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Table of Content

    10 November 2012, Volume 23 Issue 21
    Research on Hydrodynamic Lubrication Performance of Journal Bearings Based on General Film Thickness Equation Using CFD Software
    LONG Xiao-Beng, NIU Kun, WEI Sai-Yuan
    2012, 23(21):  2521-2524. 
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    A finite element model for journal bearings possessing the general film thickness equation was established by FLUENT and COMSOL Multiphysics respectively. Three-dimensional simulation was conducted numerically for the pressure distribution of the hydrodynamic journal bearing. The load capacity and the related parameters were calculated under the Reynolds boundary conditions through the programming. Compared CFD results with the numerical results, the following conclusions can be drawn: For non-circular arc bearings and circular arc bearings based on the general profile equation, the hydrodynamic performance of journal bearings calculated by FLUENT and COMSOL Multiphysics are similar to those gotten by numerical calculation. Compared with the circular bearing, the load capacity of the non-circular bearing is improved, which verifies the theory of the general film thickness equation to be correct. 

    Type Synthesis for 6-DOF Novel Parallel Mechanisms Based on POC Set Method
    DENG Jia-Ming, TU Tong-Zhu, CHEN Hui-Beng, LI Yun-Feng, LI Ju, YANG Ting-Li
    2012, 23(21):  2525-2530,2640. 
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    Using topological structure synthesis method based on the POC set,10 kinds of 3-translational and 3-rotation parallel mechanisms were synthesized and the synthesis procedures were given. Then, these parallel mechanisms were classified based on the structure characteristics. This method is easy for mathematical operation and the geometrical meaning and the physical meaning are clear, which may be applicable for both topological structure synthesis of non-over-constrained and generally over-constrained mechanisms. And the existence geometric condition of mechanisms synthesized by this method have generality.

    Generation of Point-contact Tooth Surfaces in Cycloid Planetary Transmission
    YI Wen-Cui-1, 2, CHEN Bing-Kui-1, LI Hai-Xiang-1
    2012, 23(21):  2531-2535. 
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    This paper proposed a formation method of cycloid planetary drive with point contact and a general principle of point-contact conjugated meshing formed by the engagement pair of cycloid planetary drive was also presented. A new way of tooth surface constructed by the tubular enveloping surface was provided.The equations of the tubular surface and the contact curves were derived simultaneously. Based on this method and the theoretical derivations, the forming theory of the tubular conjugate tooth surfaces regarding the conjugate curve as the ridge line was established ultimately. An application for the cycloid planetary transmission was given, the helical tube tooth profile of cylindrical pin tooth was constructed and the selection methods applied in position parameter and the radial of mating tube were developed. The peculiarity of point-contact cycloid planetary drive was welso discussed subsequently. 

    MB-CVT Metal Ring Elastic Mechanics Properties and Energy Loss
    ZHANG Wu-1, 2, LIU Kai-1, CUI E-Hui-1, YUAN Wan-1, DIAO Dong-1
    2012, 23(21):  2535-2541. 
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    This paper proposed a MB-CVT model on the basis of elastic mechanics theory to describe the extension of metal rings. The metal rings were simplified as combined thin wall cylinder model in the arc part and simple tension model in the straight part. The results show that, with the increasing of transmission ratio, the stress-strain in driver pulley increases while decreases first and then becomes increase in the driven pulley. On the contrary, the radial displacement first decreases and then increases in the driver pulley while increases in the driven pulley. Stress-strain and radial displacement of the innermost ring is the maximum, and the outmost ring is the minimum when transmission ratio is constant. The total extended length of ring increases with the increasing of transmission ratio, but decreases when transmission ratio is 1.The linear strain ranges from 0.04% to 0.08% herein. Total power loss scope is 27.15~86.73W, the total power loss is 34.85W when transmission ratio is 1. 

    Finite Element Analysis of Temperature Rise in Liner of Friction Hoist on Sliding
    WANG Jian-1, XIAO Xin-Meng-1, GENG Xiao-Fang-2
    2012, 23(21):  2542-2545. 
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    A Temperature rise analysis model was established considering the influence of viscoelastic on the liner heat physical properties, and analyzed by the finite element method. The influence degrees of sliding speed, liner friction coefficient, heat partition coefficients etc. were given. The temperature which changed greater in the initial stage than the last was proportionaal to sliding speed, liner friction coefficient and the pull on the light side. According to the relationship between the maximum sliding speed and the maximum sliding distance, the hoist protection system should be exerted just in time. Using the model proved by the experiments, the squirm temperature rise was analyzed detailedly, the results indicate that it is not the main reason for the liner performance degradation.

