Details of the Researcher

PHOTO

Keiichi Shirasu
Section
Graduate School of Engineering
Job title
Associate Professor
Degree

  • 博士（学術）（東北大学）

  • 修士（学術）（東北大学）

Committee Memberships 13

  • 日本付加製造学会　理事

    2023/04 - Present

  • 日本複合材料学会　代議員

    2023/04 - 2024/03

  • 日本機械学会機械材料・材料加工部門　第101期運営委員

    2023/04 - 2024/03

  • 日本機械学会機械材料・材料加工部門　代議員

    2022/04 - 2023/03

  • 日本機械学会機械材料・材料加工部門　第100期運営委員

    2022/04 - 2023/03

  • 日本機械学会機械材料・材料加工部門　第99期運営委員

    2021/04 - 2022/03

  • 日本機械学会　第99期 M&P部門第2技術委員会（講演会）幹事

    2021/04 - 2022/03

  • 日本機械学会東北支部第56期総会・講演会　実行委員

    2021/03 - 2021/03

  • 日本複合材料学会　第48回複合材料シンポジウム 実行委員

    2023/09 -

  • 日本機械学会　第30回 機械材料・材料加工技術講演会(M&P2023) OS: データ駆動型アプローチによる材料成形・加工・評価 オーガナイザー

    2023/09 -

  • 日本機械学会材料力学部門　M&M・CDM若手シンポジウム2023 実行委員（幹事）

    2023/08 -

  • The Japan Society of Mechanical Engineers ICM&P 2022 International Conference on Materials & Processing 2022　OS: Material Molding, Processing and Evaluation by Data-driven Approach オーガナイザー

    2022/11 -

  • WCCM2022　Towards Next-Generation Aircraft Design with High-Fidelity Simulation Technologiesセッション オーガナイザー

    2022/08 -

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Professional Memberships 6

  • 公益社団法人 高分子学会

  • 日本材料学会

  • 日本付加製造学会

  • 日本界面学会

  • JAPAN SOCIETY FOR COMPOSITE MATERIALS

  • 日本機械学会

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Research Interests 4

  • Multimaterial additive manufacturing

  • カーボンナノチューブ

  • 複合材料

  • 材料強度学

Research Areas 1

  • Nanotechnology/Materials / Composite materials and interfaces /

Awards 6

  1. 令和5年度学術奨励賞

    2024/05　日本材料学会　熱可塑性CFRPの力学特性・損傷進展と異種材料接合に向けた接着強度の評価に関する研究

  2. 日本機械学会奨励賞（研究）

    2019/02　日本機械学会

  3. 日本機械学会材料力学部門優秀講演表彰

    2015/11/21　日本機械学会

  4. 資源・素材学会東北支部春季大会ポスター賞 (金賞)

    2013/06/10　資源・素材学会

  5. 東北大学環境科学研究科長賞

    2012/03/27　東北大学

  6. 資源・素材学会東北支部春季大会ポスター賞 (銅賞)

    2010/06/04　資源・素材学会

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Papers 70

  1. Comparative study of thermosetting CF/epoxy and thermoplastic CF/PAEK composite laminates: Effects of stacking sequences on open-hole strength

    Kota Oine, Kazuki Ryuzono, Yoshiaki Kawagoe, Yamato Hoshikawa, Keiichi Shirasu, Yuki Takayama, Tomonaga Okabe

    Journal of Thermoplastic Composite Materials　2025/06/05

    DOI： 10.1177/08927057251344271 　

  2. Thermal oxidative degradation of cyanate- and amine-cured epoxy resins: Experiment and ReaxFF simulation

    Yoshiaki Kawagoe, Gota Kikugawa, Shohei Komori, Keiichi Shirasu, Tomonaga Okabe

    Thermochimica Acta　747　179949-179949　2025/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.tca.2025.179949 　

    ISSN： 0040-6031

  3. Multimaterial Bonding of Additively Manufactured Carbon Fiber‐Reinforced Thermoplastics/64 Titanium

    Keiichi Shirasu, Takeru Mizuno, Hironori Tohmyoh

    Advanced Engineering Materials　2025/03

    DOI： 10.1002/adem.202402221 　

  4. Experiment-free multiscale simulation of residual deformation in non-crimp fabric composites

    Yuuki Kinugawa, Yoshiaki Kawagoe, Kota Oine, Kazuki Ryuzono, Yamato Hoshikawa, Tomonaga Okabe

    Advanced Composite Materials　2024/11

    DOI： 10.1080/09243046.2024.2348861 　

  5. Pencil-Shaped Necking of Thick Al Whisker Grown by Stress-Induced Migration and Enhancement of Tensile Strength

    Thomas H. Ludwig, Keiichi Shirasu, Hironori Tohmyoh

    Advanced Engineering Materials　26　(8)　2024/04

    DOI： 10.1002/adem.202302081 　

    ISSN： 1438-1656

    eISSN： 1527-2648

  6. Fracture mechanism of carbon fiber-reinforced thermoplastic composite laminates under compression after impact

    Yoshiko Nagumo, Miyu Hamanaka, Keiichi Shirasu, Kazuki Ryuzono, Akinori Yoshimura, Hironori Tohmyoh, Tomonaga Okabe

    Journal of Composite Materials　2024/03/12

    Publisher: SAGE Publications

    DOI： 10.1177/00219983241240622 　

    ISSN： 0021-9983

    eISSN： 1530-793X

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    Thermoplastic carbon fiber-reinforced plastics (CFRPs) are increasingly utilized in the aerospace industry owing to their beneficial properties and enhanced formability relative to thermoset CFRPs. Despite the extensive use of these materials, studies focusing on compression after impact (CAI) tests with impact energies exceeding 20 J for thermoplastic CFRPs remain scarce. This study examines CAI tests on quasi-isotropic laminates of thermoplastic CFRP, subjected to a low-velocity impact energy of 27.04 J. For comparison, quasi-isotropic laminates of thermoset CFRP were subjected to a low-velocity impact energy of 36.5 J. These tests reveal that the CAI strength of both materials is comparable, notwithstanding the lower fiber volume fraction in the thermoplastic CFRP. Further, this research incorporates a finite element (FE) analysis to investigate the damage mechanisms in thermoplastic CFRP. The FE model, integrating interlaminar damage observed during the impact tests, accurately predicted the relationship between compressive stress and strain, correlating closely with the experimental outcomes. It was observed that both interlaminar and intralaminar damage propagation were constrained until the point of maximum compressive stress. Prior to reaching this maximum, a region of elevated compressive stress in the fiber direction was noted in the 0° layer near the non-impacted side. These findings indicate that the compressive stress in the fiber direction in the 0° layer adjacent to the non-impacted side is pivotal in dictating the final failure, which determines the CAI strength of thermoplastic CFRP laminates.

  7. Effect of inorganic material surface chemistry on structures and fracture behaviours of epoxy resin

    Tomohiro Miyata, Yohei K. Sato, Yoshiaki Kawagoe, Keiichi Shirasu, Hsiao-Fang Wang, Akemi Kumagai, Sora Kinoshita, Masashi Mizukami, Kaname Yoshida, Hsin-Hui Huang, Tomonaga Okabe, Katsumi Hagita, Teruyasu Mizoguchi, Hiroshi Jinnai

    Nature Communications　15　(1)　2024/03/08

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1038/s41467-024-46138-6 　

    eISSN： 2041-1723

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    Abstract The mechanisms underlying the influence of the surface chemistry of inorganic materials on polymer structures and fracture behaviours near adhesive interfaces are not fully understood. This study demonstrates the first clear and direct evidence that molecular surface segregation and cross-linking of epoxy resin are driven by intermolecular forces at the inorganic surfaces alone, which can be linked directly to adhesive failure mechanisms. We prepare adhesive interfaces between epoxy resin and silicon substrates with varying surface chemistries (OH and H terminations) with a smoothness below 1 nm, which have different adhesive strengths by ~13 %. The epoxy resins within sub-nanometre distance from the surfaces with different chemistries exhibit distinct amine-to-epoxy ratios, cross-linked network structures, and adhesion energies. The OH- and H-terminated interfaces exhibit cohesive failure and interfacial delamination, respectively. The substrate surface chemistry impacts the cross-linked structures of the epoxy resins within several nanometres of the interfaces and the adsorption structures of molecules at the interfaces, which result in different fracture behaviours and adhesive strengths.

