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TADOKORO　Chiharu
Mechanical Science DivisionProfessor
Department of Mechanical Engineering and System Design

Researcher information

■ Field Of Study
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Machine elements and tribology

Performance information

■ Paper
  • Numerical study on transient response of the bowed string
    Miwa SUEDA; Yohei ONODA; Chiharu TADOKORO; Hiroki MORI; Ken NAKANO; Takuo NAGAMINE
    Mechanical Engineering Journal, Mar. 2025, [Reviewed]
    Japan Society of Mechanical Engineers, Scientific journal
    DOI：https://doi.org/10.1299/mej.24-00441
    DOI ID：10.1299/mej.24-00441, eISSN：2187-9745
  • Controlling windscreen wiper vibration through yaw angle adjustments: A study of dynamic contact behavior using fluorescence observation　　　　　　　　　　　　　　　
    C. Tadokoro; H. Kobayashi; M. Sueda; T. Nagamine; S. C. Vlădescu; T. Reddyhoff; K. Nakano
    Frontiers in Mechanical Engineering, Nov. 2024, [Reviewed], [Lead, Corresponding], ［Internationally co-authored］
    English, Scientific journal
    DOI：https://doi.org/10.3389/fmech.2024.1471045
    DOI ID：10.3389/fmech.2024.1471045
  • Noise reduction and power generation in blower duct using Helmholtz resonator with piezoelectric diaphragm
    Chiharu Tadokoro; Takuma Ito; Takuo Nagamine
    Engineering Research Express, Volume：5, Number：2, First page：025047, Last page：025047, May 2023, [Lead, Corresponding]
    Abstract

    Ventilation duct systems are indispensable for air purification and room temperature management in industrial and commercial buildings. The noise generated by blowers for ventilating spaces should be as low as possible. In addition, to power the wireless nodes for monitoring the ventilation conditions such as temperature and pressure at any positions in all the ducts, electric power is preferred to be generated in situ without batteries and wired power supply. In this study, to demonstrate simultaneous noise reduction and in situ power generation using a Helmholtz resonator with a piezoelectric diaphragm in a straight circular pipe duct, the frequency properties of the sound pressure level (SPL) with/without the piezoelectric diaphragm and its generated voltage were measured using an in-house apparatus simulating an industrial blower duct. The experimental results show that the Helmholtz resonator with the piezoelectric diaphragm has a noise reduction performance similar to that without the piezoelectric diaphragm. Power generation was improved not only by impedance matching between the inner and outer resistance but also by the frequency resonance between the frequency of pressure fluctuation in the Helmholtz resonator and the natural frequency of the piezoelectric diaphragm. The Helmholtz resonator with the piezoelectric diaphragm achieved a noise reduction of 10 dB from an SPL of 103 dB and power generation of 12 μW at an SPL of 93 dB.
    IOP Publishing, Scientific journal
    DOI：https://doi.org/10.1088/2631-8695/acd5ac
    DOI ID：10.1088/2631-8695/acd5ac, eISSN：2631-8695
  • Concentrated Polymer Brush in Reciprocating Seal Improves Sealing Performance with Low Friction Even for Rough Surfaces and Immiscible Fluids
    Chiharu Tadokoro; Daichi Kitafuji; Takuo Nagamine; Ken Nakano; Shinya Sasaki; Takaya Sato; Keita Sakakibara; Yoshinobu Tsujii
    Tribology Letters, Volume：70, Number：4, Sep. 2022, [Reviewed], [Lead, Corresponding]
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1007/s11249-022-01646-8
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85137613139&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85137613139&origin=inward
    DOI ID：10.1007/s11249-022-01646-8, ISSN：1023-8883, eISSN：1573-2711, SCOPUS ID：85137613139
  • Exploiting the Synergy between Concentrated Polymer Brushes and Laser Surface Texturing to Achieve Durable Superlubricity
    Sorin-Cristian Vlădescu; Chiharu Tadokoro; Mayu Miyazaki; Tom Reddyhoff; Takuo Nagamine; Ken Nakano; Shinya Sasaki; Yoshinobu Tsujii
    ACS Applied Materials & Interfaces, Volume：14, Number：13, First page：15818, Last page：15829, Mar. 2022, [Reviewed], [Corresponding]
    American Chemical Society (ACS), Scientific journal
    DOI：https://doi.org/10.1021/acsami.2c00725
    DOI ID：10.1021/acsami.2c00725, ISSN：1944-8244, eISSN：1944-8252
  • Processes of molecular adsorption and ordering enhanced by mechanical stimuli under high contact pressure
    Seiya Watanabe; Chiharu Tadokoro; Koji Miyake; Shinya Sasaki; Ken Nakano
    Scientific Reports, Volume：12, Number：1, Mar. 2022, [Reviewed], [Lead, Corresponding]
    Abstract

    Adsorbed molecular films, referred to as boundary films in tribology, are widely used in various industrial products as a keyway for surface functionalisation, such as lubricity, wettability, and adhesion. Because boundary films are thin nanometre-scale molecular layers and can easily be removed, their formation process cannot be elucidated in detail. In this study, to analyse the growth dynamics of boundary films, the film thickness and molecular orientation of the boundary film of a fatty acid used as an additive in rolling contact as mechanical stimuli were measured in situ. The measurements were performed on simple test lubricants, which were composed of n-hexadecane and stearic acid, at rolling tribological condition between steel and glass (or sapphire) surfaces by ultrathin film interferometry combined with sum-frequency generation spectroscopy according to a unique protocol. The results quantitatively demonstrate shear-induced boundary film formation. The insight gained from these results is anticipated to enable the formulation of high-performance lubricant additives to further reduce friction loss and high-performance glues that can be freely designed for removability.
