Table of Content

10 July 2009, Volume 20 Issue 13

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Nonlinear Dynamic Characteristics of NC Table

Wang Linhong,;Du Runsheng;Wu Bo;Yang Shuzi

2009, 20(13):  0-1576. 

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The actions of nonlinear spring force and nonlinear frictional force on dynamic characteristics of NC table were emphatically studied by means of theoretical analysis and experimental verification. NC table was subjected to several kinds of forces such as axial forces, transverse forces, torques, frictional forces and cutting forces etc. Values of every kind of spring stiffness were intimately related to the support types of ball screw. Stiffness values varied with displacement and moving direction of NC table and shown nonlinear regulations such as soft spring property or hard spring property. The varying regulation of frictional force obeyed Streibeck curve. The conclusions are drown,that the effect of nonlinear spring can be described by Duffing equation, the effect of nonlinear frictional force can be described by van der Pol equation, and their coupling effect can be described by Lienard equation. The jump phenomenon caused by soft or hard spring property and the self-excited vibration and creep phenomenon caused by nonlinear frictional force make the stable zone of systemic responses complex.The jump phenomenon takes place under condition that the exciting frequency is close to the natural frequency and the creep phenomenon takes place under condition that the NC table moves at lower speed and in poor lubrication. The existence of limited cycles shows that nonlinear factors are stable factors to limit the unstable phenomenon expend infinitely. 

Transverse Vibration Characteristics of the Moving Paper Tape in Printing

Wu Jimei;Wang Zhongmin;Wang Yan;Wu Qiumin

2009, 20(13):  0-1637. 

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A transverse vibration model of multicolor printing group was established on the assumption that the moving paper tape of web-fed printing press was the rectangular thin film. The differential equations of the moving paper tape was established by regarding restriction on the intermediate printing cylinder as intermediate supporting, which was replaced with constraint reaction of the linear distribution. Then the frequency equation was obtained by Laplace transform method. Finally, the relationship between vibration frequency and velocity of the moving paper tape, and the relationship between vibration frequency and tension of paper tape were analyzed. It provides a theoretical basis for the optimized structural design of printing presses and amendment of the dynamic characteristics of paper tape.

An Improved Assembly Sequence Fuzzy Evaluation Method for Complex Products

Zhao Lei;Li Yuan;Zhang Kaifu;Liu Ping

2009, 20(13):  0-1576. 

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The efficiency of an assembly sequence for complex products is affected by many elements.In order to find the optimal assembly sequence,this paper
presented an improved assembly sequence fuzzy evaluation for complex products,
which combined the quantitative indexes with qualitativeones,and combined the benefit-type rules with the cost-type ones.Then forced decision(FD) was introduced and the most membership function in the fuzzy math was used to actualize the multi-objective fuzzy comprehensive evaluation.A case of aircraft component was also studied and this method can be proven to solve practical applications quit well.

Research on Rod Fastening Rotor Dynamics——axial Vibration

Wang Ailun;Luo Zhou

2009, 20(13):  0-1637. 

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Considering the contact effect of discontinuous interfaces and mechanical properties between nut and tension rod, a dynamics model of rod fastening rotor’s axial vibration was put forward by using bond graph. The theoretical results and experimental ones of an experimental rod fastening rotor’s axial vibration were contrasted. The natural frequency and vibration mode of rod fastening rotor and continuous integral rotor’s axial vibration were also contrasted respectively under different pretightening forces .The contrast results show that the model of rod fastening rotor is more precise than continuous integral model and it can settle the foundation of the further research on rod fastening rotor.

Cutting Force of Single Circumference Edge for Micro Orthogonal Turn-Milling

Zhou Min;Zhang Zhijing

2009, 20(13):  0-1576. 

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Trochoidal moving path of a single circumference edge along feed helix was analyzed in micro orthogonal turn-milling process. Calculation models of moving path equation, cut-in & cut-out angles, cutting depth and cutting width were established in single cutting period, which helped the cutting force analysis. Numerical calculation results and cutting experiments show that cutting force model based on trochoidal path is closer to the real cutting force.

Error Analysis for Pneu-pin Sensor with Differential Pressure

Wang Fengwei;Zhang Hui;Deng Shanxi;Zeng Hanping

2009, 20(13):  0-1637. 

