Table of Content

10 September 2012, Volume 23 Issue 17

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Representations & Analysis of Spatial Kinematic Chains with Adjacent Matrix Based on Constraint Function

LIU Jiang-Na, XU De-Ge

2012, 23(17):  2017-2022. 

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According to the existing problems of structural representations and analysis methods of spatial kinematic chains, a new method based on constraint function and adjacent matrix was presented. The constraint function in form of vector was firstly defined according to the constraint features of kinematic pairs. Next, the properties of constraint function were analyzed. Then, an adjacent matrix of the kinematic chains with constraint functions as elements was proposed. At last, the topological structures of spatial mechanisms were represented and analyzed by using the constraint function and the adjacent matrix. The results show that the constraint function can be applied to all kinds of kinematic pairs, which can represent comprehensive information about the type, grade, DOF, direction, properties and their changes of kinematic pairs. And the adjacent matrix of kinematic chains can be used for non-instantaneous representations and analysis of all kinds of mechanisms, which can give an overall picture of the number of links and the number, the type, grade, direction, properties of kinematic pairs, as well as the type, DOF and the spatial layout of mechanism. Two examples show the intuition, effectiveness and simplicity of using constraint function of kinematic pairs and the adjacent matrix of spatial kinematic chains to represent and analyze spatial mechanisms.

Research on Size Synthesis of Cam-linkage Mechanism in a Candy Packaging Machine

CHANG Yong-1, YANG Fu-Fu-2, LI Yan-Beng-1

2012, 23(17):  2021-2030. 

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A cam-linkage combined mechanism in an Italian candy packaging machine was researched herein, and then the scientific description was given. It was proposed that two important indices α5 and α2 which characterized and measured the transmission qualification of this mechanism, as well as mechanism synthesis theory and method with the optimal and allowable transmission qualification and the general minimum size under the condition of link initial length s20 were known.  The basic principles of determining allowable roller center zone was obtained by establishing coordinate, introducing swimming coordinate axes and especially proposing instantaneous feasible region and whole travel feasible region. Finally, the determination issues of allowable roller center zone and allowable range of cam basic radius were solved.

Numerical Simulation and Experimental Analysis of Fluid Field for Thermoset Plastic Shear Shredder Cavity

LIU Zhi-Feng, DIAO Jian, TUN Zhong-Wei, DAN Lei

2012, 23(17):  2031-2035. 

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Achieving thermosetting plastics ultra-fine grinding is the prerequisite for efficient recycling. In order to study the flow field patterns of thermosetting plastics during the process of crushing, through simplifying the internal cavity grinder model, ignoring the impact of particles, using the theory of computational fluid dynamics, and applying model of RNG k-ε turbulence and the algorithm of SIMPLER the N-S equations of gas was solved,In connection with several different options of cutter grinder cavity structure, wall structure, and mill speed, the pressure field and velocity field of the cutting shredders were analyzed via numerical simulation, and making the triple helix cutter and ladder wall structure as an experimental test plane. The results show that material can get very small particle under this condition. Tests show that material can get very small particle under the condition and it also generates the free basic particle during the process of grinding, meanwhile the condition of milling group during the process of sampling is found.

Design of Permanent Magnet Biased Axial-radial Magnetic Bearing Based on Accurate Magnetic Circuit

HONG Bei, DENG Zhi-Quan, DIAO Xu-Sheng, LIU Cheng-Zi, HUA Chun

2012, 23(17):  2036-2040,2047. 

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Permanent magnet biased axial-radial magnetic bearing is highly integrated,and can realize axial and radial suspend simultaneously. It has a compact configuration, the volume and weight are reduced obviously. However, its magnetic field distribution is complicated, bias and control magnetic field are coupled. In order to design a magnetic bearing accurately and increase the design efficiency, this paper divided the leakage and soft magnetic material routes according to the 2D FE simulation, established an accurate magnetic circuit including the leakage and soft magnetic material reluctance. The circuit can be used to observe the flux distribution in each route, verified and regulated the magnetic bearing structure parameters, so the FE simulation times of the basic structure parameters were reduced. An experimental sample was designed, 3D FE simulation and experiments were processed to test the design sample. The results show that the design method is rational and right.

