Tribology Online
Online ISSN : 1881-2198
ISSN-L : 1881-218X
Current issue
Displaying 1-6 of 6 articles from this issue
  • Ayo Famakinwa, Tadahiro Shibutani
    2022 Volume 17 Issue 2 Pages 71-77
    Published: April 15, 2022
    Released on J-STAGE: April 15, 2022

    Improvement of condition-based monitoring for large bore 2-stroke marine engine cylinder liners and piston rings require close monitoring of anomaly wear elements in drain cylinder oil. This paper presents monitoring of seagoing ship engines because the environment of sailing affects the internal combustion conditions leading to mechanical failure of the cylinder liners. We presented condition-based monitoring of cylinder liners using X-ray to analyze drain cylinder oil samples. The approach for condition-based monitoring uses X-ray results to estimate wear amount and machine learning algorithm on elements in the drain cylinder oil samples. The wear amount is quantified for the purpose to estimate the degradation of cylinder liner materials through the drain cylinder oil samples, machine learning algorithm to evaluate the correlation of detected elements in drain oil samples. Finally, wear rate estimation to know the remaining useful life of the cylinder liner. Our results contributed to the improvement of condition-based monitoring of cylinder liners wear elements by quantification and machine learning to correlate elements in oil samples. Correlating wear elements facilitate quick decision-making on maintenance policies for slow-speed large bore 2-stroke engines.

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  • Miho Morita, Shodai Tachiyama, Ko Onodera, Alan Hase
    2022 Volume 17 Issue 2 Pages 78-85
    Published: April 30, 2022
    Released on J-STAGE: April 30, 2022

    Sulfur and phosphorus additives are used in lubricants as extreme-pressure and antiwear agents, which are typically used together to ensure reliability over a wide range of lubrication conditions. However, the working mechanism of the combined additive system has not been clearly defined due to difficulties obtaining information on the material surface where these additives work. This is because this surface is constantly being worn during testing. Therefore, in situ analysis applying an acoustic emission (AE) technique was proposed. AEs are elastic stress waves generated during the deformation and fracture of solids, which can be measured in real-time, providing information with respect to the magnitudes and types of damage. In this paper, an application of the AE helps to clarify how each additive acts on the surface in real-time. The working mechanism to understand improved reliability using both sulfur and phosphorous additives was investigated by the AE technique, along with conventional surface analysis methods. It is concluded that wear reducing properties were improved by the reaction of sulfur additives to remove the protruded parts, followed by the reaction of phosphorous additives to form a protective antiwear film.

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  • Kouki Imai, Alan Hase
    2022 Volume 17 Issue 2 Pages 86-96
    Published: May 15, 2022
    Released on J-STAGE: May 15, 2022

    The purpose of this study is to identify tribological phenomena that occur on a machined surface under grinding, using acoustic emission (AE) sensing. The study investigated features exhibited by AE signals due to a change of state of the machined surface during the finish grinding of glass materials. An AE sensor was attached to a glass test piece, and the AE signals generated by using a grinding wheel rotating at high speed were measured. It was found that differences in the grain size of the grinding wheel and the hardness of the test piece changed the amplitude of the AE signal, and that there was a correlation between the amount removed by grinding and the AE mean value. In addition, a frequency analysis of the AE signal waveforms revealed that the AE frequency components generated during friction and during grinding differ. It was also found that a change in grinding ability of the grinding wheel, due to it wearing flat or to abrasive grains falling away, can be established from the change in AE mean value and the peak position in the AE frequency spectrum.

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  • Flavien Foko Foko, Christoph Burkhart, Stefan Thielen, Bernd Sauer
    2022 Volume 17 Issue 2 Pages 97-109
    Published: June 15, 2022
    Released on J-STAGE: June 15, 2022

    This paper presents a semi-analytical method for analyzing the sealing capability of radial shaft sealing (RSS). For this purpose, a microscale contact model is used to simulate the mounting procedure between the sealing lip and the shaft for different sealing lip wear states and to determine the shear stresses along the axial direction in the sealing contact. The sealing lip geometry used in the simulation is subjected to continuous wear, which is applied incrementally after each iteration. The resulting shear stresses in the sealing contact form the driving force responsible for pumping behavior in the axial direction and thus can provide information about the sealing ability of RSS. For this reason, the work integral of the simulated shear field is built and correlated with the sealing ability. The method presented in this paper provides a new approach to the analysis of the sealing mechanism based on the simulation of the energy difference in the sealing contact. Furthermore, the change of this energy over time due to friction and wear was determined. The total work integral change was related to the experimentally measured change in the reverse pumping value of the sealing system.

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  • Hiroshi Tani, Norio Tagawa, Shouhei Kawada, Renguo Lu, Shinji Koganeza ...
    2022 Volume 17 Issue 2 Pages 110-117
    Published: June 15, 2022
    Released on J-STAGE: June 15, 2022

    Boundary lubrication films adsorbed on solid surfaces reduce friction and wear by reducing solid contact and have a significant contribution to the friction coefficient. To probe the contact mechanism at the surface, it is necessary to understand the elastic properties of both the solid surface and the boundary lubricant film. However, it is difficult to determine the elastic properties because the boundary lubricant film is a monolayer adsorbed on a solid surface. In this study, samples deposited on silicon substrates using the Langmuir–Blodgett (LB) method were prepared to determine the elastic modulus of the boundary lubricant film. The Young’s moduli of fatty acid films adsorbed on Si substrates deposited by the LB method and rinsed with acetone were measured using time-of-flight secondary ion mass spectroscopy (TOF-SIMS) with Ar gas cluster ion beams (Ar-GCIBs). The coverage of the fatty acid films after rinsing decreased with the carbon number of the fatty acids. The final Young’s moduli can be obtained by correcting the Young’s moduli measured using Ar-GCIB with the coverage of fatty acid films. Those were independent of the carbon number (C14‒C20) of the fatty acids and were estimated to be approximately 45 GPa.

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  • Jagjit Singh Maan, Rajeev Kumar Awasthi
    2022 Volume 17 Issue 2 Pages 118-125
    Published: June 30, 2022
    Released on J-STAGE: June 30, 2022

    The purpose of this work is to investigate the effect of cylindrical, kite and triangular shaped dimples on static, dynamic and stability performance of partial textured hydrodynamic journal bearing working under turbulent regime. The texture geometry significantly affects the performance of a journal bearing in terms of better load carrying capacity, frictional, stiffness, damping and stability parameter. The increasing demand of high rotor speed necessitates to study the influence of texture geometrical parameters under turbulent regime for which cavitation is commonly observed phenomenon. Three different partial textured journal bearings having cylindrical, kite and triangular shaped dimples on their surfaces are undertaken. The dimensionless Reynolds equation for Newtonian iso-viscous compressible lubricant is modified for turbulence and mass conservation for both cavitated/non-cavitated zone throughout the solution domain. Using linear complementarity approach (LCP) the equation is discretised into linear algebraic equation by using Finite Element Method. The static and dynamic parameters are computed with various dimple depths at fixed eccentricity ratio.

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