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        <title>Frontiers in Mechanical Engineering | Tribology section | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/mechanical-engineering/sections/tribology</link>
        <description>RSS Feed for Tribology section in the Frontiers in Mechanical Engineering journal | New and Recent Articles</description>
        <language>en-us</language>
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        <pubDate>2026-05-13T17:09:17.985+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2026.1798703</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2026.1798703</link>
        <title><![CDATA[Effect of micro-pit arrangement on the behavior of gas parallel slider bearings]]></title>
        <pubdate>2026-04-30T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Fuxi Liu</author>
        <description><![CDATA[Surface texturing is helpful in decreasing the friction, decreasing the wear, and increasing the fluid film stiffness. This investigation studies the influence of micro-pit arrangement on the behavior of gas parallel slider bearings (GPSB) by employing the multi-grid finite element method using the Matlab software. The pressure distribution of GPSB with micro-pits was investigated. The results showed that the position offset ratio of micro-pits had negligible effect on the maximum pressure and minimum pressure of GPSB with micro-pits. Meanwhile, the effect of the geometrical parameters of micro-pits on the average pressure of GPSB was investigated for different position offset ratios. Geometrical parameters of micro-pits included depth of micro-pits, radius of micro-pits, transversal spacing, longitudinal boundary distance, and longitudinal spacing. It was found that both depth and radius of micro-pits corresponding to maximized average pressure were controlled by the position offset ratio of micro-pits. The findings of this paper imply that the optimized micro-pit arrangement could improve the hydrodynamic pressure of gas parallel slider bearings.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2026.1757067</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2026.1757067</link>
        <title><![CDATA[Adsorption behavior of sodium carboxylates on iron oxide surface in water and their tribological properties]]></title>
        <pubdate>2026-04-17T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Tomoaki Okano</author><author>Hideaki Hattori</author><author>Naoki Akamatsu</author><author>Naoki Yamashita</author><author>Tomoko Hirayama</author>
        <description><![CDATA[The tribological performance of sliding surfaces in water can be improved by using lubricating solutions containing additives such as water-soluble sodium carboxylates, which reduce friction and prevent corrosion. These additives adsorb onto metal surfaces to exert their functions; however, the structural characteristics at the metal-solution interface and their influence on tribological properties remain largely unexplored. This paper investigated how water-soluble sodium carboxylates adsorb on iron oxide in water and how the adsorption structure governs boundary lubrication. To investigate the effect of headgroup multiplicity at a constant chain length (C10), sodium decanoate (monocarboxylate) and disodium sebacate (dicarboxylate) were compared as sample additives. Reciprocating ball-on-disk tests showed that sodium decanoate reduced the steady state friction coefficient by ≈70% relative to pure water, whereas disodium sebacate provided only a limited reduction and friction increased with cycling. Neutron reflectometry and frequency-modulation atomic force microscopy (FM-AFM) revealed that sodium decanoate forms a structured adsorption layer with an interfacial thickness of ≈3.5 nm or more, while disodium sebacate produces a much less ordered layer. Quartz crystal microbalance with dissipation monitoring (QCM-D) further indicated faster adsorption time for sodium decanoate than for disodium sebacate. These results support the hypothesis that low friction in aqueous lubrication requires not only adsorption but also the formation of a sufficiently thick and ordered boundary layer on iron oxide.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1749899</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1749899</link>
        <title><![CDATA[Simulation-based parameter optimization and experimental assessment of single- and multi-dimple textures in full-film lubrication]]></title>
        <pubdate>2026-01-27T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Raphael Scharf</author><author>Michael Pusterhofer</author><author>Florian Grün</author><author>Paul Staudinger</author>
