Article
Chemistry, Physical
Marius Bause, Tristan Bereau
Summary: The article introduces a Maximum Caliber method for dynamical reweighting of complex systems, mapping trajectories to a Markovian description and reducing configurational space dimensionality to collective variables. This approach expands dynamical reweighting to larger systems and across a wide range of driving forces.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Mechanics
Rajasekhara Reddy Mutra, J. Srinivas
Summary: This paper presents an optimization-based methodology to predict bearing coefficients using measured dynamic responses in a rotor supported on floating ring bearings. The unknown bearing stiffness and damping coefficients of the ideal rotor system are identified by predicting the deviations in frequency response amplitudes. The approach is relatively simple and can be applied to any kind of bearings.
Article
Engineering, Mechanical
Jan Rendl, Stepan Dyk, Lubos Smolik
Summary: This work investigates the nonlinear dynamics of four-segment tilting pad journal bearings, focusing on pad fluttering phenomenon, which disappears at relative eccentricities lower than 0.34. Through computational modeling and bifurcation diagrams analysis, this observation is crucial for high-speed rotating machinery supported on TPJBs.
NONLINEAR DYNAMICS
(2021)
Article
Engineering, Mechanical
Yazhou Mao, Lilin Li, Daqing Li, Jingyang Zheng
Summary: This paper investigates the turbulent lubrication performance of a textured hydrodynamic journal bearing (THJB) and analyzes the effects of structural and working parameters on the bearing performance. The results show that turbulent lubrication is suitable for actual operating conditions, but the system tends to be unstable as the eccentricity ratio and rotational speed increase.
Article
Engineering, Mechanical
Mohammad Arif, Saurabh Kango, Dinesh Kumar Shukla
Summary: This study investigates the combined influence of slip boundary condition and non-Newtonian lubricants on the tribological performance of hydrodynamic textured journal bearing. The modified Reynolds equation with considering the Elrod cavitation model is solved to accurately predict the effect of air/vapor bubble formation in the diverging zone of the slip-texture bearing. The results show that changing the rheology of the lubricant from Newtonian to Pseudoplastic significantly improves the maximum pressure, average rise in temperature, and lubricant-bearing friction-force of the slip-texture bearings.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Mechanical
Penghai Zhang, Jun Zha
Summary: The study shows that the speed mainly affects the amplitude of the high-speed error motion of porous journal air bearing, while the frequency information remains unaffected. As the speed increases, the averaging coefficient of the error motion also increases, leading to a decrease in accuracy.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Multidisciplinary
Shilei Han
Summary: The paper presents a new Arbitrary Lagrangian-Eulerian formulation for dynamic problems of geometrically exact, sliding shells. Unlike previous research, the sliding motions in this formulation are not prescribed at sliding boundaries, and the existence of configurational forces is identified. The paper derives the configurational momentum equation that governs the evolution of sliding motions in a consistent variational framework.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Mathematics, Applied
Rajesh C. Shah, Rajiv B. Shah
Summary: This paper derived a generalized ferrofluid based lubrication equation for variable and strong magnetic fields, and applied it to the study of porous journal bearings. The results showed that the dimensionless load-carrying capacity increases with eccentricity ratio and the effect of magnetic field in the x-direction for a thin layer of the porous region.
ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK
(2022)
Article
Engineering, Multidisciplinary
Shijie Wei, Junru Wang, Jian Cui, Shanshan Song, Huacong Li, Jiangfeng Fu
Summary: This paper presents a study on ultrasonic-based measurement for the dynamic oil film thickness of fuel pump. The circumferential oil film thicknesses in a journal bearing are measured using a complex model and a resonance model. The minimum oil film thickness is extracted by fitting the measured points with the initial circle. The measured results are verified with classical DHL simulations, and the maximum relative error is shown to be lower than 15%.
Article
Mathematics, Interdisciplinary Applications
Shao-Wen Yao
Summary: The article discusses the importance of the thin film equation in electroanalytical chemistry and introduces the fractal variational principle obtained by modifying the thin film equation using fractal derivatives. This principle is helpful for studying the structure of the approximate solution.
FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY
(2022)
Article
Engineering, Mechanical
S. Beamish, R. S. Dwyer-Joyce
Summary: This article presents the design of a journal bearing test platform that utilizes ultrasonic transducers for high-accuracy film thickness measurements. The platform is capable of simulating loading patterns found in real components and allows detailed analysis of the film thickness response to rapidly changing loads. The results demonstrate the advantages of the ultrasonic technique in studying phenomena at the shaft-bearing interface and the successful implementation of the snapshot technique for measurements.
