Table of Content

10 February 2008, Volume 19 Issue 3

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Control for Floating Raft Isolation System

Zhao Cheng;Chen Dayue

2008, 19(3):  253-257. 

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A semi-active fuzzy sliding mode controller was designed for floating raft isolation system with electro-rheological (ER) damper.Coefficient of sliding mode surface was selected in accordance with Hurwitz stable judgement of sliding mode motion equation. According to reaching condition and the controlled damping force assuring the increment of energy dissipation of stable system, a semi-active fuzzy sliding mode controller was designed.Force transmissibility, input force,and output force response of floating raft isolation system, respectively, under chirp exciting signal and dual-frequency exciting signal were simulated. The simulation results indicate that the performance of floating raft isolation system designed with semi-active static output feedback fuzzy sliding mode control method is remarkably better than those of optimally passive damping.

Study on Micro Multi-tooth Tool of Machining Micro-grooves Inside Micro-heat-pipe

Li Yong;Tang Yong;Xiao Bowu;Li Xibing,

2008, 19(3):  258-261. 

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Separately adopted GCr15 and W18Cr4V micro multi-tooth tools to machine axial micro-grooves inside the cylindrical micro-heat-pipe, a series of experiments have been done by oil-filled steel-ball spinning process to analyze the tool effect, wear and fracture. It was studied how did the tooth-shape of micro multi-tooth tool affect the micro-groove shape and how did the working position of multi-tooth tool affect groove-wall surface roughness and groove path. The multi-tooth tool wear and fracture characteristics were introduced. It is proved that the form of GCr15 tool failure in machining micro-grooves is tooth-broken or tooth-collapsed, and its life is short. Differently, the form of W18Cr4V tool failure is of wear, and its life is long.

Optimal Measurement Configurations for Robot Calibration Based on
Genetic Algorithm

Wang Dongshu;Zhang Wenbing

2008, 19(3):  262-266. 

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The selection of measurement configurations in robot calibration was investigated.Observability index of the robot pose measurement configuration was achieved through singular value decomposition, using the observability index as the optimization objective function,a set of robot measurement configurations were selected with genetic algorithm,so that the effect of measurement and modeling errors in parameter estimation can be minimized.Experimental results demonstrate that its calibration effect is superior to that of the random selection measurement configurations.

Study on Active Vibration Response Suppression for Elastic Linkage Mechanisms Applying Model Predictive Control Method

Li Pengfei;Liu Hongzhao;Yuan Daning

2008, 19(3):  266-271. 

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Based on the discrete state-space equations of linkage mechanisms, a model predictive control (MPC) strategy was proposed for the active control of elastic vibration responses. In order to simplify the control model, the complicated influence factors such as coupling effects between elastic deformation and rigid-body motion of mechanism,geometrical non-linearity due to elastic deformation and high order model responses etc. were treated as disturbances. The predictive model to estimate responses of the linkage mechanism was derived. The MPC method with on-line predictive error correction was adopted for suppressing the elastic vibration of linkage mechanism. By using this control strategy, the on-line calculation time of control system is reduced. Numerical simulation and experimental investigation show the effectiveness of the above presented method.

Offset Loading Coefficient Method on the Intensity Analysis of Lift-arms

Jiang Feng;Li Jianfeng;Li Fangyi;Wang Yuling

2008, 19(3):  272-276. 

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Through the operating cycle analysis of a loaders, the offset loading coefficient was proposed to accurately compute the force of loaders.In this new method, upright loading was considered as a special instance of offset loading.The force analysis of offset loading and upright loading was unified into the same continuous function. And then the stress changing trend of the lifting arms could be analyzed quantificationally by the aid of finite element software.It is shown that the position damaged greatly may be the joints between lift arms and bucket during the offset loading.But the offset loading with a certain extent can not influence the working equipment greatly.CAE model is improved based on the experimental results and the experimental results show the validity of the improved CAE model.

