Article
Engineering, Mechanical
Anatoliy Serdjuchenko, Aleksandr Ursolov, Yuriy Batrak
Summary: An analytical approach based on the asymptotic technique is used to estimate the hydrodynamic pressure in the lubrication film of water-lubricated stave bearings with a length/diameter ratio greater than 1. The results indicate that the type of stave, eccentricity, and misalignment of the journal have a significant impact on the pressure field.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Multidisciplinary Sciences
Ali Abbaspur, Mahmood Norouzi, Pooria Akbarzadeh, Seyyed Amirreza Vaziri, Melika Mokhtari Sharghi, Kyung Chun Kim, Mirae Kim
Summary: This paper presents a novel analytical solution for journal-bearing viscoelastic lubrication using the perturbation method. The investigation focuses on the impact of characteristic parameters such as mobility factor, eccentricity ratio, and Weissenberg number on the fluid film pressure distribution, load capacity, and shear stress.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Mechanical
Shengbo Li, Alexander Babin, Denis Shutin, Yuri Kazakov, Yifan Liu, Zhaobo Chen, Leonid Savin
Summary: This study proposes an approach for designing rotating machines with water lubricated active hybrid journal bearings. The adjustable lubricant supply pressure in the bearing influences the journal position, and a machine learning based model predictive controller is used to reduce energy consumption.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Mathematics
Francisco J. Suarez-Grau
Summary: The study focuses on the asymptotic behavior of micropolar fluid flows in a thin domain with a periodic oscillating boundary. Depending on the limit of the ratio of eta(epsilon)/epsilon as epsilon tends to zero, the existence of three different regimes is proven. In each regime, a generalized Reynolds equation considering the microstructure of roughness is derived.
BULLETIN OF THE MALAYSIAN MATHEMATICAL SCIENCES SOCIETY
(2021)
Article
Engineering, Mechanical
Alexey V. Kornaev, Elena P. Kornaeva, Leonid A. Savin, Yuri N. Kazakov, Alexander Fetisov, Alexey Yu. Rodichev, Sergey V. Mayorov
Summary: This paper presents a theoretical and experimental study on the viscosity wedge effect in a thin incompressible fluid film, aiming to reduce shaft vibrations and friction coefficient through optimization of viscosity distribution. Experimental results align with simulation results, demonstrating the potential positive impact of the viscosity wedge on reducing vibrations and friction in fluid film bearings.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Arthur Mereles, Diogo Stuani Alves, Katia Lucchesi Cavalca
Summary: Rotating machines with fluid-type bearing can experience instabilities known as oil-whirl and oil-whip due to the interaction between the fluid media and the rotating shaft. Identifying the type of bifurcation in these instances is crucial for determining safety and predicting behavior. This study presents a method based on center manifold reduction (CMR) to analyze these bifurcations and obtain limit cycles. The results show that the proposed method is reliable for characterizing sub-critical and super-critical bifurcations and predicting limit cycle amplitudes.
NONLINEAR DYNAMICS
(2023)
Article
Thermodynamics
Yang Zheng, Cheng Xu, Zheng Xinghua, Chen Haisheng
Summary: The paper presents a set of new equations SCF-RANS equations to describe turbulent flow and heat transfer of supercritical fluid, taking into account the fluctuation of thermal physical properties. Various model methods for the new correlation term have been discussed for closing the equations, providing reference information for these new correlations. The SCF-RANS equations not only offer a formulation specific to supercritical fluid flow and heat transfer, but also represent the most sophisticated form of the RANS equations with consideration of all physical properties as variables.
JOURNAL OF THERMAL SCIENCE
(2021)
Article
Engineering, Chemical
Yuanying Du, Hui Quan
Summary: This study establishes mixed-flow lubrication equations based on classical laminar and turbulent lubrication theories to investigate the lubrication characteristics of water-lubricated rubber bearings (WLRBs) in mixed-flow state. The results show that the mixed-flow lubrication equations are more suitable for WLRBs under actual operating conditions compared to laminar and turbulent theories. The study provides important reference for accurate analysis of WLRBs lubrication characteristics in practical engineering applications.
LUBRICATION SCIENCE
(2022)
Review
Engineering, Mechanical
Alberto Betti, Paola Forte, Enrico Ciulli
Summary: This paper reviews the effects of turbulence in tilting pad journal bearings. Turbulence has significant impact on the bearing performance, which can be beneficial or detrimental. The main turbulence models and simulation strategies are discussed, as well as the experimental works in this field. The evidence for laminar-to-turbulent transition is emphasized and its reliability is assessed. Future research directions are suggested.
Article
Engineering, Mechanical
Luiz Henrique Jorge Machado, Oscar R. Sandoval, Jose Victor Matos Carvalho Pereira, Juliana Primo Basilio de Souza, Fabricio Jose Pacheco Pujatti, Marco Tulio C. Faria
Summary: This experimental study investigates the thermohydrodynamic behavior of automotive turbochargers operating on semi-floating ring bearings with different axial groove shapes. The results show that a new half-ellipse groove shape presents slightly better THD performance, indicating an improved thermal behavior compared to the original triangular groove shape used in the turbocharger.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2022)
Article
Physics, Applied
Yaoke Wang, Ping Guo
Summary: In this study, the dynamic characteristics of near field levitation bearings were investigated by defining and deriving two types of system stiffness through theoretical analysis. The results indicate that the proposed stiffness model can effectively predict levitation force and height, and eliminate structural resonance effects. Additionally, unique dynamic behaviors were investigated and predicted based on the stiffness model.
