Article
Engineering, Mechanical
Daofei Wang, Jialong Yang, Pengchong Wei, Wei Pu
Summary: This article focuses on the application of grease lubrication in rolling element bearings and the establishment of a mixed EHL model. Experimental results show that the grease friction behavior corresponds well with the variation of grease film thickness.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Kazuyuki Yagi, Wataru Matsunaka, Joichi Sugimura
Summary: This study investigates the effect of textured patterns on lubrication performance in starved hydrodynamic lubrication. Longitudinal or transverse grooves on discs are found to improve lubricant supply into the lubricated area at high sliding conditions, compared to a flat disc.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Tao He, Q. Jane Wang, Xin Zhang, Yuchuan Liu, Zhe Li, Hun June Kim, Seongchan Pack
Summary: This paper introduces a novel visco-elastohydrodynamic lubrication model for studying the lubrication behavior between a rigid sphere and a viscoelastic layer on an elastic half-space. The model is validated through comparisons with experimental data, confirming its effectiveness in predicting lubrication performance.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Mechanical
Donglong Li, Chen Zhu, Anying Wang, Tao He
Summary: This paper develops a semi-analytical model using the numerical equivalent inclusion method (EIM) and fast Fourier transforms (FFT) to analyze the viscoelastohydrodynamic lubrication (VEHL) behavior of polymer-based composites. The model investigates the viscoelastic behavior of these composites under different relaxation times and analyzes the influence of inhomogeneities on contact pressure and film thickness, as well as the stress fields caused by multiple voids and hollow spheres.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Chemical
W. Habchi, P. Sperka, S. Bair
Summary: This study investigates the governing mechanisms of minimum film thickness in elastohydrodynamic lubricated contacts. It is found that lubricant inlet rheology only governs the minimum film thickness in the theoretical line contact configuration, while in real contacts, it is also influenced by the high-pressure viscosity response of the lubricant. The study confirms that a higher viscosity at high pressure leads to a lower minimum film thickness, in line with experimental observations.
Article
Engineering, Mechanical
Xinming Li, Feng Guo, Gerhard Poll, Yang Fei, Ping Yang
Summary: This study investigates the evolution of grease films in rolling elastohydrodynamic lubrication (EHL) contacts with glass disc revolutions. The patterns of grease film evolution were found to be highly related to speed ranges and grease structures, shedding light on mechanisms such as transfer of thickener lumps, decay in film thickness due to starvation, and the formation of an equilibrium film. The primary mechanisms governing grease film formation in different lubricated contacts were clarified through the research.
Article
Mechanics
A. Kolivand, S. Li, Q. Zhang
Summary: This study found that lower lubricant viscosity can extend fatigue life under severe starvation condition, contradicting the EHL rule under fully flooded lubrication condition. Additionally, experimental observation supports that under starvation condition, film thickness increases when shifting from high viscosity base oil to a lower one.
Article
Engineering, Mechanical
Alberto Porras-Vazquez, Nicolas Fillot, Philippe Vergne, David Philippon, Guillermo E. Morales-Espejel
Summary: This study focuses on characterizing the roller-end/flange contact in rolling-element bearings, specifically analyzing the impact of spinning and starvation on the film thickness. The goal is to provide analytical expressions to predict film thickness under specific operating conditions.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Alberto Porras-Vazquez, David Philippon, Nicolas Fillot, Philippe Vergne, Nicolas Devaux, Lionel Lafarge, Guillermo E. Morales-Espejel
Summary: This study evaluates the effects of lubricant starvation on the film thickness of spinning large-size point contacts from an experimental standpoint. A dedicated experimental setup is introduced and validated, and novel experimental measurements are presented to corroborate earlier numerical trends and describe the behavior of such contacts from a kinematic perspective.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Mechanical
G. Boidi, P. G. Gruetzmacher, A. Kadiric, F. J. Profito, I. F. Machado, C. Gachot, D. Dini
Summary: This study demonstrated the potential of fast laser texturing techniques in improving the tribological performance of bearings and mechanical components. Dimples were found to reduce friction effectively compared to smooth surfaces, while grooves had less beneficial effects. Additionally, dimples promoted the formation of full film lubrication conditions at lower speeds.