    Tool Axis Control Method for Impeller Tunnel Milling Using Non-orthogonal 4-axis Machine
    TUN Bao-Hai-1, HAN Fei-Yan-1, YANG Jian-Hua-1, QIN Chao-2
    2012, 23(21):  2546-2551. 
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    For milling of  free-form impeller channel using nonorthogonal 4-axis machine,a tool axis control method was proposed, which interpolated tool axis by rotating it through a revolution axis in a constraint surface.Through analyses of the tool axis constraint conditions,a unit cone which met the constraint conditions was established in work coordinate system.An algorithm was presented to calculate initial tool axis of  the clean-up machining,then the interference-free tool axis of every contact point was generated in a clean-up tool path.Sequentially the surface area on the unit cone was calculated, which determined by the corresponding clear-up tool axis,and interpolated clean-up tool axis by rotating it in a same angle on this area to get the tool axis of the impeller channel milling,finally a machine kinematics constraints was established to smooth it.Examples show that the method can calculate the smooth and interference-free tool axis of the impeller channel accurately and efficiently when it is machined by using non-orthogonal 4-axis machine.

    Design and Human-machine Motion Mapping Analysis of an Ankle Rehabilitation Robot
    YI Song
    2012, 23(21):  2552-2556. 
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    A kind of rehabilitation robot was advanced to help the ankle rehabilitation of the disabled. Based on the analysis of degrees of freedom, this ankle rehabilitation robot was structurally based on a 3-PUS/S parallel mechanism. Screw theory showed that this rehabilitation robot could make spherical movements which were the same as those of the human ankle. Furthermore, inverse kinematics was derived for this robot. To solve the problem of the inconsistency between the rotation center of this robot and the human ankle, mapping was made from the human ankle to the rehabilitation robot. Finally, motion mapping was verified by numerical simulation. 

    Finite Element Simulation on Electric Hot Machining
    LIU Xin, XU Wen-Ji, SUN Jing, ZHANG Lin
    2012, 23(21):  2556-2561. 
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    Based on orthogonal regression experiments, an empirical equation for heating resistance of EHM was established, data shows that the cutting current has the largest influence on the heating resistance. This empirical equation was adopted in the finite element simulation (FES), an empirical equation was obtained to describe the temperature rising generated by joule heat of the heating resistance. With 3D cutting model and Umbrello constitutive equations, both 3D finite element simulation and verification experiments were carried out to study the cutting force and temperature field in the EHM, results show that low cutting force appears when cutting current I≥160A, the highest temperature of the cutting area shows at the cutting scrap of the deformation area, the optimal heating current I which gives the correspondent optimal cutting temperature is 168A~190A.

    Mechanical Property Analysis of a Swing-arm Transport Mechanism
    CHEN Zhe-Wu, QING Qi-Xiang, WEN Gui-Lin, HOU Feng-Fei
    2012, 23(21):  2562-2567. 
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    A swing-arm transport mechanism was designed on the basis of the analysis of constraints during the transfer process of inspections, the theoretical analysis and numerical calculation were conducted for the mechanical characteristics caused by serious work conditions by using kinematics and dynamics and the forces of hinged joint on the components were obtained, and every structure part was designed in initial conditions of the obtained forces and the development of prototype machine was finished. The results of theorefical calculation and physical and numerical experiments show that the theory and simulation calculation model are correct and effective, the structure designs are reasonable, and the plan of transfer is feasible. This provides a solid foundation for the follow-up engineering.

    Reconstruction of Reachable Workspace of Human Limbs
    LI Qian, JI Xiao-Min, GAO Feng
    2012, 23(21):  2568-2572. 
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    In order to improve the authenticity of virtual human's motion in the ergonomic assessment, this paper established a motion model of the upper limbs with 7 degrees of freedom. Based on this model and the true angle range of the human joints' activities, all the reachable points of the limb endpoint were calculated, and an optimization algorithm was presented to extract the useful points from the mass of reachable points. By using the reverse software, the optimized reachable points were transformed into three-dimensional reachable space of the upper limbs. Finally, the obtained workspace model was bound to the virtual human and applied in the static or dynamic assessment. It shows that the proposed method can facilitate reachable assessment of upper limbs and rational design of operating devices.

