Article
Engineering, Chemical
Can Ma, Qichao Yang, Xiaohang Sun, Kelong Zhang, Liansheng Li
Summary: In this study, the performance of an externally pressurized gas journal bearing lubricated with R134a vapor in an oil-free refrigeration centrifugal compressor is investigated using the finite difference method (CFD) to solve the Reynold equations. The load capacity, stiffness, and mass flow rate of the refrigerant vapor are obtained under various operational parameters and compared with those in air gas bearings. The effects of average clearance, eccentricity ratios, and supply vapor pressure on the static characteristics of journal bearings are discussed in detail. The study concludes that the optimal operational parameters for R134a vapor gas journal bearings are different from air journal bearings, and these factors should be considered in the design process.
Article
Thermodynamics
H. Zhang, X. Guan, T. Wang, A. U. Z. Robin, C. H. Mu
Summary: This study focuses on the aerostatic guideway of an ultra-precision micromachine tool. Different structures of orifices and pressure-equalizing grooves (PEG) were designed and simulated to improve the load performance. The results showed that the extended PEG had the best load performance, and the width and depth of the PEG had different effects on load capacity and stiffness.
JOURNAL OF APPLIED FLUID MECHANICS
(2023)
Article
Engineering, Chemical
Huaqi Lian, Chengjun Rong, Yulong Li
Summary: The study found that increasing bearing surface temperature leads to an increase in load but an initial increase and subsequent decrease in static stiffness, while increasing supply gas temperature results in a decrease in both load and static stiffness. These insights can be valuable for designing gas bearings using refrigerant gases.
Article
Energy & Fuels
Tao Nie, Kun Yang, Lei Zhou, Xin Wu, Yin Wang
Summary: This study investigates the application of surface texture technology in reducing friction in journal bearings of internal combustion engines. Through simulation models and experimental validation, it examines the effect of texture shape and position on the load capacity of the bearings.
Article
Geochemistry & Geophysics
J. A. Priest, M. Abbas, J. L. Hayley
Summary: Laboratory tests on gas-saturated hydrate-bearing sand specimens showed that the formation of hydrate led to significant increases in stiffness and strength of the sand. Water saturation subsequently resulted in a reduction of around 90% in stiffness and 70% in strength. The changes in behavior were attributed to the dissociation and dissolution of the hydrate, with remaining hydrate acting as more of a pore filler.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Engineering, Multidisciplinary
Liming Teng, Jinbo Jiang, Xudong Peng, Jiyun Li
Summary: This paper investigates a structural form called double-sided spiral groove gas face seal. The steady-state performances, such as film load-carrying capacity and film stiffness, of gas face seals with different groove arrangements are compared. The complete dynamic behavior history is obtained by considering various factors such as axial and angular excitations, gas lubrication, seal rings vibration, and fluid film thickness changes. The effects of groove depths and equilibrium film thickness on the dynamic performance are studied, and the mechanisms of unstable conditions are analyzed. The results show that the double-sided grooving method provides improved gas film load-carrying capacity and stiffness, ensuring stable operation under various conditions.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Engineering, Mechanical
Donghyun Lee, Hyungsoo Lim, Byungock Kim, Byungchan Jeon, Junyoung Park
Summary: This study developed an externally pressurized bearing for a turbo expander used in a hydrogen liquefaction plant. The rotor-bearing system was designed through numerical modeling, and its performance was analyzed. The results showed that the system had sufficient separation margin with the critical speed and the predicted critical speed matched well with the simulation.
Article
Engineering, Mechanical
Yukun Wu, Changlin Li, Jianjun Du, Tun Liu, Xiangyun Zuo
Summary: This paper investigates the problem of pneumatic hammer vibration through a dynamic model and verifies the model correctness using a flexible sensor. The analysis results indicate that pneumatic hammer vibration tends to occur when the mass and supply pressure exceed the critical values.