        <description><![CDATA[The specific geometrical modification of surfaces is a current field of research to enhance the tribological properties in lubricated sliding contacts. As many parameters influence the performance of textures, a numerical approach is used to identify optimal parameters for a single-dimple and multi-dimple textured convergent oil film gap. To ensure that such surface textures can be easily manufactured, the widely used milling manufacturing technique is employed. Additionally, a novel test methodology was implemented on a rheometer/tribometer to evaluate the performance of these textures in full-film lubrication. Both a numerical and an experimental approach are used. In this experimental methodology, the rotational speed, temperature, and minimum oil film gap are varied. The experiments show that the single-dimple texture leads to the highest load-carrying capacity. The drag force of both textures is similar at 23 °C and is lower than that of the untextured oil film gap. As the temperature increases, this beneficial effect of reducing drag is no longer observed. However, the load-carrying capacity of both textures remains higher than that of the untextured oil film gap.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1707301</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1707301</link>
        <title><![CDATA[Study on robotic projectile launching based on multi-factor analysis and parameter optimization]]></title>
        <pubdate>2025-12-03T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Jiaming Luo</author><author>Yang Chen</author><author>Yijing Cheng</author><author>Jie Lin</author><author>Zhongge Wang</author><author>Xiongfei Yin</author>
        <description><![CDATA[The precision of projectile launching mechanisms, which utilize counter-rotating friction wheels, is critical for system effec-tiveness. This study introduces a hybrid approach combining multi-physics simulation with an intelligent optimization algo-rithm to determine key design parameters. Initially, Finite Element Analysis (FEA) and kinematics simulations were conducted on a 3D model to generate a comprehensive dataset linking operational conditions to projectile dynamics. This dataset then served to train a neural network for velocity prediction. Subsequently, a genetic algorithm was implemented to optimize the friction coefficient and inter-wheel gap by targeting a desired exit velocity range. The proposed methodology successfully identifies optimal parameter configurations, offering a robust, data-driven solution to a complex design challenge.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1584451</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1584451</link>
        <title><![CDATA[Fretting wear of lubricated DLC coating systems]]></title>
        <pubdate>2025-07-16T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Samuel J. McMaster</author><author>Shahriar Kosarieh</author><author>Tomasz W. Liskiewicz</author><author>Ben D. Beake</author>
        <description><![CDATA[Diamond-like Carbon (DLC) coatings are well known for their use in protection against fretting wear due to their low friction and wear properties. DLCs are metastable, allowing them to graphitise under applied load to create a graphitic transfer layer which reduces friction. Their high intrinsic residual stresses also enable them to resist cracking effectively under fretting. Few studies have analysed the lubricated fretting performance of DLC coating systems. This work focuses on a series of lubricants with different additives and friction modifiers to explore their effects. This study analyses the performance of a DLC coating system (a-C:H) applied to hardened M2 tool steel and 316L stainless steel under loads of 20 and 40 N under dry fretting and lubricated fretting conditions. Lubricated uncoated substrates were also analysed for comparison. The counterfaces used were 10 mm diameter 52,100 steel balls. The lubricants tested included a base oil and a fully formulated oil, with and without the addition of MoDTC. Gross slip fretting was achieved using a bespoke electrodynamic shaker unit. Nanoindentation was employed to measure the mechanical properties of the coatings and substrates. Contact pressure and lubricant type had significant effects on the running-in behaviour of the coatings. Increased contact pressure led to instability in the running-in period. Lubrication reduced the dissipated energy in the contact, thereby decreasing wear. However, fully formulated oils and those containing MoDTC performed worse due to their higher viscosity, which impacted oil entrainment in the contact area. This study provides insights into the lubricated fretting performance of DLC coatings showing that these coatings can perform well, with the potential for further improvements with optimisations to the lubricant to the system. Performance improvements can be gained in automotive components such as high pressure bearings and gears.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1554211</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1554211</link>
        <title><![CDATA[Mechanical characteristics analysis of the downhole completion string in the open hole section of a small wellbore]]></title>
        <pubdate>2025-07-02T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Liangliang Dong</author><author>Weijian Yang</author><author>Hongli Li</author><author>Bo Li</author><author>Xiaohua Zhu</author>
