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Influence of Particles on the Loading Capacity and the Temperature Rise of Water Film in Ultra-high Speed Hybrid bearing

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Chinese Journal of Mechanical Engineering 2015年第3期28卷 541-548页

作者： ZHU Aibin LI Pei ZHANG Yefan CHEN Wei YUAN Xiaoyang key laboratory of education ministry for modern design and rotor-bearing System Xi'an Jiaotong University

Ultra-high speed machining technology enables high efficiency, high precision and high integrity of machined surface. Previous researches of hybrid bearing rarely consider influences of solid particles in lubricant and ultra-high speed of hybrid bearing, which cannot be ignored under the high speed and micro-space conditions of ultra-high speed water-lubricated hybrid bearing. Considering the impact of solid particles in lubricant, turbulence and temperature viscosity effects of lubricant, the influences of particles on pressure distribution, loading capacity and the temperature rise of the lubricant film with four-step-cavity ultra-high speed water-lubricated hybrid bearing are presented in the paper. The results show that loading capacity of the hybrid bearing can be affected by changing the viscosity of the lubricant, and large particles can improve the bearing loading capacity higher. The impact of water film temperature rise produced by solid particles in lubricant is related with particle diameter and minimum film thickness. Compared with the soft particles, hard particles cause the more increasing of water film temperature rise and loading capacity. When the speed of hybrid bearing increases, the impact of solid particles on hybrid bearing becomes increasingly apparent, especially for ultra-high speed water-lubricated hybrid bearing. This research presents influences of solid particles on the loading capacity and the temperature rise of water film in ultra-high speed hybrid bearings, the research conclusions provide a new method to evaluate the influence of solid particles in lubricant of ultra-high speed water-lubricated hybrid bearing, which is important to performance calculation of ultra-high speed hybrid bearings, design of filtration system, and safe operation of ultra-high speed hybrid bearings.

关键词： hybrid bearing liquid-solid flow solid particles loading capacity temperature rise

Unified Coordinate System Model for Performance Calculation of Fix-pad Journal bearing with Different Pad Preload

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 537-542页

作者： ZHU Aibin YANG Yulei CHEN Wei YUAN Xiaoyang key laboratory of education ministry for modern design and rotor-bearing System Xi'an Jiaotong University

Traditional model for calculating performance parameters of a fix-pad journal bearing leads to heavy workload, complicated and changeable formulae as it requires deriving various geometric formulae with different bearing types such as circular journal bearing, dislocated bearing and elliptic bearing. Considering different pad preload ratios for non-standard bearing, traditional model not only becomes more complicated but also reduces scalability and promotion of the calculation programs. For the complexly case of traditional model while dealing with various fix-pad journal bearings, unified coordinate system model for performance calculation of fix-pad journal bearing is presented in the paper. A unified coordinate system with the bearing center at the origin is established, and the eccentricity ratio and attitude angle of axis relative to each pad are calculated through the coordinates of journal center and each pad center. Geometric description of fix-pad journal bearing is unified in this model, which can be used for both various standard bearing and non-standard bearing with different pad preload ratios. Validity of this model is verified with an elliptical bearing. Performance of a non-standard four-leaf bearing with different pad preload ratios is calculated based on this model. The calculation result shows that increasing preload ratio of the pad 1 and keeping that of the left three pads constant improves bearing capacity, stiffness and damping coefficients. This research presents a unified coordinate system model unifies performance calculation of fix-pad journal bearings and studied a non-standard four-leaf bearing with different pad preload ratios, the research conclusions provides new methods for performance calculation of fix-pad journal bearings.

关键词： fix-pad journal bearing performance calculation unified coordinate system model

New Immersed Boundary Method on the Adaptive Cartesian Grid Applied to the Local Discontinuous Galerkin Method

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Chinese Journal of Mechanical Engineering 2018年第2期31卷 176-185页

作者： Xu-Jiu Zhang Yong-Sheng Zhu Ke Yan You-Yun Zhang key laboratory of education ministry for modern design&rotor-bearing System Xi'an Jiaotong University

Currently, many studies on the local discontinuous Galerkin method focus on the Cartesian grid with low computational e ciency and poor adaptability to complex shapes. A new immersed boundary method is presented, and this method employs the adaptive Cartesian grid to improve the adaptability to complex shapes and the immersed boundary to increase computational e ciency. The new immersed boundary method employs different boundary cells(the physical cell and ghost cell) to impose the boundary condition and the reconstruction algorithm of the ghost cell is the key for this method. The classical model elliptic equation is used to test the method. This method is tested and analyzed from the viewpoints of boundary cell type, error distribution and accuracy. The numerical result shows that the presented method has low error and a good rate of the convergence and works well in complex geometries. The method has good prospect for practical application research of the numerical calculation research.