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1038/s41598-022-07854-5
    DOI ID：10.1038/s41598-022-07854-5, eISSN：2045-2322
  • Enhancing durability of concentrated polymer brushes using microgrooved substrates　　　　　　　　　　　　　　　
    Mayu Miyazaki; Ken Nakano; Chiharu Tadokoro; Sorin-Cristian Vlădescu; Thomas Reddyhoff; Shinya Sasaki; Yoshinobu Tsujii
    Wear, Volume：482-483, First page：203984, Last page：203984, Oct. 2021, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.wear.2021.203984
    DOI ID：10.1016/j.wear.2021.203984, ISSN：0043-1648
  • Durability Improvement of Concentrated Polymer Brushes by Multiscale Texturing
    Seiya Watanabe; Eri Kodama; Chiharu Tadokoro; Keita Sakakibara; Ken Nakano; Shinya Sasaki; Yoshinobu Tsujii
    Tribology Letters, Volume：69, Number：3, Sep. 2021, [Reviewed]
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1007/s11249-021-01474-2
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85109350464&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85109350464&origin=inward
    DOI ID：10.1007/s11249-021-01474-2, ISSN：1023-8883, eISSN：1573-2711, SCOPUS ID：85109350464
  • Anti-vibration and traction control of rotary sliding systems by orthogonal rotation providing transverse sliding　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Yuto Aso; Takuo Nagamine; Ken Nakano
    Tribology International, Volume：159, First page：106992, Last page：106992, Jul. 2021, [Reviewed], [Lead, Corresponding]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2021.106992
    DOI ID：10.1016/j.triboint.2021.106992, ISSN：0301-679X
  • In Situ Raman-SLIM Monitoring for the Formation Processes of MoDTC and ZDDP Tribofilms at Steel/Steel Contacts under Boundary Lubrication
    Hikaru Okubo; Chiharu Tadokoro; Shinya Sasaki
    Tribology Online, Volume：15, Number：3, First page：105, Last page：116, May 2020, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.15.105
    DOI ID：10.2474/trol.15.105, eISSN：1881-2198
  • Lubricating Properties of Cyano-Based Ionic Liquids against Tetrahedral Amorphous Carbon Film
    Shouhei Kawada; Hikaru Okubo; Seiya Watanabe; Chiharu Tadokoro; Ryo Tsuboi; Shinya Sasaki; Masaaki Miyatake
    Coatings, Volume：10, Number：2, First page：153, Last page：153, Feb. 2020, [Reviewed]
    MDPI AG, Scientific journal
    DOI：https://doi.org/10.3390/coatings10020153
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85080924179&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85080924179&origin=inward
    DOI ID：10.3390/coatings10020153, eISSN：2079-6412, SCOPUS ID：85080924179
  • Concentrated Polymer Brush as Reciprocating Seal Material for Low Leakage and Low Friction　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Kosuke Sato; Takuo Nagamine; Ken Nakano; Shinya Sasaki; Takaya Sato; Keita Sakakibara; Yoshinobu Tsujii
    Tribology Transactions, Volume：63, Number：1, First page：20, Last page：27, Jan. 2020, [Reviewed], [Lead, Corresponding]
    English, Scientific journal
    DOI：https://doi.org/10.1080/10402004.2019.1650213
    DOI ID：10.1080/10402004.2019.1650213, ISSN：1040-2004, eISSN：1547-397X, Web of Science ID：WOS:000493170200001
  • Super-Low Friction of Thermal-Treatment-Concentrated Polymer Brushes (TT-CPBs) under Boundary Lubrication: A Practical Method to Shorten the Swelling Time of CPBs in Solvents　　　　　　　　　　　　　　　
    Hikaru Okubo; Chiharu Tadokoro; Keita Sakakibara; Ken Nakano; Shinya Sasaki; Yoshinobu Tsujii
    Tribology Online, Volume：14, Number：4, First page：226, Last page：236, Nov. 2019, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.2474/trol.14.226
    DOI ID：10.2474/trol.14.226, ISSN：1881-2198, eISSN：1881-2198, Web of Science ID：WOS:000507987500009
  • MECHANICAL STRUCTURE DESIGN TO AVOID FRICTION-INDUCED INSTABILITIES: IN-PLANE ANISOTROPY AND IN-PLANE ASYMMETRY
    Ken Nakano; Naohiro Kado; Chiharu Tadokoro; Takuo Nagamine
    Facta Universitatis, Series: Mechanical Engineering, Volume：17, Number：2, First page：113, Last page：113, Jul. 2019, [Reviewed]
    The stability of a two-degree-of-freedom (2DOF) sliding system with the velocity-weakening friction was examined by the eigenvalue analysis, where the in-plane anisotropy and the in-plane asymmetry were considered. The obtained eigenvalues were organized by using the minimum modal damping ratio as the stability maps. Selecting a stable point in the stability map corresponds automatically to embedding the Yaw-Angle-Misalignment (YAM) method in the mechanical structure design to avoid the instability. If we accept the mechanical structure design of sliding systems with the in-plane anisotropy and the in-plane asymmetry, we can find new stable conditions spread widely in the two-dimensional space, which are invisible from the conventional point of view.