        <description><![CDATA[For horizontal wells with small wellbores and large-diameter pipe strings, pipe sticking is prone to occur during oilfield completion operations. Avoiding pipe sticking can effectively save construction costs. In this paper, dynamics and Hertz contact theory are adopted, taking into account the influence of small wellbores and large-diameter pipe strings. Based on the principle of scaling, an experimental bench for the running-in of completion pipe strings is built, and a three-dimensional finite element model for analyzing the axial force and contact force of the completion pipe strings in the open-hole staged fracturing is established. The variation laws of the wellhead axial force, axial force along the well depth and contact force during the running-in process of the completion pipe strings are analyzed. The results show that with the increase in the packer size and friction coefficient in the open-hole section and the decrease in the radius of the open-hole section, the wellhead axial force will decrease, and the contact force will increase accordingly. The neutral point moves upward, the length of the pipe string section under axial pressure increases, and the pipe strings with buckling deformation are all under axial pressure. The pipe string will first buckle near the kick-off point, and then the buckling will extend upward along the straight section from the kick-off point. Moreover, the closer to the kick-off point, the more severe the buckling. The research in this paper provides a theoretical basis for the decision-making of the running-in of completion pipe strings.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1591795</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1591795</link>
        <title><![CDATA[A model describing the oxidation rate of lubricating greases]]></title>
        <pubdate>2025-06-06T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Christoph Schneidhofer</author><author>Michael Schandl</author><author>Nicole Dörr</author><author>Piet M. Lugt</author>
        <description><![CDATA[IntroductionGrease oxidation in rolling bearings causes a loss of grease in the track and hence a loss of lubricity in the bearing. This work addresses loss of grease via evaporation and oxidation due to thermal-oxidative stress applied to two lubricating greases.MethodsFor this purpose, the oxidation stability of two greases was determined using a modified micro-coking test over a wide temperature range from 100°C to 190°C. Grease analyses by means of antioxidant content, oxidation and weight loss were used to develop a lifetime model to describe the change in mass as a function of temperature, time, and grease type due to oxidation based on the Arrhenius equation.Results and discussionThe developed model describes the correlation between the findings from grease analyses and shows increased oxidation and evaporation after the induction period when antioxidants are almost consumed.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1608716</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1608716</link>
        <title><![CDATA[Effect of surfactant self-assembly on lubrication performance in oil-based systems: the role of reverse micelles and vesicles]]></title>
        <pubdate>2025-05-30T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Haiyang Gu</author><author>Tomoko Hirayama</author>
        <description><![CDATA[Surfactants are effective additives for oil-based lubricants, capable of reducing friction under boundary lubrication conditions through their self-assembly into nanostructures. Understanding the relationship between their self-assembled structures and lubrication properties is essential for optimizing performance. In this study, the aggregation behavior of C12E4 in dodecane and its effects on friction and anti-wear properties were investigated. The results showed that C12E4 formed small reverse micelles at lower water concentrations, transitioning to larger reverse vesicles at higher concentrations. Elevated temperatures caused vesicle collapse, leading to the formation of smaller aggregates. Small reverse micelles effectively reduced friction and wear, while larger vesicles increased friction due to their obstructive effect. At higher temperatures, friction coefficients converged as reverse vesicles ruptured under shear. Neutron reflectometry (NR) revealed a strong correlation between the density of the adsorbed layer and frictional properties. As a powerful technique, NR enables direct, nanometer-scale characterization of adsorption layers formed by lubricant additives at solid–liquid interfaces, providing critical insights into the structural basis of lubrication performance. These findings underscore the pivotal role of surfactant self-assembly in oil-based lubrication and highlight the importance of optimizing water content and temperature to achieve effective friction reduction. They offer valuable guidance for developing surfactant-based lubricant additives, particularly for enhancing boundary lubrication performance under high-load and high-temperature industrial conditions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1585472</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1585472</link>
        <title><![CDATA[Preventing electrically induced subsurface initiated pitting failures (incl. WSF, WEC, WEA) with copper based lubricant additives]]></title>
        <pubdate>2025-05-21T00:00:00Z</pubdate>
        <category>Methods</category>
        <author>Sergei Mamykin</author><author>Marc Ingram</author><author>Leyla Alieva</author><author>Varvara Privalova</author>