    Effects of Polished Surface Quality on Corrosion Resistance of Stainless Steel Products
    HUANG Jia-1, YAN Qiu-Sheng-1, LU Jia-Bin-1, LIU Bing-Yao-2, CHEN Yong-Jin-2
    2012, 23(21):  2573-2577. 
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    The chemical immersion method and potentiodynamic polarization method were employed to investigate the effects of surface roughness on corrosion resistance of 304 stainless steel in neutral chloridion solution. The results indicate that with increase of the surface roughness, the mean maximum depth and size of the pits increase. The surface openness parameter δ is proposed to characterize the smoothness degree of the polished surface, and it is approximate negatively and linearly correlated with the pits depth and size. The surface openness parameter δ is more greater, the breakdown potential Eb is more higher, the maintaining passivity current Jpass is more smaller and the corrosion resistance is much better. 

    Design and Experiment of Preforming Tube for Bulging-pressing Compound-deforming Automobile Axle Housing
    CUI E-Beng, WANG Lian-Dong, YANG Li-Yun, YANG Dong-Feng
    2012, 23(21):  2577-2580. 
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    A design method of preforming tube for bulging-pressing compound-deforming automobile housing was offered, and the ratio of the sectional perimeter, bulging part of performing tube to the corresponding position of axle housing sample, was defined as sectional coefficient K. For a small automobile axle housing, the forming simulation of preforrming tube on different k values was carried out with software ANSYS, then the boundary dimension of the axle housing was analyzed and the corner radius in the dome part was measured especially, by which the values range of the k was decided. Based on the forming technology determined by the above design method, the axle housing samples were produced successfully with a common press, and the feasibility of the design method was verified by measuring the boundary dimension.

    Virtual Experimental Platform Design for Physical Model of Human Vocal Fold
    CHEN Dong-Fan-1, CHEN Wei-Chao-2, GAO Xiang-2, HAN Xin-Gan-2
    2012, 23(21):  2581-2585. 
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    Difficulty for the human vocal fold invasive research, this paper designed a physical model of the human vocal fold experimental platform. Firstly,this paper described the overall design of the virtual experimental platform and related equipment, and then using 3D modeling software the experimenal platform was design. Finally the paper introduced the physical model of the vocal and the related testing equipment and the experimental verification. The  human vocal fold experimental platform can get many useful experimental data and find the generation of the sound and support disease research.

    Study on View Planning of Eliminating Occlusion and Holes in 3D Digitization of Objects
    CHEN Tian-Fan-1, 2, GAO Cheng-Hui-1, HE Bing-Wei-1
    2012, 23(21):  2585-2590. 
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    Focusing on the problems of occlusion and holes in view planning research,a new method was presented, which could eliminate effectively the problems of occlusion and holes with establishing minimum contain box of the hole boundary point clouds. The whole process of view planning was divided into two parts: the laser scanning view planning of side surfaces and the scanning view planning of hole and occlusion surfaces. The parallel surface of least-square plane about hole boundary points was used as the movement plane of vision system scanning hole surfaces,so the translational motion range of the vision system was greater than the plane range of the minimum contain box,and the point cloud data of hole surfaces were obtained. Finally, experimental results show the effectiveness of this method.  

    Research on Modularity Method of Complex Products Based on BOM
    CHEN Tan-Hui, ZHOU De-Jian, FENG Zhi-Jun, YUAN Hai-Yang
    2012, 23(21):  2590-2593. 
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    A new modular division method based on BOM was proposed herein. Product structure tree (PST) consisted of nodes (part or parts) was formed based on the BOM of complex products, correlation matrix (CM) and correlation graph (CG) were calculated through an analysis of relativity of geometric structure, functional and physics, the degree of modularization (DM) was defined and calculated based on CM and CG. With the optimization of DM, the modular was divided into the range of PST. As an example, the methods were applied to the working unit of loaders, and the method was verified.

    Temperature Data Processing for Breakout Prediction Based on Wavelet Analysis
    ZHANG Ben-Guo-1, LI Jiang-1, WANG Ge-1, SUN Li-Feng-2, ZHANG Zhi-Ke-3
    2012, 23(21):  2594-2596. 
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    A wavelet-based de-noising method was introduced into the breakout prediction system in the continuous casting process to conduct the noise reduction. Temperature data collected by thermocouples was multi-scale decomposed. The threshold was applied to the wavelet coefficients, the temperature signals were reconstructed and the temperature date were de-noised. The trend of the temperature changing can be well shown by the de-noised data results.