关键词： Immersed boundary method Adaptive Cartesian grid Local discontinuous Galerkin method Reconstruction Heat transfer equation

An improved practical model for wear prediction of revolute clearance joints in crank slider mechanisms

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Science China(Technological Sciences) 2013年第12期56卷 2953-2963页

作者： LI Pei CHEN Wei ZHU AiBin key laboratory of education ministry for modern design and rotor-bearing System Xi’an Jiaotong University

A stationary clearance link algorithm(SCLA)for calculating the reaction-force of revolute clearance joints in crank slider mechanisms is proposed in this *** SCLA is more efficient than other algorithms of the same ***,based on the Winkler foundation model,an unsymmetrical Winkler foundation model and a double elastic layer Winkler model are *** integrating a dynamic model and the unsymmetrical Winkler foundation model with Archard wear model,an improved integrated wear prediction model is also generated.A series of experiments have been performed to compare with the predicted analysis data,and the results showed a good *** a real industry application,with the double elastic layer Winkler model,the integrated wear prediction model was successfully used to predict the wear depth of the joint bearing(bimetallic bearing)for the cantilever crane of a concrete pump truck of Sany Heavy Industry.

关键词： revolute clearance joint stationary clearance link algorithm unsymmetrical Winkler foundation model double elastic layer Winkler model

Magnetic-field-driven switchable adhesion of NdFeB/PDMS composite with gecko-like surface

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Nano Research 2023年第5期16卷 6840-6848页

作者： Xiaotian Shi Lei Yang Sheng Li Yanjie Guo Zhibin Zhao key laboratory of education ministry for modern design and rotor-bearing System Xi’an Jiaotong UniversityXi'an 710049China

Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex ***,the simple fabrication of adhesive structures and reliable control of adhesion remain ***,we developed a neodymium iron boron/polydimethylsiloxane(NdFeB/PDMS)magnetic composite with optimal mechanical and magnetic *** we fabricated lamellar structures and setal arrays using a molding and magnetic field-induced process,imitating the multi-level adhesion system of gecko *** lamellar can be deformed under the action of a magnetic field to control the adhesion,the setal array is used to enhance adhesion and provide self-cleanability to the adhering *** adhesion was realized by applying an external magnetic field,where the maximum adhesion strength was 5.1 kPa,the switchable range was within 40%.Through finite element analysis simulations and experimental verification,it was proved that the adhesion force variation was ascribed to the magnetic field-induced surface ***,we installed the adhesive on the end of the robotic arm,realizing the transfer of the target *** work provides a simple method to fabricate a gecko-like surface and a practical strategy to realize switchable adhesion,which sheds light on broad application potential in production lines,medical products,more.

关键词： switchable adhesives dry adhesion gecko bionics magnetic field

Optimized Mask-RCNN model for particle chain segmentation based on improved online ferrograph sensor

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Friction 2024年第6期12卷 1194-1213页

作者： Shuo WANG Miao WAN Tonghai WU Zichen BAI Kunpeng WANG key laboratory of education ministry for modern design and rotor-bearing System Xi’an Jiaotong UniversityXi’an 710049China

Ferrograph-based wear debris analysis(WDA)provides significant information for wear fault analysis of mechanical *** decades of offline application,this conventional technology is being driven by the online ferrograph sensor for real-time wear state ***,online ferrography has been greatly limited by the low imaging quality and segmentation accuracy of particle chains when analyzing degraded lubricant oils in practical *** address this issue,an integrated optimization method is developed that focuses on two aspects:the structural re-design of the online ferrograph sensor and the intelligent segmentation of particle *** enhancing the imaging quality of wear particles,the magnetic pole of the online ferrograph sensor is optimized to enable the imaging system directly observe wear particles without penetrating ***,a light source simulation model is established based on the light intensity distribution theory,and the LED installation parameters are determined for particle illumination uniformity in the online ferrograph *** this basis,a Mask-RCNN-based segmentation model of particle chains is constructed by specifically establishing the region of interest(ROI)generation layer and the ROI align layer for the irregular particle *** these measures,a new online ferrograph sensor is designed to enhance the image acquisition and information extraction of wear *** verification,the developed sensor is tested to collect particle images from different degraded oils,and the images are further handled with the Mask-RCNN-based model for particle feature *** results reveal that the optimized online ferrography can capture clear particle images even in highly-degraded lubricant oils,and the illumination uniformity reaches 90%in its imaging *** importantly,the statistical accuracy of wear particles has been improved from 67.2%to 94.1%.