  8. Constructing and characterizing various multi-component crosslinked epoxy resins based on molecular dynamics simulations with a curing reaction model

    Yinbo Zhao, Gota Kikugawa, Keiichi Shirasu, Yoshiaki Kawagoe, Tomonaga Okabe

    Polymer　297　126817-126817　2024/03

    Publisher: Elsevier BV

    DOI： 10.1016/j.polymer.2024.126817 　

    ISSN： 0032-3861

  9. Dissipative Particle Dynamics Simulation for Reaction-Induced Phase Separation of Thermoset/Thermoplastic Blends

    Yoshiaki Kawagoe, Gota Kikugawa, Keiichi Shirasu, Yuuki Kinugawa, Tomonaga Okabe

    The Journal of Physical Chemistry B　2024/02/19

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/acs.jpcb.3c07756 　

    ISSN： 1520-6106

    eISSN： 1520-5207

  10. Micromechanics study of short carbon fiber-reinforced thermoplastics fabricated via 3D printing using design of experiments

    Keiichi Shirasu, Yudai Yamaguchi, Yamato Hoshikawa, Gota Kikugawa, Hironori Tohmyoh, Tomonaga Okabe

    Materials Science and Engineering: A　891　145971-145971　2024/01

    Publisher: Elsevier BV

    DOI： 10.1016/j.msea.2023.145971 　

    ISSN： 0921-5093

  11. Influence of Fiber Orientation on Failure of Welded Single-lap Joint with Welding Technology of Thermoset FRP Peer-reviewed

    Tadashi Watanabe, Masato Honma, Mototsugu Tanaka, Keiichi Shirasu, Yoshiaki Kawagoe, Tomonaga Okabe

    Materials System　41　37-45　2024

    DOI： 10.34401/materialssystem.41.0_37 　

  12. Toward Integrated Aircraft Design with Carbon Fiber Reinforced Thermoplastic (CFRTP)

    Yoshiaki Abe, Keiichi Shirasu, Shugo Date, Tomonaga Okabe, Shigeru Obayashi

    Advanced Computational Methods and Design for Greener Aviation　59　229-239　2024

    DOI： 10.1007/978-3-031-61109-4_15 　

  13. Multiscale model for failure prediction of carbon-fiber-reinforced composites under off-axis load

    Tadashi Watanabe, Yoshiaki Kawagoe, Keiichi Shirasu, Tomonaga Okabe

    International Journal of Solids and Structures　112489-112489　2023/09

    Publisher: Elsevier BV

    DOI： 10.1016/j.ijsolstr.2023.112489 　

    ISSN： 0020-7683

  14. Experimental and numerical investigation of the relationship between material defects and elastoplasticity behavior of 3D-printed carbon-fiber-reinforced thermoplastics under compressive loading

    Yamato Hoshikawa, Keiichi Shirasu, Ryo Higuchi, Yoshiaki Kawagoe, Hironori Tohmyoh, Tomonaga Okabe

    Composites Science and Technology　110116-110116　2023/06

    Publisher: Elsevier BV

    DOI： 10.1016/j.compscitech.2023.110116 　

    ISSN： 0266-3538

  15. Molecular-scale investigation on relationship between thermal conductivity and the structure of crosslinked epoxy resin

    Yinbo Zhao, Gota Kikugawa, Yoshiaki Kawagoe, Keiichi Shirasu, Tomonaga Okabe

    International Journal of Heat and Mass Transfer　198　123429-123429　2022/12

    Publisher: Elsevier BV

    DOI： 10.1016/j.ijheatmasstransfer.2022.123429 　

    ISSN： 0017-9310

  16. Lap-shear strength and fracture behavior of CFRP/3D-printed titanium alloy adhesive joint prepared by hot-press-aided co-bonding

    Keiichi Shirasu, Masayoshi Mizutani, Naoki Takano, Hajime Yoshinaga, Tsuyoshi Oguri, Ken ichi Ogawa, Tomonaga Okabe, Shigeru Obayashi

    International Journal of Adhesion and Adhesives　117　2022/09

    DOI： 10.1016/j.ijadhadh.2022.103169 　

    ISSN： 0143-7496

  17. シアネート硬化エポキシ樹脂の熱機械特性に関する実験的評価と分子動力学シミュレーション

    Yoshiaki Kawagoe, Shohei Komori, Gota Kikugawa, Keiichi Shirasu, Tomonaga Okabe

    Journal of the Japan Society for Composite Materials　48　(4)　134-141　2022/07/15

    Publisher: The Japan Society for Composite Materials

    DOI： 10.6089/jscm.48.134 　

    ISSN： 0385-2563

    eISSN： 1884-8559

  18. A novel single-stroke path planning algorithm for 3D printers using continuous carbon fiber reinforced thermoplastics

    Kohei Yamamoto, Jose Victorio Salazar Luces, Keiichi Shirasu, Yamato Hoshikawa, Tomonaga Okabe, Yasuhisa Hirata

    Additive Manufacturing　55　102816-102816　2022/07

    Publisher: Elsevier BV

    DOI： 10.1016/j.addma.2022.102816 　

    ISSN： 2214-8604

  19. Multiscale modeling of process-induced residual deformation on carbon-fiber-reinforced plastic laminate from quantum calculation to laminate scale finite-element analysis

    Yoshiaki Kawagoe, Kenji Kawai, Yuta Kumagai, Keiichi Shirasu, Gota Kikugawa, Tomonaga Okabe

    Mechanics of Materials　170　104332-104332　2022/07

    Publisher: Elsevier BV

    DOI： 10.1016/j.mechmat.2022.104332 　

    ISSN： 0167-6636

  20. Experimental and numerical study on open-hole tension/compression properties of carbon-fiber-reinforced thermoplastic laminates

    Keiichi Shirasu, Junpei Tsuyuki, Ryo Higuchi, Sota Onodera, Tomonaga Okabe

    Journal of Composite Materials　56　(14)　2211-2225　2022/06

    Publisher: SAGE Publications

    DOI： 10.1177/00219983221096880 　

    ISSN： 0021-9983

    eISSN： 1530-793X

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    The stress-strain responses and damage initiation/propagation mechanisms of T700G/LM-PAEK, an open-hole carbon-fiber-reinforced thermoplastic were investigated experimentally and numerically. To obtain the mechanical properties necessary for numerical simulations, uniaxial tensile/compressive, double cantilever beam, and end notched flexure tests were conducted. T700G/LM-PAEK was found to have comparable or higher Young’s modulus, strength, and interlaminar fracture toughness relative to thermoset CFRPs with carbon fiber of a similar grade. These superior mechanical properties are mainly attributable to the higher toughness and ductility of the thermoplastic resin. The interfacial fracture toughnesses were evaluated by finite element analysis with the cohesive zone model to determine the interlaminar fracture toughnesses for crack initiation and propagation. Based on the above experimental and numerical results, the stress strain response and damage evolution of open-hole specimens were analyzed by a quasi-3D extended finite element method (XFEM) and compared with the experimental results. The computational model with the elastoplastic constitutive law provided an accurate prediction of the stress-strain response in both open-hole tension and compression (OHT and OHC, respectively), suggesting that the elastoplastic constitutive law should be considered in XFEM to guarantee the accuracy of strength prediction for both OHT and OHC. The OHT model showed that the Weibull criterion was satisfied without any delamination at the failure strain, corresponding to the brittle failure mode due to fiber breakage. For the OHC simulation, the damage initiation of 0°-ply kinking was observed at 88% of the peak stress. These predicted damage mechanisms agreed reasonably well with the experimental observations.