        <description><![CDATA[Premature bearing failures in large electric machines such as wind turbines and locomotives are often caused by White Etching Cracks (WEC), White Etching Areas (WEA), and White Structure Flaking (WSF)—phenomena that, despite extensive study, remain not fully understood. This work introduces a new hypothesis of WEC, WEA and WSF formation combining Garkunov’s scientific discoveries of “hydrogen wear of metals” and the “wearlessness effect” with the existing knowledge and offers a possible solution. To test this hypothesis and solution, a prototype lubricant containing oil-soluble copper salts was evaluated using an electrically induced WEC test on a three ring-on-roller tribometer. The test applied high contact pressures and direct current to simulate operating conditions, followed by subsurface serial sectioning to examine material degradation. The results showed that the reference lubricant exhibited typical WEC and WEA damage, while the copper-based candidate lubricant prevented such failures entirely. This outcome supports the idea that hydrogen activity plays a central role in damage formation, and that targeted additives can prevent it by reducing surface temperatures and forming protective film, which blocks hydrogen diffusion. These findings offer a scientifically grounded and practically viable solution to extend bearing life and prevent costly failures in high-load, high-reliability applications.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1588494</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1588494</link>
        <title><![CDATA[Editorial: Visualization techniques in tribology]]></title>
        <pubdate>2025-03-18T00:00:00Z</pubdate>
        <category>Editorial</category>
        <author>Taisuke Maruyama</author><author>Satoru Maegawa</author><author>Hikaru Okubo</author><author>Thomas Reddyhoff</author><author>Sorin-Cristian Vlădescu</author>
        <description></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1522524</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1522524</link>
        <title><![CDATA[An in situ experimental method for monitoring the viscosity change and oil amount during the sliding test]]></title>
        <pubdate>2025-03-07T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Hiroshi Shiomi</author><author>Shingo Obara</author>
        <description><![CDATA[This study measures the changes in the viscosity and oil volume of lubricants in a vacuum sliding test under starved EHL to evaluate the lubrication life of a small amount of lubricants, and investigates their time transition and a mechanism of lubrication life. Starved EHL is observed in ball bearings lubricated with a small amount of lubricant, which require low friction torque even at high speeds, such as bearings used in artificial satellites. Under starved oil conditions, the oil film formed in the contact area becomes thin, so it is important to accurately estimate the oil film thickness in order to avoid solid contact. Since viscosity and oil volume affect the oil film thickness in the contact area, it is important to know how they change during the test. In this study, a method was proposed to measure viscosity and oil quantity without breaking the vacuum during a sliding test using a small amount of oil in a vacuum. Using this method, changes in viscosity and oil quantity until the end of lubrication life were measured in a sliding test using a small amount of MAC. As a result, an increase in viscosity and a decrease in oil quantity were observed. The measured results discussed the relationship between the increase in viscosity and the frictional work or sliding distance and indicated that the lubrication condition at the end of lubrication life was severely starved.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1542074</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1542074</link>
        <title><![CDATA[Evaluation of different erosion models for predicting guide vane wear in Francis turbine]]></title>
        <pubdate>2025-02-20T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Rakish Shrestha</author><author>Kushal Shrestha</author><author>Sailesh Chitrakar</author><author>Bhola Thapa</author><author>Hari Prasad Neopane</author><author>Zhongdong Qian</author><author>Zhiwei Guo</author>
        <description><![CDATA[Guide vanes (GVs) are one of the components of the Francis turbine that are most vulnerable to erosion. Presence of hard minerals including feldspar and quartz cause erosion on the surface of GVs. This results in damage and disturbances in the functioning of the turbine. Computational Fluid Dynamics (CFD) methods are useful to estimate erosion but are dependent significantly on erosion models used for simulations. A three guide vane cascade (3GV) rig is a simplified setup that recreates the flow around GVs. Previous studies have used the setup to visualize the secondary flows around the GVs using Particle Image Velocimetry (PIV) and CFD techniques that could be one of the major causes of erosion in Francis turbine. In this study, an Eulerian-Lagrangian approach with Reynolds Averaged Navier Stokes (RANS) based Shear Stress Transport (SST) turbulence model has been used to develop a numerical model of the same rig. The erosion caused by