TRIBOLOGY TRANSACTIONS
(2022)
Article
Engineering, Mechanical
Woo-Ju Jeon, Sung-Ho Hong
Summary: A flexible structure is used to enhance the lubrication performance of a misaligned journal bearing. The bearing, which represents a sliding bearing, suffers damage from metal-to-metal contact caused by misalignment. To improve this issue, a journal bearing with a flexible structure is proposed. Numerical evaluation and elastohydrodynamic lubrication analysis considering elastic deformation are conducted, comparing lubrication performance based on variations in the flexible structure's geometry and minimum film thickness. Comparisons are also made between the journal bearing with and without the flexible structure. The flexible structure, in the form of a groove, is applied to the high load-bearing area of the journal bearing, experiencing elastic deformation through the generated oil film pressure to obscure a larger oil film. The numerical analysis demonstrates that the journal bearing with a flexible structure can enhance lubrication performance in misalignment conditions.
Article
Engineering, Mechanical
Anil Singh, Satish C. Sharma
Summary: This study focuses on the numerical investigation of the performance effects of geometric imperfections on a porous hybrid journal bearing system operating under turbulent flow conditions. The Reynolds equation governing the lubricant flow in the bearing space is modified using turbulent lubrication theory, and the performance parameters are computed using FEM. The combined effect of turbulent flow conditions and geometric imperfections results in enhanced values of performance indicators.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Review
Engineering, Mechanical
Sitae Kim, Dongil Shin, Alan B. Palazzolo
Summary: This review summarizes the effects of nonlinear elements in fluid film journal bearings on rotor-bearing systems, including sub- and super-synchronous, chaos and thermally induced instability responses. It also discusses the importance of nonlinear, thermo-elasto-hydrodynamic aspects of journal bearings in high-performance turbomachines, and presents nonlinear solution methodologies and numerical tools for analyzing nonlinear vibration responses induced by bearings.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Mechanics
Ru-Dai Xue, Xiao-Hui Xiong, Xiao-Bai Li, Guang Chen
Summary: The study investigates the effect of turbulent inflow on the aerodynamic characteristics of a high-speed train. It analyzes the impact of different turbulent inflow conditions on various parameters such as aerodynamic loads, surface pressure, vorticity, vortex structure, turbulence characteristics, Reynold stresses, etc. The results show that turbulent inflow increases the variability of aerodynamic loads and strengthens the Reynolds stresses on the leeward side of the train. Additionally, the study examines the dominant modes and frequency characteristics of aerodynamic loads using spectral proper orthogonal decomposition and aerodynamic admittance function methods.
Article
Engineering, Mechanical
Busra Duran, Jerome Cavoret, David Philippon, Fabrice Ville, Arnaud Ruellan, Frank Berens
Summary: This study analyzes the changes in the physicochemical properties and tribological performances of gear transmission oils during field operation, finding differences from traditional engine oils.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Baocheng Liu, Hongsheng Chen, Jun Zhou, Jing Wang, Wenxian Wang, Xiaochun Chen, Sanxiao Xi
Summary: This study used fast hot pressing sintering to fabricate WC/AlCoCrFeNi2.1 metal matrix composites (MMCs). It was found that the addition of reinforced particles increased the microhardness, nanoindentation and wear resistance of the MMCs. During frictional processes, an oxide film formed, providing material protection, enhancing stability and reducing friction-induced losses.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Pradip Kumar Verma, Alok Singh
Summary: This study investigates the mechanical properties and wear resistance of CoMoMnNiV high entropy alloy reinforced aluminium matrix composite processed through stir-squeeze casting assisted with an ultrasonic transducer. The results show significant improvements in mechanical properties and wear resistance, with the composite containing 8 wt% HEA demonstrating the highest resistance to wear. Optical microscopy, SEM, and an optical profilometer were used for a thorough examination of the microstructure and worn surface.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Zhenghai Yang, Yingjian Song, Jinlong Jiao, Wenbo Li, Bao Shangguan, Yongzhen Zhang
Summary: This study investigated the friction, wear properties, and current-carrying properties of copper-graphite composites paired with brass C28000. The results showed that the current-carrying properties of the composite materials were excellent, but their wear rate was the main limiting factor. Furthermore, an increase in the thickness of the graphite layer led to an improvement in the uniformity of damage.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Moustafa Mahmoud Yousry Zaghloul, Karen Steel, Martin Veidt, Michael T. Heitzmann
Summary: This research evaluates and compares the impact of different material types on the tribological characteristics of Polyamide 6 composites, and finds that glass fiber-reinforced Polyamide 6 exhibits better friction and wear performance under high-pressure velocity factors.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Shaoqing Qin, Lida Zhu
