Table of Content

25 December 2010, Volume 21 Issue 24

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Choosing Optimum and Kinematical Analysis of End-effectors of Chinese Massage Robot

YIN Xiao-Qin, HU Yong-Gen, MA Lv-Zhong, CHEN Xiu-Xiang, GONG Zhi-Jiang

2010, 21(24):  2899-2903. 

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In the light of Chinese medical massage techniques——fluttering

method, pressing method, kneading method and rolling method, the degrees of freedom

(DOF) and application of force of every Chinese massage technique were obtained. According to the DOF,a general design was proposed, particularly, a great variety of parallel

mechanisms. The required swing range and driving force parameter of these parallel

mechanisms based on rolling method by ADAMS were obtained, and the best one

was chosen and made.

The kinematical simulation curves which verified the validity of theoretical analysis were given by ADAMS.Thus, its kinematical performance is fine, and inverse solution and positive solution are simple. It may provide the way for the robot control and commercialization.

An Algorithm for Tool Path Control in Five-axis CNC Machining Proesses

GENG Cong, XU Dong, ZHANG Xiao-Hui

2010, 21(24):  2904-2909. 

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The currently existing 5-axis NC machining systems tend to make axes of rotation vary with feed shaft to realize the control of the tool path, ignoring the problem of the interpolation of tool orientations. This will result in nonlinear errors and collisions between tools and work pieces. Aiming at the problems mentioned above, a novel algorithm for tool path control was proposed. In this algorithm, tool orientations were obtained by using great circle interpolation and NURBS curve fitting method was used to fit orientations produced in the interpolation. NURBS interpolation was also used to obtain the position of each axis in real-time. This algorithm improves machining accuracy and lowers data storage. Finally, the effectiveness and practicality of this method were verified by simulation and actual machining. Results show that the algorithm has advantages of small nonlinear error and smooth transition.

Numerical Simulation on Flow Field inside Micro Hydrocyclone Based on CFD

YUAN Zhi, HONG Hai-Ge, ZHANG Jing, LI Gong-Qing

2010, 21(24):  2910-2914. 

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The meshes and boundary conditions of a micro hydrocyclone were determined. Based on RSM and computational fluid dynamics(CFD) calculation software, the pressure field distribution, velocity field distribution and the path line of the separated medium flowing in hydrocyclone were simulated numerically.The results of numerical simulation were analyzed for flowing distribution characteristics of the separated medium. 

Research on Disturbance Observer for Permanent Magnet Synchronous Motor Driving Hydraulic Pump

ZHANG Gong-Juan, QUAN Long

2010, 21(24):  2914-2917. 

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In a permanent synchronous motor driving hydraulic system,the nonlinear factors such as parameter variations,hysteresis and load disturbance etc. lead to the system performance decrease.The load observer and model following control strategy were adopted respectively to estimate the interference and compensate for the disturbance impact on the system. Simulation and experimental results show the dynamic response time is short, dynamic speed drop is small, and anti-interference performance is enhanced by adopting model following control and it has better steady-state robustness and higher tracking control precision.

Uncertainty Evaluation of Freeform Surface Best Fit Based on Bootstrap Method

CHEN Man-Yi, WANG Jian-Jun

2010, 21(24):  2918-2920,2951. 

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Freeform surface best fit is the foundation of evaluation of freeform surface errors．Using the Bootstrap method which is based on statistical method，joint confidence interval of freeform surface best fit parameters among the measurement data and the nominal geometry can be derived．The uncertainty of the freeform surface best fit can be represented as the joint confidence interval．Bootstrap method is independent of the detailed measurement and freeform surface best fit procedure，which is just an additional numerical analysis procedure．The uncertainty of the freeform surface best fit can be obtained from the measurement data．

Steady-state Characteristics of Proportional Pilot-operated Relief Valve with Low Power Consumption

LI Yong, DING Fan, SHEN Yuan-De

2010, 21(24):  2921-2925. 

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A pilot relief valve based on a low-power proportional solenoid was developed. Considering the nonlinear factors of hydrokinetic, dynamic process of main and pilot valve spools, fluid flow equations of the orifices and fluid compressible equations,a mathematical model of the proposed valve was established and analyzed by the simulation software of Simulink, and the influence of low-power proportional solenoid’s structure and performance parameters on steady-state control characteristics was discussed.The simulation results accord with the experimental ones,show that the proposed valve has excellent stable control and load characteristics, low steady-state power consumption of 8.1W, low temperature rise of stator coil.