the sediment-laden flow has been quantified and visualized by employing Finnie, Nandakumar, Oka, and Tabakoff and Grant erosion models. This study has been conducted to determine which of the erosion model predicts the erosion pattern closer to the real case of eroded GV of Jhimruk Hydro-Electric Plant (HEP). The focus of the study is the clearance gap (CG) of the GV. By dividing the CG into sections and comparing the erosion predictions by different erosion models with the actual erosion, Finnie erosion model is found to be the most suitable model for this application. The severity and area affected due to erosion as predicted by this model is found to most closely match the erosion observed in the CG of the real hydropower plant’s GV, specially at three different locations: trailing edge of suction side (SS-TE), leading edge of suction side (SS-LE) and the middle of the leading edge (MS-LE).]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2025.1473028</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2025.1473028</link>
        <title><![CDATA[Hydrodynamic performance testing of artificial textures using a novel pin-on-disc test method]]></title>
        <pubdate>2025-02-17T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Michael Pusterhofer</author><author>Michael Maier</author><author>Raphael Scharf</author><author>Florian Haumer</author><author>Florian Grün</author>
        <description><![CDATA[In times of global climate change, the reduction in friction in technical applications is of crucial significance. Surface textures are one possibility for reducing friction in lubricated contacts. To provide a deeper understanding of the effects of surface textures on the tribological performance, this study analyzes wedge-shaped, textured lubrication gaps using a novel test rig with an in situ lubrication gap height measurement. Using this experimental pin-on-disc setup, chevron-shaped and cylindrical textures with two different heights (ht = 10 and 50 µm) were tested under full-film lubrication conditions. The pin was tilted in a very precise way to generate a convergent lubrication gap. The test results show the potential for friction reduction using textures. In general, it can be stated that the investigated textures show clearly different behavior compared to the smooth reference specimens. Mostly, a reduction in friction force was measured for the texture specimens, which was accompanied by a reduction in the lubrication gap height. The system still operates in full-film lubrication, but there is a higher risk of entering the mixed-friction regime. In summary, no universal performance trend for single textures can be stated; it needs to be checked for each specific operating point which texture provides the best enhancement.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1469546</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1469546</link>
        <title><![CDATA[Mechanisms of cage noise generation in machine tool bearings]]></title>
        <pubdate>2025-01-21T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Kazuho Takeshima</author><author>Keisuke Mutoh</author><author>Kenji Imanishi</author><author>Shunichi Oshima</author>
        <description><![CDATA[Cage instability in ball bearings can lead to torque fluctuations and significant noise. In machine tool spindles, which require high rotational precision, outer ring-guided cages are often preferred over common ball-guided cages. While outer ring-guided cages suppress instability modes caused by sliding friction between the cage and balls, increased interaction between the cage and outer ring can introduce other instability modes, leading to noise. Despite the critical implications of these findings, prior research into this specific type of cage instability, incorporating both experimental and analytical perspectives, remains limited. Therefore, in this study, we utilized a high-speed camera system to conduct visualization tests on cage behavior in grease-lubricated angular contact ball bearings used in machine tools. Through detailed image-processing of the results, we identified specific behaviors associated with cage noise. To facilitate the optimal design of the cage to stabilize these behaviors, we developed a dynamic analysis model focusing on the friction between the cage and the outer ring under grease lubrication, considering fluid pressure effects. The validity of this model was confirmed through experiments at various rotational speeds. This analytical model enabled us to elucidate the underlying mechanisms driving cage instability. The insights gained from this research are expected to significantly enhance the fundamental understanding of cage design principles aimed at eliminating cage noise.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1526120</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1526120</link>
        <title><![CDATA[Review on experimental investigation of sediment erosion in hydraulic turbines]]></title>
        <pubdate>2024-12-20T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Rakish Shrestha</author><author>Prithivi Gurung</author><author>Sailesh Chitrakar</author><author>Bhola Thapa</author><author>Hari Prasad Neopane</author><author>Zhiwei Guo</author><author>Zhongdong Qian</author>
