Loading...

Table of Content

    10 July 2014, Volume 25 Issue 13
    Experimental Studies of End-wall Flow in a Four-stage Low-speed Axial Compressor
    Zhang Chenkai, Hu Jun, Wang Zhiqiang
    2014, 25(13):  1705-1711. 
    Asbtract ( )   PDF (735KB) ( )  
    References | Related Articles | Metrics

    Detailed flowfield measurements were made in the end-wall region of a four-stage low-speed large-scare axial compressor test rig. Two ten-hole survey boundary layer probes, one four-hole pneumatic probe, and several dynamic pressure probes each bedded with a high-frequency response Kulite sensor, were designed and manufactured to aid the test. Boundary layer region and mainflow region could be clearly distinguished from the boundary layer measurement results. A few parameters, including boundary layer thickness, displace thickness, momentum loss thickness, energy loss thickness and blockage coefficient were calculated based on the measurements. Results from turbulent boundary layer empirical formula of plate are in good agreement with the measurements, which indicates an excellent way of boundary layer effect estimation. Outlet flowfield of the third-stage rotor, measured by the displacement mechanism driven four-hole probe, shows that the lower end-wall boundary layer thickness is clearly smaller than that of the upper region, which can be contributed to the hub rotation. The evolution trajectory of TLV is identified evidently by dynamic pressure measurements. The maximum aerodynamic load point on the blade moves from the trailing to the leading edge as flowrate decreases, which leads to the forward movement of the tip leakage vortex inception point.

    Design for High-speed Ball Screw Running-life Test Machine Based on Linear Motor
    Tong Liang, Wang Zhun
    2014, 25(13):  1711-1714. 
    Asbtract ( )   PDF (516KB) ( )  
    References | Related Articles | Metrics

    A high-speed ball screw running-life test machine based on a linear motor was designed according to the testing requirements for the high-speed ball screw. A high-speed ball screw running-life test machine which used the linear motor as the loading mechanism, the rotation servo motor for the screw drive mechanism and the programmable multi-axis controller as motion controller, was designed and met the testing requirements of life testing and related parameters of the ball screw in the case of the long-running high-speed, high acceleration, big load under the conditions of continuous stable varying loading. The test results demonstrate the feasibility of the system.

    Design and Sealing Analysis of Ultr-high Pressure Water Cleaning Rotary Device
    Sun Ling, Gong Yongjun, Wang Zuwen, Zhang Zengmeng
    2014, 25(13):  1715-1718. 
    Asbtract ( )   PDF (488KB) ( )  
    References | Related Articles | Metrics

    An ultr-high pressure water cleaning rotary plate was designed for the large wallrust removal climbing robot, the structure and working principles of the cleaning rotary plate were introduced, and the design directing at the cleaning rotary seal was calculated and analyzed. Practical applications show the cleaning plate meets the requirements of little leakage, high rust removal efficiency, and simultaneous drying during rust removal.

    Calculation of Equivalent Linear Damping Coefficient of a Magnetorheological Damper
    Guo Yaohui, Chen Enwei, Lu Yimin, Liu Zhengshi, Xia Zengqiang
    2014, 25(13):  1719-1723. 
    Asbtract ( )   PDF (520KB) ( )  
    References | Related Articles | Metrics

    Based on modified Bouc_Wen model this paper analyzed the performance of MR damper, and the equivalent linear damping coefficient of MR damper was calculated. Based on the modified Bouc_Wen model simulation date, the relationship among the MR damper equivalent linear damping coefficient, control voltage and MR damper movement amplitude was established through the curve fitting regression analysis method, and its accuracy was verified. Results display that the equivalent linear damping coefficient model has higher accuracy, and the relative error is within 1%. For the vibration systems which contained strongly nonlinear and large damping coefficient of MR damper, the new model will greatly reduce the calculation of the vibration analysis and the stability study of the system in a constant frequency value. Besides the model also provides a theoretical basis for the applications of MR damper control.