Research on Discharge Mechanism and Correction Value of Multi-cutting Based on Composite Cooling Liquid

LIU Zhi-Dong, ZHANG Yan, WANG Zhen-Xin, XU An-Yang

2010, 21(24):  2925-2928. 

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The discharge mechanism and relationship between theoretical correction value and practical correction value of multi-cutting of the high speed WEDM were studied by using composite cooling liquid. The research result presents the electrode discharge still maintaines traditional gap-discharging theory and the practical correction value of multi-cutting is anatomized with theoretical correction value with a comprehensive consideration of different discharging gaps of the first and the last cutting.

High-speed On/off Valve Hydraulic Position Control System Based on DSP

HE Juan, YUAN Rong-Yue

2010, 21(24):  2929-2931. 

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A digital controller for hydraulic servo system based on DSP was designed, where the TMS320LF2407A chip was adopted for the main processor. The controller can enhance the control precision of the hydraulic servo control system and reduce the overshoot, enhance the tracking capabilities, and then achieve real-time control. So it meets the system dynamic control requirements. 

A Class of Centrifugal Flywheel’s Chaos Mathematical Model and Its Linear Feedback Control

CHEN Di-Yi, DAN,LIN,MA Xiao-Xi, CHEN Hai-Chao

2010, 21(24):  2932-2936. 

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Through the analysis of a class of centrifugal flywheel system,this paper gave its mathematical model.By analysing its complex dynamics, such as Lyapunov exponent spectrum, bifurcation diagram, Poincaré diagram,time-domain waveform diagram and the spectrogram,a chaotic mathematical model was established to describe the dynamic process.Then, the control of the centrifugal flywheel system can be converted into chaotic system control. It controlled the chaotic systems of the centrifugal flywheel system by the adaptive control method, and it achieved the goal through the simulation of MATLAB. The results show that chaotic system can be controlled well by adaptive control, and the system can come to a steady state. The control method can greatly improved dynamic performance and anti-disturbance capacity of the system.

Multidisciplinary View-modeling Techniques for MDO of Complex Products

TUN Bao-Gui, JU Gong, LI Diao-Xue, WANG Zheng-Zhuang, LIU Jing

2010, 21(24):  2936-2941. 

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A multidisciplinary view-modeling technique for MDO of complex products was proposed and the master model-oriented multiple disciplines concurrent modeling technical routine was given. Through constructing the process model for multi-level decomposing and mapping of complex product design, the product composing nature of multiple disciplines was analyzed.A multidisciplinary concurrent design approach was

 put forward in order to achieve the independent function and minimum information of each discipline subsystem. The conflict problems of multidisciplinary view-models were solved by means of the consistency rules for modeling and collaborative running strategies. The multi-level application architecture of multidisciplinary view-modeling technique was established by the object-oriented programming method. Based on the integration of optimization technology and CAD/CAE technologies, collaborative simulation and optimization of multidisciplinary view-models can be realized certainly. Also, this technique was used in car-body modeling and simulation for multidisciplinary optimization, the dynamic interaction and multidisciplinary sharing of the design information really come true. The product design level is improved effectively and design efficiency is promoted greatly.

Comparable Study on New and Old Formulas for Calculating DOFs of Mechanisms

and Structures

OU Yang-Fu, CA Han-Zhong, LIAO Meng-Jun

2010, 21(24):  2942-2948. 

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By the study of the factors in main four DOF formulas, checking calculation of about 30,000 examples, analysis and comparisons for years,a new formula was proved to be correct, as well as Kutzbach Qrubler Formula.These two formulas work for all the DOF calculation in plain and space mechanisms,and reveal the basic law of kinetic mechanisms and structures, while others are not refined. It is found

 that for redundant DOF in parallel manipulator, over constraint is surplus DOF, λ, in the new formula.The new formula also involves double meanings of surplus frame, auto-rotating double DOF and surplus DOF and the new concept of sphere contraction, which set a theoretical basis for correctly calculating DOF to make new machines.

Development on Technology of Optimizing Crimp Process about Degreasing Unit 

ZHOU Qiang-Tian, BAI Zhen-Hua, HE Gao, ZHANG Dong-Dong, ZHANG Li-Min

2010, 21(24):  2948-2951. 