#br# CAI System for On-machine Vision Inspection of CNC Milling Machines

JIA Rui-Xue, LEI Rong-Qing

2012, 23(17):  2041-2047. 

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Based on on-machine vision inspection system invented for CNC milling machines, an on-machine measurement CAI sytem was introdued. The CAI system was implemented by C# language programming on the AutoCAD.NET API of the AutoCAD platform. The CAI system functions included element extraction and recognition, path planning, NC codes generation, inspection process simulation, data post-processor and comparison. In the CAI system, an optimal inspection path was generated firstly by a graphic interactive manner according to the requirements of the inspection tasks. Then, the path was translated into NC codes which were used for controlling CNC Milling machines to inspect the measured workpiece. To ensure validity and the security, the inspection process can be simulated vividly by the generated NC codes. At last, the inspection report provided the comparison of measurement values and specification results. The research results show that the proposed CAI system can improve the inspection efficiency and shorten milling cycle.

Research on Free-form Curve Reconstruction Based on an Improved Genetic Algorithm

WEN Xiu-Lan, WANG Dong-Xia, CHENG Dang-Gong, SHU Xiao-Chun

2012, 23(17):  2048-2052. 

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Free-form curve reconstruction method was proposed based on an IGA. The IGA employed real coding and generation-alternation model based on the minimal generation gap(MGP) and blend crossover operators (BLX-α). Compared with conventional optimization methods, it has the advantages of simple algorithm and high optimization efficiency. Firstly, free-form curve was expressed by NURBS. The average value of Euclidean distance between the points on reconstructed curve and measured data was regarded as the objective function. Curve parameterization, knot vectors and the weights of control points were optimized by IGA. Then, the coordinates of control points were calculated by the least square method according to the parametric values of data points and the weights of control points optimized by IGA and then the free-form curve was reconstructed. Finally, the experimental results show the proposed method has the advantages of rapid computation speed, high accuracy of reconstructed curve, and has strong robustness and it can reconstruct free-form curve with different degrees and different numbers of control points. 

Type Synthesis of Dual-driven 2T3R 5-DOF Parallel Mechanism Based on Lie Group Theory

FAN Cai-Xia-1, 2, LIU Hong-Zhao-1

2012, 23(17):  2053-2057. 

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Based on Lie group theory a systematic approach for type synthesis of dual-driven 5-DOF parallel mechanism was proposed. By using the proposed method, a family of dual-driven 5-DOF parallel mechanism with two-translation and three-rotation was synthesized, some new dual-driven 5-DOF parallel mechanisms were obtained。Finally, the calculation of DOF and the selection of active pairs for a novel parallel mechanism were performed, and the result shows that the method of type synthesis proposed herein is correct and feasible. 

Optimization of Cutting Parameters in Helical Milling Process Based on Pareto Genetic Algorithm

WANG Hai-Yan, QIN Xu-Da, LIN Cheng-Jie

2012, 23(17):  2058-2061. 

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Helical milling is an advanced hole-making technique for difficult-to-cut materials in the aviation industry. Rotational speed of the spindle, feed every tooth and depth of cut per revolution in the axial direction are main three cutting parameters in the machining process. The cutting parameters in helical milling of titanium alloy under steady state were optimized by using a Pareto-based multi-objective genetic algorithm (MOGA) with two objectives including material removal rate and tool life. The influence of the cutting parameters on the surface quality of holes was thought over. Finally, experiments were carried out to validate the effectiveness of the cutting parameters.

Research on a Multifunction Sensor Based on Nanocrystalline Soft Magnetic Alloy for Measuring Torque, Rotational Speed and Angular Displacement

DAN Yan-Beng, ZHOU Qiang-Gui, CANG Yong

2012, 23(17):  2062-2065,2070. 