  21. Uncovering the Mechanism of Size Effect on the Thermomechanical Properties of Highly Cross-Linked Epoxy Resins

    Yinbo Zhao, Gota Kikugawa, Yoshiaki Kawagoe, Keiichi Shirasu, Naoki Kishimoto, Yingxiao Xi, Tomonaga Okabe

    The Journal of Physical Chemistry B　126　(13)　2593-2607　2022/04/07

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/acs.jpcb.1c10827 　

    ISSN： 1520-6106

    eISSN： 1520-5207

  22. Open-hole tensile properties of 3D-printed continuous carbon-fiber-reinforced thermoplastic laminates: Experimental study and multiscale analysis

    Yamato Hoshikawa, Keiichi Shirasu, Kohei Yamamoto, Yasuhisa Hirata, Ryo Higuchi, Tomonaga Okabe

    Journal of Thermoplastic Composite Materials　2022

    DOI： 10.1177/08927057221110791 　

    ISSN： 0892-7057

    eISSN： 1530-7980

  23. Epitaxial pyrolytic carbon coatings templated with defective carbon nanotube cores for structural annealing and tensile property improvement

    Fan Liu, Keiichi Shirasu, Toshiyuki Hashida

    Journal of Materials Science　2021/09/17

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1007/s10853-021-06523-8 　

    ISSN： 0022-2461

    eISSN： 1573-4803

  24. Amine/epoxy stoichiometric ratio dependence of crosslinked structure and ductility in amine-cured epoxy thermosetting resins

    Nobuyuki Odagiri, Keiichi Shirasu, Yoshiaki Kawagoe, Gota Kikugawa, Yutaka Oya, Naoki Kishimoto, Fumio S. Ohuchi, Tomonaga Okabe

    Journal of Applied Polymer Science　138　(23)　2021/06/15

    DOI： 10.1002/app.50542 　

    ISSN： 0021-8995

    eISSN： 1097-4628

  25. Study on the mechanical and electrical properties of twisted CNT yarns fabricated from CNTs with various diameters

    Yoku Inoue, Kohei Hayashi, Motoyuki Karita, Takayuki Nakano, Yoshinobu Shimamura, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

    Carbon　176　400-410　2021/05

    DOI： 10.1016/j.carbon.2021.01.139 　

    ISSN： 0008-6223

  26. Molecular Dynamics Simulations and Theoretical Model for Engineering Tensile Properties of Single-and Multi-Walled Carbon Nanotubes

    Keiichi Shirasu, Shunsuke Kitayama, Fan Liu, Go Yamamoto, Toshiyuki Hashida

    Nanomaterials　11　(3)　795-795　2021/03/19

    Publisher: MDPI AG

    DOI： 10.3390/nano11030795 　

    eISSN： 2079-4991

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    To apply carbon nanotubes (CNTs) as reinforcing agents in next-generation composites, it is essential to improve their nominal strength. However, since it is difficult to completely remove the defects, the synthesis guideline for improving nominal strength is still unclear, i.e., the effective strength and the number of nanotube layers required to improve the nominal strength has been undermined. In this study, molecular dynamics simulations were used to elucidate the effects of vacancies on the mechanical properties of CNTs. Additionally, the relationships between the number of layers and effective and nominal strengths of CNTs were discussed theoretically. The presence of extensive vacancies provides a possible explanation for the low nominal strengths obtained in previous experimental measurements of CNTs. This study indicates that the nominal strength can be increased from the experimentally obtained values of 10 GPa to approximately 20 GPa by using six to nine nanotube layers, even if the increase in effective strength of each layer is small. This has advantages over double-walled CNTs, because the effective strength of such CNTs must be approximately 60 GPa to achieve a nominal strength of 20 GPa.

  27. Cure Path Dependency in Crosslinked Structure of DGEBA/DICY/DCMU Thermosetting Resin Peer-reviewed

    Nobuyuki ODAGIRI, Keiichi SHIRASU, Yoshiaki KAWAGOE, Tomonaga OKABE

    Materials System　38　21-30　2021/03

    DOI： 10.34401/materialssystem.38.0_21 　

  28. Experimental and Numerical Evaluation of Open Hole Tensile Properties of 3D Printed Continuous Carbon Fiber Reinforced Thermoplastics Peer-reviewed

    Yamato HOSHIKAWA, Keiichi SHIRASU, Junpei TSUYUKI, Tomonaga OKABE, Ryo HIGUCHI, Kohei YAMAMOTO, Yasuhisa HIRATA

    Materials System　38　49-54　2021/03

    DOI： 10.34401/materialssystem.38.0_49 　

  29. Thermoset resin curing simulation using quantum-chemical reaction path calculation and dissipative particle dynamics

    Yoshiaki Kawagoe, Gota Kikugawa, Keiichi Shirasu, Tomonaga Okabe

    Soft Matter　17　(28)　6707-6717　2021

    Publisher: Royal Society of Chemistry (RSC)

    DOI： 10.1039/d1sm00600b 　

    ISSN： 1744-683X

    eISSN： 1744-6848

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    <p>We proposed a coarse-grained curing simulation technique for thermoset resin that combines DPD with an <italic>ab initio</italic> quantum calculation. An all-atom MD system was reconstructed from the DPD system using reverse mapping to evaluate several properties.</p>

  30. Molecular dynamics simulation of cross-linking processes and material properties for epoxy resins using first-principle calculation combined with global reaction route mapping algorithms

    Yutaka Oya, Masahiro Nakazawa, Keiichi Shirasu, Yuki Hino, Kyosuke Inuyama, Gota Kikugawa, Jing Li, Riichi Kuwahara, Naoki Kishimoto, Hiroki Waizumi, Masaaki Nishikawa, Anthony Waas, Nobuyuki Odagiri, Andrew Koyanagi, Marco Salviato, Tomonaga Okabe

    Chemical Physics Letters　762　2021/01

    DOI： 10.1016/j.cplett.2020.138104 　

    ISSN： 0009-2614

  31. Machine learning-assisted high-throughput molecular dynamics simulation of high-mechanical performance carbon nanotube structure

    Yi Xiang, Koji Shimoyama, Keiichi Shirasu, Go Yamamoto

    Nanomaterials　10　(12)　1-13　2020/12

    DOI： 10.3390/nano10122459 　

    eISSN： 2079-4991

  32. Phonon transport probed at carbon nanotube yarn/sheet boundaries by ultrafast structural dynamics Peer-reviewed

    Masaki Hada, Kotaro Makino, Hirotaka Inoue, Taisuke Hasegawa, Hideki Masuda, Hiroo Suzuki, Keiichi Shirasu, Tomohiro Nakagawa, Toshio Seki, Jiro Matsuo, Takeshi Nishikawa, Yoshifumi Yamashita, Shin ya Koshihara, Vlad Stolojan, S. Ravi P. Silva, Jun ichi Fujita, Yasuhiko Hayashi, Satoshi Maeda, Muneaki Hase

    Carbon　170　165-173　2020/12

    DOI： 10.1016/j.carbon.2020.08.026 　

    ISSN： 0008-6223

  33. Liquid-Phase Assisted Engineering of Highly Strong SiC Composite Reinforced by Multiwalled Carbon Nanotubes

    Yuchi Fan, Erhong Song, Tufail Mustafa, Ruicong Liu, Pengpeng Qiu, Weiwei Zhou, Zhenxing Zhou, Akira Kawasaki, Keiichi Shirasu, Toshiyuki Hashida, Jianjun Liu, Lianjun Wang, Wan Jiang, Wei Luo