    University of Nis, Scientific journal
    DOI：https://doi.org/10.22190/fume190415018n
    DOI ID：10.22190/fume190415018n, ISSN：0354-2025, eISSN：2335-0164
  • Wear acceleration mechanism of diamond-like carbon (DLC) films lubricated with MoDTC solution: Roles of tribofilm formation and structural transformation in wear acceleration of DLC films lubricated with MoDTC solution　　　　　　　　　　　　　　　
    Hikaru Okubo; Chiharu Tadokoro; Taro Sumi; Noriyoshi Tanaka; Shinya Sasaki
    Tribology International, Volume：133, First page：271, Last page：287, May 2019, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2018.12.029
    DOI ID：10.1016/j.triboint.2018.12.029, ISSN：0301-679X, eISSN：1879-2464, Web of Science ID：WOS:000458943500026
  • Diprotic ammonium palmitate ionic liquid crystal and nanodiamonds in aqueous lubrication. Film thickness and influence of sliding speed　　　　　　　　　　　　　　　
    F.J. Carrión; M.D. Avilés; K. Nakano; C. Tadokoro; T. Nagamine; M.D. Bermúdez
    Wear, Volume：418-419, First page：241, Last page：252, Jan. 2019, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.wear.2018.12.011
    DOI ID：10.1016/j.wear.2018.12.011, ISSN：0043-1648
  • Macroscopic tribological properties of thick concentrated polymer brush on rough steel under lubrication with ionic liquid　　　　　　　　　　　　　　　
    Keisuke Sato; Hikaru Okubo; Yuki Hirata; Chiharu Tadokoro; Ken Nakano; Yoshinobu Tsujii; Shinya Sasaki
    Jurnal Tribologi, Volume：20, First page：97, Last page：113, Sep. 2018, [Reviewed]
    Scientific journal
  • Stabilizing effect arising from parallel misalignment in circular sliding contact　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Takuo Nagamine; Ken Nakano
    Tribology International, Volume：120, First page：16, Last page：22, Apr. 2018, [Reviewed], [Lead]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2017.12.003
    DOI ID：10.1016/j.triboint.2017.12.003, ISSN：0301-679X
  • Synergy of two fatty acids as additives on lubricity of a nematic liquid crystal 5CB　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Shoki Araya; Masaya Watanabe; Hikaru Okubo; Ken Nakano; Shinya Sasaki
    Lubrication Science, Volume：30, Number：3, First page：83, Last page：90, Apr. 2018, [Reviewed], [Lead, Corresponding]
    English, Scientific journal
    DOI：https://doi.org/10.1002/ls.1406
    DOI ID：10.1002/ls.1406, ISSN：0954-0075, eISSN：1557-6833, Web of Science ID：WOS:000426652800001
  • Lubricating mechanism of cyano-based ionic liquids on nascent steel surface　　　　　　　　　　　　　　　
    S. Kawada; S. Watanabe; C. Tadokoro; R. Tsuboi; S. Sasaki
    Tribology International, Volume：119, First page：474, Last page：480, Mar. 2018, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2017.11.019
    DOI ID：10.1016/j.triboint.2017.11.019, ISSN：0301-679X
  • Effects of Alkyl Chain Length of Sulfate and Phosphate Anion-Based Ionic Liquids on Tribochemical Reactions
    Shouhei Kawada; Seiya Watanabe; Chiharu Tadokoro; Shinya Sasaki
    Tribology Letters, Volume：66, Number：1, Mar. 2018, [Reviewed]
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1007/s11249-017-0962-1
    DOI ID：10.1007/s11249-017-0962-1, ISSN：1023-8883, eISSN：1573-2711
  • Rotational Motions Excited by Vertical Harmonic Motions　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Kei Kadowaki; Hiroki Mori; Takuo Nagamine
    Transactions of Nanjing University of Aeronautics & Astronautics, Volume：35, Number：1, First page：51, Last page：57, Feb. 2018, [Reviewed], [Lead, Corresponding]
    Scientific journal
  • Proposal of Biomimetic Tribological System to Control Friction Behavior under Boundary Lubrication by Applying 3D Metal Printing Process　　　　　　　　　　　　　　　
    Misa Yonehara; Hikaru Okubo; Chiharu Tadokoro; Shinya Sasaki; Braham Prakash
    Tribology Online, Volume：13, Number：1, First page：8, Last page：14, 2018, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.2474/trol.13.8
    DOI ID：10.2474/trol.13.8, ISSN：1881-2198, eISSN：1881-2198, Web of Science ID：WOS:000458273600003
  • MoDTC-induced wear acceleration mechanism of a hydrogenated amorphous carbon diamond-like carbon film　　　　　　　　　　　　　　　
    Hikaru OKUBO; Hiroaki MAEDA; Shouhei KAWADA; Chiharu TADOKORO; Shinya SASAKI
    Transactions of the JSME (in Japanese), Volume：84, Number：861, First page：17, Last page：00564, 2018, [Reviewed]
    Japan Society of Mechanical Engineers, Scientific journal
    DOI：https://doi.org/10.1299/transjsme.17-00564
    DOI ID：10.1299/transjsme.17-00564, ISSN：2187-9761, eISSN：2187-9761, J-Global ID：201802273712836223
  • Piezoelectric power generation using friction-induced vibration　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Aya Matsumoto; Takuo Nagamine; Shinya Sasaki
    Smart Materials and Structures, Volume：26, Number：6, First page：065012, Last page：065012, Jun. 2017, [Reviewed], [Lead, Corresponding]
    English, Scientific journal
    DOI：https://doi.org/10.1088/1361-665x/aa7042