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Based on the pneumatic path of differential pressure type, this paper introduced the design and working principles of the pneu-pin sensor. To improve the accuracy and sensitivity of pneumatic measurement, the main errors were analyzed, such as fluctuation of working pressure, electrical errors, air quality and nonlinear errors. The corresponding methods were adopted to compensate the errors. The measurement range of pneu-pin sensor is about 55μm, with 0.02μm in resolution and less than 0.25μm in static error. Therefore, pneumatic measurement technology researched herein can provide theoretical and experimental bases for high accuracy, high resolution and non-contact dimensional measurement.

Research on Dynamic Spatial Indexing Structure of Triangular Mesh Surface Model

Sun Dianzhu;Liu Jian;Li Yanrui;Zhu Changzhi

2009, 20(13):  0-1576. 

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R*S-tree as a efficient dynamic spatial indexing structure of triangular mesh surface model was proposed, which took the minimum bounding rectangle(MBR) of triangle as its data nodes and the circumscribing sphere parameter of node-MBR were regarded as the optimality principle of the nodes, and the node splitting was realized through clustering by use of k-means algorithm based on new clustering assignation regulation.After that the dynamic spatial indexing structure of triangular mesh surface model was established.And it can improve efficiently the spatial inquiring efficiency on the triangles of triangular mesh surface model, then it has important significance to realize the related geometric operation of triangular mesh surface model quickly.

Dynamic Simulation and Experimental Research on the Crank Press Driven by a Brushless DC Motor

Sun Yousong;Xiao Yang;Shi Guoliang;Wei Hang;Li Mian;Huang Kaisheng;Li Youxin

2009, 20(13):  0-1637. 

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The authors developed an experimental 250kN servo crank press driven by a brushless DC motor. The common asynchronous motor was substituted and the mechanical flywheel and clutch were canceled. A big capacitor was used in the circuit in order to save and release electric energy. Theoretic analysis on the driving and transmission system of the press was carried out and the mathematic model of the electromechanical system was established. Both numerical simulation and experiments were done and the results coincide each other, proving the correctness of the model. The servo crank press can get any desired stroke curves, realizing the working flexibility. The capacitor can run as an "electric flywheel", saving and releasing electric energy and reducing the current shock by 86%.

Design and Research on Driving Device of Puncturing Mud Robot

Zhang Zhonglin;Wang Liquan;Ye Xiufen;Wang Zhuo

2009, 20(13):  0-1576. 

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Through studying on impacting construction of steerable air-powered impact mole in trenchless technology at home and abroad, the driving device of puncturing mud robot was designed. The device machinery characteristics and working principles were recounted and three-dimensional model of the device was established and device virtual assembly was finished. The parameter equation of driving device was educed and effect from main parameter on output capability was analyzed. Based on analysis results, testing of impacting capability about driving device were put up and the academic results of the impacting capability were validated. The testing results indicate also that this driving device can meet puncturing power needs. This paper can provide reference for collectivity design of puncturing mud robot.

Research on Climbing Capacity of Self-reconfiguration Modular Exploration Robots System

Zhang Liping;Ma Shugen,;Li Bin;Zhang Zheng

2009, 20(13):  0-1624. 

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A new self-reconfiguration modular exploration robots system(RMERS) was introduced herein.Three basic configurations of RMERS child-robots
were analyzed in detail: the serial connection with arm ahead; the serial connection with arm behind; and the loop connection with end to end. Taking two child-robots for examples, the statics of every combination for the child-robot systems on slope were analyzed. Based on these, the simulation experiments based on the real model parameters
were researched on the child-robot configurations,and the results show that the climbing capability of different configurations has tight correlation with their connection style. The serial connection with arm ahead is the strongest in climbing.The real experiments validate the simulation results. At the same time, according to the experimental results,it indicates that the stability of the serial connection with arm ahead is worse,and the loop connection with end to end is the best configuration for its stability and good climbing capacity.

Application of Pressure Test System in Fuel Pumping System

Liu Yajun;He Zhanshu;Huang Jiabin;Li Ping

2009, 20(13):  0-1576. 