    Flexible Pneumatic Finger Rehabilitation Apparatus Based on FPA and Its Control System
    Huang Pengcheng, Yang Qinghua, Bao Guanjun, Lin Xue, Zhang Libin
    2014, 25(13):  1724-1728,1743. 
    Asbtract ( )   PDF (581KB) ( )  
    References | Related Articles | Metrics

    Due to the shortcomings in flexibility, applicability and safety of existing finger rehabilitation apparatus, a flexible pneumatic finger rehabilitation apparatus was designed based on FPA, flexible bending joints were adopted based on FPA as a substitue of pure mechanical structure, while it was compressed gas-driven and mainly made by rubber. The control system of the rehabilitation apparatus was designed with three modules according to the tasks required from the finger rehabilitation apparatus with bionic rehabilitation purpose: the pattern recognition module was responsible for identifying the main intention by collectting and analyzing the finger sEMG, and generating training programs of rehabilitation exercise; angle feedback module detected the motion of rehabilitation apparatus by AS5045 in real-time, and feedback data to the host controller; main control module controled the training programs above-mentioned and real-time feedback signals of the rehabilitation motions so as to complete the exercise training. The results show that the steady-state error is less than 0.6° when the bending expectations of the two joints is either 15° or 30°, the proposed control system performs well in the identification of the sEMG, in the detection and the feedback of the rehabilitation motions, as well as in the rehabilitation training, thus proves the finger rehabilitation apparatus proposed and its control system is feasible and effective.

    Research on Abrasive Flow Machining Experiments of Non-linear Tubes
    Li Junye, Xu Ying, Yang Lifeng, Liu Weina
    2014, 25(13):  1729-1734. 
    Asbtract ( )   PDF (608KB) ( )  
    References | Related Articles | Metrics

    In order to discuss the machining mechanism and technology of abrasive flow machining for non-linear tube parts, a common rail tube was employed as the experimental subject. A self-developed abrasive flow polishing solution was used to machine non-linear tubes, and the key processing parameters were obtained during the machining processes. Through the analysis of these processing parameters, dominant relationship between the surface roughness of parts and machining parameters was evaluated quantifiably, the impact of key processing parameters on surface precision of the parts was explored. It is concluded that the abrasive flow machining can improve non-linear tube parts surface quality obviously, and improve the working reliability and service life of non-linear tube parts. The experimental results can provide the technology reference for the optimization of abrasive flow machining theories, and offer the guiding significance for determination of the optimal technology plan of abrasive flow machining non-linear tube parts.

    Error Correction Method for a Detecting Instrument of Joint Bearings' Spherical Sizes
    Shao Dongsheng, Yu Xiaofen, Meng Fanliang, Hu Jinzhong
    2014, 25(13):  1734-1738. 
    Asbtract ( )   PDF (552KB) ( )  
    References | Related Articles | Metrics

    A method of online identification and correction was brought up to direct at instru-ment's characteristics of dedicated to measure different sizes' series workpieces. It could identify and correct instrument systematic errors accurately by online measuring series workpieces and analysising measurement results. This method has advantages of no need of standard components, low-cost and significantly improving the measurement accuracy.Experimental results show that the deviations between the instrument and precision instrument are in 10μm or less,and the maximum measurement error has been corrected from 0.110mm to 0.004mm,by this method the measurement precision of this instrument  is  improved significantly to meet the accuracy requirements of enterprises.

    Design Method of Power Coupling Mechanism Scheme for Double Side Motors Coupling Drive Transmission
    Gai Jiangtao, Huang Shoudao, Zhou Guangming, Li Shenlong
    2014, 25(13):  1739-1743. 
    Asbtract ( )   PDF (500KB) ( )  
    References | Related Articles | Metrics

    According to the characteristics of transmission of tracked vehicle, a new double side motors coupling drive transmission scheme was put forward. Based on planetary transmission components comprehensive analysis method, the basic principle of component combination was given for power coupling mechanism scheme optimum seeking. And the rotational speed and torque mathematical transformation models were set up between input and output. A new characteristic parameter was put forward to represent renewable power utilization as a quantitative evaluation index. So this paper proposed a suitable design method for double input double output coupling mechanism scheme. Accordingly, a coupling mechanism example was designed. The results show that coupling mechanism can realize steering renewable power mechanical recirculation. Compared with double side motors independently drive transmission, power demand of coupling drive transmission is only 0.65 times. Meanwhile, the correctness and feasibility of the design method were also validated.

