS SOLID-FLUID INTERFACE WITH FLUID-STRUCTURE INTERACTION
  Tomohisa Kojima; Kazuaki Inaba; Kosuke Takahashi
  PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE - 2015, VOL 5, 2015, English
  2015 - 2015
• Evaluation of Blood Vessel Stresses near a Cerebrovascular Branch with an Aneurysm
  Oda Kentaro; Oshima Shuzo; Inaba Kazuaki; Takahashi Kosuke
  The Computational Mechanics Conference, 22 Nov. 2014, The Japan Society of Mechanical Engineers, Japanese
  22 Nov. 2014 - 22 Nov. 2014, 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 Evaluation of pillar array clustering induced by capillary force
  FURUTA Masakazu; TAKAHASHI Kosuke; INABA Kazuaki; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 19 Jul. 2014, The Japan Society of Mechanical Engineers, Japanese
  19 Jul. 2014 - 19 Jul. 2014, 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 Strength evaluation of Steel-Aluminum welded joint
  FUKAZAWA Hiroshi; MIURA Yasufumi; TAKAHASHI Kousuke; INABA Kazuaki; KISHIMOTO Kikuo; HASHIMURA Toru
  M&M材料力学カンファレンス, 19 Jul. 2014, The Japan Society of Mechanical Engineers, Japanese
  19 Jul. 2014 - 19 Jul. 2014, 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.
• TRANSIENT BEHAVIOR OF WATER HAMMER IN A TWO-PIPE SYSTEM
  Kazuaki Inaba; Masaya Kamijukkoku; Kosuke Takahashi; Kikuo Kishimoto
  PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE - 2013, VOL 4: FLUID-STRUCTURE INTERACTION, 2014, English
  2014 - 2014
• OS1703 Tack performance evaluation of pressure-sensitive adhesive by observation of peeling behavior
  YAMAGATA Yuichiro; TAKAHASHI Kosuke; INABA Kazuaki; KISHIMOTO Kikuo; INAO Yoichi; SUGIZAKI Toshio
  M&M材料力学カンファレンス, 12 Oct. 2013, The Japan Society of Mechanical Engineers, Japanese
  12 Oct. 2013 - 12 Oct. 2013, 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 Evaluation of plate deformation induced by liquid bridge formation due to wettability
  TAKAHASHI Kosuke; SUGITA Seiji; INABA Kazuaki; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 12 Oct. 2013, The Japan Society of Mechanical Engineers, Japanese
  12 Oct. 2013 - 12 Oct. 2013, 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 Wave propagation of water hammer in compound tube
  TAKEDA Kengo; INABA Kazuaki; TAKAHASHI Kousuke; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 12 Oct. 2013, The Japan Society of Mechanical Engineers, Japanese
  12 Oct. 2013 - 12 Oct. 2013, 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
  2013 - 2013
• OS1212 The effect of adherend stiffness on stick-slip phenomenon in peeling test
  KUMAGAI Satoshi; TAKAHASHI Kosuke; INABA Kazuaki; KISHIMOTO Kikuo; YAMADA Mikinori; YNAKA Masaaki
  M&M材料力学カンファレンス, 22 Sep. 2012, The Japan Society of Mechanical Engineers, Japanese
  22 Sep. 2012 - 22 Sep. 2012, 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 Delamination Test and Evaluation Method of Particle-Reinforced Composites for Repairs
  NAKAMOTO Hiroaki; HAYABUSA Keisuke; NOHMI Motohiko; KISHIMOTO Kikuo; INABA Kazuaki; TAKAHASHI Kosuke; ARAI Daisuke
  M&M材料力学カンファレンス, 22 Sep. 2012, The Japan Society of Mechanical Engineers, Japanese
  22 Sep. 2012 - 22 Sep. 2012, 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 Improving the crush properties of cylinder with pattern-indented surface
  KAWAKITA Jun; GODA Toshihiro; TAKAHASHI Kosuke; INABA Kazuaki; KISHIMOTO Kikuo; HASHIMURA Toru
  M&M材料力学カンファレンス, 22 Sep. 2012, The Japan Society of Mechanical Engineers, Japanese
  22 Sep. 2012 - 22 Sep. 2012, 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 Deformation of a pillar array induced by surface tension of a liquid bridge
  SUGITA Seiji; TAKAHASHI Kosuke; INABA Kazuaki; KISHIMOTO Kikuo
  M&M材料力学カンファレンス, 22 Sep. 2012, The Japan Society of Mechanical Engineers, Japanese
  22 Sep. 2012 - 22 Sep. 2012, 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.
• 109 Investigation of Evaluation method of Interfacial Strength for Resin Repair Material
  HAYABUSA Keisuke; NAKAMOTO Hiroaki; KISHIMOTO Kikuo; ARAI Daisuke; INABA Kazuaki; TAKAHASHI Kosuke
  学術講演会講演論文集, 2012, 日本材料学会, Japanese
  2012 - 2012
• PS06 Damage detection in CFRP using statistical analysis of temperature characteristic of resistance
  SUZUKI Yoshiro; TODOROKI Akira; TAKAHASHI Kosuke; MIZUTANI Yoshihiro; MATSUZAKI Ryosuke
  M&M材料力学カンファレンス, 24 Jul. 2009, The Japan Society of Mechanical Engineers, Japanese
  24 Jul. 2009 - 24 Jul. 2009, 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 Statistical damage detection of CFRP using electrical resistance changes due to temperature change
  TAKAHASHI Kosuke; TODOROKI Akira; SHIMAMURA Yoshinobu; IWASAKI Atsushi; MATSUZAKI Ryosuke
  M&M材料力学カンファレンス, 24 Oct. 2007, The Japan Society of Mechanical Engineers, Japanese
  24 Oct. 2007 - 24 Oct. 2007, 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
  Kosuke Takahashi; Akira Todoroki; Yoshinobu Shimamura; Atsushi Iwasaki
  PROGRESSES IN FRACTURE AND STRENGTH OF MATERIALS AND STRUCTURES, 1-4, 2007, English
  2007 - 2007
• 510 Application of Statistical Diagnostic Method Using Electrical Resistance Changes for the Damage Detection of GFRP
  TODOROKI Akira; TAKAHASHI Kosuke; IWASAKI Atsushi
  埼玉ブロック大会(講演会)講演論文集, 2005, 日本機械学会関東支部, Japanese
  2005 - 2005

