Sano, Tomohiko

写真a

Affiliation

Faculty of Science and Technology, Department of Mechanical Engineering （Yagami）

Position

Assistant Professor/Senior Assistant Professor
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Papers 【 Display / hide 】

  • Jumping dynamics of spherical shells driven by snap-through buckling

    T Abe, S Shimizu, Y Nakahara, H Takahashi, G Ishigami, T Sano

    Bulletin of the American Physical Society  2024

    Accepted

  • Crack propagation on bilayer spherical shells

    T Sano, N Sekiya, Y Akiba

    Bulletin of the American Physical Society  2024

    Accepted

  • Bending rigidity of fluid-running tubes

    S Shibuya, T Sano

    Bulletin of the American Physical Society  2024

    Accepted

  • Bending deformation of tape-springs by a curved indenter

    S Nomura, T Sano

    Bulletin of the American Physical Society  2024

    Accepted

  • Randomly stacked open cylindrical shells as functional mechanical energy absorber

    TG Sano, E Hohnadel, T Kawata, T Métivet, F Bertails-Descoubes

    Communications Materials 4 (1), 59 （Communications Materials)  4 （ 1 ）  2023.12

    Accepted

    　View Summary

    Structures with artificially engineered mechanical properties, often called mechanical metamaterials, are interesting for their tunable functionality. Various types of mechanical metamaterials have been proposed in the literature, designed to harness light or magnetic interactions, structural instabilities in slender or hollow structures, and contact friction. However, most of the designs are ideally engineered without any imperfections, in order to perform deterministically as programmed. Here, we study the mechanical performance of randomly stacked cylindrical shells, which act as a disordered mechanical metamaterial. Combining experiments and simulations, we demonstrate that the stacked shells can absorb and store mechanical energy upon compression by exploiting large deformation and relocation of shells, snap-fits, and friction. Although shells are oriented randomly, the system exhibits statistically robust mechanical performance controlled by friction and geometry. Our results demonstrate that the rearrangement of flexible components could yield versatile and predictive mechanical responses.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Reviews, Commentaries, etc. 【 Display / hide 】

  • Erratum: Twist-Induced Snapping in a Bent Elastic Rod and Ribbon [Phys. Rev. Lett. <b>122</b> , 114301 (2019)]

    Tomohiko G. Sano, Hirofumi Wada

    Physical Review Letters (American Physical Society (APS))  129 ( 6 )  2022.08

    ISSN  00319007

    　View Summary

    After the publication of this Letter, the authors realized a mistake in the analysis of the linear response theory. On page 3, left column, we stated, “Retaining the terms up to the quadratic orders in Erod and taking the flat-ribbon limit h/w?0, we arrive at the Euler-Lagrange equations for ? and ? as ?'=?/R and ?'' '' - ( G - 2 ) ? '' / R 2 + ? / R 4 = 0 , where G=(1+?)/2.” The correct form of the Euler-Lagrange equation for ?(s) should be the following: (Formula Presented). he quadratic term -A2?2/(2R2) was incorrectly omitted in the expansion of elastic energy Erod . Including that term leads to a modified third term (1-G)?/R4 in the left-hand side of Eq. (1). We updated the Supplemental Material, which now provides the correct analytical solution of Eq. (1) for arbitrary G. In the G?0 limit, the solution correctly reduces to Eq. (2) defined in this Letter. All other equations and analyses are correct; hence, the conclusions remain unchanged.

  • Stochastic Mean Field Model of Heat Engine partitioned by Fluctuating Piston

    Tomohiko G. Sano, Hisao Hayakawa

     2014.12

    　View Summary

    We propose a stochastic mean field model of heat engine partitioned by a<br />
    finite-mass piston. The time evolution equations for the density and the<br />
    temperature of the enclosed gas are proposed, taking into account the<br />
    stochastic equation of motion of the piston, and the energy conservation for<br />
    the gas. Though the heat cycle consisting of finite-time heating and cooling<br />
    processes is under strong non-equilibrium situations, i. e., the ratio of<br />
    temperatures of two reservoirs is large, we analyze the efficiency and the<br />
    power, and derive the semi-analytical expression for the efficiency. We find<br />
    that the obtained efficiency at the maximum power operation is close to the<br />
    Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency, if the piston is<br />
    sufficiently heavy and elastic for collisions with particles, even when the<br />
    system is far from equilibrium. However, the extra heat due to the finiteness<br />
    of the piston-mass or its inelasticity lowers the efficiency from the CNCA<br />
    efficiency. The results of our stochastic mean field model are consistent with<br />
    those for our event driven molecular dynamics simulation.