NONLINEAR DYNAMICS
(2023)
Article
Engineering, Mechanical
Chuanbing Zhang, Hongrui Ao, Hongyuan Jiang
Summary: Hybrid gas dynamic bearings (HGDBs) are designed to enhance the viscous damping and stiffness of conventional gas foil bearings (GFBs). The coupling of rarefied gas effect, roughness effect, and gas leakage effect decreases the static load-carrying capacity, while dynamic coefficients are influenced by the dynamic sliding bearing model.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Chemistry, Physical
Han Yan, Changlei Ke, Nan Peng, Kongrong Li, Xiaohua Zhang, Lianyou Xiong, Bin Dong, Jing Li, Liqiang Liu
Summary: This paper introduces a new simplified load capacity prediction model for high-speed externally pressurized hydrogen journal bearings to optimize their performance. The model allows for accurate calculation of the bearing load capacity without the need for complex numerical analysis and computer programming. Experimental results show that the predicted model aligns well with results obtained from finite difference method technique.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Thermodynamics
Yuntang Li, Ruirui Li, Yueliang Ye, Xiaolu Li, Yuan Chen
Summary: A novel gas journal bearing with different sized and unevenly distributed orifices is proposed in this paper, showing better static and dynamic performance compared to traditional bearings. Thin gas film thickness, high supply pressure, and large eccentricity ratio are important factors for improving load capacity, with improved stability of the new bearing observed at an eccentricity ratio of 0.25-0.3.
ADVANCES IN MECHANICAL ENGINEERING
(2021)
Article
Engineering, Mechanical
Jiawei Wang, Jiuqi Huang, Sen Jiang, Ange Nsilani Kouediatouka, Qi Liu, Guangneng Dong
Summary: The aim of this study is to analyze numerically the influence of operating conditions and structure parameters on the performance of a four-rectangle recessed hydrostatic journal bearing, considering the limitation of recess pressure being smaller than supply pressure. A new calculation method is proposed to ensure both lower time consumption and higher accuracy compared to traditional and simplified methods. The effects of operating conditions and structure parameters on load capacity, attitude angle, and eccentricity ratio are examined, along with the pressure distribution. The results provide valuable guidance for the design and application of hydrostatic journal bearings.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Chemistry, Multidisciplinary
Gregor Schilling, Robert Liebich
Summary: This paper investigates the influence of a nominal bearing clearance on the lift-off behavior and load-carrying capacity of gas polymer bearings (GPBs). An experimental study with five different bearing gap configurations and a range of static loads is conducted. The results show significant differences in the load-carrying capacity between bump-type and gas polymer bearings, and the effects are described and explained. The findings highlight the importance of considering these differences in the design process of rotors supported in GPBs.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Multidisciplinary
Vladimir Kodnyanko, Stanislav Shatokhin, Andrey Kurzakov, Yuri Pikalov, Iakov Pikalov, Olga Grigorieva, Lilia Strok, Maxim Brungardt
Summary: Aerostatic bearings offer minimal friction losses, high durability, and environmental friendliness, but typically have low load-bearing capacity and high compliance. This study introduces a novel double-row aerostatic journal bearing with microgrooves to reduce compliance and improve load capacity, with experimental verification showing promising results. The proposed improvement significantly increases the load capacity of aerostatic journal bearings, making it a practical choice for future applications.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Mechanical
Nilesh D. Hingawe, Skylab P. Bhore
Summary: This paper investigates the influence of texture geometrical parameters on the tribological performance of meso scale air journal bearing. Through numerical simulations and optimization, it is found that textured air bearings have higher load carrying capacity and lower friction coefficient compared to plain air bearings.
SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES
(2021)
Article
Engineering, Chemical
Yexiang Fu, Fuwang Zhao, Zejia Zhao, Hui Tang, Suet To, Ching-Hsiang Cheng
Summary: This study reports a method that combines hydrothermal synthesis with ultraprecision machining to fabricate a hierarchical coated surface, improving its hydrophobicity. The experimental results show that the hierarchical surface has a larger contact angle and better water droplet bouncing behavior, indicating excellent water repellency.
JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY
(2023)
Article
Green & Sustainable Science & Technology
Wai Sze Yip, Suet To
Summary: This study combines social network analysis (SNA) and principal component analysis (PCA) to prioritize Ultra-precision machining (UPM) factors based on their combined characteristics. It uses SNA results as input for PCA to generate principal components, which are then combined into multiple characteristic performance indexes (MPCI). Few case studies validate the effectiveness of adjustments in UPM factors with high MPCI on machining outcomes. The study contributes to providing a comprehensive reference for prioritizing UPM factors and developing practical machining strategies.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2023)
Article
Chemistry, Physical
Dan Xu, Hong Zhong, Mitch Guijun Li, Sandy Suet, Lin Lu
Summary: Solar-driven steam generation is an attractive solution to the freshwater and energy crisis, utilizing abundant solar energy and undrinkable water resources with low environmental impact. To achieve practical solar evaporation, efficient solar absorbers with broad spectrum response, high heat conversion, low cost, and stability are crucial. Additionally, preventing salt crystal accumulation on the evaporation surface is vital for maintaining long-term evaporation efficiency.
Article
Engineering, Manufacturing
Zi-Hui Zhu, Peng Huang, Suet To, Li-Min Zhu, Zhiwei Zhu
Summary: A fast-tool-servo-controlled shear-thickening micropolishing method is proposed for removing undesired surface diffraction on diamond-turned microstructured surfaces. The method allows for controllable material removal by adjusting the gap width and achieves improved surface quality.
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE
(2023)
Article
Materials Science, Multidisciplinary
Hanheng Du, Zhiwei Zhu, Zuankai Wang, Suet To
Summary: This study proposes a novel piezoelectrically actuated cutting system for fabricating high-aspect-ratio and hierarchical micro/nanostructure arrays. The mechanical structure is designed based on the circular flexure hinge, and a finite element model is established to analyze its resonant frequencies and mode shapes. The effectiveness and flexibility of the proposed cutting system are demonstrated by fabricating micro/nanostructure arrays with varying features.
MATERIALS & DESIGN
(2023)
Article
Engineering, Mechanical
Tengfei Yin, Hanheng Du, Guoqing Zhang, Wei Hang, Suet To
Summary: This paper investigates the formation mechanism of surface waviness in ultra-precision grinding. A dynamics model of the aerostatic bearing wheel spindle is developed to analyze its vibration characteristics. Surface waviness formation models are established considering wheel spindle vibration (WSV) and non-uniform wheel topography (NWT) as the origins of waviness. Grinding experiments are conducted to validate the models. The study provides useful insights for optimizing grinding conditions to enhance surface quality and tribological properties.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Chemistry, Analytical
Xin Li, Yinggang Wang, Hongyu Chen, Wenhong Zhao, Qianfa Deng, Tengfei Yin, Suet To, Zhe Sun, Xi Shen, Wei Hang, Julong Yuan
Summary: In this study, polyurethane, damping cloth, and non-woven fabric were selected as polishing pads. The HPMJ conditioning technology was found to be better than traditional diamond conditioning in terms of keeping the polishing pad surface clean and preventing the hole structure from being blocked. Additionally, the HPMJ conditioned polishing pad had a longer service life and a more stable material removal rate.