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To improve the versatility of sensor, a new non-contact sensor to measure angle, rotational speed and torque at the same time was discussed. First, the structure and principle based on magneto-elastic effect of nanocrystalline soft magnetic alloy were presented. Second its output mathematical model and sensitivity formula were derived. Finally a measuring experiment was made at 25~100℃ temperature range , 0～450N·m torque range and 500～3525r/min rotational speed range. The testing results are that the sensor's temperature drift is as 0.002 03% F.S/℃ for 25℃, its maximum linearity 0.81% F.S, repeatability error 0.50% F.S, hysteresis error 0.85% F.S and rotational speed maximum relative error 0.70%. The experimental results also show the sensor's sensitivity is as 1.26mV/N·m and measurement precision is as 1.0%, so it can be used for general engineering applications.

Experimental Research of Cutting Parameter Optimization Based on Machining Temperature

CHENG Jing-1, HUANG Cong-Lin-2, LIU Chao-3, ZHANG Bi-Yu-3

2012, 23(17):  2066-2070. 

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Based on the best machining temperature, with the help of cutting experiment, taking the ratio that the value of cutting-tool wear divided by surface area machined on workpiece surface as an evaluating level, a method defining cutting parameters was presented in a manufacturing condition for milling. Firstly, the relationships between cutting speeds and temperatures, the ratios above mentioned, were gained from the experiments. And the relationship between the optimal cutting parameters and temperatures were described. Then, the mechanics of cutting-tool wear at the best cutting temperature was analyzed through the status of its wear. Finally, the optimal equation of the cutting parameters was established. So a new approach to optimize cutting parameters was studied. Further a basic governing was also provided for construction of a cutting database of metal materials.

Model Establishment and Numerical Analysis of Welded Wheel Axle of Four-wheel-juxtaposed Landing Gear

HUANG Ming-Min-1, 2, ZUO Dui-Wen-2, LI Xiang-Feng-2, HONG Hong-Feng-2, WANG Min-2

2012, 23(17):  2071-2074. 

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Aiming to learn the loading formality of a four-wheel-juxtaposed landing gear of large airplane, loading model of its welded main wheel axle was established during the landing process. Finite element analysis was done about the force distribution on the welded main wheel axle by taking plane EL-76 as example. Results show that equivalent stress is greatest in two welding seams, where fracture may take place with highest ratio. The first landed wheel suffers cyclical loading, which may lead to fatigue fracture of the axle.

Research on Intelligent Fault Diagnosis for Large-scale Wind Turbines Based on Ontology

ZHOU An-Mei, XU De-Ge, TUN Xue-Meng, LIU Jian, LI Rong

2012, 23(17):  2075-2080. 

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Aimed at the problem that some fault diagnosis methods for large-scale wind turbines are more complicated and the maintainers are hard to grasp it, an ontology-based intelligent fault diagnosis system for wind turbines was developed. It can assist the maintainers to select the appropriate fault diagnosis methods. The system described the domain knowledge in the form of ontology, and provided an interface for information interactivity. The rule sets for fault diagnosis methods reasoning were built. An ontology-based intelligent fault diagnosis system was built based on Java platform, and it can be used for intelligent fault diagnosis of wind turbines.

Stochastic Topology Optimization of Continuum Structure Based on Stochastic Perturbation

LI Jing-Kui-1, ZHANG Xi-Min-2

2012, 23(17):  2080-2083. 

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A concept of STOD of continuum structure was proposed. Assuming the random parameters of the continuum to meet normal distribution, according to the mean and variance of random parameters, by using method of stochastic perturbation finite element analysis (SFEA), the unit stress's mean and variance were calculated.Using linear congruential random number generators (LCGs), the pseudo-randoms of unit stress were obtained. The unit stress Euclidean distance was used to be as the criterion, and the stochastic topology optimization of continuum structure was gotten by K nearest neighbor (KNN).Finally, the numerical examples were given. 

Design and Experimental Research for Urethra Valve of Bladder Power Pump

LIU Chun-Bao-1, LI Xiao-1, GUAN Ting-2

2012, 23(17):  2084-2087. 

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A mathematical model of the urethra valve was built based on the theories of electromagnetics and hydromechanics. The model was used to analyze the characteristics of the urethra valve effected by different electromagnet current, air gap and so on. The validity of the model was confirmed through the comparison between simulations and experiments. The effects of the urethra valve on the micturition characteristics of the bladder power pump were studied on simulation experimental system. The results show that the increasing of electromagnet current and the decreasing of air gap between electromagnet and urethra valve are beneficial to increasing maximal urine flow rate and decreasing urine flow time. The research provides the basis for characteristics analysis and optimal structure design of the bladder power pump.