        <description><![CDATA[Sediment erosion in turbine materials is caused by various flow phenomena. The study of these phenomena can identify suitable measures to minimize their effect on the turbine. Various experimental test rigs have been developed alongside numerical analysis to study erosion and predict wear. In hydraulic turbines, erosion in Francis turbines is mostly seen at the guide vanes and runners, and in Pelton turbines, the needle and the bucket regions are the most vulnerable components. Prediction of wear due to erosion in various parts of the turbine is difficult, as wear depends on the properties of flow, base material, and sediment. Past studies have shown that the test rigs developed to investigate erosion have considered reducing the number of independent parameters to simplify the experiment. Erosion rates and wear patterns are predicted through both quantitative and qualitative methods. This article aims to conduct a systematic review of experimental setups and the results of those studies. This work is expected to be useful in understanding the vulnerable areas of erosion in hydraulic turbines and different mathematical relationships developed to quantify erosion, as well as to know the contemporary understanding in the sector of experimental investigation of sediment erosion.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1488803</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1488803</link>
        <title><![CDATA[The effect of inner ring groove on leakage reduction in dry gas seals and its visualization verification]]></title>
        <pubdate>2024-12-19T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Masayuki Ochiai</author><author>Yuta Ohya</author>
        <description><![CDATA[This study investigates the impact of incorporating an Inner Ring Groove (IRG) on the leakage characteristics of dry gas seals, commonly used in turbomachinery such as gas turbines and compressors. The primary objective is to enhance sealing performance and reduce gas leakage, which is critical for improving the efficiency of these machines. The research focuses on various groove shapes, including spiral grooves for single-direction rotation and T-grooves and tree grooves for bi-directional rotation. The experimental setup involved measuring air leakage rates across different seal configurations, both with and without the IRG. The results indicated that while the IRG increased leakage in spiral groove seals, it significantly reduced leakage in T-groove and tree groove seals. Specifically, the IRG reduced leakage by approximately 26% in T-groove seals and 15.8% in tree groove seals, compared to their standard configurations. Additionally, the study employed Particle Image Velocimetry (PIV) to visualize gas flow within the seal gaps. The visualization revealed that the IRG altered the flow dynamics, particularly in T-groove seals, where it redirected the gas flow from a radial to a circumferential direction, thereby reducing leakage. In contrast, the IRG in spiral groove seals promoted radial flow, leading to increased leakage. These findings suggest that the application of IRGs can be particularly effective in bi-directional rotation seals, offering a potential design modification to enhance sealing performance. The study concludes that while IRGs may not be suitable for all groove types, their strategic application can lead to significant improvements in leakage reduction and overall efficiency of dry gas seals.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1504347</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1504347</link>
        <title><![CDATA[Studies on dielectric spectroscopy of oxidatively degraded Poly(α-olefin)]]></title>
        <pubdate>2024-11-27T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Shunsuke Iwase</author><author>Taisuke Maruyama</author><author>Satoshi Momozono</author><author>Satoru Maegawa</author><author>Fumihiro Itoigawa</author>
        <description><![CDATA[Failures in tribological components such as bearings can significantly affect the performance and lifespan of machinery, necessitating the implementation of effective condition monitoring technologies. This study verified the feasibility of dielectric spectroscopy (DES) as a method for detecting abnormalities before damage occurs. A comparative evaluation was conducted between dielectric relaxation parameters and measurements from size exclusion chromatography, total acid number, and viscosity for oxidatively degraded poly (α-olefin) oils. The results confirmed that DES is an effective method for assessing the oxidative degradation state of lubricants. These findings suggest that DES could be applied to oil film condition monitoring and predictive maintenance.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1488407</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1488407</link>
        <title><![CDATA[Exploring the additive compatibility and tribological behavior of regular and high oleic soybean oil]]></title>
        <pubdate>2024-11-25T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Piash Bhowmik</author><author>Brajendra K. Sharma</author><author>Majher I. Sarker</author><author>Kalidas Mainali</author><author>Yachao Wang</author><author>Clement Tang</author><author>Sougata Roy</author>