Article
Engineering, Manufacturing
Zhanwen Sun, Sujuan Wang, Suet To, Shijun Xu, Guangyu Guo
Summary: Ultra-precision diamond cutting is a promising method for fabricating precision parts of titanium alloys. This study proposes an analytical specific cutting energy (SCE) model that takes into account various factors such as material microstructures, spring back, size effect, cutting edge effect, temperature evolution, and tool-chip frictional states. The results show that the cutting edge effect and spring back contribute to a high SCE at small undeformed chip thickness. The study also suggests an energy-oriented machining parameters optimization method to minimize the SCE in UPDC of titanium alloys.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Article
Automation & Control Systems
Peizheng Li, Sujuan Wang, Suet To, Zhanwen Sun, Jie Jiao, Shijun Xu
Summary: This study proposes a semi-ductile diamond milling method that can produce high-quality microstructured surfaces with high efficiency by fully considering the curvature variation, microstructure geometry characteristics, and machining parameters. By establishing a semi-ductile machining model and the relationship between machining parameters and fragmentation length, determining the dynamically changing tool trajectory, and conducting a comparison experiment, it is demonstrated that the method has high quality and efficiency in creating microstructures on hard and brittle materials.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Engineering, Mechanical
Changlin Liu, Suet To, Xuexiang Sheng, Jianfeng Xu
Summary: This paper explores the formation mechanism of crystal defects in single-crystal silicon during elliptical vibration cutting (EVC) using molecular dynamics simulation. The study finds that the cutting stage in EVC greatly influences the surface morphology, including elastic recovery and side flow. The preferred slip motion during subsurface damage formation is distinct in the extrusion and shear stage. The influence of cutting temperature and speed on crystal defects formation is also investigated, revealing the increase in proportion of Shockley partial dislocations at elevated temperature and the suppression of crystal defects generation with higher speed ratio.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Biochemistry & Molecular Biology
C. H. Wong, E. A. Buntov, W. S. Yip, S. To, M. B. Guseva, A. F. Zatsepin
Summary: Through Monte Carlo simulation, we investigated the kink structures in free-standing carbon nanowires under high temperatures. Our study found that short carbon chains exhibit disordered kink structures at high temperatures, which may enhance the chemisorption of negatively charged atoms and provide important insights for the development of high-temperature chemisorption materials.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Engineering, Manufacturing
Pan Guo, Mingyu Liu, Yuanping Zhou, Zhiwen Xiong, Shaojian Zhang, Suet To
Summary: In ultra-precision machining of micro-structured functional surfaces, tool servo dynamic errors, namely tool servo tracking error and tool servo induced vibration, have negative impacts on surface quality. The study reveals two crucial suggestions for improving surface quality: firstly, the tool path should be at least fourth-order differentiable; secondly, the second-order derivative of tool path (required acceleration) should be less than the rated acceleration provided by the tool servo.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Article
Automation & Control Systems
Yan-Ning Fang, Xiaonan Pu, Suet To, Bernard Hon, Li-Min Zhu, Zhiwei Zhu
Summary: To overcome the limitations of current piezo-actuated triaxial fast tool servos (FTSs), a novel normal-stressed electromagnetic triaxial FTS with a compact structure and high resonant frequency is proposed. It achieves triaxial motions in the range of hundreds of micrometers and utilizes a single armature for decoupled and noncontact driving forces. The prototype of the triaxial FTS shows excellent agreement with the design target in terms of static and dynamic performances. The system is further enhanced with a linear active disturbance rejection control and an iterative learning scheme for fast and accurate trajectory tracking. By fabricating a hexagonal spherical microlens array, the triaxial FTS demonstrates its capability with a high level of spatial accuracy and good surface quality.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Chemistry, Multidisciplinary
Changlin Liu, Wai Sze Yip, Suet To, Bolong Chen, Jianfeng Xu
Summary: This article investigates the deformation mechanisms of CdTe during nano-grinding through molecular dynamics (MD) simulation. The results show that the dominant grinding mechanism changes from elastic deformation to ploughing and cutting as the grinding depth increases. The grain size affects the transition from ploughing to cutting and the generation of subsurface damage and dislocations.
Article
Engineering, Chemical
Louis Luo Fan, Wai Sze Yip, Zhanwan Sun, Baolong Zhang, Suet To
Summary: This study investigates the effect of substrate-to-filament distances on coating thickness, diamond purity, coating grain size, and ZrO2 machining performance during HFCVD. The results indicate that smaller substrate-to-filament distances lead to decreased grain size and coating thickness, resulting in improved machining quality for diamond-coated milling tools.
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)