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Against the defects of bonding, loose winding, heart-shaped winding that occurred frequently in use of traditional methods to set the crimp process of degreasing unit,after a number of field experiments and theoretical studies,and considering fully the equipment and the technical characteristics of degreasing unit, and also changed the previous thought that the setting value of the coiling tension of degreasing unit usually on the basis of the tabular method. Integrated the degreasing process and the process of hood-type annealing furnace firstly and closely,setting the minimum value of the defects bonding as the optimization objective function, and setting a constraint condition that both loose winding and heart-shaped winding were eliminated,then a new scheme to optimize and set the coiling tension of degreasing unit was put forward. As the variation curve of coiling tension with the change in radius was given in conic form, the optimization method is simple, practical and convenient.By using the technology of synthesized optimization, the distribution of internal stress in steel coil is more reasonable.And it can lessen the probability of some defects in a maximum extent, such as bonding, loose winding, heart-shaped winding and so on. So the production efficiency, quality of product and the rolling yield of downstream unit will be improved.

Non-contact Linear Piezoelectric Actuator Based on Near-field Acoustic Levitation

SUN Yun-Chao, CHEN Chao

2010, 21(24):  2952-2956. 

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Realizing the good prospect of NFAL in application in the fields of aerospace engineering, material science, production line of high purity material and micro-machine assembly, a non-contact linear piezoelectric actuator was designed herein. This actuator, which operated by the acoustic field with high intensity generated by vibration of a Langevin-type transducer, can suspend and transport the objects along the direction of the traveling wave of linear plate. Firstly, through dynamic analysis and structure design, a couple of Langevin-type transducers were manufactured and their dynamic characteristic parameters were measured. Finally, non-contact linear piezoelectric actuator based on NFAL was produced successfully, the maximum unit area weight of which can suspend and transport is 3.06g.

Waveform Restoral of Multiple Mixed Acoustical Source Signals Based on Independent Component Analysis and Wavelet Packet Decomposition

JIAN Su-Xiang, YANG Shi-Ti, JIAO Wei-Dong, HU Gong-Sheng

2010, 21(24):  2956-2961. 

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A new method for acoustical sources waveform restoral was proposed, by the joint use of ICA and WPD.First, the number of incoherent sources in a mixing system was estimated by clustering analysis based on singular value decomposition. Furthermore, original multi-channel acoustical observations were dimensionally reduced according to minimum correlation criterion. Then, independent source components

were primarily extracted from the reduced observations, by the ICA based redundancy reduction. Finally, WPD technique was applied to denoise the extracted source signals. Thus, multiple mixed acoustical sources were separated and their waveforms were restored. Experimental results indicate that the new ICA-WPD based method enable effective separation and correct waveform restoral of acoustical source signals which are mixed and corrupted by strong additive noise, and establishment of a solid base for some succedent applications such as acoustical sources recognition and acoustic diagnostic, etc.

clustering analysis based on singular value decomposition;minimum correlation criterion;waveform

Research on Modeling Method for Virtual Stamping Production Line System of Automobile Panels

LIN Zheng-Yang, SHI Wei-Yuan, ZHANG Wei

2010, 21(24):  2962-2967. 

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Due to the virtual stamping production line system of automobile panels with large-scale assembly model, the modeling method based on one-level assembly relation and assembly skeleton model was proposed in order to improve the real time abilities of interoperating kinematics simulation for huge data digital mock-up under virtual environment. Assembly model was generated by motion skeleton model and sub-assembly model, which was composed of solid model or polygonal representation and its assembly skeleton model. In order to avoid repeat restriction and the complex solution of kinematics simulation, those components with relative motion in the assembly model needed to be parts or products of only one level assembly relation, i.e. “one-level”assembly method. Assembly skeleton model was obtained by restructuring the assembly reference of parts and reflect them on the virtual models in order to make models become parameterized and automated. Motion skeleton model described the motion relation of parts or products by motion pairs. From practical application, this modeling method is approved validated.

Multi-level Design Reuse Method Based on Integrated Model

JIANG Wei-Guang, LU Jian-Sha, SHANG Hong-Chao, WU Jian-Wei

2010, 21(24):  2967-2972. 