    Research on Stability Analysis Method of n-order Variable Cross-Section Compression Bars
    Wang Xin, Yi Huaijun, Zhao Rixin, Xiao Hua
    2014, 25(13):  1744-1747,1799. 
    Asbtract ( )   PDF (481KB) ( )  
    References | Related Articles | Metrics

    For the stability of n-order variable cross-section compression bars, the differential equations concerning the flexible curve equation were established. Based on the boundary conditions of neighbored-order, a critical load coefficient equation was built by solving the differential equations. And Newton iteration method was applied to calculate the critical load. As a case of telescopic boom for 1200 ton all-terrain crane, comparison results of calculation were analyzed among Newton iteration method, secant method and stability of ANSYS, which indicate the rationality of the critical load coefficient equation and efficiency of Newton iteration method.

    Maintenance Optimization for Wind Power Generation Equipment Based on Ontology and FTF
    Zhou Anmei, Yu Dejie, Liu Jian, Li Rong
    2014, 25(13):  1748-1754. 
    Asbtract ( )   PDF (759KB) ( )  
    References | Related Articles | Metrics

    To meet the needs of maintenance optimization for wind power generation equipment, an ontology-based fault tree analysis(FTA) method was presented, which was the combination of failure mode effects and criticality analysis(FMECA) and FTA. According to the characteristics of failure modes, the FMECA ontology of wind power generation equipment was modeled from four steps. The fault tree could be deduced from the ontology, then the risk priority numbers of the minimal cut sets were calculated, which was used to guide maintenance plan optimization. The problem that FMECA  could not  investigate multiple failure modes might be solved, and the sharing, reuse and reasoning of maintenance knowledge was realized. The application examples show that the maintenance efficiency of wind power generation equipment can be increased greatly by means of the proposed method.

    Numerical Simulation on Flow Field of Opposed Biconical Cone Screw Seawater Hydraulic Pump
    Wang Xinhua, Gao Yan, Gong Zhiben, Cai Jiaoyan
    2014, 25(13):  1755-1759. 
    Asbtract ( )   PDF (593KB) ( )  
    References | Related Articles | Metrics

    In order to study the effects of pressure on the new-type opposed biconical cone screw seawater hydraulic pump, a three-dimensional model of the new-type pump and the corresponding fluid dynamics model were presented. The flow fields for different pump pressure conditions and different positions of the cone screw rotor were numerically simulated, where the pressure distribution in the sealing cavity and the hydraulic force on the rotor were obtained.Analyses show that, the pressure distribution divided by the meshing lines of cone screws and bush is gradually increased from the inlets to the outlet; the axial hydraulic forces on the two symmetrical cone screws are equal in magnitude but opposite in direction; direction of the hydraulic force on rotor rotates in the opposite direction of rotator's rotation, while the force value is constant.

    Application of Multifractal Detrended Fluctuation Analysis to Severity Identification of Rolling Bearing Damages
    Lin Jinshan, Chen Qian
    2014, 25(13):  1760-1765. 
    Asbtract ( )   PDF (544KB) ( )  
    References | Related Articles | Metrics

    The multifractal spectrum of bearing vibration data was estimated using MFDFA. As a result, the shapes and positions of the multifractal spectrum could be largely determined by the left-end, right-end and extreme points of the multifractal spectrum. Subsequently, coordinates of these characteristic points were used as characteristic parameters for describing dynamic properties of the bearings.MFDFA, together with four conventional temporal statistical parameters, wavelet transform(WT) and empirical mode decomposition(EMD), was exploited to recognize severity of damage of bearing balls and outer-races separately. Each of the Mahalanobis-distance(MD), BP neural network and support vector machine (SVM) algorithms was employed to classify the feature parameters derived from each of WT, EMD and MFDFA. Moreover, the effectiveness of these algorithms in severity identification of bearing damage was compared. The results show that the methods associating MD with MFDFA and associating SVM with WT or EMD perform better than the others. The conclusions drawn in the early work seem to be further confirmed.