  • 9aAY-6 Granular rotor : Is is possible to infer athermal granular fluctuation from the dynamics of the rotor?

    Sano Tomohiko, Kanazawa Kiyoshi, Sagawa Takahiro, Hayakawa Hisao

    Meeting abstracts of the Physical Society of Japan (The Physical Society of Japan (JPS))  69 ( 2 ) 160 - 160 2014.08

    ISSN  1342-8349

  • 29pBD-11 Microscopic derivation of non-Gaussian Langevin equations

    Kanazawa Kiyoshi, Sano Tomohiko, Sagawa Takahiro, Hayakawa Hisao

    Meeting abstracts of the Physical Society of Japan (The Physical Society of Japan (JPS))  69 ( 1 ) 356 - 356 2014.03

    ISSN  1342-8349

  • 29pBD-12 Fluctuating Heat Engine under Dry Friction

    Sano Tomohiko, Hayakawa Hisao

    Meeting abstracts of the Physical Society of Japan (The Physical Society of Japan (JPS))  69 ( 1 ) 356 - 356 2014.03

    ISSN  1342-8349

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Designing principles of mechanical metamaterials based on the studies of heterogeneous elastic materials

    2018.04
    -
    2024.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Early-Career Scientists , Principal investigator

    　View Summary

    複雑な内部自由度をもつ構造物の力学応答をデザインする指針を明らかにする。一般に、自然な構造物では通常起こり得ない特異な力学特性を示す材料は、メカニカルメタマテリアルと呼ばれる。構造を圧縮すると通常は圧縮方向に垂直にふくらむ(ポアソン比が正)が、逆に垂直にも縮むもの(ポアソン比が負)が例として挙げられる。メカニカルメタマテリアルは対称性の高い内部構造を用いて開発されており、その非対称性や乱れが全体に与える影響は明らかにされていない。本研究は構造の乱れと不均一性がメカニカルメタマテリアルに与える影響を系統的に考察することにより、力学応答を自在にデザインするための指針を解明する。
    本研究はくしゃくしゃに丸めた紙に代表される内部構造を持つ弾性材料の力学特性を明らかにすることを目的にしている。初年度は、丸めた紙の皺を系統的に生成する方法を確立し、皺が発生する過程での力学的性質を実験的に明らかにした。同じ直径の金属柱を二つ用意し、一つをリニアステージに取り付ける。そしてもう一つをロードセルと共に光学定盤に固定する。金属柱に紙(Mylar sheet)を巻きつけ、巻きつけた紙を金属柱より少し大きな直径をもつアクリル円筒内に入れ、紙のもう一端を光学定盤に固定した金属柱に固定する。リニアステージの変位制御により、巻きつけた紙に対して圧縮と伸張を繰り返し、その際に発生する力を変位の関数として測定した。この繰り返しにより系統的に皺を発生することができる。ロードセルで測定した力変位曲線の結果から、皺を発生させる力にも先行研究で知られている「皺の全長」と圧縮伸張回数の関係に類似した関係式が実験的に得られた。紙に皺を発生させるという一見乱雑な過程にも普遍的な数理構造があることが示唆された。研究成果は未だ公表に至っていないが、共同研究者との議論を重ね解析を続けている。またアメリカ物理学会に参加し関連研究の情報収集を行なった。
    内部構造を持つ弾性材料の簡単な問題として、円筒に切れ込みを入れたシェル構造体の力学特性を定量的にあきらかにした。切れ込みの入った円筒は、切れ込みのない円筒の場合と比べ、変形の緩和長が大きくなることがわかった。切り紙のような構造デザインを考える際の指針になりうると考えている。

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Courses Taught 【 Display / hide 】

  • SPECIAL LECTURE SERIES ON MULTIDISCIPLINARY AND DESIGN SCIENCE

    2024

  • MECHANICS OF FLEXIBLE MATERIALS AND STRUCTURAL DESIGN

    2024

  • INDEPENDENT STUDY ON INTEGRATED DESIGN ENGINEERING

    2024

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    2024

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 1

    2024

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