    A New Approach for Part Family Search Based on Artificial Neural Network
    WANG Jun, ZHANG Yan
    2012, 23(21):  2597-2600. 
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    It is usually difficult to search for a part family belonged to a new part when production flow analysis is used for part family classification. This paper presented a new approach for part family search based on artificial neural network. In this approach, the relationship between manufacturing process and part family was converted into the relationship between part codes and part family, an artificial neural network was employed to realize the intelligent and nonlinear mapping from part code to part family based on the existing part code,manufacturing process and parts family and  then intelligent part family search can be realized. The principle of the approach, artificial neural network samples, and training process were discussed. The feasibility and effectiveness of this approach was tested with real cases.

    Tracking Control of Robotic Manipulator Using a Hybrid Controller Composed of an Artificial Neural Network and a PD Sub-controller
    HE Gong-Lin-1, LIU Wen-Guang-1, HONG Xiang-2
    2012, 23(21):  2601-2606,2611. 
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    Aimed to make the robot manipulator tracking desired trajectory with high precision, a hybrid controller composed of a FLNN controller and PD controler was proposed. Firstly, a dynamics model of the manipulator was given and the characteristics of the model were presented. Then, the property of the FLNN to approximate nonlinear function unformly was investigated. After that, a control system with two closed control loop was constructed for the robot manipulator, and the error dynamics equation for the system was obtained, and an uncertainty dynamics function for the manipulator was derived. Then, a FLNN was intrduced into the system to approximate the uncertainty dynamics function. Finally, a FLNN-PD controller based on the FLNN's approximation was designed for the system, and a weight learning algorithm was planned for the FLNN. Simulations were performed on that system so as to validate the proposed controller. The results show that the position tracking error and speed tracking error of the robot joints are controlled within ±0.002rad and ±0.1rad/s respectively which means that the a robot based on the FLNN-PD controller is able to tracking desired trajectory with high precision. 

    Efficient 5-axis NC Milling of Spiral Bevel Gears Using Disc Cutter with Concave End and Its Machining Simulation
    LI Geng-Geng-1, DENG Xiao-Zhong-1, 2, WEI Bing-Yang-2, LI Tian-Xin-1, YANG Jian-Jun-2
    2012, 23(21):  2607-2611. 
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    In order to solve the small cutting strip width and low machining efficiency problem when spiral bevel gears were NC machined by ball-end cutter,a efficient machining method of 5-axis NC milling spiral bevel gears by a disc cutter with concave end was presented. Based on the traditional machining theory, spiral bevel gear geometry structure was held. The cutter yaw angle was determined in order to avoid gouge interference. Then the cutter tilt angel was determined according to sculptured surface end-milling theory in order to obtain big cutting strip width. Finally, a spiral bevel gear was NC machined virtually, and the machining method feasibility was verified.

    Crashworthiness Reliability Design of Thin-walled Tube Based on Uncertainly Criterion
    ZHANG Yong, XU Xi-Feng, YANG Yong-Bai, ZHANG Cheng
    2012, 23(21):  2612-2616. 
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    To improve the crashworthiness of thin-walled tube, the high precision approximate models of the thin-walled were established based on the reliability theory and approximate technology,furthermore, a reliability optimization method was proposed based on the product quality engineering. Reliability optimal results meet better the requirements of the crashworthiness and energy absorption of thin-walled tube by comparing to the traditional certain optimal result,and increase the efficiency of optimization design greatly,meantime,which makes reliability of thin-walled tube improve greatly.

    #br# Product Configuration Rules Based on Service Decision Table
    HU Gao-1, LU Yu-Jun-1, CA Jiang-Chao-2, JIA Hua-Wu-3, HONG Yin-1
    2012, 23(21):  2616-2619. 
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    Scholars both at home and abroad had done a large number of researches for product configuration theory, but the technology to extract product configuration knowledge from product service data was absence, so the product configuration rules based on service decision table were put forward herein. The various working condition informations belongs to product service process were sum up as product service characteristics, when product service features as the condition attributes, whether product service features matching service product as decision attributes, an original rough set decision table was built up.The original rough set decision table  was  consistency decomposed,  condition attribute reduced and decision rules fused, then  product configuration rule form of  service decision table was acquired. The case of axis temperature alarm was adopted to explain above research thinking.