    DOI ID：10.1088/1361-665x/aa7042, ISSN：0964-1726, eISSN：1361-665X, Web of Science ID：WOS:000401631700001
  • The Effects of Surface Texturing on Friction Performance under Reciprocating Sliding Condition
    Tianchi Qin; Chiharu Tadokoro; Shinya Sasaki
    Key Engineering Materials, Volume：739, First page：36, Last page：41, Jun. 2017, [Reviewed]
    In this research, we focus on the improvement of frictional performance of piston ring achieved by Laser Surface Texturing. Five kinds of samples (non-texture, dimple 100μm, dimple120μm, groove 45 degrees to sliding direction and groove 90 degrees to sliding direction) were tested under reciprocating sliding condition. The results showed that the sample of groove 90 degrees to sliding condition has the maximum decrease on either average friction coefficient (26%) or friction coefficient at end points of stock (33%). And we think that under boundary lubrication regime, the uniformity of distribution of the texture and flow of oil in contact surface are the key factors which affect the friction coefficient.
    Trans Tech Publications, Ltd., Scientific journal
    DOI：https://doi.org/10.4028/www.scientific.net/kem.739.36
    DOI ID：10.4028/www.scientific.net/kem.739.36, eISSN：1662-9795
  • Measurements of lubricant film thickness by optical interference　　　　　　　　　　　　　　　
    K. Nakano; C. Tadokoro; S. Maegawa
    Journal of the Surface Science Society of Japan, Volume：38, Number：3, First page：111, Last page：116, Mar. 2017, [Reviewed], [Invited]
    公益社団法人 日本表面科学会, Japanese, Scientific journal
    DOI：https://doi.org/10.1380/jsssj.38.111
    DOI ID：10.1380/jsssj.38.111
  • Effects of Si particles of Al-Si alloys on frictional properties of hydrogenated amorphous carbon (a-C:H) films/Al-Si alloys tribopairs under lubrication with fully formulated oil　　　　　　　　　　　　　　　
    Hikaru OKUBO; Yuki NODA; Chiharu TADOKORO; Yuki HIRATA; Shinya SASAKI
    Transactions of the JSME (in Japanese), Volume：83, Number：850, First page：16, Last page：00543, 2017, [Reviewed]
    Japan Society of Mechanical Engineers, Scientific journal
    DOI：https://doi.org/10.1299/transjsme.16-00543
    DOI ID：10.1299/transjsme.16-00543, ISSN：2187-9761, eISSN：2187-9761, J-Global ID：201702219853058216
  • Effects of Molecular Structure of Zinc Dialkyldithiophosphates on Tribological Properties of a Hydrogenated Amorphous Carbon Film under Boundary Lubrication　　　　　　　　　　　　　　　
    Hikaru Okubo; Seiya Watanabe; Chiharu Tadokoro; Yuki Hirata; Shinya Sasaki
    Tribology Online, Volume：12, Number：5, First page：221, Last page：228, 2017, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.2474/trol.12.221
    DOI ID：10.2474/trol.12.221, ISSN：1881-2198, eISSN：1881-2198, Web of Science ID：WOS:000415194300002
  • In Situ Raman Observation of the Graphitization Process of Tetrahedral Amorphous Carbon Diamond-Like Carbon under Boundary Lubrication in Poly-Alpha-Olefin with an Organic Friction Modifier
    Hikaru Okubo; Chiharu Tadokoro; Yuki Hirata; Shinya Sasaki
    Tribology Online, Volume：12, Number：5, First page：229, Last page：237, 2017, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.12.229
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85035363835&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85035363835&origin=inward
    DOI ID：10.2474/trol.12.229, ISSN：1881-218X, eISSN：1881-2198, SCOPUS ID：85035363835
  • Influence of Ink Composition on Tribological Properties of Ballpoint Pen　　　　　　　　　　　　　　　
    Mariko Isokane; Chiharu Tadokoro; Shinya Sasaki; Braham Prakash
    Tribology Online, Volume：12, Number：5, First page：257, Last page：261, 2017, [Reviewed]

    In this work, the influence of ink composition on the tribological properties of ballpoint pens has been examined with a view to improve writing smoothness and pen lifetime. Friction experiments were performed using a ball on plate tribometer in order to simulate the sliding contact of a ballpoint pen. Ballpoint pen ink is composed of various solvents, resins, friction modifiers, colorants. To determine the basic tribological properties of ballpoint pen ink, this study focuses on the investigating the influence of different ink compositions: solvents, resins, and phosphate on the tribological behavior. The worn surfaces of specimens from tribological tests using different ink compositions were analyzed by using Fourier-transform infrared spectroscopy. Tribological tests were performed on eight different lubricant compositions including: i) the solvents without additives ii) the solvents with the resins and iii) the solvents with the friction modifiers. The results showed that for Oil A the tribological properties were affected by the molecular weight of the resin and the addition of phosphate reduced the coefficients of friction. Similar results were not observed for Oil B. In addition, it was found that the ratio of the components of the base oil affects the tribological properties of ballpoint pen ink.