    Advanced Science　7　(21)　2020/11/01

    DOI： 10.1002/advs.202002225 　

    eISSN： 2198-3844

  34. Microstructure-elastic property relationships in carbon fibers: A nanoindentation study Peer-reviewed

    Keiichi Shirasu, Kenta Goto, Kimiyoshi Naito

    Composites Part B: Engineering　200　2020/11/01

    DOI： 10.1016/j.compositesb.2020.108342 　

    ISSN： 1359-8368

  35. Effects of high-temperature thermal annealing on properties of aligned multi-walled carbon nanotube sheets and their composites Peer-reviewed

    Tran Huu Nam, Ken Goto, Yoshinobu Shimamura, Yoku Inoue, Go Yamamoto, Keiichi Shirasu, Toshiyuki Hashida

    Composite Interfaces　1-18　2020/06/02

    Publisher: Informa {UK} Limited

    DOI： 10.1080/09276440.2019.1670000 　

  36. Mechanical anisotropy of PAN-based and pitch-based carbon fibers Peer-reviewed

    Keiichi SHIRASU, Chiemi NAGAI, Kimiyoshi NAITO

    Mechanical Engineering Journal　2020/03

  37. Effect of carbon fibres on the static and fatigue mechanical properties of fibre metal laminates Peer-reviewed

    Kimiyoshi Naito, Keiichi Shirasu, Yoshihisa Tanaka

    Fatigue & Fracture of Engineering Materials & Structures　2020/03/01

    Publisher: Wiley

    DOI： 10.1111/ffe.13211 　

  38. Enhanced tribological performance of alumina composites reinforced with acid-treated carbon nanotubes under water lubrication Peer-reviewed

    Keiichi Shirasu, Takuto Miyaura, Go Yamamoto, Takaharu Suzuki, Kimiyoshi Naito, Toshiyuki Hashida

    Diamond and Related Materials　101　2020/01

    DOI： 10.1016/j.diamond.2019.107657 　

    ISSN： 0925-9635

  39. Stack-coating of multishell carbon layers templated with carbon nanotube Peer-reviewed

    Materials Today Communications　21　100608　2019/08

  40. How do the mechanical properties of carbon nanotubes increase? An experimental evaluation and modeling of the engineering tensile strength of individual carbon nanotubes Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

    Materials Research Express　6　(5)　055047　2019/02/22

    Publisher: {IOP} Publishing

    DOI： 10.1088/2053-1591/ab069f 　

  41. Mechanical and thermal expansion properties of aligned carbon nanotube reinforced epoxy composites Peer-reviewed

    Keiichi Shirasu, Itaru Tamaki, Go Yamamoto, Toshiyuki Hashida

    Mechanical Engineering Journal　2019

  42. Effect of graphitization on mechanical properties of untwisted carbon nanotube yarn and its strength development mechanism Peer-reviewed

    KIM Taesung, 林晏理, 二川秀史, 白須圭一, 山本剛, 橋田俊之, 細井厚志, 川田宏之, 川田宏之

    日本機械学会論文集(Web)　84　(860)　ROMBUNNO.17‐00585(J‐STAGE)-00585-17-00585　2018

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/transjsme.17-00585 　

    ISSN： 2187-9761

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    <p>Carbon nanotube yarn, which is an aggregation of Carbon nanotubes (CNTs), enables CNTs to be used on macro scale. However, tensile strength of the CNT yarn is much lower than CNT itself, and improvement of the mechanical properties is a challenge for practical application of the yarns. CNTs composing the yarns include some defect structures and impure materials, and their presence can cause a decrease in tensile strength of the yarn. In this study, untwisted CNT yarns were fabricated by dry spun method and graphitized at a temperature of 2800°C for the purpose of improving mechanical properties. Additionally, strength of a CNT composing the yarn and interactive force between the CNTs were evaluated to clarify strength development mechanism of the graphitized CNT yarn. Crystallinity of the CNT yarn was improved more than ten times, and defect structures and impure materials was removed by the graphitization treatment. As a result of single fiber tensile tests, strength of the yarn was increased by 20~35% after the graphitization. On the other hand, strength of the CNT composing the yarn was decreased. The breaking form of the CNT yarn was changed from pulling out of CNT bundles to rapture of the bundles by the graphitization, indicating an increase of interactive force between the bundles. In addition, as a result of pulling out simulations by molecular dynamics method, it was indicated that the pulling out of the CNT bundles were suppressed by increase in van der Waals force. Consequently, the improvement of mechanical properties of the untwisted CNT yarns was not due to the change in the strength of the CNT in the yarns but the main cause was the increase in the interactive force between the CNTs.</p>

  43. Development of large-movements and high-force electrothermal bimorph actuators based on aligned carbon nanotube reinforced epoxy composites Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Yoku Inoue, Toshio Ogasawara, Yoshinobu Shimamura, Toshiyuki Hashida

    SENSORS AND ACTUATORS A-PHYSICAL　267　455-463　2017/11

    DOI： 10.1016/j.sna.2017.10.051 　

    ISSN： 0924-4247

  44. Potential use of CNTs for production of zero thermal expansion coefficient composite materials: An experimental evaluation of axial thermal expansion coefficient of CNTs using a combination of thermal expansion and uniaxial tensile tests Peer-reviewed

    Keiichi Shirasu, Akihiro Nakamura, Go Yamamoto, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

    COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　95　152-160　2017/04

    DOI： 10.1016/j.compositesa.2016.12.027 　

    ISSN： 1359-835X

    eISSN： 1878-5840

  45. Friction and wear properties of carbon nanotube/alumina composites under water lubricated conditions

    Keiichi Shirasu, Takuto Miyaura, Go Yamamoto, Toshiyuki Hashida

    21th International Conference on Composite Materials, ICCM21　2017

  46. Effects of structural defects on strength and fracture properties of multi-walled carbon nanotubes Peer-reviewed

    Itaru TAMAKI, Keiichi SHIRASU, Takamichi MIYAZAKI, Go YAMAMOTO, Raman BEKAREVICH, Kaori HIRAHARA, Yoshinobu SHIMAMURA, Yoku INOUE, Toshiyuki HASHIDA

    Transactions of the JSME (in Japanese)　83　(847)　2017

    DOI： 10.1299/transjsme.16-00283 　

    ISSN： 2187-9761

  47. Key factors limiting carbon nanotube strength: Structural characterization and mechanical properties of multi-walled carbon nanotubes Peer-reviewed

    Keiichi Shirasu, Itaru Tamaki, Takamichi Miyazaki, Go Yamamoto, Raman Bekarevich, Kaori Hirahara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

    Mechanical Engineering Journal　42o017　(5)　2017

    DOI： 10.1299/transjsme.17-00029 　

    ISSN： 2187-9745

  48. Evaluation of Tensile Properties of Multi-Walled Carbon Nanotubes Synthesized by Chemical Vapor Deposition Peer-reviewed

    Itaru Tamaki, Keiichi Shirasu, Takamichi Miyazaki, Go Yamamoto, Raman Bekarevich, Kaori Hirahara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

    Asia-Pacific Conference on Fracture and Strength 2016 (APCFS2016)　2016/09

  49. Temperature dependence of axial thermal expansion coefficient of multi-walled carbon nanotubes (A procedure based on measurements of coefficient of thermal expansion for aligned carbon nanotube/epoxy composites) Peer-reviewed

    Keiichi SHIRASU, Akihiro NAKAMURA, Go YAMAMOTO, Toshio OGASAWARA, Yoshinobu SHIMAMURA, Yoku INOUE, Toshiyuki HASHIDA