Summary: In this paper, the surface and subsurface damage of laser assisted grinding CrCoNi medium entropy alloys were investigated using molecular dynamics simulations. The results showed that the application of laser energy can reduce cutting forces and minimize subsurface damage.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Kaikui Zheng, Youxi Lin, Tingzheng Lai, Chenghui Gao, Ming Liu, Zhiying Ren
Summary: The study investigated the use of waste foundry resin-bonded sand as a substitute for copper in resin-based brake material. It found that the waste sand was more favorable for improving the overall friction and wear properties of the material compared to copper. Waste sand benefited the material by forming a friction layer, leading to increased friction coefficient and stability. Brake material with 10-15% waste sand showed excellent heat-fade resistance.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Dayang Li, Fanhao Zhou, Yutong Gao, Kun Yang, Huimin Gao
Summary: This article introduces a continuous prediction model based on deep learning for predicting the power output of steam turbines. The model uses long short term memory (LSTM) method to develop a trend prediction model and optimizes the prediction model through feature selection method. Experimental results show that the model outperforms other models in terms of prediction performance.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Tomohiro Toyoda, Ryo Yasuike, Toshihiro Noda
Summary: In this study, a elasto-plastic constitutive model of friction incorporating the concept of superloading surface was developed based on the subloading friction model. The proposed model achieves a smooth transition of friction by describing the evolution rule of structure, treating the state with static friction coefficient larger than kinetic friction coefficient as the bulkiness of structure. The positive definiteness of the plastic multiplier, loading condition, and material parameters were derived, and the validity of the proposed model in accordance with the subloading-friction model was confirmed through a stick-slip simulation of a mass-spring system.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
P. Balaji, B. Surya Rajan, K. Sathickbasha, P. Baskara Sethupathi, Deviga Magadevan
Summary: This study emphasizes the importance of using a variety of solid lubricants with different oxidation temperature regimes to enhance the tribological performance of brake pads.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Jian Ma, Yancong Liu, Javad Mostaghimi, Na Zhang
Summary: This paper investigates the influence of preparation strategies on the lubrication properties of surface textures. Three laser scanning strategies are proposed to achieve a sinusoidal textured surface, and the evolution of surface structure and chemical composition is discussed. The findings show that ridge structures enhance anti-wear properties but also increase the friction coefficient. However, the oil cover preparation method prevents the formation of ridges and improves wettability.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Mohammad Roostaei, Arvin Taghizadeh Tabrizi, Hossein Aghajani
Summary: In this research, the Al2O3/MoS2 nanocomposite coating layer was successfully applied on the surface of Ti-6Al-4 V alloy. The relation between the surface characteristics and wear resistance of the coating was studied using atomic force microscopy analysis and pin-on-disk wear test method. The results showed that the nanocomposite coating significantly reduced the wear rate and provided an equation to calculate the Lancaster coefficient.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Musa Bilgin, Sener Karabulut, Halil Karakoc, Yunus Kayir, Murat Sarikaya
Summary: This study investigates various methods to improve the machinability efficiency of Inconel 718 alloy while considering their effect on microstructural properties. The results show that hot+PMQL, hot+SiCNMQL, and hot+Al2O3-NMQL contribute significantly to the improvement of machinability characteristics. The EBSD analysis also reveals that a limited area is affected by heat in the hot machining environment and that the removal of the heated layer during milling process helps preserve the microstructure.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Q. Gao, Y. Fan, Y. G. Wu, J. L. Liu, J. Wang, L. Li
Summary: Fretting wear significantly affects the hysteresis behavior of the contact surface and leads to joint degradation. This study investigates the influence of harmonic normal force on the evolution of interface morphology and contact parameters with fretting wear. The results show that the harmonic normal force can significantly influence the hysteresis loop and the energy dissipation distribution on the contact surface.
TRIBOLOGY INTERNATIONAL
(2024)
Article
Engineering, Mechanical
Benjamin Weiland, Floriane Leclinche, Anis Kaci, Brigitte Camillieri, Betty Lemaire-Semail, Marie -Ange Bueno
Summary: This study presents a systematic approach to generating control signals for a tactile simulator that simulate the touch of textile fabrics. By using a friction modulation tactile surface and acquiring forces from real surfaces with artificial finger mimicking fingerprints, control signals are generated and processed in the frequency domain before sending them to the tactile stimulator. The study focuses on the potential benefits of incorporating fingerprint information in fabric simulations to achieve a more realistic tactile perception. A sensory analysis with 36 participants using the generated control signals showed better discrimination without fingerprint information.
TRIBOLOGY INTERNATIONAL
(2024)