Article
Engineering, Multidisciplinary
Wenjie Zhou, Yifan Wang, Guangkuan Wu, Bo Gao, Weibin Zhang
Summary: This paper presents a new numerical method, including finite element method and mixed method, to study the lubricated characteristics of journal bearing. The calculated results obtained by this method are validated and further research is conducted to investigate the effects of various parameters on the bearing performance. The stiffness and damping coefficients of the bearing are also calculated. The theoretical model and calculated results provide useful references for the design of journal bearing and rotor coupled system.
AIN SHAMS ENGINEERING JOURNAL
(2022)
Article
Engineering, Marine
Wu Ouyang, Qilin Liu, Qichao Cheng, Gao Wan, Yong Jin
Summary: In this study, the centralized dynamic characteristics of traditional journal bearings were investigated. It was found that a distributed dynamic characteristic will be generated along the axial direction for journal bearings with a large aspect ratio. A suitable loading method was developed, and a corresponding test-rig was set up. Two excitation methods were proposed. Experimental results showed that the eight-time cross excitation method had a higher signal-to-noise ratio and provided more accurate identification results. The study also revealed that shaft bending is the main factor contributing to the increase in local dynamic characteristic coefficients.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Guangshuo Feng, Bo Liu, Liuyuan Li, Yiben Zhang
Summary: The dynamic coefficients of air foil bearings were calculated using time-domain identification in this paper. This method does not require linearization of the system equations and is applicable to different air foil bearing models. The calculation results of foil models with axial uniform deformation and axial independent deformation showed significant differences. Furthermore, the accuracy of the dynamic coefficient method was compared for different disturbance amplitudes, and it was found to have good accuracy over a large disturbance range.
Article
Engineering, Mechanical
Yuanyuan Liu, Xiaodong Sun, Kian K. Sepahvand, Steffen Marburg
Summary: This paper introduces an analytical model of a three-pad squeeze film bearing and analyzes its static and dynamic performance through numerical methods, showing good agreement with experimental results. The study suggests that eccentricity can be controlled by adjusting vibration amplitude or nominal clearance of the bearing, while decreasing rotation speed or increasing vibration amplitude will increase direct stiffness and damping coefficients.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Multidisciplinary
Yang Kang, Zizhen Qiu, Qiming Fan, Hao Zhang, Zhanqun Shi, Fengshou Gu
Summary: This paper proposes a novel estimation method for accurately estimating the time-varying dynamic coefficients (TVDCs) of journal bearings without the need for a tachometer. The method combines a phase-based approach to extract the instantaneous angular speed and an iteration strategy based on the square-root cubature Kalman filter (SRCKF) to estimate the TVDCs in the time domain. Simulation and experimental studies demonstrate the effectiveness of the proposed method in estimating the TVDCs of journal bearings under speed-variable conditions and different levels of measurement noise.
Article
Engineering, Mechanical
T. A. El-Sayed, Hussein Sayed
Summary: This study investigates the stability and bifurcations of a flexible Jeffcott rotor system supported by hydrodynamic journal bearings. Nonlinear bearing stiffness and damping coefficients are used to represent the bearing forces, approximated to the third order using Taylor expansion. The results demonstrate that this approach allows for a detailed analysis of the rich dynamics of rotor-bearing systems.
NONLINEAR DYNAMICS
(2022)
Article
Engineering, Mechanical
Jie Yang, Rupeng Zhu, Heow Pueh Lee
Summary: The influence of the non-Gaussian rough surface on the characteristics of the journal bearing is investigated in this study. The results demonstrate that journal bearings with surface roughness exhibit better steady-state and dynamic performances compared to those with smooth surfaces.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Philipp Zemella, Thomas Hagemann, Bastian Pfau, Hubert Schwarze
Summary: This paper presents measurement results for a five-pad tilting-pad journal bearing in different load conditions. The findings indicate significant nonlaminar flow and subsynchronous as well as supersynchronous vibrations in the investigated rotor speed range. The impact of surface speed, bearing load, and oil flow rate on measured and predicted stiffness and damping coefficients of the bearing is explored.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2021)
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
Engineering, Mechanical
Deepak Byotra, Sanjay Sharm
Summary: This study investigates the impact of texture shape, number of textures, and nanoparticle additives on the dynamic characteristics of journal bearings. Finite element method is used to solve the governing Reynold's equation and calculate performance parameters. The results show that the arc-shaped texture with certain characteristics exhibited higher stiffness and damping coefficient compared to other shapes, and the addition of nanoparticle additives further improved these parameters.
INDUSTRIAL LUBRICATION AND TRIBOLOGY
(2023)
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, Electrical & Electronic
Danilo Alvaro da Silva, Gregory Bregion Daniel, Katia Lucchesi Cavalca
Summary: Several theoretical models have been developed for predicting the performance of tilting pad journal bearings. However, reliable validation of these predictions requires a robust test rig design. This study presents a novel test rig project that can measure rolling-element bearings and fixed-geometry, hydrodynamic journal bearings, and reproduce diverse operating conditions to validate different models applied to the bearings.