Research and Simulation on Characteristic of Hydraulic Power Source under Motor Rotor Broken Bar Fault

CHEN Jiang-Cheng, GU Li-Chen, LIU Pei-Jin

2012, 23(17):  2088-2092. 

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The pulsations of electromagnetic torque, rotational speed and power of the motor caused by rotor broken bar fault were analyzed herein. By means of multi-loop method, a mathematical model of hydraulic power source under rotor broken-bar fault was established. The mechanical parameters, electrical parameters and liquid parameters were simulated. The results show that the input and output parameters of hydraulic power source have different degree pulsation. That due to the edge-frequency components of stator current is coupled to the rotor system. The pulse degree and frequency increase with the increasing degree of fault and load, thus the stability operation of hydraulic power source is influenced. Another conclusion points out the efficiency of hydraulic power source is decreased during the fault. 

Rigid-flexible Coupling Dynamics Modeling of Robot Manipulators and Modal Analysis during Swing

WANG Bin-Dui-1, 2, FANG Shui-Guang-1, YAN Dong-Meng-1

2012, 23(17):  2092-2097. 

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For the robot with flexible manipulators,a rigid-flexible coupling dynamics model was established based on the Jourdain variation principle. Assumed model method was used to transform physical coordinate to modal coordinate, and to decouple the dynamics equations. According to adult arm size, ADAMS was adopted to built virtual prototype for simulation. The element interpolation function was designed. An algorithm was programmed using MATLAB to solve dynamics equations. And angle curves of manipulator obtained by ADAMS and MATLAB were compared. In view of four kinds of material: carbon fiber, aluminum, polyethylene and polypropylene, swing simulation of manipulators were done under the gravity. Figures and tables quantitatively described displacement of end deformation, spectrum and first-order and second-order vibration modal. And deformation and modal parameters were contrastively analyzed. The results show that the natural frequency of the manipulator increases and the transverse displacement of the manipulator end decreases as the ratio of the elastic modulus and density increases. Carbon fiber can be approximately modeled as a rigid body; carbon fiber and aluminum material are suitable for humanoid robot body parts; polypropylene has better integrated performance of the stiffness and flexible. The dynamics and solving method are proper.

Application of Phase-sensitivity Detector in Air-coupled Ultrasonic Testing

WEI Dong-1, ZHOU Zheng-An-2

2012, 23(17):  2098-2102. 

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The signal to noise ratio(SNR) of air-coupled ultrasonic testing is very poor and there is long time pulse residue, so it needs to adopt appropriate signal processing method to enhance the SNR of received signals. Factors which affected the received signals in ultrasonic testing process were analyzed. Phase sensitivity detection technology was presented to process the received signals, and ultrasonic testing information could be acquired by the calculation of phase signals. The principles of super-heterodyne receiver and phase sensitivity detector were introduced, some problems which should be payed attention in ultrasonic testing process were explained. Based on the research results, air-coupled ultrasonic testing system with phase sensitivity detector is constituted. Experimenal results of image testing on carbon fiber reinforced plastic plate indicate that, phase sensitivity detection technology can improved SNR of system and testing effects in evidence.

New Technology Analysis on Metal Strips No-burr Precision Slitting

YAN Qiu-Sheng-1, HUANG Sheng-Wei-2, LI Zhong-Rong-2, BO Ji-Sheng-1, LAI Zhi-Min-1

2012, 23(17):  2102-2106. 

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Based on analyzing the metal strips slitting processing and its main defects as well as the deburring technology, a new technology of metal strips precision slitting with no-burr was proposed. The upper and the lower pair of disc cutter to axial negative clearance and radial positive clearance were set so that the sheet metal surface formed shear incision that not separated,then additional pressure-roller made plastic shear oppression separation, which was ductile fracture separation of the residual material layer in the cutting process to control material stress and strain state. The no-burr precision slitting process is achieved by setting the upper and the lower pair of disc cutter clearance to make the material of cutting edge action zone in compressive stress state and form incision by plastic shear deformation.