    #br# Investigation into Fuzzy PID Active Suspension to Improve Heavy Truck Roll Stability
    CHEN Yi-Jie-1, HE Jie-2, ZHANG Wei-Hua-1, DAN Qin-1, CHEN Mo-Wei-1
    2012, 23(21):  2620-2625. 
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    A self-adaptive fuzzy PID active suspension control strategy was proposed to improve roll stability of a two-axial heavy truck. A 4 DOF model of half truck- bilateral track random excitation road coupled model was developed based on MATLAB/Simulink considering the nonlinearity of air suspensions. Control parameters of PID active suspension were tuned in real-time using fuzzy reasoning and corresponding improvements of roll angle, roll factor was evaluated under step steering, double-lane-change tests. Simulation results indicate that the strategy enhances roll stability under various maneuvers and road levels, while ensuring steering ability.

    Microstructure and Mechanical Properties of CMT Welding-brazing Joint for Dissimilar Materials between Aluminums and Galvanized Steels
    TU Gang, CAO Rui, CHEN Jian-Gong
    2012, 23(21):  2625-2629. 
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    The dissimilar materials, aluminum alloys and galvanized steels were joined by CMT welding-brazing method. Analyzing the macro feature of cross-section, microstructure, the defects and mechanical properties of welding-brazing joints with SEM, EDAX, tension text, it is shown that the lap joints with better properties and better weld appearance are formed between the aluminum alloys and galvanized steels. From the microstructure and formation of weld metal, the cross-section of the joint can be divided into four zones: weld metal, middle interface, transitional interface and zinc-rich zone. There is a continuous and compact inter-metallic compound layers with a thickness of 3~4μm, which is formed in the brazing interface zone between the weld metal and the galvanized steel sheet. The main components of the layer are Fe3Al,FeAl2,Fe2Al5 and FeAl3,then, the zinc-rich zone is mainly composed of aluminum-rich solid solution and residue of Zn. Tensile strength tests show that the joint is fractured in the aluminum  heat affect zone, and the joint strength with 204MPa is obtained.

    Calculation of Pressure and Power Required by Continuous Extrusion of Copper Bus Bar by Slab Method
    XU Meng, DAI Na-Na, ZHONG Yi
    2012, 23(21):  2630-2633. 
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    The pressure and power required by continuous extrusion of copper bus bar was calculated and the analytical expression of the inlet stress of the extending mould was obtained herein. The analytical expression shows the rules of the pressure changing with the variation of thickness and flakiness ratio of products. Taking the torque caused by flash of metal and plug into account, the power required by continuous extrusion of copper bus bar with a specification of 204.5mm×7.5mm was calculated by employing the proposed method, and the results show good agreement with the experimental values. The error of calculation is 12%, and is able to meet the engineering application. Therefore, the proposed method can provide reference for the design of extrusion mould and rational selection of copper bus bar continuous extrusion machine.

    Optimization Design of EV Electro-Hydraulic Composite Braking System Control Algorithm with Multi-boundary Conditions
    LI Yu-Fang-1, ZHOU Li-Li-2
    2012, 23(21):  2634-2640. 
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     According to the characteristics of pure EV power system, an optimization design method of brake force control algorithm of electro-hydraulic composite brake system with multi-boundary conditions was proposed. And based on the analysis of boundary conditions, including the braking strength requirements, ECE regulations, and motor/battery characteristics etc, a reasonable range of brake force distribution ratio was achieved. And braking force distribution approach between the front and rear axles was brought out by considering such factors as the braking strength of demand and using frequency of the various adhesion coefficient roads. And the simulation analysis verifies the rationality and effectiveness of the brake force distribution algorithm.

    Drive Scheme Design and Characteristic Analysis of Multi-range Hydro-mechanical CVT
    XU Li-You-1, ZHOU Zhi-Li-1, BANG Qiao-Li-1, WANG Ban-Ban-2
    2012, 23(21):  2641-2645. 
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    To improve the transmission ratio discontinuity problem during the gear shift process in a multi-gear fixed step ratio transmission of the tractors, a hydro-mechanical CVT for tractors was developed. Taking DFH 1302R tractor as the research object, the stepless speed regulation characteristics, condition of smooth shifting, torque characteristics, power split flow characteristics, efficiency characteristics and tractive characteristics of HMCVT were analyzed. By theoretical analysis, the results show that the designed HMCVT has advantages of wide speed governing range, large power transmission, high drive efficiency and steady transmission, which can meet the requirements of complicated variable working conditions of the tractors. 