    Self-lubricating Performance of Phenolic Resin Bond Abrasive Tools Filled with Inclusion Complex of β-CD and Oleic Acid
    Peng Wei, Guan Jiju, Huang Yishen, Li Wei, Xu Xuefeng
    2014, 25(13):  1766-1772. 
    Asbtract ( )   PDF (841KB) ( )  
    References | Related Articles | Metrics

    The inclusion complex of β-CD and oleic acid was prepared as a filler of phenolic resin-based abrasive tools. The effects of the contents and testing conditions on mechanical and tribological properties of the abrasive tools were investigated. The state of the complex in the abrasive tools was detected and the self-lubricating mechanism of the abrasive tools was analyzed. The results show that the mechanical properties of abrasives decrease with the filling of complex, while the strength and hardness conditions can still meet the using requirements when the content is less than 20%. The filling of complex reduces both the friction coefficient and wear rate of the abrasive tools. Under different loads and velocities, the friction coefficients of abrasives decrease with the filling of complex, and the effects are much better with the increase of loads and velocities, while the wear rate increases in some extent. The oleic acidin the complex is released in the friction process, and the releasing oleic acid works together with β-CD to form a self-lubricating layer on the steel surface. The lubricating layer has effects of self-lubrication, anti-wear and an improvement of the surface quality.

    Study on Climbing Type Current Phenomenon in EDM of Semiconductors
    Pan Huijun, Liu Zhidong, Qiu Mingbo, Tian Zongjun
    2014, 25(13):  1773-1778. 
    Asbtract ( )   PDF (720KB) ( )  
    References | Related Articles | Metrics

    The phenomenon of climbing type current in semiconductor EDM was studied. Results show that the main influence factor that leads to the climbing type current is the changes of the contact resistance. The value of contact resistance is decided by the contact area of the high-temperature region. Properties of climbing type current curve were researched and the influences of temperature, thermal conductivity and phase change energy on contact resistance and current were  discussed. At last, the influences of electric parameters on the machining process  were  researched. It is found that big pulse width, high voltage and small duty ratio can increase the processing efficiency greatly.

    Experimental Research on Dressing of Monolayer Brazed Diamond Grinding Wheel
    Zhang Bei, Fu Yucan, Su Honghua
    2014, 25(13):  1778-1783. 
    Asbtract ( )   PDF (651KB) ( )  
    References | Related Articles | Metrics

    For the sake of high efficiency and precision performance requirements of monolayer brazed diamond grinding wheel, dressing of monolayer brazed diamond grinding wheel with orderly distributed grains was studied. A monolayer brazed diamond dressing tool with orderly distributed grains was used herein during the dressing process of brazed grinding wheel. The dressing method aimed at controlling grinding wheel topography with changes of dressing tool grit size and regulation of dressing speed ratio, which achieved precision manufacturing level of zirconia from the identification of its surface roughness. The topography of grinding wheel was measured and analyzed, and the data indicate that grain height uniformity is improved  greatly as well as grain tip can not be passivated.

    Identification and Optimal Correction for Assembly Design Defects of Diaphragm Clutch Based on Constraint Relationship Net
    Lü Gang, Fan Shouwen, He Xinluo, Zhou Lianxu
    2014, 25(13):  1784-1790. 
    Asbtract ( )   PDF (624KB) ( )  
    References | Related Articles | Metrics

    Association method for assembly design parameters of mechanical products and its constraint relationship judgement functions was proposed, data structure for nodes of assembly constraint relationship net was studied, construction method for assembly constraint relationship net was given, taboo list travel method for assembly constraint relationship net was described, identification models and methodology for assembly design defects based on constraint relationship net were proposed. Starting from design defect node of assembly constraint relationship net, taking the sum of constraint path weights as objective function, correction  paths for assembly design defects were optimized utilizing ant colony algorithm. An example of assembly design defects identification and correction for diaphragm clutch was given, identification and correction results show that identification models and correction methodology proposed herein can identify assembly design defects quickly, and enhance correction  quality and efficiency for assembly design defects effectively.