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Aimed at the requirements of design reuse in

product development, a design reuse system based on integrated model was proposed to support multi-level and multi-granularity design reuse. Case retrieval system was used to realize similar case retrieval of product and parts, suitable for reuse of design knowledge which was difficult to represent by model. Product structure configuration system could realize rapid structure configuration for a kind of variant products, suitable for reuse of parts’ structure and module. Based on this, parametric system could drive parametric model by mapping property sets, suitable for reuse of parts’ parameters and features. Finally, this method was validated by the development of variant design system of multi-level design reuse for a shock absorber plant.

Parameter Matching and Simulation for Hybrid Electric Bus Power-train System

LUO Yu-Chao, HU Qi-Dong, ZHANG Gui-Lian

2010, 21(24):  2973-2978. 

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A kind of hybrid electric bus structure scheme was proposed herein, and its characteristics was expounded. In the investigation, the power and the torque requirements for the powertrain were calculated by simulation models, and parameters for powertrain components were designed preliminarily. After that, the engine, ISG motor, drive motor and battery energy management were modeled in MATLAB/Simulink. The simulation results show that the parameter design of each powertrain component is reasonable, and the vehicle can achieve predetermined performance goals.

Dynamics Simulation of Double-half-revolution Wheel-legged Rover

HONG Yong-Meng, TU Xiao-Liu, SHANG Wen-Cheng

2010, 21(24):  2979-2982,2988. 

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Taking a double-half-revolution wheel-legged rover as research

object, this paper established its virtual prototyping model, and set the movement coupling relationship among the rods of the wheel-legged mechanism and the 3D collision attributes between the rods and the ground. Dynamics simulations in ADAMS software were done, including walking in flat ground and climbing over the vertical obstacle. Given the angular velocity of the drive motors, the bodywork mass displacement, velocity and acceleration curves changing with time were obtained, and the contact forces between the rods and the ground were also simulated. Simulation results show that the rover has strong vertical obstacle-climbing capability and small perpendicular fluctuation of rover body.

A Topology Optimization Method Based on Memetic Algorithm

CHEN Zhi-Min, DIAO Long-Biao, QIU Gao-Bei, GAO Liang

2010, 21(24):  2983-2988. 

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Topology optimization method was presented based on Genetic algorithms using evolutionary global search strategy can find better solutions, but it search slowly, and need a large number of iterations. Topology optimization method based on Memetic algorithm using evolutionary global search strategy and local search strategy. The local search strategy is abuttal entropy filter method, it searches near the individuals which are generated by evolutionary method.The abuttal entropy filter method

delets some invalid elements in individuals and checkerboard,then it can find a better

individual near the old one.Memetic algorithm inherites advantages of the genetic algorithm to discover the global optimal solution, and overcomes the deficiencies of the genetic algorithm. Using Memetic algorithm to solve some classic examples, compared the results with the solution of using genetic algorithms,the nature and effectiveness of topology optimization method based on Memetic algorithm were described.

Principles and Precision Verification of Synthetic Parameter Examination Instrument for New Type Worm Gear Pair

ZHENG Yong, BANG Dong-Lin, WANG Xian-Quan, YANG Ji-Sen, CHEN Zi-Ran

2010, 21(24):  2989-2994. 

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In order to realize high-precision verification of a worm gear’s transmission quality, a new examination instrument of worm gear pair was developed. The paper adopted the principles combining the traditional TE testing theory by digital counting and secondary subdivision of pulse signals,integrating the new electronics technology such as field programmable gate array(FPGA),to ensure the high-precision and advancement of the instrument. Analysis of the main error source of the instrument was carried out.According to the national standard of worm gear pair，the instrument can be applied to detect the high-precision worm gear pair over 5-level accuracy.

Quantitative Description Model of Surface Integrity for Machined Parts

CENG Quan-Ren, LIU Geng, LIU Lan

2010, 21(24):  2995-2999,3008. 

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The existing standard and development about description and

 measurement of surface integrity for machined parts were summarized. According to the requirements of surface integrity for the parts with precision machining, a quantitative model

of description for surface integrity was proposed and the parameters of characteristics within the description model were definitely detailed. Considering the specific parts and corresponding machining processes, a conceptual model of surface integrity for machined parts was

 established by combining the natures of surface integrity. This research offers theoretical basis and feasible operational framework for the control of surface integrity and improvement of the fatigue life for machined parts.

