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A combined airfoil with secondary feather inspired by the golden eagle and its influences on the aerodynamics

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Chinese Physics B 2019年第3期28卷 246-255页

作者： Di Tang Zhongyong Fan Mingxia Lei Binbin Lv Li Yu Hao Cui College of mechanical Engineering Zhejiang University of Technology High Speed Aerodynamic institute China Aerodynamics Research and Development Center Zhejiang Museum of Natural History Shenyang Aircraft design and research institute of AVIC

Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.

关键词： aerodynamics large prey secondary feather three-dimensional scanning

Analytical Model of Temperature Field in Unsteady Stage of Friction Plug Welding

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第5期36卷 789-797页

作者： YAN Chongjing ZHENG Yongle College of mechanical and electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China Shanghai Aircraft design and research institute Shanghai 201206P.R.China

The temperature field in unsteady phase greatly affects the quality of friction plug welding(FPW).An analytical model is put forward to correlate the process parameters and the temperature field in unsteady phase of *** the von Mises criterion for plastic deformation and linearizing the heat flux,the model is achieved by Laplace *** predicated peak temperature and peak time agree with the experiment data,with errors of about 4%and 8%,of AA7075-T6 FPW.

关键词： friction plug welding(FPW) unsteady stage temperature field analytical model

Engagement Angle Modeling for Multiple-circle Continuous Machining and Its Application in the Pocket Machining

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Chinese Journal of mechanical Engineering 2017年第2期30卷 256-271页

作者： Shixiong WU Wei MA Haiping BAI Chengyong WANG Yuexian SONG mechanical and electrical Engineering institute GuangdongUniversity of TechnologyGuangzhou 510006China

The progressive cutting based on auxiliary paths is an effective machining method for the material accumulating region inside the mould pocket. But the method is commonly based on the radial depth of cut as the control parameter, further more there is no more appropriate adjustment and control approach. The end-users often fall to set the parameter correctly, which leads to excessive tool load in the process of actual machining. In order to make more reasonable control of the machining load and toolpath, an engagement angle modeling method for multiplecircle continuous machining is presented. The distribution mode of multiple circles, dynamic changing process of engagement angle, extreme and average value of engage- ment angle are carefully considered. Based on the engagement angle model, numerous application techniques for mould pocket machining are presented, involving the calculation of the milling force in multiple-circle continuous machining, and rough and finish machining path planning and load control for the material accumulating region inside the pocket, and other aspects. Simulation and actual machining experiments show that the engagement angle modeling method for multiple-circle continuous machining is correct and reliable, and the related numerous application techniques for pocket machining are feasible and effective. The proposed research contributes to the analysis and control tool load effectively and tool-path planning reasonably for the material accumulating region inside the mould pocket.

关键词： Pocket · Engagement angle · Milling force Circle · High·speed machining

Crystallography of Zr poisoning of Al-Ti-B grain refinement using edge-to-edge matching model

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Journal of Central South University 2013年第10期20卷 2635-2642页

作者：黄元春肖政兵刘宇 School of mechanical and electrical Engineering Central South University Light Alloy research institute Central South University

The mechanism of zirconium poisoning on the grain-refining efficiency of an Al-Ti-B based grain refiner was studied. The experiment was conducted by melting Al-5Ti-1B and Al-3Zr master alloys together. The edge-to-edge matching model was used to investigate and compare the orientation relationships between the binary intermetallic compounds present in the Al-Ti-B-Zr system. The results show that the poisoning effect probably results from the combination of Al3 Zr with Al3 Ti and the decreased amount of Ti solute, for Al3 Ti particles have good crystallographic relationships with Al3 Zr. Totally six orientation relationships may present between them, while they play vital roles in grain refinement. TiB2 particles appear to remain unchanged because of a bit large misfit. Only one orientation relationship may present between them to prevent Al3 Zr phase from forming on the surface of TiB2, though TiB2 is agglomerated. The theoretical calculation agrees well with the experimental results. The edge-to-edge matching model is proved to be a useful tool for discovering the orientation relationships between phases.