关键词： wear particle analysis online ferrography particle image acquisition particle chain segmentation

Enhanced micro/nano-tribological performance in partially crystallized 60NiTi film

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Friction 2021年第6期9卷 1635-1647页

作者： Wanjun HE Qunfeng ZENG key laboratory of education ministry for modern design and rotor-bearing System Xi’an Jiaotong UniversityXi’an 710049China

The microstructure,mechanical and micro/nano-tribological properties of the 60NiTi film annealed at different temperature were *** results reveal that annealing as-deposited 60NiTi film at 300,375,and 600℃ for 1 h leads to structural relaxation,partial crystallization and full crystallization,*** with the structurally relaxed structure,the partially crystallized structure exhibits increased hardness but decreased elastic *** is because that the elastic modulus is reduced by Voigt model while the hardness is improved by composite *** to the highest hardness and ratio of hardness to elastic modulus(H/E),the partially crystallized 60NiTi film has the lowest penetration depth and residual depth(i.e.,groove depth).Besides,the results also reveal that ductile plowing is the dominant wear mechanism for all the annealed 60NiTi *** the condition of the ductile plowing,coefficient of friction and wear resistance are related to penetration depth and residual depth,***,the partially crystallized 60NiTi film shows the best tribological performance at the micro/*** current work not only highlights the important roles of hardness and H/E in improving the micro/nano-tribological properties but also concludes an efficient and simple method for simultaneously increasing hardness and H/E.

关键词： 60NiTi film partial crystallization micro/nano-friction hardness ratio of hardness to elastic modulus

Dynamic Vision-Based Machinery Fault Diagnosis With Cross-Modality Feature Alignment

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IEEE/CAA Journal of Automatica Sinica 2024年第10期11卷 2068-2081页

作者： Xiang Li Shupeng Yu Yaguo Lei Naipeng Li Bin Yang key laboratory of education ministry for modern design and rotor-bearing System Xi’an Jiaotong UniversityXi’an 710049China IEEE

Intelligent machinery fault diagnosis methods have been popularly and successfully developed in the past decades,and the vibration acceleration data collected by contact accelerometers have been widely *** many industrial scenarios,contactless sensors are more *** event camera is an emerging bio-inspired technology for vision sensing,which asynchronously records per-pixel brightness change polarity with high temporal resolution and low *** offers a promising tool for contactless machine vibration sensing and fault ***,the dynamic vision-based methods suffer from variations of practical factors such as camera position,machine operating condition,***,as a new sensing technology,the labeled dynamic vision data are limited,which generally cannot cover a wide range of machine fault *** at these challenges,a novel dynamic vision-based machinery fault diagnosis method is proposed in this *** is motivated to explore the abundant vibration acceleration data for enhancing the dynamic vision-based model performance.A crossmodality feature alignment method is thus proposed with deep adversarial neural networks to achieve fault diagnosis knowledge *** event erasing method is further proposed for improving model robustness against *** proposed method can effectively identify unseen fault mode with dynamic vision *** on two rotating machine monitoring datasets are carried out for validations,and the results suggest the proposed method is promising for generalized contactless machinery fault diagnosis.

关键词： Condition monitoring domain generalization eventbased camera fault diagnosis machine vision

Rapid solution for analysis of nonlinear fluid film force and dynamic behavior of a tilting-pad journal bearing-rotor system with turbulent and thermal effects

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Friction 2020年第2期8卷 343-359页

作者： Yingze JIN Zhaoyang SHI Xiaojing ZHANG Xiaoyang YUAN key laboratory of the education ministry for Modem design and rotor-bearing systems Xi'an Jiaotong UniversityXi'an 710049China

To analyze the nonlinear dynamics of a tilting-pad journal bearing(TPJB)-rotor system with high accuracy and speed,the database method(DM)is modified to rapidly determine the nonlinear fluid film force(NFFF)of a TPJB while considering turbulent and thermal effects.A high-accuracy,large-capacity NFFF database for a single pad is constructed by numerically solving the turbulent adiabatic hydrodynamic model for five equivalent state variables of the journal,which are discretized in the pad *** remaining variables are not discretized in the DM.A combined linear and parabolic interpolation polynomial based on the database is established to accurately calculate the NFFF of the tilting pads;thus,the NFFF of a four-pad TPJB is obtained in the bearing *** DM is applied to analyze and compare the nonlinear dynamic behavior of a water-lubricated TPJB-Jeffcott rotor system with and without turbulent and thermal *** present DM solution without these effects and the previous DM solution are shown to be *** results demonstrate the importance of the flow regime and the negligibility of temperature increases in the nonlinear dynamics of a water-lubricated *** work contributes to the accurate and efficient analysis of the nonlinear dynamics of high-speed TPJBs and low-viscosity-fluid-lubricated TPJBs.

关键词： tilting-pad journal bearing nonlinear fluid film force rotor dynamics turbulent flow thermal effect