• 高分子材料工学特論, 2024年, 修士課程, 工学院
• システム工学特論Ⅰ, 2024年, 修士課程, 工学院
• 大学院共通授業科目（教育プログラム）：One program for Global Goals, 2024年, 修士課程, 大学院共通科目
• 高分子材料工学特論, 2024年, 博士後期課程, 工学院
• システム工学特論Ⅰ, 2024年, 博士後期課程, 工学院
• 国際交流Ⅱ, 2024年, 学士課程, 国際本部
• 専門横断科目（一般科目）：複合領域, 2024年, 学士課程, 専門横断科目
• 材料強度学, 2024年, 学士課程, 工学部
• 計算工学Ａ, 2024年, 学士課程, 工学部
• 機械工学概論, 2024年, 学士課程, 工学部

• THE ADHESION SOCIETY OF JAPAN
• JAPAN SOCIETY FOR COMPOSITE MATERIALS
• THE SOCIETY OF MATERIALS SCIENCE, JAPAN
• THE JAPAN SOCIETY OF MECHANICAL ENGINEERS

• エポキシ樹脂のミクロゲル構造に起因する接着界面の初期き裂発生機構解明
  科学研究費助成事業
  01 Apr. 2024 - 31 Mar. 2028
  高橋 航圭
  日本学術振興会, 基盤研究(B), 北海道大学, 24K00752
• Experimental and Numerical Studies on Multiscale Dynamics of Adhesion for Soft Adhesives
  Grants-in-Aid for Scientific Research
  01 Apr. 2024 - 31 Mar. 2027
  山口 哲生; 齊藤 尚平; 高橋 航圭
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), The University of Tokyo, 24K00595
• CFRPの疲労劣化の機構解明と余寿命推定法の確立
  戦略的な研究開発の推進 未来社会創造事業 探索加速型
  2022 - 2026
  荒井 政大
  CFRPは、飛行機や自動車等において大幅な軽量化が期待でき、その結果として全世界の二酸化炭素排出量を有効に低減できる材料として期待されている。機体の使用寿命を延ばすことでさらなるCO2排出量の低減を実現するためには、これらの機器の長期使用における損傷評価と余寿命の評価が極めて重要である。本研究ではこれらのCFRPに生じる損傷の発生と進展のメカニズムを詳細に解明し、損傷と破壊のモデルを構築する。さらにはCFRPの疲労劣化診断技術を確立し、疲労・破壊の評価モデルと組み合わせることで、高精度な余寿命評価を実現する。疲労・破壊モデルとエントロピー・電子スピン・熱伝導率等の物性評価手法を有効に組み合わせることで、CFRPの損傷進展とその余寿命を適切に評価し、最終的に機器の使用総寿命を2倍に伸ばすことが可能なモノづくりを提案する。
  科学技術振興機構, 名古屋大学
• 粘着界面のはく離メカニズムに基づくはく離強度評価指標の確立
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
  Apr. 2021 - Mar. 2024
  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．
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21K03765
• 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
  Strategic Basic Research Programs (PRESTO-SAKIGAKE)
  Nov. 2020 - Mar. 2024
  Japan Science and Technology Agency, Hokkaido University, Principal investigator
• 微細多孔薄膜粘着シートの併用による接着性能強化技術の開発
  A-STEP (Adaptable and Seamless Technology Transfer Program through Target-driven R&D)
  Nov. 2020 - Mar. 2022
  Japan Science and Technology Agency, Hokkaido University, Principal investigator
• Criteria of Peeling Process on Soft Adhesion Interface Based on Wettability of Solid Surface
  Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists
  01 Apr. 2018 - 31 Mar. 2020
  Takahshi Kosuke
  In this study, we suggested the failure criteria of adhesive tapes. Peel test and probe tack test were individually conducted to extract a common property between these tests, which represent essential adhesion strength of PSA (Pressure-Sensitive Adhesive) tape. The separation energies obtained from these tests were compared in terms of strain rates of PSA layers during separation process. PSA tapes of different visco-elastic properties were prepared by changing the amount of the curing agent in order to also investigate the influence of visco-elasticity of the PSA material. As a result, it was found that the separation energy is an identical property of PSA tape, which is logarithmically proportional to strain rate of PSA layer