    Japanese Society of Tribologists, English, Scientific journal
    DOI：https://doi.org/10.2474/trol.12.257
    DOI ID：10.2474/trol.12.257, eISSN：1881-2198, CiNii Articles ID：130006250699
  • Polarization Observations of Adsorption Behavior of Fatty Acids Using Optical Anisotropy of Liquid Crystal　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Shoki Araya; Hikaru Okubo; Ken Nakano; Shinya Sasaki
    Tribology Letters, Volume：64, Number：2, Nov. 2016, [Reviewed], [Lead, Corresponding]
    English, Scientific journal
    DOI：https://doi.org/10.1007/s11249-016-0765-9
    DOI ID：10.1007/s11249-016-0765-9, ISSN：1023-8883, eISSN：1573-2711, Web of Science ID：WOS:000386776100012
  • Effects of structure of zinc dialkyldithiophosphates on tribological properties of tetrahedral amorphous carbon f ilm under boundary lubrication　　　　　　　　　　　　　　　
    Hikaru Okubo; Seiya Watanabe; Chiharu Tadokoro; Shinya Sasaki
    Tribology International, Volume：98, First page：26, Last page：40, Jun. 2016, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2016.02.025
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84960092837&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84960092837&origin=inward
    DOI ID：10.1016/j.triboint.2016.02.025, ISSN：0301-679X, SCOPUS ID：84960092837
  • Effects of concentration of zinc dialkyldithiophosphate on the tribological properties of tetrahedral amorphous carbon films in presence of organic friction modifiers　　　　　　　　　　　　　　　
    Hikaru Okubo; Seiya Watanabe; Chiharu Tadokoro; Shinya Sasaki
    Tribology International, Volume：94, First page：446, Last page：457, Feb. 2016, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2015.10.008
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84946135760&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84946135760&origin=inward
    DOI ID：10.1016/j.triboint.2015.10.008, ISSN：0301-679X, SCOPUS ID：84946135760
  • Effect of microstructure of low-carbon steels on frictional and wear behaviour　　　　　　　　　　　　　　　
    Akihiro Naka; Takashi Kobayashi; Shinji Katou; Ryo Tsuboi; Chiharu Tadokoro; Shinya Sasaki
    Tribology International, Volume：93, First page：696, Last page：701, Jan. 2016, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2015.05.014
    DOI ID：10.1016/j.triboint.2015.05.014, ISSN：0301-679X, eISSN：1879-2464, Web of Science ID：WOS:000366788000024
  • Ultralow Friction of a Tetrahedral Amorphous Carbon Film Lubricated with an Environmentally Friendly Ester-Based Oil
    Hikaru Okubo; Seiya Watanabe; Chiharu Tadokoro; Shinya Sasaki
    Tribology Online, Volume：11, Number：2, First page：102, Last page：113, 2016, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.11.102
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84969497804&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84969497804&origin=inward
    DOI ID：10.2474/trol.11.102, ISSN：1881-218X, eISSN：1881-2198, SCOPUS ID：84969497804
  • Evaluation of Frictional Behavior of Textured Surface by Using a Newly Proposed GPS Parameter　　　　　　　　　　　　　　　
    Hiroshi Nagasaki; Chiharu Tadokoro; Ryo Tsuboi; Yuki Tokuta; Shinya Sasaki
    Tribology Online, Volume：11, Number：2, First page：354, Last page：359, 2016, [Reviewed]
    Surfaces with different topographies are formed by the various types of manufacturing processes. To express the characteristics of these surfaces, the International Organization for Standardization (ISO) defines two-dimensional (2-D) surface roughness parameters, which are used for geometrical product specification (GPS). 2-D surface roughness parameters are widely used in engineering fields. In contrast, 3-D surface roughness parameters have been standardized with the development of measurement technologies. In the field of tribology, the relationship between the surface roughness parameters and tribological characteristics has been extensively studied. However, surface roughness parameters for the expression of tribological characteristics have not yet been reported. In this research, the fast Fourier transform (FFT) method was applied to evaluate the periodicity of sliding surfaces. Using the 2-D FFT method, the 2-D power spectral density (PSD) was obtained for actual surfaces. The relationships between the 2-D PSDs and the friction characteristics of anisotropic surfaces were examined. From these results, it was determined that all the data from the 2-D PSD are required to determine the optimal direction of sliding. A new 3-D surface roughness parameter to express these relationships was proposed. It was shown that this parameter is able to determine the sliding angle where the lowest or highest friction coefficients are attained for common industrial surfaces. This parameter could be used in the design of sliding surfaces as a GPS parameter to express friction characteristics.