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There exist too high pressure caused by water hammer, inadequacy of gas-liquid separation and cavitation in fuel pumping system. A pressure test system of fuel pumping system was established by using pressure transducers and digital signal collecting system. Then the influence of flow, pipe length, setting pressure of relief valve and stiffness coefficient of main valve spring on the water hammer peak pressure at the instant of fuel pistol closing was studied according to the detected pressure signals. Finally, the relatively accurate gas-liquid separation value and critical cavitation pressure value of the system was obtained by frequency analysis and wavelet analysis.The pressure test system can diagnose and recognize the pressure of the system in real time and reliably,and provides guideline for performance optimization of fuel pumping system.

Research on the Model Principle of AMFB and Its Interaction with the AMFSDI System

Liu Zijian;Xue Feng;Zhao Shiyi;Li Li;Ai Yandi;Xiang Guangyuan

2009, 20(13):  0-1624. 

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The establishing principles and system architecture of ‘a model with four bodies’(AMFB for short) model were presented. The related manufacturing information system, namely AMFSDI was developed and an example was given. Based on the assumption that the manufacturing information system is a dissipative structure system, the interaction mechanisms between AMFB model and AMFSDI system were analyzed from the aspect of the change of system entropy.The influence of AMFB model’s interaction mechanism on the evolvement of the manufacturing information system was studied using the establishing methodology of the AMFB model and dissipative structure theory.

A Fine Registration Method for 3D Point Clouds in Reverse Engineering

Xie Zexiao;Xu Shang;Li Xuyong 

2009, 20(13):  0-1603. 

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A high-accuracy method was presented for fine registration of two partially overlapping point clouds that had been coarsely registered into a common coordinate system in reverse engineering. The proposed algorithm, which was called dual interpolating point-to-surface ICP algorithm, was principally a modified variant of point-to-surface ICP algorithm. The original correspondences were established by adopting a dual surface fitting approach using B-spline interpolation. A novel “auxiliary pair” constraint, together with surface curvature information, were employed to remove unreliable matches. The combined constraints directly utilized global rigid motion consistency in conjunction with local geometric invariant to reject false correspondences precisely and efficiently. For the two refined corresponding datasets, the least-square method was employed to solve the transformation parameters. The experimental results demonstrate that the new method guarantees accurate fine registration for 3D point clouds.

Simulation of Sliding Wear Based on Finite Element Method and 
Its Application to Wear Prediction of Link Pivot Joint

Su Yuewen;Chen Wei;Zhu Aibin;Xie Youbai

2009, 20(13):  0-1624. 

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A sliding wear simulation approach based on Archard’s wear law was proposed, in which the progressive accumulation of wear in metal pin was simulated with ANSYS software. Removal of material caused by wear was implemented by moving boundary nodes. Possible mesh distortion due to repositioning boundary nodes was settled using boundary displacement method from structural shape optimization. Through discretizing wear process into wear simulation step, total wear volume was calculated using Euler integration scheme. Two block-on-ring experiments were performed to validate above wear prediction method. Then wear problem of pin pivot joint in lifting system was analyzed and predicted with error of 12%. Results show that the complex nonlinear wear process can be simulated with a series of discrete quasi static models based on FEM, and the method proposed can be as an available tool to predict wear problems for engineering.

Research on Calculation Model and Method of Product’s Shape Similarity
Based on the Customer Measured Data

Zhou Hongming，;Chen Yarong;Zhan Yongzhao;Xue Wei;Li Fengping

2009, 20(13):  0-1603. 

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For the geometry matching search that appeared in the product configuration design based on case reasoning, the similarity model of geometric attributes denoted in the different ways was put forward, the objective function about parameter transformation was constructed by using the principle of least squares, the 6 unknown variables were solved by adopting the algorithm of bound constraint BFGS. Based on above, the formula for shape similarity concerned with the customer measured data was set forth, finally a similarity calculation example for the blade geometry was given. The result shows the similarity model for product geometric attribute and the method for similarity calculation are feasible. 

Monitoring of Tool Wear in Hard Milling Process

Shen Zhigang;He Ning;Li Liang

2009, 20(13):  0-1624. 