  Japan Society for the Promotion of Science, Grant-in-Aid for Early-Career Scientists, Hokkaido University, 18K13652
• Mechanics of fine structures considering surface energy and its application to shape control
  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
  01 Apr. 2015 - 31 Mar. 2018
  Takahashi Kosuke
  In this study, a new method of manufacturing cylindrical structure in small scale was proposed. When a thin film floated on water is pulled up, it automatically deforms due to capillarity and eventually wraps liquid drop to form a cylindrical structure. The proposed method was confirmed by polymer films and rubber sheets in various dimensions. In addition, an analytical model was established to predict size of the cylindrical structure and maximum thickness of films for formation. Molecular dynamics simulation was also conducted to show the manufacturing a graphene roll from graphene sheet.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 15K17934
• Evaluation of tack strength by criterion of cavity generation
  研究者海外派遣援助
  Sep. 2016 - Sep. 2016
  The Murata Science Foundation, Hokkaido University, Principal investigator
• 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
  第56回工学研究助成
  Apr. 2013 - Mar. 2015
  高橋 航圭
  みずほ学術振興財団, Principal investigator, Competitive research funding
• Development of in-situ damage sensing/healing system for composite structures
  Bilateral Programs( Japan–Korea Basic Scientific Cooperation Program)
  Jul. 2012 - Jun. 2014
  Takahashi Kosuke
  Japan Society for the Promotion of Science (JSPS), Principal investigator, Competitive research funding
• 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
  第29回（2013年度）マツダ研究助成
  Apr. 2013 - Mar. 2014
  高橋 航圭
  公益財団法人マツダ財団, Principal investigator, Competitive research funding
• 電気抵抗変化法を用いたCFRPの統計的損傷検知
  科学研究費助成事業 特別研究員奨励費
  2008 - 2008
  高橋 航圭
  日本学術振興会, 特別研究員奨励費, 東京工業大学, 08J07083

• 骨材抽出装置及び骨材抽出方法
  Patent right, 長尾 莉希; 佐藤 亘; 高橋 航圭, 清水建設株式会社, 国立大学法人北海道大学
  特願2023-74294, 28 Apr. 2023
  特開2024-158776, 08 Nov. 2024
• Method of designing composite material, method of evaluating composite material, and composite material
  Patent right, Sota KAMO; Kiyoka TAKAGI; Tooru SHITANI; Toshio Abe; Sae OBATA; Kosuke Takahashi
  特願16 / 059,207, 09 Aug. 2018
  特許US 11,292,576 B2
• 複合材の設計方法、複合材の評価方法及び複合材
  Patent right, 加茂宗太; 高木清嘉; 志谷徹; 阿部俊夫; 小畠彩英; 高橋航圭
  特願P2017-157393, 17 Aug. 2017
  特許P6980454
  15 Dec. 2021

• Apr. 2013 - Present
  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。