    Experimental Study on Variations of Surface Topography in Ball/Plane Contact
    Wang Aibin, Liu Kun, Wang Hongtao, Liu Xiaojun
    2014, 25(13):  1790-1794. 
    Asbtract ( )   PDF (520KB) ( )  
    References | Related Articles | Metrics

    Based on experiments, the influences of pressure, lubrication conditions and original surface topography on the surface topography variation of ball/plane contact were researched. Different original surfaces were used in the experiments. A series of ball/plane contact experiments under different pressures and different lubrication conditions were conducted. The surface of the specimens before and after the experiments were scanned by Talysurf CCI Lite Non-contact 3D optical profiler respectively, and characterized by ISO25178. The results show that the pressure, lubrication conditions, as well as the original topography of specimen have an obvious influence on the surface topography after the experiments, and the specific relationship among them is obtained.

    Evaluation Method of Three-dimensional Rough Surface Based on Dual-tree Complex Wavelet Transform Methods
    Ren Zhiying, Gao Chenghui, Lin Jianxing, Shen Ding
    2014, 25(13):  1795-1799. 
    Asbtract ( )   PDF (558KB) ( )  
    References | Related Articles | Metrics

    At present, wavelet transform applied to the establishment of three-dimensional rough surface datum was mainly the first and the second-generation wavelet. However, they had some defects such as the shift variation and poor directional selectivity and so on, especially the selection of optimum wavelet base and the determination of the times of wavelet decomposition, which was always the difficult points of surface evaluation. Now the third generation wavelet DT-CWT was used for valuation of three-dimensional rough surfaces, by comparing the datum errors and maximum reconstruction error of the actual reconstruction images of the three wavelets as well as simulation of three-dimensional rough surface, the optimality of DT-CWT was obtained. Band energy method was employed to ascertain the times of wavelet decomposition and then mean square error S which was the characterization parameter of three dimensional simulation surfaces was used to check the correctness of decomposition times. Finally, the reference surface of the three dimensional nonstationary random rough surface with fractal properties was extracted by DT-CWT transform. The results prove the effectiveness.

    Modeling and Simulation for Giant Forging Hydraulic Press Synchronous Control System
    Liu Zhongwei, Deng Yingjian
    2014, 25(13):  1800-1806. 
    Asbtract ( )   PDF (687KB) ( )  
    References | Related Articles | Metrics

    In order to improve the rapid response of a giant die forging hydraulic press synchronous control system, based on 300MN die forging hydraulic press, the synchronous control system was redesigned according to the characteristics of 800MN die forging hydraulic press, and based on hydraulic theory and dynamics theory, a model of the synchronization control system was jointly established when moving beam run. On the  basis of that, two kind of schemes were compared through simulations, the simulation results show that the new design of  800MN synchronous control system response characteristics is substantially improved, the response speed and dynamic and static precision are of a large improvement.

    Roll Eccentricity Compensation Method Based on Discrete Assistant Closed-loop System
    Yang Yang, Wang Yiqun, Chen Gang,
    2014, 25(13):  1807-1811. 
    Asbtract ( )   PDF (559KB) ( )  
    References | Related Articles | Metrics

    An assistant closed-loop system was constructed for the compensation of roll eccentricity based on closed-loop control theory. In this system, the value of compensation could be obtained from discrete access matrix according to the phase detected or calculated. The compensation deviation, which was calculated by expected value, output value and influence compensation value of former compensation value, revised eccentricity compensation by the assistant closed-loop controller and the former compensation value in discrete access matrix. The assistant closed-loop system realizes rolling optimization, and improves the accuracy of thickness.Conventional eccentricity compensation method and eccentricity compensation method based on discrete assistant closed-loop system were used in strip mill respectively. According to the control effects under the same conditions, eccentricity compensation method based on discrete assistant closed-loop system is more effective and reliable than conventional eccentricity compensation method.