Structural Synthesis of Singularity-free Fully-isotropic Parallel Mechanisms with 2T1R-type

Zhang Yanbin,;Wu Xin;Liu Hongzhao;Zhang Minghong

2008, 19(3):  277-281. 

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A systemic method of structural synthesis was presented, which was used to achieve singularity-free fully-isotropic three-degrees-of-freedom spatial parallel mechanisms with 2T1R-type. 24 novel uncoupled and 24 fully-isotropic solutions are obtained. The Jacobian matrix linear mapping velocity vector space of the actuators and the moving platform of the fully-isotropic parallel manipulators proposed herein is the identity 3×3 matrix throughout the entire workspace, so all the mechanisms are singularity-free. The difficulty of control problem of parallel manipulators was resolved because there existed a one-to-one corresponding relation between the velocity space of actuated joints and the velocity space of moving platform. Moreover, design principles of limbs for the fully- isotropic parallel mechanism were explored.

Study on Energy Ratio of SDDC Hydraulic Connector

Wang Kexiong;Guo Qing;Zhang Jin

2008, 19(3):  281-284. 

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The energy equation of SDDC mode hydraulic connector was established during working, on the basis of analysis of energy transformation and utilization. According to the energy equation, a calculation model was set up, for single compact energy, compact frequency, and hydraulic energy ratio. At the same time, the influences of pump rate and pressure, dimensions and hammer mass on working process and hydraulic energy utilization were obtained. The results indicate the single compact energy, working frequency, and hydraulic energy ratio increase while the pump rate and rate increases. Also, the dimensions and hammer mass have obvious effects on the hydraulic energy ratio.

Measurement with CMM and Transmission Quality Evaluation of Globoidal Cam Profile Surface

Ge Rongyu;Feng Xianying;Song Xianchun;Yang Guanglei

2008, 19(3):  285-288. 

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Based on the analysis of the mathematic model of globoidal cam profile surface, the coordinate measuring machine was used to inspect the point coordinates of cam profile with the equal radius. A point by point comparision method was described with which all the measured data were used to calculate the position relation between the measuring coordinate system and the cam coordinate system. A least squares B spline fitting method was also introduced to approximate all coordinate data in the cam coordinate system. Based on the conjugate relations at the contact point between the fitted curve and the follower, the real follower movement can be solved to evaluate the transmission quality of globoidal cam profile surface. At last, a practical example was given to show the effectiveness and usefulness of the proposed algorithm.

Error Modeling and Analysis of Spiral Bevel Gear Grinder with Six Axes Five Linkages

Chen Shuhan;Yan Hongzhi;Ming Xingzu;Zhang Rong

2008, 19(3):  288-294. 

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Taking spiral bevel gear grinder with six axes five linkages as the object, multi-body system theory was utilized to establish the grinder synthesis error model and obtain six degrees of freedom error expressions in this model as well as the experimental confirmation. Additionally, the changing rule between the six errors from three kinds of movements of the spindle and the grinding wheel tool point six degrees of freedom errors were analyzed separately. The error tendency of teeth space of gear, helix angle, pitch, tooth profile was discussed. This study offers a theoretic basis for the design and the error compensations of spiral bevel gear grinder with six axes five linkages.

Optimal Design of Parallel Manipulator Based on Configuration Bifurcation

Chen Weishan;Chen Hua;Xie Tao;Liu Junkao

2008, 19(3):  295-299. 

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For a given set of motion input parameters, the parallel manipulator is possibly at the states of configuration bifurcation. In order that the parallel manipulator can move at will when the lengths of links changed in determinate regions, we optimized the mechanism by considering configuration bifurcation. Based on the idea of analyzing the movement state of parallel manipulator in link space, sixteen kinds of extreme poses for 6-DOF parallel manipulator were described with the vector expressions of link lengths. In order to avoid configuration bifurcations, the bifurcation characteristics of extreme poses were analyzed by homotopy method and static bifurcation condition. The kinematic controllable condition of the designed manipulator was analyzed, which makes the manipulator controllable in the length area of links.