        <description><![CDATA[As the demand for biobased lubricating oils continues to rise, there is a growing focus on exploring diverse oil types. Particularly noteworthy is the surge in demand for high oleic oils, which offer enhanced stability, and a richer oleic acid content compared to their regular oil counterparts. However, the performance of high oleic soybean oil (HOSO) with additives compared to regular soybean oil (RSO), remains unclear. This study is focused on revealing the compatibility of both regular soybean oil (RSO) and high oleic soybean oil (HOSO) with select antiwear and antioxidant additives, specifically zinc dialkyl dithiophosphate (ZDDP), and zinc dialkyl dithiocarbamate (ZDDC) combined with antimony dialkyldithiocarbamate (ADDC), along with a comparative performance analysis of these additives. Reciprocating friction, wear, and electrical contact resistance-based analyses were conducted to evaluate additive compatibility and wear mechanisms at room temperature lubrication conditions. Interestingly, it was observed that for the select additives, the compatibility with regular soybean oil (RSO) was better than that of high oleic soybean oil (HOSO). RSO with additives showed around 28% reduction of wear volume whereas, it was only 8% for HOSO with additives. Additional physiochemical property analyses were conducted on the lubricants to correlate the observed tribological behavior. The worn-out surfaces of the test samples were characterized thoroughly to reveal the dominant wear mechanisms.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1471045</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1471045</link>
        <title><![CDATA[Controlling windscreen wiper vibration through yaw angle adjustments: a study of dynamic contact behavior using fluorescence observation]]></title>
        <pubdate>2024-11-07T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Chiharu Tadokoro</author><author>Hiroaki Kobayashi</author><author>Miwa Sueda</author><author>Takuo Nagamine</author><author>Sorin-Cristian Vlădescu</author><author>Tom Reddyhoff</author><author>Ken Nakano</author>
        <description><![CDATA[Friction-induced vibration in the wiper system of passenger cars not only causes impaired visibility as a result of uneven water film distribution on the windscreen surface, but also leads to noise problems by transmitting vibrations as sound to the passengers. In this study, a novel experimental apparatus was developed to simulate the wiper system, enabling the change in normal support stiffness and the precise adjustment of the yaw angles of a shortened rubber blade and its flexible base relative to the drive direction of a glass plate. The use of fluorescence observation provided a significant advantage, enabling precise measurements of the position of the rubber blade tip and the water film thickness in the contact area of the rubber blade and the glass plate during operation. In conjunction with this, an accelerometer and a gap sensor were employed to measure the normal and tangential motions of the support structures, respectively. This comprehensive setup allows for precise control of blade support conditions, and provides accurate measurement for motions of rubber blade and support structures, making it a powerful tool for investigating friction-induced vibration in the wiper system. The experimental results clearly demonstrated the effectiveness of applying large yaw angles to both the rubber blade and the flexible base in suppressing friction-induced vibration, resulting in smooth motion at any drive speed. These findings have the potential to improve wiper performances under actual operating conditions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/fmech.2024.1489311</guid>
        <link>https://www.frontiersin.org/articles/10.3389/fmech.2024.1489311</link>
        <title><![CDATA[Application of the electrical impedance method to steel/steel EHD point contacts]]></title>
        <pubdate>2024-11-06T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Taisuke Maruyama</author><author>Daichi Kosugi</author><author>Shunsuke Iwase</author><author>Masayuki Maeda</author><author>Ken Nakano</author><author>Satoshi Momozono</author>
        <description><![CDATA[The authors have previously developed the electrical impedance method which simultaneously measure the thickness and breakdown ratio of oil films in EHD (elastohydrodynamic) contacts. Furthermore, using a ball-on-disc-type apparatus, the authors have also confirmed that the accuracy of oil film measurement by the developed method is comparable to that of optical interferometry (i.e., glass-steel contacts). In this study, we discussed the experimental results obtained by applying the electrical impedance method to steel-steel contacts using a steel disc instead of a glass disc. It was found that under the mixed lubrication regime where wear occurs, the oil film thickness obtained by this method is calculated to be significantly thicker than the theoretical value. This can be attributed to the increase in the apparent dielectric constant of the lubricant due to wear particles in the lubricant.]]></description>
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