    Japanese Society of Tribologists, English, Scientific journal
    DOI：https://doi.org/10.2474/trol.11.354
    DOI ID：10.2474/trol.11.354, ISSN：1881-2198, eISSN：1881-2198, CiNii Articles ID：130005149917
  • Effect of Surface Texturing on Friction Transition of C/C Composite Material　　　　　　　　　　　　　　　
    Satoshi Hoshino; Chiharu Tadokoro; Shinya Sasaki
    Tribology Online, Volume：11, Number：2, First page：426, Last page：431, 2016, [Reviewed]
    Carbon-carbon (C/C) composites are widely used as sliding materials owing to their excellent mechanical properties. However, it is well known that the C/C composites exhibit an unstable frictional behavior called the friction transition, the main mechanism of which remains unclear. In this study we focused on the mechanism of the friction transition by examining the morphology of wear debris obtained using a thrust-cylinder-type tribotester. Moreover, to improve the tribological properties of C/C composites, we discussed the effect of surface texturing. The sliding results suggested that agglomeration of wear debris caused the friction transition. Furthermore, the friction transition was prevented by the effects of surface texturing.
    Japanese Society of Tribologists, English, Scientific journal
    DOI：https://doi.org/10.2474/trol.11.426
    DOI ID：10.2474/trol.11.426, ISSN：1881-2198, eISSN：1881-2198, CiNii Articles ID：130005149920
  • Tribological properties of a diamond-like carbon film under lubrication with commercial fully formulated oils　　　　　　　　　　　　　　　
    Hikaru OKUBO; Hirochika FUKUDA; Ryo TSUBOI; Chiharu TADOKORO; Shinya SASAKI
    Transactions of the JSME (in Japanese), Volume：82, Number：838, First page：15, Last page：00679, 2016, [Reviewed]
    Japan Society of Mechanical Engineers, Scientific journal
    DOI：https://doi.org/10.1299/transjsme.15-00679
    DOI ID：10.1299/transjsme.15-00679, ISSN：2187-9761, eISSN：2187-9761, J-Global ID：201602242176687045
  • Correlation between Nano-Mechanical and Macro-Tribological Properties of Tribofilms Derived from Organic Phosphoric Additives
    Chisaki Hashimoto; Hikaru Okubo; Chiharu Tadokoro; Shinya Sasaki
    Tribology Online, Volume：11, Number：5, First page：632, Last page：638, 2016, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.11.632
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84988733973&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84988733973&origin=inward
    DOI ID：10.2474/trol.11.632, ISSN：1881-218X, eISSN：1881-2198, SCOPUS ID：84988733973
  • Quick measurement of electrorheological effect for small amounts of nematic liquid crystal
    Chiharu Tadokoro; Yuki Hosomi; Ken Nakano
    Measurement Science and Technology, Volume：26, Number：8, First page：085303, Last page：085303, Aug. 2015, [Reviewed], [Lead, Corresponding]
    IOP Publishing, Scientific journal
    DOI：https://doi.org/10.1088/0957-0233/26/8/085303
    DOI ID：10.1088/0957-0233/26/8/085303, ISSN：0957-0233, eISSN：1361-6501
  • Evaluation of ultraviolet-nanoimprint-lithography release agent properties by using TriboIndenter　　　　　　　　　　　　　　　
    Kota Funakoshi; Chiharu Tadokoro; Ian Thomas Clark; Toshiro Okawa; Jun Taniguchi; Shinya Sasaki
    Microelectronic Engineering, Volume：141, First page：150, Last page：154, Jun. 2015, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.mee.2015.02.007
    DOI ID：10.1016/j.mee.2015.02.007, ISSN：0167-9317
  • Tribological properties of a tetrahedral amorphous carbon (ta-C) film under boundary lubrication in the presence of organic friction modifiers and zinc dialkyldithiophosphate (ZDDP)　　　　　　　　　　　　　　　
    Hikaru Okubo; Chiharu Tadokoro; Shinya Sasaki
    Wear, Volume：332-333, First page：1293, Last page：1302, May 2015, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.1016/j.wear.2015.01.023
    DOI ID：10.1016/j.wear.2015.01.023, ISSN：0043-1648, eISSN：1873-2577, Web of Science ID：WOS:000357438100080
  • Observation of the Tribo-Film Formation Derived from ZnDTP by Using FT-IR
    Hirotomo Watanabe; Chiharu Tadokoro; Shinya Sasaki
    Key Engineering Materials, Volume：642, First page：259, Last page：263, Apr. 2015, [Reviewed]
    To understand the effects of tribo-film formation derived from ZnDTP (zinc dialkyl ditio phosphate) on friction behavior, friction tests were carried out with varying sliding time. The sliding surfaces were analyzed using Fourier transform infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). On the basis of the surface analytical results of the tribo-film, the absorption bands in the region of 1300-1000 cm-1 assigned as polyphosphate appeared in all IR spectra after the sliding. The friction behavior of ZnDTP was related to the intensity change of the IR spectra peak at 1200 cm-1.