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When high-speed milling (HSM) technology was applied to the cutting processes of steels in their hardened states, drastical reduction of tool life is a big problem. In order to identify the state of the tool wear accurately and promptly, combinations of signal processing techniques, such as time-domain averaging, discrete wavelet transform and Hilbert spectrum analysis were adopted for extracting relevant features from the measured force signals. Tool conditions were identified directly through the recognition of these features by means of Mahalanobis distance method. Practical application results on a CNC vertical milling machine show that the proposed method is accurate for feature extraction and efficient for condition monitoring of the cutting tools.

Research on Rotor Dynamics with Sudden Change Mass

Wang Zongyong;Lin Wei;Wen Bangchun

2009, 20(13):  0-1603. 

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Dynamic model and equation of a nonlinear rotor system with sudden change mass were established based on rotor dynamics. Using numerical integration method, the influence of working frequency, sudden mass ratio and nonlinear stiffness on axis displacement was studied. Transient time after the mass suddenly changed was defined and the rubbing parameter region was determined. The conclusion indicates that sudden increased mass has huge influence on the axis displacement of both flex rotor and rigid rotor, sudden decreased mass can enhance axis displacement of flex rotor system, too; transient time is related with system damp, axis azimuth when mass suddenly changed and operating frequency; rubbing parameters region will increase with sudden change mass amplitude and mass eccentricity enhancing, and etc.

Characteristics of Gap State with Large Fluid Flow Multi-hole Flushing

Li Lei;Gu Lin;Zhao Wansheng

2009, 20(13):  0-1624. 

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Due to adoption of large fluid flow multi-hole flushing in bunched-electrode EDM, a powerful effective flushing can be obtained. As a result, gap states with new characteristics, such as: no arc, frequent temporary short, long breakdown time lag and increase of gap voltage with decrease of discharge current were discovered. Hence, based on simulations of dielectric fluid flow field, the comparison between multi-hole flushing and traditional injection flushing were conducted to analyze the causes for those gap states.It provides the preparation of special design about monitor, control and pulse generator adaptive systems in bunched-electrode EDM. 

Elasto-quasi-static Analysis of Multi-ring Gear Reducers

Zhang Jun;Song Yimin;Zheng Qibin

2009, 20(13):  0-1603. 

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To obtain actual loading state of the components, a representative MRGR, named three-ring gear reducer featuring a phase-angle difference of 120 degrees, was investigated in details. Key influences were taken into account including the elasticity of high-speed shafts, gear-couplers, meshing teeth and bearings, and additional rotation angle of the supporting shaft. The compatibility conditions of elastic deformations were derived by means of the so-called force-displacement hybrid method. Finally, the elasto-quasi-statics equation of the over-constrained mechanism was developed. By solving the governing elasto-quasi-static equations of the system, the loads and deformations of main parts can be obtained. The comparison between the simulation results and FEA results validates the high precision of the model discussed herein.

Study on Cutting Force for Milling Hardened Steel Arc Path with Micro-end Mill

Wang Xiaochun;Hu Yingning;Cao Jingyuan;Long Weiren;Su Jiaqiang

2009, 20(13):  0-1624. 

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On a high-speed machining center，arc and straight line path constrast experiments were completed by milling 45 hardened steel (HRC52) with 2mm micro-end mill and using single factor method. The aim was to find out the influence laws of cutting parameters on the milling force by analyzing the cutting force signals. The result is that the cutting force is much bigger in straight line path than that in arc path， then a cutting force empiricial formulas under experimental conditions was obtained.

Investigation of Characterization Method for the Contact Fatigue-life of Coating

Piao Zhongyu,;Xu Binshi;Wang Haidou;Pu Chunhuan

2009, 20(13):  0-1603. 

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Fe-based alloy coating was deposited by a supersonic plasma spraying device. The ball-and-disc tester was used to conduct contact fatigue experiments of the coating. Weibull distribution was used to deal with the life data, and Weibull plot was obtained. The life parameters of coating could be obviously abtained through Weibull plot. And the failure probability of random cycle was achieved by Weibull plot under identical contact stress and frictional condition. The result shows this method can be utilized to characterizate and predict the fatigue life of coating effectively.