Article
Engineering, Mechanical
H. P. Evans, R. W. Snidle
Summary: Duncan Dowson's groundbreaking contribution to elastohydrodynamic lubrication theory has had a significant impact on the understanding of lubrication in gear tooth contacts and provided a reliable reference formula in gear design standards. This paper demonstrates the application of elastohydrodynamic lubrication theory in engineering component design and highlights the importance of considering surface roughness effects in micro-elastohydrodynamic lubrication for addressing current issues like micropitting.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Article
Engineering, Mechanical
Marius Wolf, Sergey Solovyev, Fatemi Arshia
Summary: Analytical equations for central film thickness in slender elliptic contacts were investigated in this paper, with a new formula derived to be significantly more accurate than current equations. Experimental studies and discussions on minimum film thickness will be presented in a subsequent publication.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2022)
Article
Engineering, Mechanical
V Ripard, D. Goncalves, F. Ville, J. H. O. Seabra, J. Cavoret, P. Charles
Summary: The study analyzed lubrication starvation using the Starvation Degree parameter through tests with different operating conditions and types of greases to prevent damage such as scuffing.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2022)
Article
Engineering, Chemical
Wassim Habchi, Philippe Vergne
Summary: The study introduces a quantitative method for predicting minimum film thickness in elastohydrodynamic-lubricated circular contacts based on central film thickness. Comparison with traditional film thickness formulae and recent expressions revealed the former's inability and the latter's tendency to overestimate the central-to-minimum film thickness ratio. The proposed approach was validated against numerical and experimental data, showing excellent agreement.
Article
Engineering, Mechanical
Kazuyuki Yagi, Kazuki Nishida, Joichi Sugimura
Summary: This study investigates the traction behaviors of lubricant films with anomalous shapes under elastohydrodynamic lubrication conditions. Lubricants with anomalous film shapes exhibit solid-like behavior with sharp traction peaks at low slide-to-roll ratios, while lubricants with conventional film shapes show a gradual increase in traction coefficient with increasing slide-to-roll ratios. The similarity of traction behavior to that of traction fluids supports the solidification of films with anomalous shapes.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Review
Engineering, Multidisciplinary
Michal Michalec, Petr Svoboda, Ivan Krupka, Martin Hartl
Summary: This paper reviews the increasing demand for hydrostatic bearings application in recent decades, along with the related design optimization processes and future directions. Starting from hydrostatic lubrication theory and the Industry 4.0 trend, it discusses possible measures for improving the performance and maintenance of hydrostatic bearings.
ENGINEERING SCIENCE AND TECHNOLOGY-AN INTERNATIONAL JOURNAL-JESTECH
(2021)
Article
Engineering, Mechanical
Daniel Kvarda, Radovan Galas, Milan Omasta, Lu-bing Shi, Haohao Ding, Wen-jian Wang, Ivan Krupka, Martin Hartl
Summary: A numerical model is used to evaluate friction in water-contaminated wheel-rail contact, with the plastic deformation model predicting more accurate transition in mixed lubrication regime.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Cheney Quinn, David Necas, Petr Sperka, Max Marian, Martin Vrbka, Ivan Krupka, Martin Hartl
Summary: This study investigates the effects of kinematic conditions, configuration, viscoelasticity, and lubricant viscosity on friction in lubricated compliant contacts. Experimental data was used to develop a numerical simulation predicting fluid friction in compliant contacts, revealing that viscoelastic effects are present in all configurations and that slide-to-roll ratio affects rolling friction in all configurations.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Multidisciplinary
Michal Michalec, Vojtech Polnicky, Jan Foltyn, Petr Svoboda, Petr Sperka, Jakub Hurnik
Summary: Hydrostatic bearings have many advantages in large-scale moving mechanisms and structures, but there are often limitations in manufacturing, transportation, and assembly. Manufacturing and assembly errors significantly affect the overall performance of hydrostatic bearings. This study proposes a methodology to estimate allowed assembly errors and evaluates the effects of compliant support on assembly errors of hydrostatic multi-pad bearings.
