Journal: Tribology International

Abbreviation

Tribol. int.

Publisher

Elsevier

Journal Volumes

ISSN

0301-679X

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Publications 1 - 10 of 15
  • Numerical modeling and design decisions for aerostatic bearings with relatively large nozzle sizes in Magic-Angle Spinning (MAS) systems
    Item type: Journal Article
    Deb, Rajdeep; Hunkeler, Andreas; Wilhelm, Dirk; et al. (2022)
    Tribology International
    Numerical stability analysis for aerostatic bearings was performed to obtain optimized design parameters for small submillimeter to millimeter range diameter cylindrical rotors. Such rotors are used in nuclear magnetic resonance (NMR) application to rotate sample around an axis inclined by magic angle (54.74°) relative to the magnetic field direction at rotational frequencies of about 100 kHz (magic-angle spinning, MAS). The governing Reynolds equation for the fluid film between rotor and bearing was modified for small size aerostatic bearings with relatively large nozzle diameters. The modified Reynolds equation was solved using a finite-volume method to obtain pressure and film thickness around the rotor. This led to the solution of the maximum stable inertial force as a function of rotational frequency and design parameters. The comparison with aerostatic bearings with infinitesimal nozzle sizes was obtained for supported rotor weight and critical vibrational frequency of the rotor. The stable inertial force was found to correspond to a specific nozzle diameter and a specific rotor–bearing clearance. Numerical investigation also shows an enhancement of stable inertial force with decreasing nozzle number or increasing molecular mass of the impinging gas for a specific range of nozzle parameters. Experimental observations further confirmed the role of nozzle diameter, nozzle number and molecular weight of the gas in enhancing the rotor spinning frequency. Further, design decisions were made based on such analysis and were tested for varying rotor size and bearing properties. Using design optimization based on numerical simulation, the maximum frequency of rotation for a home-built 0.4 mm MAS rotor could be enhanced from 25 kHz up to 110 kHz, still below the extrapolation from large rotors.
  • Evaluation and quantification of friction using Ionic Liquids in small, self lubricating journal bearings
    Item type: Journal Article
    Trachsel, Mathis; Pittini, Raniero; Dual, Jürg (2018)
    Tribology International
  • Friction between human skin and medical textiles for decubitus prevention
    Item type: Journal Article
    Rotaru, G. M.; Pille, D.; Lehmeier, F. K.; et al. (2013)
    Tribology International
  • Reactions of zinc-free anti-wear additives in DLC/DLC and steel/steel contacts
    Item type: Conference Paper
    Equey, Sébastien; Roos, Sigfried; Mueller, Ulrich; et al. (2008)
    Tribology International
  • Investigation of journal orbit and flow pattern in a dynamically loaded journal bearing
    Item type: Journal Article
    Christiansen, Christian K.; Walther, Jens Honoré; Klit, Peder; et al. (2017)
    Tribology International
  • Stability and dynamics of an orifice based aerostatic bearing with a compliant back plate
    Item type: Journal Article
    Maamari, Nadim; Krebs, A.; Weikert, Sascha; et al. (2019)
    Tribology International
  • The influence of geometrical and rheological non-linearity on the calculation of rubber friction
    Item type: Journal Article
    Scaraggi, Michele; Comingio, Davide; Al-Qudsi, Ahmad; et al. (2016)
    Tribology International
  • Influence of metallic and oxidized iron/steel on the reactivity of triphenyl phosphorothionate in oil solution
    Item type: Conference Paper
    Mangolini, Filippo; Rossi, Antonella; Spencer, Nicholas D. (2011)
    Tribology International
  • A water-responsive, gelatine-based human skin model
    Item type: Journal Article
    Dabrowska, Agnieszka K.; Rotaru, Gelu M.; Spano, Fabrizio; et al. (2017)
    Tribology International
    The properties of human skin strongly depend on hydration. Skin friction, elasticity and roughness change significantly in the presence of water. This paper presents a new bio-mimicking gelatine-based physical skin model that simulates the frictional behaviour of human skin against a widely-used standard textile under dry and wet conditions and over a broad range of applied normal load (0.5–5 N) and amount of water at the interface (0–100 μl/cm2). The proposed skin model shows good agreement with the frictional behaviour of human skin both in dry and wet conditions. In addition, the tensile Young's modulus and surface roughness exhibit changes as a function of the amount of water that are similar to those of human skin. Potential applications of the model are in the testing and development of textile materials that mechanically interact with human skin.
  • Hardness, friction and wear studies on hydrogen peroxide treated bovine teeth
    Item type: Journal Article
    Mundra, Shishir; Mohan, Veena; Gwyer, James; et al. (2015)
    Tribology International
    A possible problem with peroxide based tooth whitening is the loss of tooth hardness and higher susceptibility to enamel surface wear. This study focussed on the effects of acidic and neutral hydrogen peroxide solutions (6 and 30% w/v) on hardness, friction and wear of bovine enamel. The experiments showed that treatments with neutral peroxide reduced wear and the loss of enamel hardness up to 2–3 times. In addition, further investigation on remineralisation with amorphous calcium phosphate showed an increase in hardness after treatment. Friction coefficients of teeth against steel varied between 0.25 and 0.7, and wear coefficients ranged between ≈10−6 and 10−7 mm3/N m. From this study, it is possible to explain the wear behaviour of HP treated enamel with changes in hardness. © 2015 Elsevier Ltd.
Publications 1 - 10 of 15