    Study on Multi-parameter Optimization of Occupant Restraint System Based on Global Sensitivity Analysis and Kriging Model
    Ma Tao, Zhang Weigang, Tang Ting, Zhang Yang
    2014, 25(13):  1812-1816. 
    Asbtract ( )   PDF (524KB) ( )  
    References | Related Articles | Metrics

    Aiming at the problems of multi-parameter and high nonlinearity in the optimal design of occupant restraint system, a method of parameters global sensitivity analysis based on Kriging model was raised. This method evaluated the sensitivity of each parameter through calculating the contribution of design parameters to the variance of response. On the basis of these data, the design parameters which were more important to response were chosen as optimization variables, additionally. Multi-island genetic algorithm was used to realize optimal design. The results of optimal design indicate that in contradistinction to initial design values, the value of human injury WIC(weighted injury criterion) is reduced by 11.9%, it provides a good reference for actual engineering design.

    Simulation Analysis of Traction Control for Anti-slip Control of Four Wheel Drive Vehicle
    Hu Jianjun, Yang Zhenhui, Liu Hui, Ge Peng
    2014, 25(13):  1817-1823. 
    Asbtract ( )   PDF (809KB) ( )  
    References | Related Articles | Metrics

    In order to improve the vehicle dynamics and driving stability of full-time 4WD vehicle, dynamic models of engine, inter-axle and inter-wheel electronic limited-slip differential and hydraulic system were established, engine target torque fuzzy controller, inter-axle torque distribution fuzzy controller and inter-wheel torque distribution PID controller were designed. Integrated traction control strategy was proposed, and the acceleration performance was analyzed by simulating on low-μ road, step-μ road, split-μ road and ramp road. The results indicate that the strategy can regulate the drive torque quickly according to the slip of driving wheels, inhibit the excessive slip of driving wheels effectively, improve the dynamic performance and passing ability on bad roads obviously, and show a good adaptability.

    Study on Steering Performance of Hydro-mechanic Differential Steering Mechanism in Tracked Vehicle
    Cao Fuyi, Zhou Zhili, Xu Liyou
    2014, 25(13):  1823-1827. 
    Asbtract ( )   PDF (579KB) ( )  
    References | Related Articles | Metrics

    Generalized method of the dynamic analysis and modelling of mechanical system was used for tracked vehicle steering performance. The grounding track skid(slippage), steering centre offset and etc. was considered in steering process, the force analysis and calculation were finished, and the steering dynamics model of tracked vehicle was established based on hydro-mechanical differential. The model was solved using Newton-Raphson method. A steering performance evaluation index was provided. The steering performance changing trend of tracked vehicle was simulated referring to prototype based on hydro-mechanical differential. It is verified by experimental results that the model can reflect the changing trend of tracked vehicle steering performance. The theoretic basis for hydro-mechanical differential steering mechanism design and running control of tracked vehicle is provided.
     

    Development of Crack Arrest by Using Electromagnetic Heating and Its Applications on Welding Joint Strengthening
    Fu Yuming, Zheng Lijuan, Li Yanfang, Xiang Long
    2014, 25(13):  1828-1837. 
    Asbtract ( )   PDF (761KB) ( )  
    References | Related Articles | Metrics

    The recent research and development progress in electromagnetic heating crack arrest and weld strengthening were summarized from theoretical analysis, numerical simulation and experimental research. By a pulse current generator (model ZL-2) for components, the welded joints with crack were discharged by electromagnetic heating. The test results show pulse discharge can curb the rapid expansion of welding cracks,repair the internal cracks of weld joints and raise the mechanical bearing properties of weld joints.Finally the future prospect of its engineering  applications in the welding field were reviewed herein.

    Development of Large-scale End-effector for Space Station
    Tan Yisong, Ren Limin, Zhang Haibo
    2014, 25(13):  1838-1845. 
    Asbtract ( )   PDF (669KB) ( )  
    References | Related Articles | Metrics

    Researches and applications of large-scale end-effector for space station were introduced. Performance characteristics, key technologies and typical applications of space shuttle end-effector, Canada end-effector, Japan JEMRMS end-effector and European Space Agency end-effector were overviewed in detail. Ultimately, common technologies and future development trends for space station end-effctor were given, which provide a reference for the construction and development of China's own space station.