    Transactions of the JSME (in Japanese)　82　(844)　2016

    DOI： 10.1299/transjsme.16-00228 　

  50. Preparation and performance evaluation of electrothermal actuators using aligned carbon nanotube reinforced epoxy composites, Peer-reviewed

    Keiichi Shirasu, Akihiro Nakamura, Go Yamamoto, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

    Mechanical Engineering Journal　3　(4)　15-00607-15-00607　2016

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/mej.15-00607 　

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    <p>By using an aligned multi-walled carbon nanotube (MWCNT) reinforced epoxy composite, an electrothermal bimorph actuator was fabricated and its load and deformation capacities were investigated. The composite has a negative coefficient of thermal expansion (CTE) as well as large Young's modulus. To evaluate the actuator property, a composite/aluminum laminate was prepared and a U-shaped actuator was formed by cutting off the middle part of the composite/aluminum laminate. The Young's modulus of the composites increased linearly with increasing MWCNT volume fraction, and that of the composite containing 27 vol.% MWCNTs reached 56.8 ± 3.9 GPa. We also demonstrated that the actuator showed a large bending displacement and force output under low voltage stimulation. The bending displacement and force output of the actuator with the free length of 16 mm reached 7.6 mm and 9.0 mN under a DC voltage of 5.2 V, respectively. Furthermore, the actuator fabricated in this study showed higher values of work output per unit volume compared to the actuators reported in previous studies within the frequency between 0.05 Hz and 0.5 Hz. The enhanced performance was attributable mainly to the high Young's modulus of both composite and aluminum layers and the huge mismatch of the coefficient of thermal expansion in the composite/aluminum laminate.</p>

  51. Negative axial thermal expansion coefficient of carbon nanotubes: Experimental determination based on measurements of coefficient of thermal expansion for aligned carbon nanotube reinforced epoxy composites Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Itaru Tamaki, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

    CARBON　95　904-909　2015/12

    DOI： 10.1016/j.carbon.2015.09.026 　

    ISSN： 0008-6223

    eISSN： 1873-3891

  52. Effects of processing conditions on microstructure, electrical conductivity and mechanical properties of MWCNT/alumina composites prepared by flocculation Peer-reviewed

    Weili Wang, Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Toshiyuki Hashida

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY　35　(14)　3903-3908　2015/11

    DOI： 10.1016/j.jeurceramsoc.2015.06.027 　

    ISSN： 0955-2219

    eISSN： 1873-619X

  53. Relationship between microstructure and mechanical properties in acid-treated carbon nanotube-reinforced alumina composites Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Yo Nozaka, Weili Wang, Toshiyuki Hashida

    JOURNAL OF MATERIALS SCIENCE　50　(20)　6688-6699　2015/10

    DOI： 10.1007/s10853-015-9223-6 　

    ISSN： 0022-2461

    eISSN： 1573-4803

  54. Microstructure-property relationships in pressureless-sintered carbon nanotube/alumina composites Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Weili Wang, Toshiyuki Hashida

    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　617　179-186　2014/11

    DOI： 10.1016/j.msea.2014.08.068 　

    ISSN： 0921-5093

    eISSN： 1873-4936

  55. Inclined slit-based pullout method for determining interfacial strength of multi-walled carbon nanotube-alumina composites Peer-reviewed

    Yo Nozaka, Weili Wang, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

    CARBON　78　439-445　2014/11

    DOI： 10.1016/j.carbon.2014.07.024 　

    ISSN： 0008-6223

    eISSN： 1873-3891

  56. Tensile mechanical properties of carbon nanotube/epoxy composite fabricated by pultrusion of carbon nanotube spun yarn preform Peer-reviewed

    Yoshinobu Shimamura, Kahori Oshima, Keiichiro Tohgo, Tomoyuki Fujii, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida, Ken Goto, Toshio Ogasawara, Kimiyoshi Naito, Takayuki Nakano, Yoku Inoue

    COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　62　32-38　2014/07

    DOI： 10.1016/j.compositesa.2014.03.011 　

    ISSN： 1359-835X

    eISSN： 1878-5840

  57. Fabrication and mechanical evaluation of aligned multi-walled carbon nanotube sheet/alumina laminated ceramic composites

    Yamamoto, G, Shirasu, K, Nozaka, Y, Shimamura, Y, Inoue, Y, Hashida, T

    16th European Conference on Composite Materials, ECCM 2014　2014

  58. Microstructure and mechanical properties of multi-walled carbon nanotube/alumina composites prepared by a novel flocculation method

    Wang, W.L, Yamamoto, G, Shirasu, K, Nozaka, Y, Hashida, T

    16th European Conference on Composite Materials, ECCM 2014　2014

  59. Structure-property relationships in thermally-annealed multi-walled carbon nanotubes Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Yoshinori Sato, Toshiyuki Takagi, Toshiyuki Hashida

    CARBON　66　219-226　2014/01

    DOI： 10.1016/j.carbon.2013.08.061 　

    ISSN： 0008-6223

    eISSN： 1873-3891

  60. カーボンナノチューブの機械的特性

    山本剛, 白須圭一, 玉木格, 橋田俊之

    日本複合材料学会誌　40　(6)　255-259　2014

    Publisher:

    ISSN： 0385-2563

  61. Effects of annealing treatment of carbon nanotube on the fracture properties of carbon Nanotube/Alumina composites Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Yo Nozaka, Mamoru Omori, Toshiyuki Hashida

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　79　(802)　706-710　2013

    DOI： 10.1299/kikaia.79.706 　

    ISSN： 0387-5008

  62. Evaluation of mechanical properties and microstructures of multi-walled carbon Nanotube/Alumina composites prepared by pressureless sintering Peer-reviewed

    Yo Nozaka, Go Yamamoto, Keiichi Shirasu, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　79　(802)　764-768　2013

    DOI： 10.1299/kikaia.79.764 　

    ISSN： 0387-5008

  63. Development of Pressureless Sintering Method for Carbon Nanotube/Alumina Composites and Their Microstructure-Property Relationships Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Takahumi Nakamura, Toshiyuki Hashida

    Journal of Solid Mechanics and Materials Engineering　7　(3)　394-402　2013

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/jmmp.7.394 　

    ISSN： 1880-9871

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    Multi-walled carbon nanotube (MWCNT)/alumina composites with different amounts of MWCNTs were prepared by a simple mechanical mixing method followed by a pressureless sintering. The effects of microstructures including grain size, MWCNT location, fracture patterns of the matrix and dispersibility of MWCNTs on the mechanical properties of the resultant composites were investigated. It was demonstrated from microstructural observations and fracture tests of the composites that grain size, MWCNT location and fracture patterns had no significant impact on the mechanical properties of the composites prepared under the processing conditions used in this research. In contrast, the state of MWCNT dispersion within the composites was shown to be one of the important factors affecting the strength and toughness enhancement in our composites. The dispersibility of MWCNTs decreased monotonically as a function of MWCNT volume fraction. The degradation in the mechanical properties observed for the composites with a higher amount of MWCNTs was shown to be associated with the dispersibility of MWCNTs, and a MWCNT agglomerate was anticipated to act as imperfections and led to a reduction of mechanical properties.