Article
Engineering, Aerospace
Yu ZHOU, Longtao SHAO, Can ZHANG, Fenzhu JI, Jiang LIU, Guo LI, Shuiting DING, Qi ZHANG, Farong DU
Summary: This paper presents a simple experimental method to obtain the minimum film thickness and dynamic stiffness of bump-type foil journal bearing (BFJB) using the journal orbit. Results show that the experimental and numerical results fluctuate initially due to dry friction, but agree well once a gas film is generated to separate the shaft from the top foil. The proposed experimental method effectively predicts film thickness and dynamic characteristics, and can be used to predict rotor-bearing systems dynamics.
CHINESE JOURNAL OF AERONAUTICS
(2021)
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
Fanming Meng, Yifei Zhang, Linlin Su, Haiyang Yu, Yong Zheng
Summary: This study investigates the compound texture effect on the dynamic characteristics of the journal bearing film, finding that the reasonably arranged compound texture can significantly increase the direct stiffness coefficients and damping coefficients of the bearing-rotor system, resulting in higher critical speed.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY
(2021)
Article
Engineering, Mechanical
Rosaria Del Toro, Maria Laura De Bellis, Marcello Vasta, Andrea Bacigalupo
Summary: This article presents a multifield asymptotic homogenization scheme for analyzing Bloch wave propagation in non-standard thermoelastic periodic materials. The proposed method derives microscale field equations, solves recursive differential problems within the unit cell, establishes a down-scaling relation, and obtains average field equations. The effectiveness of this approach is validated by comparing dispersion curves with those from the Floquet-Bloch theory.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Yue Bao, Zhengcheng Yao, Yue Zhang, Xueman Hu, Xiandong Liu, Yingchun Shan, Tian He
Summary: This paper proposes a novel triple-gradient phononic acoustic black hole (ABH) beam that strategically manipulates multiple gradients to enhance its performance. The study reveals that the ABH effect is not solely brought about by the thickness gradient, but also extends to the power-law gradients in density and modulus. The synergistic development of three different gradient effects leads to more pronounced and broader bandgaps in PCs.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Matthias Ryser, Jason Steffen, Bekim Berisha, Markus Bambach
Summary: This study investigates the feasibility of replacing complex experiments with multiple simpler ones to determine the anisotropic yielding behavior of sheet metal. The results show that parameter identifiability and accuracy can be achieved by combining multiple specimen geometries and orientations, enhancing the understanding of the yield behavior.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Wenjun Li, Pengfei Zhang, Siyong Yang, Shenling Cai, Kai Feng
Summary: This study presents a novel two-dimensional non-contact platform based on Near-field Acoustic Levitation (NFAL), which can realize both one-dimensional and two-dimensional transportation. Numerical and experimental results prove the feasibility and ease of this method.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Shuo Liu, Lu Che, Guodong Fang, Jun Liang
Summary: This study presents a novel lamina conjugated bond-based peridynamic (BB-PD) model that overcomes the limitations of material properties and is applicable to composite laminates with different stacking sequences. The accuracy and applicability of the model are validated through simulations of elastic deformation and progressive damage behavior, providing an explanation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Omar El-Khatib, S. Kumar, Wesley J. Cantwell, Andreas Schiffer
Summary: Sandwich-structured honeycombs (SSHCs) are hierarchical structures with enhanced mass-specific properties. A model capable of predicting the elastic properties of hexagonal SSHCs is presented, showing superior in-plane elastic and shear moduli compared to traditional honeycombs, while the out-of-plane shear moduli are reduced.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Zhi-Jian Li, Hong-Liang Dai, Yuan Yao, Jing-Ling Liu
Summary: This paper proposes a process-performance prediction model for estimating the yield strength and ultimate tensile strength of metallic parts fabricated by powder bed fusion additive manufacturing. The effect of main process variables on the mechanical performance of printed metallic parts is analyzed and the results can serve as a guideline for improvement. The accuracy of the proposed model is validated by comparison with literature.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Saman A. Bapir, Kawa M. A. Manmi, Rostam K. Saeed, Abdolrahman Dadvand
Summary: This study numerically investigates the behavior of an ultrasonically driven gas bubble between two parallel rigid circular walls with a cylindrical micro-indentation in one wall. The primary objective is to determine the conditions that facilitate the removal of particulate contamination from the indentation using the bubble jet. The study found that the bubble jet can effectively remove contamination from the indentation for certain ranges of indentation diameter, but becomes less effective for larger indentation diameters.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
E. Polyzos, E. Vereroudakis, S. Malefaki, D. Vlassopoulos, D. Van Hemelrijck, L. Pyl
Summary: This research investigates the elastic and damage characteristics of individual composite beads used in 3D printed composites. A new analytical probabilistic progressive damage model (PPDM) is introduced to capture the elastic and damage attributes of these beads. Experimental results show strong agreement with the model in terms of elastic behavior and ultimate strength and strain.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)