关键词： crystallography Al-Ti-B Zr edge-to-edge matching model poisoning mechanism

Multiscale Theories and Applications:From Microstructure design to Macroscopic Assessment for Carbon Nanotubes Networks

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Chinese Journal of mechanical Engineering 2023年第3期36卷 18-35页

作者： Jiachao Ji Yulin Jin Anping Hua Chunhua Zhu Junhua Zhao Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan UniversityWuxi 214122China institute of Mechanics and Advanced Materials School of Mechanical EngineeringJiangnan UniversityWuxi 214122China

Carbon nanotube(CNT)networks enable CNTs to be used as building blocks for synthesizing novel advanced materials,thus taking full advantage of the superior properties of individual *** analyses have to be adopted to study the load transfer mechanisms of CNT networks from the atomic scale to the macroscopic scale due to the huge computational *** them,fully resolved structural features include the graphitic honeycomb lattice(atomic),inter-tube stacking(nano)and assembly(meso)of *** an atomic scale,the elastic properties,ultimate stresses,and failure strains of individual CNTs with distinct chiralities and radii are obtained under various loading conditions by molecular *** dependence of the cohesive energies on spacing distances,crossing angles,size and edge effects between two CNTs is analyzed through continuum modeling in *** mesoscale models,which neglect the atomic structures of individual CNTs but retain geometrical information about the shape of CNTs and their assembly into a network,have been developed to study the multi-level mechanism of material deformation and microstructural evolution in CNT networks under stretching,from elastic elongation,strengthening to damage and *** paper summarizes the multiscale theories mentioned above,which should provide insight into the optimal assembling of CNT network materials for elevated mechanical performance.

关键词： Carbon nanotube networks Hierarchical structures Multiscale theories Mesoscale model

Efficient aero-structural design optimization: Coupling based on reverse iteration of structural model

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Science China(Technological Sciences) 2015年第2期58卷 307-315页

作者： ZUO Ying Tao GAO Zheng Hong CHEN Gang WANG Xiao Peng LI Yue Ming National Key Laboratory of Aerodynamic design and research Northwestern Polytechnical University State Key Laboratory for Strength and Vibration of mechanical Structures Xi'an Jiaotong University Shanghai Electro-mechanical Engineering institute

Traditional coupled multi-disciplinary design optimization based on computational fluid dynamics/computational structure dynamics(CFD/CSD)aims to optimize the jig shape of aircraft,and general multi-disciplinary design optimization methodology is *** special consideration is given to the aircraft itself during the *** main drawback of these methodologies is the huge expanse and the low *** solve this problem,we put forward to optimize the cruise shape directly based on the fact that the cruise shape can be transformed into jig shape,and a methodology named reverse iteration of structural model(RISM)is proposed to get the aero-structural performance of cruise *** main advantage of RISM is that the efficiency can be improved by at least four times compared with loosely-coupled aeroelastic analysis and it maintains almost the same fidelity of loosely-coupled aeroelastic *** optimization framework based on RISM is *** aerodynamic and structural performances can be optimized simultaneously in this framework,so it may lead to the true optimal *** aerodynamic performance was predicted by N-S solver in this *** shows that RISM predicts the aerodynamic and structural performances very well.A wing-body configuration was optimized by the proposed optimization *** drag and weight of the aircraft are decreased after optimization,which shows the effectiveness of the proposed framework.

关键词： aero-structural optimization reverse iteration cruise shape CFD/CSD true optimum semi-coupled

Quasi-static Analysis of Thrust-loaded Angular Contact Ball Bearings Part Ⅱ:Results and Discussion

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Chinese Journal of mechanical Engineering 2012年第1期25卷 81-87页

作者： CHEN Wenhua1,2,MA Zikui1,GAO Liang1,LI Xinglin3,and PAN Jun2 1 institute of mechanical design,Zhejiang University,Hangzhou 310027,China 2 institute of mechanical design and Manufacturing,Zhejiang Sci-Tech University,Hangzhou 310018,China 3 State Testing Laboratory of Hangzhou Bearing Test & research Center,Hangzhou 310022,China 1. institute of mechanical design Zhejiang University Hangzhou 310027 China 2. institute of mechanical design and Manufacturing Zhejiang Sci-Tech University Hangzhou 310018 China 3. State Testing Laboratory of Hangzhou Bearing Test & research Center Hangzhou 310022 China