  64. Fabrication and evaluation of carbon nanotube/alumina composites by precursor method

    Shirasu, K, Yamamoto, G, Nozaka, Y, Omori, M, Hashida, T

    ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials　2012

  65. Measurements of carbon nanotube tensile strength and mechanical properties of carbon nanotube/alumina composites prepared by pressureless sintering

    Yamamoto, G, Shirasu, K, Nozaka, Y, Takagi, T, Hashida, T

    ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials　2012

  66. Effects of surface modification of carbon nanotube on the mechanical properties of multi-walled carbon nanotube/alumina composites Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　78　(790)　843-854　2012

    DOI： 10.1299/kikaia.78.843 　

    ISSN： 0387-5008

  67. Nanotube fracture during the failure of carbon nanotube/alumina composites Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Toshiyuki Hashida, Toshiyuki Takagi, Ji Won Suk, Jinho An, Richard D. Piner, Rodney S. Ruoff

    CARBON　49　(12)　3709-3716　2011/10

    DOI： 10.1016/j.carbon.2011.04.022 　

    ISSN： 0008-6223

  68. Evaluation of crack bridging characteristics in carbon nanotube/alumina composites using single fiber pullout testing method Peer-reviewed

    Go Yamamoto, Keiichi Shirasu, Toshiyuki Takagi, Toshiyuki Hashida

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　77　(777)　779-783　2011

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/kikaia.77.779 　

    ISSN： 0387-5008

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    The crack bridging behavior of multi-walled carbon nanotube-reinforced alumina matrix composites has been investigated using a single fiber pullout testing method. Contradictory to the conventional understanding (which have reported that pullout phenomena evidently occurred in the bulk nanotube-reinforced alumina composites), the pullout experiments using an in situ SEM method with a nanomanipulator system demonstrated that strong load transfer was revealed, and no pullout behavior was observed for all 15 MWCNTs. The MWCNTs, rather than pulling out from the alumina matrix, broke in the outer-shells and the inner section was pulled away, leaving the outer-shells of the fragment in the matrix. This implies that tougher ceramics with MWCNT can be obtained by creating the appropriate interaction between the matrix and MWCNT: not too week but also not too strong to permit an adequate load transfer between the two parts and thus a consequent pulling out without breakage of MWCNT. Our finding suggests important implications for the design of tougher ceramic composites with MWCNTs. The important factor for such tougher ceramic composites will thus be the use of 'strong' MWCNTs having higher mechanical performance (as well as a good dispersion in the matrix).

  69. Effect of surface modification of carbon nanotube on the strength properties of carbon nanotube/alumina composites and their fracture process Peer-reviewed

    Shirasu, K, Yamamoto, G, Omori, M, Aizawa, Y, Hashida, T

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　77　(777)　774-778　2011

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/kikaia.77.774 　

    ISSN： 0387-5008

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    We report the mechanical properties and microstructures of multi-walled carbon nanotube (MWCNT)/alumina composites made with MWCNTs that absorb negatively charged functional groups at the MWCNT ends and along their length from an acid treatment. We conducted the fracture surface observations of the composites, in order to evaluate the effects of the acid treatment conditions of MWCNTs on the mechanical properties of the composites and the microstructures such as dispersibility and protrusion length of MWCNTs. According to the SEM observations, it was found that the dispersibility of MWCNTs affected the mechanical properties of the composites, and the protrusion length of MWCNTs decreased with increasing of the acid treatment time of MWCNTs. These observations revealed that the high structural homogeneity rather than pullout behavior of MWCNTs leads to an increase in the mechanical properties of the MWCNT/alumina composite. There is an optimal acid treatment time for improving the mechanical properties of the composites. The dispersibility of the MWCNTs and mechanical properties of the composites was increased by the acid treatment with treated for 2 hours compared to the pristine MWCNTs and acid treatment MWCNTs with treated for 0, 0.5, 1, 3 and 4 hours.

  70. Preparation of carbon nanotube reinforced alumina composites and examination of their fracture mechanisms Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　77　(779)　1041-1045　2011

    DOI： 10.1299/kikaia.77.1041 　

    ISSN： 0387-5008

Show all ︎Show first 5

Misc. 17

  1. 第21回国際複合材料会議報告

    上田政人, 大窪和也, 白須圭一, 仲井朝美, 西川雅章, 松崎亮介, 藤垣元治, 河井昌道, 喜多村竜太, 高坂達郎, 水口周, 大谷章夫, 鈴木浩治, 西田裕紀, 野田淳二

    日本複合材料学会誌　44　(1)　25-37　2018

  2. Effect of crystallinity on axial thermal expansion coefficient of carbon nanotubes: Experimental and simulation studies Peer-reviewed

    Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

    Proceedings of the 5th Asian Symposium on Materials and Processing　2018

  3. Estimation of crack width in porous media by nano/micro particles Peer-reviewed

    Junzhe Cui, Anna Suzuki, Satoshi Uehara, Keiichi Shirasu, Takatoshi Ito

    Proceedings of the 15th International Conference of Flow Dynamics　2018

  4. Evaluation of carbon nanotube strength for application to composite materials Invited

    Keiichi Shirasu

    Research & Reviews: Journal of Material Sciences; Proceedings of 13th International Conference on Advanced Materials and Nanotechnology　5　(6)　69　2017

  5. 142 Evaluation of Thermal Expansion Properties of Aligned Multi-Walled Carbon Nanotube Reinforced Epoxy Composites and its Application

    NAKAMURA Akihiro, SHIRASU Keiichi, TAMAKI Itaru, YAMAMOTO Go, HASHIDA Toshiyuki

    2016　(51)　81-82　2016

    Publisher: The Japan Society of Mechanical Engineers

  6. OS0525 Preparation and mechanical evaluation of aligned multi-walled carbon nanotube/epoxy composites

    NAKAMURA Akihiro, SHIRASU Keiichi, YAMAMOTO Go, SHIMAMURA Yoshinobu, INOUE Yoku, HASHIDA Toshiyuki

    2014　"OS0525-1"-"OS0525-3"　2014/07/19

    Publisher: The Japan Society of Mechanical Engineers

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    Two types of epoxy composites reinforced with an aligned multi-walled carbon nanotube (MWCNT) sheet and its thermal annealed analog were prepared and the effects of thermal annealing on the mechanical properties of the composites were investigated by conducting uniaxial tensile tests. The MWCNTs with lengths exceeding 1 mm were vertically grown on a Si substrate by chemical vapor deposition method, and were converted to horizontally aligned MWCNT sheets by pulling them out. The MWCNT sheets were then thermally-annealed at 2000℃ under Ar + 5% H_2 atmosphere. The composites containing annealed MWCNTs exhibited higher Young's modulus and tensile strength than those of the composites containing as-received MWCNTs. Uniaxial tensile experiments of individual MWCNTs revealed that thermal annealing led to an increase in Young's modulus, suggesting that the improvement in Young's modulus of the composites may be associated with the increase in the mechanical properties of individual MWCNTs. Young's modulus and tensile strength of the composites containing 22 vol.% annealed MWCNTs reached 94 ± 11 GPa and 474.2 ± 57.7 MPa, respectively.

  7. GS21 Friction Properties of Multi-Walled Carbon Nanotube/Alumina Composites Prepared by Flocculation Method

    NAKAMURA Takafumi, WANG Weili, SHIRASU Keiichi, YAMAMOTO Go, HASHIDA Toshiyuki

    2014　"GS21-1"-"GS21-3"　2014/07/19

    Publisher: The Japan Society of Mechanical Engineers

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    Carbon nanotubes (CNTs) have extremely high tensile strength and elastic modulus, good flexibility and low density. In addition, CNTs are expected to have lubrication properties like other carbon-derived materials including graphite and diamond-like carbon. In this study, alumina ceramics reinforced with multi-walled CNTs (MWCNTs) were prepared by a flocculation method and the effects of the MWCNT content on mechanical and tribological properties of the composites were investigated. The results showed that the bending strength and fracture toughness simultaneously increased for the composite containing 10.0 vol.% MWCNTs. The friction coefficient of the composites containing 5.5 vol.% MWCNTs was about 0.15, measured by the ball-on-disk wear tests using alumina balls as a counterpart in air. Microstructural observations of the fractured and polished surfaces of the composites implied that the size of a MWCNTs agglomerate is one of the important factors for improving friction properties of the composite. It is suspected that there may be an optimal MWCNTs content for improving the mechanical and friction properties of the composites.