Dynamics Analysis of Intermittent High-speed Milling

LIN Zi-Xiong, HUANG Xiang, LIANG Rui-Jun, Muhammad Masud Akhtar

2010, 21(24):  3000-3004. 

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A two-dimensional stability analysis model based on the intermittent cutting dynamics was proposed to analyze the bifurcation occurred at a fixed point after losing the stability. The system’s dynamics behavior around the Second Hopf and flip bifurcations was described by the iterative solutions and phase diagrams. Before and after the

Second Hopf bifurcation occurs, the system solution is gone through symptotically

stable to unstable after the bifurcation, the more close to the bifurcation value, the iterative solutions of the system more slowly progressive convergence or divergence.Before and after the flip bifurcation occurs, the system solution is a “jump” stability through bifurcation after “jumping” divergence instability, the more close to the bifurcation value, the iterative solutions of the system more slowly “jump” convergence or divergence;Simulation comparion of one and two dimensional stability analysis models was shown and the experimental verification for the two dimensional model proves the model reliability.

 

Dynamic Analysis for Electric Spindle Rotor System of Magnetic Levitation Grinder Considering Grinding Force

TIAN Jie, LI Xiang-Bin

2010, 21(24):  3005-3008. 

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This paper built an elastic bearing model for the rotor of grinder electric spindle supported by electromagnet bearing and analyzed the mode of the rotor, educed the laws about the rotor inherent frequencies changing along with bearing

stiffness.Then,it analyzed steady state response characteristics of the rotor while applying grinding force. According to the node displacements of danger interface,stability of

spindle system is ensured initially.

 

Influence of Laser Different Waveform on Accuracy of Metal Direct Forming 

DENG Xing, ZHANG An-Feng, SHU Gang-Xian, LI Di-Chen, LEI Bing-Heng-

2010, 21(24):  3009-3013. 

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For the problem fabricating a part with small feature size in

the LDMF process, the influence of laser waveform features on the accuracy of direct metal forming was studied through numerical simulation and experiments. Research shows: compared with the continuous wave, square wave and sine wave have higher rates of heating and cooling, and the square wave has the greatest temperature gradient. Under the conditions of the same average output power, square wave and sine wave make the molten pool reach a higher temperature. As to the same process, direct metal forming with square wave only requires smaller average output power, which reduces the heat input and improves the accuracy of the direct metal forming by reducing the heat-effected zone. The part with smallest feature size can be got by square wave in the process of thin-walled part forming, which improves the accuracy of LDMF.

Effects of Void Content on Mechanical Properties of Carbon/Epoxy Composite Laminates

ZHANG A-Ying, ZHANG Dong-Xin, LI De-Gong, SHU Hong-Yan, XIAO Hai-Yang, GU Jin

2010, 21(24):  3014-3018. 

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Quantitative characterization of void content, distribution, shape, size of the laminates was obtained by ultrasonic C-scan, microscopic inspection and image analysis software. The effects rule of void content on interlaminar shear strength

(ILSS), longitude tensile strength and compress strength were discussed. The results show that the laminate lay up type affects the void distribution; void length, area and aspect ratio increase with the increasing void content; the void content,ILSS,longitude tensile strength and compress strength, and the laminate lay up type affect longitude tensile modulus.

Research on Formation Mechanism of White Layer in Grinding of Annealed Bearing Steel

HUANG Xiang-Meng, ZHOU Zhi-Xiong, YANG Jun, SHANG Ai-Min

2010, 21(24):  3018-3023. 

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During the grinding process of GCr15 annealed bearing steel, the grinding temperature and the grinding force were measured on line by using the thermocouple technique and 3-axis piezoelectric dynamometer respectively.The microstructure，residual austenite content, sub-grain size and micro-strain were detected with scanning electron microscope and X-ray diffraction.The contact stress and plastic strain of grinding surface were simulated by using the finite element method. White layer formation mechanism of annealed steel was discussed. The results indicate white layer consists of cryptocrystalline martensite and retained austenite. The white layer is a product of phase transformation, but may generate at temperatures below the nominal austenitization temperature of the steel. Rapid heating and rapid cooling, plastic deformation and high contact stress result in white layers in grinding process. Plastic deformation and high contact stress can reduce phase temperature and refine crystal grain.