    Trans Tech Publications, Ltd., Scientific journal
    DOI：https://doi.org/10.4028/www.scientific.net/kem.642.259
    DOI ID：10.4028/www.scientific.net/kem.642.259, eISSN：1662-9795
  • Complex Impedance Measurement Applied to Short-Time Contact Between Colliding Steel Surfaces
    Takahiro Nihira; Kazuyoshi Manabe; Chiharu Tadokoro; Shingo Ozaki; Ken Nakano
    Tribology Letters, Volume：57, Number：3, Mar. 2015, [Reviewed]
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1007/s11249-015-0478-5
    DOI ID：10.1007/s11249-015-0478-5, ISSN：1023-8883, eISSN：1573-2711
  • Vibrational Spectroscopic Study on Lubrication and Corrosive Wear Mechanisms of Imidazolium Based Ionic Liquids　　　　　　　　　　　　　　　
    Watanabe, S.; Nakano, M.; Miyake, K.; Tadokoro, C.; Sasaki, S.
    Ionic Liquids - Current State of the Art, First page：545, Last page：556, 2015, [Reviewed]
    English, Scientific journal
    DOI：https://doi.org/10.5772/59132
    DOI ID：10.5772/59132, ORCID：45208080, Web of Science ID：WOS:000404740400021
  • Effects of ZnDTP on lubricity of ashless friction modifiers for H-free DLC film　　　　　　　　　　　　　　　
    Hikaru OKUBO; Ryo TSUBOI; Chiharu TADOKORO; Shinya SASAKI
    Transactions of the JSME (in Japanese), Volume：81, Number：824, First page：14, Last page：00656, 2015, [Reviewed]
    Japan Society of Mechanical Engineers, Scientific journal
    DOI：https://doi.org/10.1299/transjsme.14-00656
    DOI ID：10.1299/transjsme.14-00656, ISSN：2187-9761, eISSN：2187-9761, J-Global ID：201502280449859474
  • Effects of Hydrogen on Frictional Properties of DLC Films
    Hikaru Okubo; Kenta Oshima; Ryo Tuboi; Chiharu Tadokoro; Shinya Sasaki
    Tribology Online, Volume：10, Number：6, First page：397, Last page：403, 2015, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.10.397
    Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84954551743&origin=inward
    Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84954551743&origin=inward
    DOI ID：10.2474/trol.10.397, ISSN：1881-218X, eISSN：1881-2198, SCOPUS ID：84954551743
  • Minimization of Friction at Various Speeds Using Autonomous Viscosity Control of Nematic Liquid Crystal
    Chiharu Tadokoro; Takahiro Nihira; Ken Nakano
    Tribology Letters, Volume：56, Number：2, First page：239, Last page：247, Nov. 2014, [Lead]
    Springer Science and Business Media LLC, Scientific journal
    DOI：https://doi.org/10.1007/s11249-014-0404-2
    DOI ID：10.1007/s11249-014-0404-2, ISSN：1023-8883, eISSN：1573-2711
  • Effect of yaw angle misalignment on brake noise and brake time in a pad-on-disc-type apparatus with unidirectional compliance for pad support　　　　　　　　　　　　　　　
    Naohiro Kado; Naoya Sato; Chiharu Tadokoro; Antonin Skarolek; Ken Nakano
    Tribology International, Volume：78, First page：41, Last page：46, Oct. 2014, [Reviewed]
    Elsevier BV, Scientific journal
    DOI：https://doi.org/10.1016/j.triboint.2014.04.033
    DOI ID：10.1016/j.triboint.2014.04.033, ISSN：0301-679X
  • Kinetic Friction Coefficient Measured in Tribotesting: Influence of Frictional Vibration　　　　　　　　　　　　　　　
    Naohiro Kado; Chiharu Tadokoro; Ken Nakano
    Tribology Online, Volume：9, Number：2, First page：63, Last page：70, 2014, [Reviewed]
    Japanese Society of Tribologists, Scientific journal
    DOI：https://doi.org/10.2474/trol.9.63
    DOI ID：10.2474/trol.9.63, eISSN：1881-2198
  • Yawing Angular Misalignment Provides Positive Damping to Suppress Frictional Vibration: Basic Applicability to Disc Brake Systems
    Ken Nakano; Chiharu Tadokoro; Naohiro Kado
    SAE International Journal of Passenger Cars - Mechanical Systems, Volume：6, Number：3, First page：1493, Last page：1498, Sep. 2013, [Reviewed]
    SAE International, Scientific journal
    DOI：https://doi.org/10.4271/2013-01-2069
    DOI ID：10.4271/2013-01-2069, ISSN：1946-4002
  • ALE Finite Element Analysis of Plastic Indentation Process of Lubricated Plate by the Ball Collision　　　　　　　　　　　　　　　
    Masanori TSUKUI; Shingo OZAKI; Kazuyoshi MANABE; Chiharu TADOKORO; Ken NAKANO
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A, Volume：79, Number：800, First page：477, Last page：488, 2013, [Reviewed]
    In the present study, we apply an Arbitrary Lagrangian-Eulerian (ALE) finite element method, which can rationally solve the interaction behavior between the fluid flow and the nonlinear solid deformation, to the simulation of indentation process of lubricated elastoplastic plates by the ball collision. As have been reported by numerous experimental works, it is also shown by the present numerical approach that the characteristic of lubricant affects indentation profiles. For instance, the indentation profile represents the conical shape due to viscous property of lubricant, while the profile represents the bowl-type shape under the dry condition. Based on the systematic numerical investigation, it is confirmed in the case of lubricated condition that the indentation is formed through the pressure of a fluid. Then, a squeeze effect of viscous flow and a shut-up of lubricant, which is caused by velocity of lateral flow, are observed. Furthermore, it is understood that the conical shape of indentation profile is formed at an initial contact stage, and then its size similarly grow up during loading. Thus, it is confirmed that the ALE finite element method is one of effective methods for the examination of impact problems on lubricated surfaces.