  8. 140 ナノ領域特性評価に基づくカーボンナノチューブ/アルミナ複合材料の破壊機構解明に関する研究

    野坂 陽, 王 偉礼, 白須 圭一, 山本 剛, 橋田 俊之

    講演論文集　2014　(49)　81-82　2014

    Publisher: 一般社団法人日本機械学会

  9. SL10 Development of CNT Composite Materials

    YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

    2012　"SL10-1"-"SL10-3"　2012/09/22

    Publisher: The Japan Society of Mechanical Engineers

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    Carbon nanotubes (CNTs) have attracted enormous attention from many researchers of material science, and their physical properties have been intensively clarified. The next step of carbon nanotube research should be development of high performance CNT materials with industrial applications. Production of CNT composites represents one of great targets for the application. In this study, alumina has been selected as the matrix of CNT composites because of its low cost and high performance. The final goal is to develop a design-fabrication-evaluation methodology for CNT ceramic matrix composites and to produce high performance composites on the basis of the method to be developed. MWCNT/alumina composites were prepared by a simple mechanical mixing method followed by pressureless sintering. The effects of MWCNT addition on mechanical, tribological and electromagnetic-wave absorption properties of the pressureless sintered-MWCNT/alumina composites will be discussed.

  10. GS37 Effects of Strength Properties and Dispersibility of Carbon Nanotube on the Fracture Properties of Carbon Nanotube/Alumina Composites

    SHIRASU Keiichi, YAMAMOTO Go, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

    2012　"GS37-1"-"GS37-3"　2012/09/22

    Publisher: The Japan Society of Mechanical Engineers

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    In this research, effects of the multi-walled carbon nanotubes (MWCNTs) addition on mechanical properties and microstructures of spark plasma-sintered MWCNT/alumina composites were investigated by using four types of MWCNTs that were annealed at different temperatures. The annealing temperatures were 1200, 1800, 2200 and 2600℃. Experimental results showed that bending strength of the composites was increased up to 1800℃, and they were decreased gradually with increasing annealing temperature of MWCNTs. According to the fracture surface observation, dispersibility of the MWCNTs tended to decrease with increasing the annealing temperature of the MWCNTs, and fracture toughness of the composites corresponded to the dispersibility of the MWCNTs. The present study implies that the effectiveness of the use of MWCNTs having a higher load carrying capacity and dispersibility for preparation of stronger and tougher ceramic composites.

  11. S042013 Fabrication and Evaluation of Carbon Nanotube/Alumina Composites by Pressureless Sintering and Influence of Carbon Nanotube Tensile Strength on Their Composite Mechanical Properties

    YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, TAKAGI Toshiyuki, HASHIDA Toshiyuki

    Mechanical Engineering Congress, Japan　2012　"S042013-1"-"S042013-5"　2012/09/09

    Publisher: The Japan Society of Mechanical Engineers

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    In this research, the effects of MWCNT addition on mechanical properties and microstructures of pressureless sintered MWCNT/alumina composites were investigated by using four types of MWCNTs having different fracture characteristics and dispersibility. It was demonstrated that it is possible to fabricate MWCNT/alumina composites by pressureless sintering at a temperature of 1400℃. Fracture tests showed that the MWCNTs annealed at 2200℃ was the most effective in improving the mechanical properties of the MWCNT/alumina composites, and 0.9 vol.% MWCNT addition resulted in 25% and 45% simultaneous increase in bending strength (742.6 ± 13.1 MPa) and fracture toughness (5.83 ± 0.19 MPa m^<1/2>), respectively, compared with MWCNT-free sintered bodies. An improvement in the fracture properties may be attributed to the use of the MWCNT having a higher load carrying capacity. For the larger amount of the MWCNTs, strong correlation between mechanical properties of the composites and dispersibility of the MWCNTs was observed, and the degradation of mechanical properties was shown to be primarily attributed to the severe phase segregation. Our finding suggests that the important factor for the preparation of ceramics composites with MWCNT for higher strength and toughness will thus be the use of MWCNT having a much higher load carrying capacity as well as a good dispersion in the matrix.

  12. 146 Mechanical Properties of Multi-Walled Carbon Nanotube/Alumina Composites Prepared by Pressureless Sintering

    YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHDA Toshiyuki

    2012　(47)　98-99　2012/03/13

    Publisher: The Japan Society of Mechanical Engineers

  13. 215 Development of Fabrication Method of Carbon Nanotube/Alumina Composites and Evaluation of Their Mechanical Properties

    SHIRASU Keiichi, YAMAMOTO Go, NOZAKA You, OMORI Mamoru, HASHIDA Toshiyuki

    2012　(47)　236-237　2012/03/13

    Publisher: The Japan Society of Mechanical Engineers

  14. 191 Observation of the Carbon Nanotube/Alumina Composites Fracture Process and Improvement of Their Mechanical Properties

    SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, AIZAWA Yoichi, HASHIDA Toshiyuki

    2011　(46)　184-185　2011/03/15

    Publisher: The Japan Society of Mechanical Engineers

  15. 112 Preparation of Carbon Nanotube Reinforced Alumina Composites and Examination of Their Fracture Mechanisms

    SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

    Materials and processing conference　2010　(18)　"112-1"-"112-5"　2010/11/27

    Publisher: The Japan Society of Mechanical Engineers

  16. 007 Evaluation of Crack Bridging Characteristic in Carbon Nanotube/Alumina Composites Using Single Fiber Pullout Testing Method

    YAMAMOTO Go, SHIRASU Keiichi, TAKAGI Toshiyuki, HASHIDA Toshiyuki

    2010　274-276　2010/10/09

    Publisher: The Japan Society of Mechanical Engineers

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    The crack bridging behavior of multi-walled carbon nanotube-reinforced alumina matrix composites has been investigated using a single fiber pullout testing method. Contradictory to the conventional understanding (which have reported that pullout phenomena evidently occurred in the bulk nanotube-reinforced alumina composites), the pullout experiments using an in situ SEM method with a nanomanipulator system demonstrated that strong load transfer was revealed, and no pullout behavior was observed for all 15 MWCNTs. The MWCNTs, rather than puffing out from the alumina matrix broke in the outer-shells and the inner section pulled away, leaving the outer-shells of the fragment in the matrix. This implies that tougher ceramics with MWCNT can be obtained by creating the appropriate interaction between the matrix and MWCNT: not too week but also not too strong to permit an adequate load transfer between the two parts and thus a consequent pulling out without breakage of MWCNT. Our finding suggests important implications for design of tougher ceramic with MWCNTs. The important factor for such tougher ceramics will thus be the use of 'strong' NWCNTs having higher mechanical performance (as well as a good dispersion in the matrix).

  17. 008 Effect of Surface Modification of Carbon Nanotube on the Strength Properties of Carbon Naotube/Alumina Composites and their Fracture Process

    SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, AIZAWA Yoichi, HASHIDA Toshiyuki

    2010　271-273　2010/10/09

    Publisher: The Japan Society of Mechanical Engineers

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    We report the mechanical properties and microstructures of multi-walled carbon nanotube (MWCNT)/alumina composites made with MWCNTs that have nanoscale defects on their surfaces from an acid treatment We conducted the fracture surface observations of the composites, in order to evaluate the effects of the acid treatment conditions of MWCNTs on the mechanical properties of the composites and the microstructures such as dispersibility and pullout length of MWCNTs. It was found that the dispersibiity of MWCNTs affected the mechanical properties of the composites. The composites with 0.9 vol.% MWCNTs that were acid-treated for 2 hours showed a higher mechanical properties than those of the composites with identical MWCNTs content that were acid-treated for 0, 0.5, 1, 3 and 4 hours. According to the SEM observations, the pullout length of MWCNTs decreased with increasing of acid treatment time of MWCNTs, and the diameter changed at the tip of some MWCNTs.