PRECISION ENGINEERING-JOURNAL OF THE INTERNATIONAL SOCIETIES FOR PRECISION ENGINEERING AND NANOTECHNOLOGY
(2022)
Article
Engineering, Biomedical
Matus Ranusa, Pavel Cipek, Martin Vrbka, David Palousek, Ivan Krupka, Martin Hartl
Summary: Additive manufacturing enables customization of implants, but designing wear-resistant articulating surfaces is challenging. Understanding the interaction between surfaces and lubricant fluid, as well as the lubrication film formation mechanism, is necessary.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2022)
Article
Engineering, Mechanical
Michal Michalec, Jakub Hurnik, Jan Foltyn, Petr Svoboda
Summary: Hydrostatic bearings are important components in various industrial applications, but large-scale bearings often face complications with pad alignment and levelling. A contactless measurement method based on optical tracking has been developed for film thickness diagnostics of hydrostatic bearings. The results show good agreement between the optical measurement and proximity sensors, as well as analytical calculations. This method can be utilized to improve pad levelling, alignment, or film thickness diagnostics of hydrostatic bearing pads.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2023)
Article
Engineering, Chemical
S. Reitschuster, E. Maier, T. Lohner, K. Stahl, K. Bobzin, C. Kalscheuer, M. Thiex, P. Sperka, M. Hartl
Summary: The potential of diamond-like carbon (DLC) coatings on thermoplastic polymers for reducing friction and wear in highly stressed rolling-sliding contacts was evaluated. The results showed that DLC coatings could reduce friction on the considered polymers under specific lubrication conditions. In terms of wear behavior, DLC coatings showed potential especially under severe mixed lubrication conditions.
Article
Engineering, Multidisciplinary
Daniel Kvarda, Simon Skurka, Radovan Galas, Milan Omasta, Lu-bing Shi, Haohao Ding, Wen-jian Wang, Ivan Krupka, Martin Hartl
Summary: The effect of top of rail lubricant composition on adhesion was investigated, with solid particles for friction modification found to be the most dominant component. Optimized top of rail lubricant substances showed the best adhesion performance and resilience to overdosing.
ENGINEERING SCIENCE AND TECHNOLOGY-AN INTERNATIONAL JOURNAL-JESTECH
(2022)
Article
Engineering, Multidisciplinary
Pavel Cipek, Martin Vrbka, David Rebenda, David Necas, Ivan Krupka
Summary: This study focuses on the role of albumin protein in the lubrication process of synovial joints. Experimental results show that hyaluronic acid reduces friction and increases the area of albumin adsorbed boundary layer, while phospholipids have the opposite effect. The combination of albumin and c-globulin has no significant effect on the particles count of albumin clusters adsorbed in the contact.
ENGINEERING SCIENCE AND TECHNOLOGY-AN INTERNATIONAL JOURNAL-JESTECH
(2022)
Article
Engineering, Chemical
K. Bobzin, C. Kalscheuer, M. Thiex, P. Sperka, M. Hartl, S. Reitschuster, E. Maier, T. Lohner, K. Stahl
Summary: The purpose of this study was to improve the wear resistance of polymers in highly stressed tribological contacts by developing and depositing diamond-like carbon (DLC) coatings on polymers. The coatings showed the ability to undergo high plastic deformations without delamination and the possibility of forming a composite layer under dry conditions. Additionally, changes in sp(2) chain and sp(2) cluster size and distribution were observed during dry contact conditions.