Hardware-In-Loop Simulation of HEV System Based on CAN

Hu Jianjun;Zhao Yusheng;Qin Datong

2008, 19(3):  300-304. 

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Using the ISG type mild hybrid electric vehicle(HEV) as research object, a Hardware-In-Loop simulation system of hybrid electric powertrain had been built by using dSPACE. A Hardware-In-Loop simulation experiment of hybrid electric powertrain control unit was carried out based on CAN, and the dynamic characteristics of hybrid electric powertrain was tested and analyzed under different working modes such as engine start-up, accelerating assist and battery charging at equable speed. The research lays a foundation for control strategy optimization of hybrid electric powertrain control unit.

Compression of B-spline Based on Local Coordinate Second-order Prediction

Liu Jun;Wang Qifu;Chen Liping;Liu Yunhua

2008, 19(3):  304-307. 

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To reduce the data size of CAD product model, we presented an algorithm to compress the B-spline curves and surfaces based on second-order prediction in local coordinate system. The algorithm procedure included constructing local coordinates for control points,first-order prediction in local coordinate system,second-order prediction,quantization and entropy coding for second-order prediction errors.We analyzed the curve and surface distortion brought by quantization. Experimental results show that of the prediction error is lesser and the distribution is more centralized than that of the previous work.The algorithm can obtain higher compression ratios.

Study on Modeling of the Product Design Knowledge Based on Task-structure

Wang Ke;Liao Wenhe;Guo Yu;Yu Feng

2008, 19(3):  308-313. 

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This paper presented a task-structure modeling and a PCM (propose-critique-modify) method for product design knowledge modeling, based on analysis of application characteristics of product design knowledge. A united product design task decomposing structure for standard products, optional products and series products was proposed, and was figured with an tree and/or chart. A knowledge model of four layers structure was presented, by the model, knowledge can be organized at hierarchical classification, and expressed with different forms of knowledge. The paper also designed a working-sheet for acquiring design knowledge, it helps to unify knowledge acquiring and knowledge bottleneck analysis. A case-road pavers design knowledge model was presented herein.

Tool Path Generation for 2D Profile Nesting Machining

Wang Yuguo;Zhou Laishui;An Luling;Jia Tongming

2008, 19(3):  313-316. 

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A new tool path generation algorithm was presented to eliminate interferences,when nesting convex mold and concave die were machined with tool paths calculated by offsetting the 2D profile directly. In the algorithm, after only three times profile offsetting, both tool paths for machining convex mold and concave die can be calculated simultaneously. And profiles composite of free form curves can also be dealt with.Finally,the examples were given to validate the algorithm.

Study on RP Paths Ordering Problem Considering Potential Start-point Effect

Huang Xiaomao;Ye Chunsheng;Mo Jianhua;Huang Shuhuai

2008, 19(3):  317-320. 

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Two mathematical models were presented for paths ordering problem (POP) in rapid prototyping (RP), considering universality of POP. Theorems were also presented and proved for how to traverse a path and predigest a non-loop-path. After conception of potential start-point had been brought in, a global greedy method for paths ordering problem (GGM-POP) was designed based on potential start-points (not only original start point) of all paths. Better global result can be brought out by this algorithm, which fits all POP and largely expands search boundary and avoids dependency on original order of point in a path.

Multidisciplinary Coupling Analysis on Shaft-bearing System Considering Misalignment Caused by Shaft Deformation

He Zhixian, ;Gui Changlin;Li Zhen, ;Sun Jun

2008, 19(3):  321-327. 