#br# Investigation of High Tensile Strength and High Electrical Conductivity Pure Copper Fabricated by Severe Plastic Deformation

DAN Feng-Jian-1, WANG Lei-Gang-2

2012, 23(17):  2106-2110. 

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Microstructure, mechanical property and electrical conductivity of pure copper fabricated by CCDC were investigated. The results show that large strain can be accumulated without changing the shape and dimension of the sample by CCDC, which leads to the grain refinement. The grain size is refined to submicrometer level after 15 passes CCDC through route B. The hardness and tensile strength improve obviously with increasing the number of CCDC. The tensile strength of the copper reaches to 459.1MPa. The elongation to failure of the material decreases, while it is still above 20%. The electrical conductivity decreases with increasing the CCDC number. But the electrical conductivity retains 91.7%IACS after 15 passes CCDC. The results indicate that bulk pure copper with high strength and excellent electrical conductivity can be fabricated by SPD process of CCDC.

Steering Control on Large Curvature Road Based on Preview Optimal Curvature Model

CHEN Huan, LING Dui, LI Shun-Ming

2012, 23(17):  2111-2116. 

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Focusing on the steering control problem of autonomous vehicle on large curvature road, this paper presented a human-like steering control model. By imitating the judgment of human driver from the road state of the preview point, two parallel fuzzy controllers were used to estimate the steering demands independently according to the yaw angle errors and lateral errors respectively. Constrained by the road curvature radius, the output of the parallel controllers was decided by the leverage principle so as to calculate the desired tunning angle of the steering wheel. Simulation results of both double-lane change and perpendicular turn illustrate the good performance which indicates that the proposed method can control the trajectory of the vehicles effectively, which ensures the driving stability and therefore can be applied to large curvature control problems.

#br# Evaluation Method for Structural Performance of Light Bus Body and Its Applications

GAO Yun-Kai, ZHANG Ting-Ting, LIU Hai-Li

2012, 23(17):  2116-2121. 

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This paper presented an evaluation method for performance analyses of light bus body structure, including stiffness and strength, mode of the body-in-white, body interface strength of seatbelt, front and rear impact safety, etc. The proposed evaluation method was applied to study the influence of the wheelbase increase on structural performance. The results can guide the body structural design.

#br# Multi-objective Optimization of Side Impact Based on BP Network Mode

ZHOU Li-Hui, CHENG Ai-Guo, CHEN Chao, DIAO Min, ZHOU Ze

2012, 23(17):  2122-2127. 

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The sampling data of thickness and material of automobile's side body key absorbing energy parts were obtained by the latin experimental design method. By combining approximate technology and multi-objective genetic algorithm, a multi-objective optimization method of side impact structure was established based on BP network model. The results show that: this method meets the requirements of GB20071, it improves the side structure's occupant protection capability, and achieves the lightweight objective, the accuracy and efficiency of BP network model meet the requirements of engineering design.

An Overview and Development Trend of Bearingless Permanent Magnet Synchronous Motors

SUN Xiao-Dong, SHU Huang-Qiu, YANG Ze-Bin

2012, 23(17):  2128-2135. 

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The generation principles of radial suspension forces of BPMSMs were introduced firstly. Then, the key technologies of BPMSMs were also overviewed, including the motor topology, mathematical model, and control strategy. Finally, in accordance with the current issues of the BPMSM technology, several possible development trends of the BPMSM technology were discussed as well.

Current Actuality and Development Tendency of Military Camouflage Technology

YA Yun-Hui, WANG Zhan, DONG De-Wei

2012, 23(17):  2136-2141. 

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Through introducing meaning of camouflage technology, the importance and significance could be understood in the modern war. Several technology of military camouflage areas and its principles and applications were illustrated in detail,including screen camouflage technology,decoy camouflage technology,color camouflage technology, etc. The current situation was discussed on the development of world military camouflage. With the development of technology, it is expounded that camouflage technology is developing towards multiband, pluralism, intelligence. With the applications of more discipline theory, camouflage technology will blend in new methods and new ideas. 