APPLIED PHYSICS LETTERS
(2021)
Article
Mechanics
Mokhtar Djeddou, Amine Mehel, Georges Fokoua, Anne Taniere, Patrick Chevrier
Summary: Computational fluid dynamics simulations were conducted to study the airflow inside a full-scale passenger car cabin, using different turbulence models. Velocity and turbulence intensity profiles were compared with experimental results, and the airflow pattern, characterized by jet flows from air vents and a large vortex structure, was visualized in different planes. The models showed limitations in predicting turbulence intensity levels, and an analysis of the Reynolds stresses and turbulence structure revealed non-realizable solutions and different turbulence states among the models.
Article
Engineering, Mechanical
Fabricio Vieira Silva, Mauricio Araujo Zanardi, Teofilo Miguel de Souza
Summary: This study investigated the dynamics of different non-Newtonian fluids in short journal bearings using computational fluid dynamics, finding that Herschel-Bulkley and Bingham non-Newtonian fluids showed advantages in various performance parameters compared to Newtonian fluid.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Kang-Seok Kim, Deug-Woo Lee, Mi-Ru Kim, Yoong-ho Jung
Summary: In this study, an experimental device was developed to verify the effectiveness of lubrication analysis. The study found that the slope parameter of the friction surface and the relative slope of the pad bearing surface have an impact on friction characteristics.
Article
Engineering, Mechanical
Bin Wei, Yinghou Jiao, Xianglin Wu
Summary: The aim of this study is to present a technical numerical method to improve the efficiency of solving the Reynolds equation for hydrodynamic bearings. The developed method effectively combines the Bi-CGSTAB algorithm with the Reynolds boundary conditions to characterize the pressure distribution within the lubricant for hydrodynamic bearings.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Mechanical
L. Bizarre, G. B. Daniel, I. F. Santos, K. L. Cavalca
Summary: The research focuses on the development of a thermohydrodynamic lubrication model for a tilting pad bearing with injection, investigating the effects of lubricant on the dynamic behavior of the bearing.
TRIBOLOGY TRANSACTIONS
(2021)
Article
Engineering, Electrical & Electronic
K. K. Nielsen, C. R. H. Bahl, Nikolaj A. Dagnaes, Ilmar F. Santos, R. Bjork
Summary: Four different magnet bearing configurations were studied experimentally and using the modeling framework MagTense. The optimal configuration was determined numerically and validated experimentally, showing that a bearing with specific magnet rings had the smallest radial force per axial lift force at an axial air gap of 1 mm. This configuration reduced the radial force significantly compared to a similar bearing without one of the magnet rings.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Engineering, Mechanical
Troy Snyder, Ilmar Santos
Summary: In this study, 3D CFD simulations were used to analyze the performance of annular seals, determining dynamic coefficients using the whirling-rotor method and assessing the accuracy of predictions through comparisons with experimental data and bulk-flow models. The results show that the open-source CFD library OpenFOAM performs well in predicting dynamic coefficients for water seals, while alternative software is needed for gas seals.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2021)
Article
Engineering, Mechanical
Kenneth M. Jensen, Ilmar F. Santos, Line K. H. Clemmensen, Soren Theodorsen, Harry J. P. Corstens
Summary: This paper discusses the real-time estimation of ground vehicle mass based on longitudinal dynamics, utilizing basic data from the vehicle controller area network bus to apply to a wide range of vehicles without relying on specific parameters. Experimental validation with two petrol-powered passenger cars equipped with different transmissions shows that the method provides accurate mass estimates within +/- 5% of the actual masses, under various driving conditions.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Engineering, Mechanical
B. R. F. Rende, A. A. Cavalini, I. F. Santos
Summary: Damage detection in structures has received great attention recently and vibration signal monitoring is a common technique. This paper uses an outlier test based on the Mahalanobis distance to identify cracks in a beam. The results show the capability of the method, but also its sensitivity to boundary conditions. The laboratory experiments highlight the importance of boundary condition changes during reassembling machine components and the influence of exchanging similar machine components when reusing data-driven models for fault detection.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Kenneth M. Jensen, Ilmar F. Santos, Line K. H. Clemmensen, Soren Theodorsen, Harry J. P. Corstens
Summary: This work investigates the real-time estimation of ground vehicle mass using OBD-II data, IMU data, and GNSS position data, which presents a two-phase approach with broad applicability. Through data validation, the method is able to estimate vehicle mass within +/- 5% of the actual value.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Engineering, Mechanical
Kenneth M. Jensen, Ilmar F. Santos
Summary: This paper provides theoretical and experimental contributions to the field of tribotronics, linking various aspects such as tribology of fluid film bearings, flexible rotor and flexible foundation dynamics, sensing systems, fluid power and hydraulic actuator dynamics, and control theory. The authors use a multi-physical modeling approach to derive a mathematical model (digital twin) that couples the subsystems. The digital twin is then used to design and optimize a feedback control system for an actively-controlled tilting pad journal bearing, resulting in significant reduction of vibration.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2022)
Article
Engineering, Mechanical
M. Gani, I. F. Santos, M. Arghir, H. Grann
Summary: A novel approach of thermal coupling between fluid and solids, as well as the implementation of saturation curves to couple temperature, enthalpy, and vapor mass fraction, is presented in the study of a mechanical seal in two-phase flow. The model successfully solves for temperature fields, heat fluxes, enthalpy, and vapor mass fraction using a coupled method. Validation of the model is achieved through good agreement with literature results in various seal behavior and two-phase flow cases.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Gabriel W. Rodrigues, Fabiano L. Oliveira, Llmar F. Santos, Marco L. Bittencourt
Summary: This paper compares different dynamical models, cavitation procedures, and numerical methods for simulating hydrodynamic lubricated bearings of internal combustion engines. The study found that different dynamical models differed in predicting journal orbits, while the finite element method with Giacopini's cavitation model showed improved numerical stability for the three types of engines.