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Books and Other Publications 9

  1. 積層造形した金属基板とCFRPを直接圧着した接合体の作製

    白須圭一, 水谷正義

    月刊機能材料，シーエムシー出版　2023/07

  2. カーボンナノチューブの表面処理・分散技術と複合化事例

    白須圭一,山本剛,橋田俊之

    技術情報協会　2019/12

    ISBN: 9784861047725

  3. Mechanical and fracture properties of carbon nanotubes

    Keiichi Shirasu, Go Yamamoto, Daniel Nelias, Toshiyuki Hashida

    InTech　2018/04

    ISBN: 9781789230536

  4. 実用化に向けたソフトアクチュエータの開発と応用・制御技術

    白須圭一, 山本剛, 橋田俊之

    シーエムシー出版　2017

  5. 電磁波吸収・シールド材料の設計とノイズ・誤動作対策

    山本剛, 白須圭一, 橋田俊之

    技術情報協会　2016

  6. Application of Aligned Carbon Nanotube-Reinforced Polymer Composite to Electrothermal Actuator

    Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

    InTech　2016

    ISBN: 9789535124702

  7. 高分子における劣化・破壊現象の写真・データ事例集～原因特定と対策のために～

    山本剛, 白須圭一, 野坂陽, 橋田俊之

    技術情報協会　2014/03/24

  8. カーボンナノチューブ・グラフェン分散技術の工業化と機能展開 – 溶液・ポリマー・金属・セラミックスへの分散 –

    山本剛, 白須圭一, 野坂陽, Weili Wang, 橋田俊之

    S&T出版株式会社　2014/02/26

    ISBN: 9784907002343

  9. 【エレクトロニクス用途における】 コンポジット材料の混練・コンパウンド技術と分散・界面制御

    山本剛, 白須圭一, 橋田俊之

    技術情報協会　2013/04/26

    ISBN: 9784861044779

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Presentations 7

  1. カーボンナノチューブの力学特性・分散技術および複合材料の開発・応用展開 Invited

    白須 圭一

    サイエンス&テクノロジーセミナー　2018/10/31

  2. Evaluation of carbon nanotube strength for application to composite materials International-presentation Invited

    SHIRASU Keiichi

    13th International Conference and Exhibition on Advanced Materials and Nanotechnology　2017/10/26

  3. CNT/セラミックス複合材料作製のための分散・混合法 Invited

    白須圭一, 山本剛, 大森守, 橋田俊之

    産学連携先端シーズマッチング　2017/10/19

  4. 準脆性材料の材料強度学的評価と応用に関する研究 Invited

    白須圭一, 山本剛, 佐藤一永, 橋田俊之

    株式会社高純度化学研究所 技術講演会　2017/08/08

  5. カーボンナノチューブを用いたセラミックス基複合材料の開発と応用展開 Invited

    山本剛, 白須圭一, 野坂陽, 橋田俊之

    第1回カーボンナノチューブコンポジットワークショップ　2013/08

  6. カーボンナノチューブ/アルミナ複合材料の作製とその機械・電気的特性評価 Invited

    山本剛, 白須圭一, 大森守, 小野崇人, 高木敏行, 橋田俊之

    平成25年度 第1回カーボンナノ材料研究会　2013/06

  7. CNT コンポジットの開発 Invited

    山本剛, 白須圭一, 野坂陽, 大森守, 高木敏行, 橋田俊之

    日本機械学会M&M2012 材料力学カンファレンス　2012/09

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Research Projects 9

  1. 3D造形による熱可塑性CFRPの革新的高効率資源循環に向けた特性発現・劣化機構解明

    白須 圭一

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(C)

    Institution: 東北大学

    2023/04/01 - 2026/03/31

  2. マテリアルズ・インフォマティクスによる新規ネットワークポリマーの創製と接着特性評価

    Offer Organization: 金森財団

    System: 研究助成

    2022/10 - 2023/09

  3. データ科学援用マルチマテリアル・アディティブマニュファクチャリング技術開発

    Offer Organization: 新エネルギー・産業技術総合開発機構

    System: 官民による若手研究者発掘支援事業

    Institution: 東北大学

    2022/10 -

  4. Development of carbon nanotubes with high nominal tensile strength by defect healing process

    Shirasu Keiichi

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Early-Career Scientists

    Institution: Tohoku University

    2019/04/01 - 2021/03/31

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    In this study, carbon nanotubes (CNTs) were heat-treated under an ethylene-argon gas mixture to repair hole defects and improve the nominal tensile strength of CNTs by adsorbing pyrolytic carbon. It was found that the nominal tensile strength of the CNTs exceeded 10 GPa by heat treatment at a temperature of about 700°C and an ethylene partial pressure of 1000 Pa. Furthermore, molecular dynamics simulations were performed to evaluate the relationship between the interlayer crosslinking, the effective tensile strength, and the nominal tensile strength of the CNTs. It was found that the nominal tensile strength exhibited the highest when the proper amount of interlayer crosslinking was introduced to break all layers of the multiwalled CNTs.

  5. 革新的合成法による無撚CNT繊維強化複合材料の創成と高強度化 Competitive

    川田宏之

    Offer Organization: 日本学術振興会

    System: 科研費 基盤研究(B)

    2018/04 - 2021/03

  6. 航空分野における現行接合以上の信頼性を達成するマルチマテリアル３D接合・最適成形技術の開発 Competitive

    大林茂

    Offer Organization: 新エネルギー・産業技術総合開発機構

    System: NEDO先導研究プログラム／新技術先導研究プログラム

    2019/07 - 2020/07

  7. CNTの力学・電気・熱的特性制御のためのナノ構造制御ガイドラインの構築 Competitive

    白須 圭一

    Offer Organization: 日本学術振興会

    System: 科研費 若手研究(B)

    2016/04 - 2019/03

  8. 柔軟で高発生力・高変位特性を有する配向CNT複合材料マイクロアクチュエータの創製 Competitive

    白須 圭一

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 研究活動スタート支援

    2015/09 - 2016/03

  9. 構成要素ナノ配列制御によるCNT/セラミックス複合材料の高度化と実用に向けた挑戦 Competitive

    白須 圭一

    Offer Organization: 日本学術振興会

    System: 日本学術振興会特別研究員(DC1)

    2012/04 - 2015/03

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Media Coverage 3

  1. 東北大の白須准教授、チタン合金とCFRP成形品の3次元造形技術を開発中

    TECH+（マイナビニュース）　https://news.mynavi.jp/techplus/article/20221108-2506737/

    2022/11

    Type: Internet

  2. 東北大学・ジャムコ，金属AM応用しチタンとCFRPを接合

    SANPO WEB　https://www.sanpo-pub.co.jp/topnews/2022/0608023102.html

    2022/06

    Type: Internet

  3. 接着剤なしで炭素繊維と合金を接合 東北大学などが開発

    日本経済新聞　https://www.nikkei.com/article/DGXZQOUC0255L0S2A600C2000000/

    2022/06

    Type: Newspaper, magazine

Other 3

  1. ソフトマテリアル研究拠点

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    http://www.masc.tohoku.ac.jp/softmaterial/index.html

  2. マルチマテリアル研究拠点：マルチマテリアルによるアディティブ・マニュファクチャリング技術開発

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    マルチマテリアル研究拠点キックオフ・シンポジウム http://masc.tohoku.ac.jp/information/?p=420 マルチマテリアル研究拠点第2回シンポジウム http://masc.tohoku.ac.jp/information/?p=551 マルチマテリアル研究拠点第3回シンポジウム http://masc.tohoku.ac.jp/information/?p=620

  3. NEDO次世代複合材創製・成形技術開発プロジェクト 研究開発項目① 複合材時代の理想機体構造を実現する機体設計後術の開発

    More details Close

    http://www.ifs.tohoku.ac.jp/~nedocae/index_project2.html