Research on Impact Motion in Metamorphic Mechanism

Yang Shiming;Jin Guoguang;Yun Jintian;Feng Zhiyou 

2009, 20(13):  0-1624. 

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Impact occurs in metamorphic mechanism when the configuration changes. For discussing the impact characteristics of metamorphic mechanism as its configuration changes, the solution method of instantaneous velocity in metamorphic mechanism at the time just after an impact was researched based upon Gauss’ principle of least constraint and Lagrange multiplier method, and the equations of solving the instantaneous velocity with constraints were obtained. The method was given to solve the impact on links and between kinematic pair elements when the configuration changed. These results may provide a theoretical basis for controlling the impact of metamorphic mechanism.

Development of a Four Wheel Independent-driving and Four Wheel Steering Electric Testing Car

Zhao Minghui;Wang Liandong;Ma Lei;Liu Chao，;An Na，

2009, 20(13):  0-1603. 

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A 4WD-4WS electric test sample car was developed, whose four wheels driven by four independent DC motors, whose rear wheel driven by a stepping motor and steered along with the front wheel.The structure and characteristics of the chassis assembly and the electric assembly were introduced. The road tests of straight running and steering were done, where the wheel driving force was controlled respectively by the identity torque mode and the identity power mode. The tests confirm the sample car being of reliable design and good performance, and offer an important flat-form for systematic doing dynamics experiments and find the optimum power distribution and steering mode.

Research on Harmonic Properties Based Fault Diagnosis Methods of Rotor System Running Up/Down

Zhang Zhanyi;Liu Jie;Ying Huaiqiao;Li Yungong;Yang Jinfu

2009, 20(13):  0-1624. 

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To extract the structural modes and non-linear characteristics of the sliding bearing rotor system during start-up and shutdown processes, a new harmonic properties based method was proposed. Firstly the harmonics can be obtained according to the 3-D spectral map, and then the vibration energy shifting properties among the harmonics was further researched by means of the order energy proportion method based on equal sampling periods. The method is adapted to synthesize the vibration characteristics of a rotor test rig during start-up and shutdown processes, which brings the harmonics and their energy proportion relations among the system to bright. By means of that, the principal fault properties are obtained, which verifies the rightness of the proposed method.

Recent Study of the Effect of Voids on Mechanics Properties of Fiber Reinforced Polymer Laminates

Zhu Hongyan;Li Dihong;Zhang Dongxing;Wu Baochang;Chen Yuyong

2009, 20(13):  0-1624. 

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The effects of void content, void morphology and void size on the mechanics properties of composite structures were discussed from the rational aspects. The research progresses of performance simulation, meso-mechanism model and finite element analysis for composites with voids were described in the view of experiments, and proposed the future research direction of void problem in the fiber reinforced polymer composites.

A New Mathematical Modelling and Simulation Method for Vehicle Ride Comfort

Li Jie;Qin Yuying;Zhao Qi

2009, 20(13):  0-1607. 

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Taking vehicle eight-degree of freedom model as an example, vehicle vibration structure was discreted based on ideas of finite element. Attributes of node displacement were prescribed and method of element transform was given. Factor matrixes of vehicle vibration equation were assembled according to positions of node displacements in vector of structure general displacements. Method of bind disposal was taken according to method of constrain displacement disposal, then mathematical model of vehicle vibration was constructed, which could be solved for displacement responses. The method for construction of mathematical model was connected with pseudo-excitation method, simulation of vehicle ride comfort was carried out. Results show that the method of constructing mathematical model and simulation is simple and easy for engineering applications.

Analysis of Accumulator Matching on Hydraulic Driving Vehicle at fluctuant loading

Shen Jianjun;Feng Zhongxu;Liu Benxue;Zhang Zhifeng;Liu Long;Tang Hongcai

2009, 20(13):  0-1629. 

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The paper probed into a method of control pressure impact using a suit of accumulator on hydraulic driving vehicle, and also built up a mathematical model of pump-controlled motor with accumulator suit. It provides good thoughts in accumulator choice and matching, and also provides a good way in study of dynamic and regulative characteristics of pump-controlled motor system matched with accumulator sufficient or not. At last simulation was made using parameters of the test-bed, and the result indicates that the theoretic analysis is useful.