Article
Engineering, Mechanical
Aleksandar Vencl, Petr Svoboda, Simon Klancnik, Adrian But, Milos Vorkapic, Marta Harnicarova, Blaza Stojanovic
Summary: In this study, three different ratios (0.2%, 0.3%, and 0.5%) of alumina in two sizes (approx. 25 and 100 nm) were used to improve the wear characteristics of ZA-27 alloy-based nanocomposites. The materials were produced through mechanical alloying and compocasting processes. Wear tests were conducted under lubricated sliding conditions and the experimental results were analyzed using the response surface methodology (RSM) to develop a mathematical model for the wear rate. Artificial neural network (ANN) was used to evaluate the accuracy of prediction, with an overall regression coefficient of 0.98729.
Article
Acoustics
Lubos Smolik, Jan Rendl, Milan Omasta, Miroslav Byrtus, Petr Sperka, Pavel Polach, Martin Hartl, Michal Hajzman
Summary: This paper investigates the effects of mechanically induced textures on the stability of journal bearings, focusing on lightly loaded bearings commonly used in vertical rotors and microturbines. The results show that textures near the minimum oil film thickness can improve stability at low loads, but have little effect at a specific load of 0.15 MPa. The paper also discusses computational methods for dealing with cavitation and highlights the sensitivity of numerical results to the density of computational mesh.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Engineering, Chemical
Michal Michalec, Martin Ondra, Martin Svoboda, Jiri Chmelik, Petr Zeman, Petr Svoboda, Robert L. Jackson
Summary: This study proposes a new two-parameter method using Computational Fluid Dynamics (CFD) to estimate the optimal proportions of a hydrostatic bearing pad. The method considers the recess area and position, and was found to reduce energetic loss by 20% compared to the traditional one-parameter approach. The results demonstrate the versatility and effectiveness of this methodology in designing optimal hydrostatic bearings with minimum energetic loss in low-speed conditions.
Article
Engineering, Electrical & Electronic
Michal Michalec, Jan Foltyn, Tomas Dryml, Lukas Snopek, Dominik Javorsky, Martin Cupr, Petr Svoboda
Summary: This study focuses on finding assembly error tolerances for common types of segmented errors in hydrostatic bearing sliders. The experimental results can be used to determine the required film thickness.
Article
Engineering, Mechanical
Jiri Krupka, Krystof Dockal, Ivan Krupka, Martin Hartl
Summary: The lubrication of polymer materials is of great importance in engineering applications. The material properties of polymers are strongly influenced by temperature, which affects the lubrication process and the viscoelastic behavior of polymers. Through experimental and model analysis, it is found that the compliant circular contact operates in the Isoviscous-elastic regime of elastohydrodynamic lubrication (EHL), and temperature and load have a significant influence on the thermomechanical response of amorphous polymer PMMA.
Article
Engineering, Mechanical
Huiyi Yang, Yang Xu, Chao Xu
Summary: This study focuses on the impact of dry friction interfaces on the dynamics of jointed structures, particularly on the statistics of contact pressure distribution. Through experimental and simulation analysis, it is found that surface roughness and contact load have significant effects on contact area, contact stiffness, and mean contact pressure.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Guanglan Hu, Houfu Dai
Summary: The effect of metal coating on the machinability of cubic silicon carbide was investigated using molecular dynamics simulation. The results showed that the type of coating has a significant impact on cutting force, surface morphology, stress, and tool wear. Among the three metals studied, Cu coating had the greatest impact on improving cutting performance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Yunfan Liu, Guozheng Ma, Lina Zhu, Cuihong Han, Zhen Li, Bin Zhang, Haichao Zhao, Haidou Wang, Shuying Chen
Summary: The service performance of coated self-lubricating spherical plain bearings can be improved by applying self-lubricating coatings, especially double-sided coatings. The presence of a large-area and complete mixed friction transfer film on the contact surfaces can cause a signal downstage before the signal mutation stage.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
Article
Engineering, Mechanical
Yakup Artun, C. Oktay Azeloglu, Gokhan Taylan
Summary: This article investigates the tribological properties of polymer journal bearings, particularly focusing on radial journal bearings made from UHMWPE and POM materials with different surface qualities. The study examines the performance of these bearings under varying load and speed conditions, and analyzes the relationship between material and surface roughness in tribological performance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2024)