Ball bearings are widely employed mechanical components characterized by high precision and quality,and usually play important roles in various rotary machines and *** advanced applications require a deep understanding of their various kinematic and tribological characteristics that are essential to predict the fatigue endurance,relieve the vibration and minimize the power dissipation of ball bearings in particular *** angular contact ball bearing under a specified operating condition is simulated with the quasi-static/creepage analytical model proposed in the preceding *** results demonstrate that the ball bearing is a statically determinate *** the balls spin on both inner and outer races means the ball is controlled by neither the inner nor the outer *** friction between the ball and raceway renders the inner and outer contact angles *** larger the coefficient of friction is,the larger the angle *** tangential traction perpendicular to the rolling direction due to the spin induces a gyro-like rotation of the ball with respect to the raceway even if no inertial effects are *** tangential elastic compliance of contacting surfaces gives rise to locked areas within the contact patch and transforms the sliding lines from circles into *** differential slip due to the close conformity of the ball and raceway makes the sliding and traction distributions asymmetric,which will influence the location of the spinning center of the ball with respect to the *** quasi-static/creepage model can be used to reveal the operating behaviors of ball bearings running under steady conditions and to optimize the design of ball bearings for specific applications.

关键词： ball bearing quasi-static creepage differential slip tangential elastic compliance

同方期刊数据库

Fast filtering algorithm based on vibration systems and neural information exchange and its application to micro motion robot

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Chinese Physics B 2014年第1期23卷 159-169页

作者：高娃查富生宋宝玉李满天 State Key Laboratory of Robotics and System Harbin Institute of Technology Department of mechanical design Harbin Institute of Technology

This paper develops a fast filtering algorithm based on vibration systems theory and neural information exchange approach. The characters, including the derivation process and parameter analysis, are discussed and the feasibility and the effectiveness are testified by the filtering performance compared with various filtering methods, such as the fast wavelet transform algorithm, the particle filtering method and our previously developed single degree of freedom vibration system filtering algorithm, according to simulation and practical approaches. Meanwhile, the comparisons indicate that a significant advantage of the proposed fast filtering algorithm is its extremely fast filtering speed with good filtering perfi^rmance. Further, the developed fast filtering algorithm is applied to the navigation and positioning system of the micro motion robot, which is a high real-time requirement for the signals preprocessing. Then, the preprocessing data is used to estimate the heading angle error and the attitude angle error of the micro motion robot. The estimation experiments illustrate the high practicality of the proposed fast filtering algorithm.

关键词： fast filtering vibration system neural information exchange micro motion robot

Temperature Variable Optimization for Precision Machine Tool Thermal Error Compensation on Optimal Threshold

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Chinese Journal of mechanical Engineering 2013年第1期26卷 158-165页

作者： ZHANG Ting YE Wenhua LIANG Ruijun LOU Peihuang YANG Xiaolan College of mechanical and electrical Engineering Nanjing University of Aeronautics and Astronautics School of mechanical Engineering Nanjing Institute of Technology

Machine tool thermal error is an important reason for poor machining accuracy. Thermal error compensation is a primary technology in accuracy control. To build thermal error model, temperature variables are needed to be divided into several groups on an appropriate threshold. Currently, group threshold value is mainly determined by researchers experience. Few studies focus on group threshold in temperature variable grouping. Since the threshold is important in error compensation, this paper arms to find out an optimal threshold to realize temperature variable optimization in thermal error modeling. Firstly, correlation coefficient is used to express membership grade of temperature variables, and the theory of fuzzy transitive closure is applied to obtain relational matrix of temperature variables. Concepts as compact degree and separable degree are introduced. Then evaluation model of temperature variable clustering is built. The optimal threshold and the best temperature variable clustering can be obtained by setting the maximum value of evaluation model as the objective. Finally, correlation coefficients between temperature variables and thermal error are calculated in order to find out optimum temperature variables for thermal error modeling. An experiment is conducted on a precise horizontal machining center. In experiment, three displacement sensors are used to measure spindle thermal error and twenty-nine temperature sensors are utilized to detect the machining center temperature. Experimental result shows that the new method of temperature variable optimization on optimal threshold successfully worked out a best threshold value interval and chose seven temperature variables from twenty-nine temperature measuring points. The model residual of z direction is within 3 μm. Obviously, the proposed new variable optimization method has simple computing process and good modeling accuracy, which is quite fit for thermal error compensation.

关键词： precision machine tool thermal error cluster analysis