INDUSTRIAL LUBRICATION AND TRIBOLOGY
(2022)
Article
Mechanics
Vergilio T. S. Del Claro, Aldemir Ap. CavaliniJr, Ilmar F. Santos, Valder Steffen Jr
Summary: In recent years, there has been a growing interest in environmental issues and efficient, sustainable systems, leading to an increased demand for the use of advanced composites in industrial machines and innovative equipments. However, modeling the dynamic behavior of composite flywheels has proven to be a complex task that current Finite Element models fail to fulfill in many design contexts. This study proposes the use of an adapted Carrera Unified Formulation to model Flywheel Energy Storage Systems, providing a more accurate and computationally efficient approach compared to traditional methods.
COMPOSITE STRUCTURES
(2022)
Article
Acoustics
Signe T. Heinemann, Janus W. Jensen, Sebastian von Osmanski, Ilmar F. Santos
Summary: There is no consensus on the best practice for modelling the compliant foil structure of Gas Foil Bearings (GFBs) in the literature. This paper focuses on the modelling of the top foil and compares four different top foil models (with and without gas injection) in terms of steady state analysis efficiency and accuracy. The results show that the model using Euler-Bernoulli beam elements is both computationally efficient and accurate for steady state analysis compared to the model using non-curved shell elements.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Engineering, Mechanical
Fabiano L. M. Oliveira, Gabriel W. Rodrigues, Ilmar F. Santos, Marco L. Bittencourt
Summary: A coupled model of multibody dynamics for internal combustion engines' main mechanism and lubricated joints is developed. The joints are regarded as hydrodynamic journal bearings, and the mass-conserving Reynolds equations are solved using the finite element method. In each time step, the Newton-Euler system of equations for the main mechanism is solved using the hydrodynamics forces obtained from the lubrication model. Output results, including hydrodynamics forces, maximum oil pressure, minimum fluid thickness, and orbits, are presented for three different crank rotations of an engine. The model is validated against a conventional lubrication model found in the literature, showing appropriate agreement of results.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2023)
Article
Engineering, Mechanical
Jefferson Silva Barbosa, Aldemir Ap Cavallini Jr, Ilmar Ferreira Santos, Valder Steffen Jr
Summary: In this study, the effects of oil pressure injection on the dynamic behavior of a hybrid-lubricated tilting-pad thrust bearing were evaluated. A thermohydrodynamic model was used to determine the equilibrium position based on pressure and temperature distributions resulting from hydrodynamic and hybrid lubrication regimes. Perturbation and frequency reduction methods were applied to determine the stiffness and damping coefficients of the bearing under various operational conditions. The results showed that the dynamic force coefficients were strongly influenced by operational conditions, such as static load and rotating speed, as well as the perturbation frequency, for both lubrication regimes. The main original contribution of this work was the quantification of the injection pressure influence on the force coefficients of hybrid-lubricated thrust bearings.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2023)
Article
Engineering, Mechanical
Thomas T. Paulsen, Ilmar F. Santos, Line K. H. Clemmensen
Summary: Rotor dynamic force coefficients of gas seals depend on operational conditions and influence the vibration levels of machines. Accurate estimations of these coefficients are crucial for designing low vibration machines. This study investigates the impact of neglected system dynamics on the estimation of these coefficients and stability margins. Results show that the baseline model affects the estimations of certain coefficients, but has a smaller impact on stability margin predictions.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Computer Science, Information Systems
Mengchu Song, Ilmar Santos, Xinxin Zhang, Jing Wu, Morten Lind
Summary: This paper proposes a mechanical functional modeling approach based on multilevel flow modeling (MFM) and an optimized condition-based maintenance (CBM) framework for diagnosing mechanical failures and predicting their future impacts. The framework utilizes reliability-centered maintenance (RCM) to determine the importance of detected failures.
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)