    Japan Society of Mechanical Engineers, Japanese, Scientific journal
    DOI：https://doi.org/10.1299/kikaia.79.477
    DOI ID：10.1299/kikaia.79.477, ISSN：0387-5008, eISSN：1884-8338, CiNii Articles ID：130003374621
  • Design Criteria on Effective Static Friction Coefficient of Elastomers　　　　　　　　　　　　　　　
    Satoru MAEGAWA; Fumihiro ITOIGAWA; Takatoshi SHINYOSHI; Atsushi SUZUKI; Chiharu TADOKORO; Ken NAKANO
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C, Volume：79, Number：803, First page：2622, Last page：2634, 2013, [Reviewed]
    In sliding friction of elastomers, the effective static friction coefficient μseff observed is not necessarily equal to the inherent real one μs possessed by the material; usually μseff < μs because of the elastic deformations of sliding objects and the propagation of shear fracture in the contact area. This indicates that focusing on elastic deformation of sliding objects can derive a new criterion of μseff for machine design. In this study, mainly through numerical simulations for a physical model assured by experiments in which measuring frictional force and observing contact area were carried out for a longitudinal line contact of polymethyl methacrylate, it is found that the stiffness ratio κ = Kbtot / Kctot (where Kbtot and Kctot are the total bulk stiffness and total tangential contact stiffness of the elastic sliding object, respectively) dominates the value of μseff.
    Japan Society of Mechanical Engineers, Japanese, Scientific journal
    DOI：https://doi.org/10.1299/kikaic.79.2622
    DOI ID：10.1299/kikaic.79.2622, ISSN：0387-5024, eISSN：1884-8354, CiNii Articles ID：130003375132
  • Measurement Error of Kinetic Friction Coefficient Generated by Frictional Vibration　　　　　　　　　　　　　　　
    Naohiro KADO; Chiharu TADOKORO; Ken NAKANO
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C, Volume：79, Number：803, First page：2635, Last page：2643, 2013, [Reviewed]
    To measure true values of kinetic friction coefficient in a force balance between the frictional force and spring force, an anti-vibration tribometer (AVT) has been developed. The AVT utilizes a novel principle that an angular misalignment between the two velocities (i.e., the driving velocity of one of contact surfaces and the moving velocity of the other surface) produces a positive damping effect to stabilize the equilibrium point and suppress frictional vibration autonomously. For example, when a sliding contact between a steel ball and a steel plate is lubricated by glycerin, the AVT provides a force balance situation at a misalignment angle φ = 30° (i.e., an anti-vibration setting), although strong frictional vibration occurs at φ = 0° (i.e., a conventional setting). By comparing the kinetic friction coefficients obtained at φ = 0° and 30°, it has been found that frictional vibration can lead to a serious error of measuring kinetic friction coefficient (e.g., a 35% underestimation at a low driving speed).
    Japan Society of Mechanical Engineers, Japanese, Scientific journal
    DOI：https://doi.org/10.1299/kikaic.79.2635
    DOI ID：10.1299/kikaic.79.2635, ISSN：0387-5024, eISSN：1884-8354, CiNii Articles ID：130003375133
  • Friction and Wear Properties of PTFE Sliding Seals -Influence of Surface Conditions of Seal Gland on Friction Properties-　　　　　　　　　　　　　　　
    Chiharu Tadokoro; Yasuo Yoshii; Hitoshi Hattori; Daisuke Nishino
    Tribology Online, Volume：5, Number：6, First page：266, Last page：270, 2010, [Reviewed], [Lead, Corresponding]
    Sealing devices are needed to prevent dust and water invading the positioning mechanisms of outdoor equipment. The frictional resistance generated by the seal frequently obstructs the smooth motion of the mechanism. The friction properties for high-speed and precision control mechanisms are required to be low and stable without lowering the sealing performance. In this study, the influence of the surface conditions of seal gland for PTFE sliding seal on friction properties was investigated experimentally. As a result, it has been found that the suitable surface condition of the seal gland for a high-speed and precision control mechanism is the electroless-nickel-plated surface of 0.1 μm Ra
    Japanese Society of Tribologists, English, Scientific journal
    DOI：https://doi.org/10.2474/trol.5.266
    DOI ID：10.2474/trol.5.266, ISSN：1881-2198, eISSN：1881-2198, CiNii Articles ID：130000453551
  • 微小動荷重制御による摩擦振動抑制法　　　　　　　　　　　　　　　
    田所 千治; 中野 健
    Volume：50, Number：11, First page：799, Last page：807, Feb. 2005, [Reviewed], [Lead]
    Scientific journal
  • 摩擦変動スペクトルに基づく接触面情報の抽出　　　　　　　　　　　　　　　
    中野健; 田所千治; 早川純平; 山本浩司
    Volume：50, Number：5, First page：409, Last page：415, Sep. 2004, [Reviewed]
    Scientific journal
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