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Multidisciplinary coupling analysis on dynamics, tribology, strength and stiffness for a shaft-bearing system was studied herein,considering misalignment caused by shaft deformation on variable load. The effect of the misalignment upon dynamic behavior, tribological characteristic of the system,and dynamical stress distribution on journal surface was discussed emphatically.Commercial software ADAMS and ANSYS assisted with self-designed programs were applied to solve the problem. Numerical results show that dynamic stress distribution on the journal surface is related to the relevant distribution of dynamic oil pressure and the variation of stress about time is decided by the dynamic response. Mechanical behaviors such as dynamic response of the system,lubrication,and dynamic stress on journal surface are changed when misalignment of journal is considered.

Quantitative Analysis of Roughness Effect on Fatigue Life of Specimen with Open Holes

Liu Jun;Liu Yongjun;Liu Yongshou;Yue Zhufeng

2008, 19(3):  327-329. 

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The fatigue testing of the specimen with a central open hole was carried out to investigate the influence of the surface roughness on the fatigue lifetime. Fracture morphology investigations were used by scanning electron microscope. The reliability analysis of specimen was carried out by detail fatigue rating.

Design of a Micro-scale Silicon Film Bending Fatigue Testing Device Based on the Resonance Principle

Ding Lei;Shang Deguang;Zhang Dacheng;Jia Guanhua;Li Haoqun

2008, 19(3):  330-334. 

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A novel micro-scale silicon film bending fatigue testing device based on the electrostatic force by comb driver was designed,which can be fabricated by means of the typical surface micromachining technology.The capacitance and the electrostatic force were analyzed theoretically for the designed arc-shaped comb driver. Based on the results of theoretical deduction,the device was analyzed by the modal and harmonic modules of the finite element analysis software ANSYS.The simulation results show that when the applied AC voltage frequency corresponds to the first frequency of the device,the specimen can obtain the maximum stress at the root of the notch. The maximum stress is proportional to the product of the applied DC bias voltage and AC voltage, which is used to evaluate the range of the test voltage.The analysis and observation of the fabrication results indicate that the designed device can satisfy the test requirements perfectly.

Research on Flatness Pattern Recognition Method Based on Virtual Instrument

Wang Yiqun;Liu Jian;Li Lianping;Ning Shurong

2008, 19(3):  334-337. 

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The paper introduced the working principle of flatness signal measurement on pneumatic flatness measuring roller, developed a flatness pattern recognition system by virtual instrument LabVIEW, which was made up of polynomial least square method, orthogonal polynomial least square method, fuzzy pattern recognition based on Euclidean distance. By measuring on-line tension signal of cold mill aluminum stripe on pneumatic flatness measuring roller, three flatness pattern recognition methods were applied respectively. Test shows the flatness pattern recognition system possesses good stability and validity, and good real time measurement and graphics interface communion capability of system provide significant foundation for flatness closed loop control.

Two-layer DSM Method for Multi-tech System Product Design

Zhao Liang;Xu Zhengrong

2008, 19(3):  338-342. 

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To solve the problems in multi-tech system product design such as the low efficiency and frequent reworking as well as iteractive processes,the two-layer design structure matrix(DSM) method was presented.Plastic injection molding machine system design was taken as an example,and the design information was described into two levels to illustrate the optimization principle and assessing criteria. Additionally,the key mission was picked up and the relationship between two layers was built,then accomplishing the transform from complex relationship within coupling missions to simple processing communication.The result demonstrates that the optimization about process planing works with less reworking,simple coupling and clear process.

Development System for Large Rock Model Based Virtual Instrument Depository

Mao Yongfang;Yin Aijun;Qin Yi;Qin Shuren

2008, 19(3):  342-346. 

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The paper introduced the concept of rock model,and based on the analysis of resources in the rock model based large virtual instrument depository,the concept of intelligent system whose model and construction were introduced in detail was employed to realize the automatic assembling of the virtual instruments.And the scheme to realize automatic assembling of virtual instruments was discussed,which included the layered management of resources in the instrument depository,the rule set building up for the intelligent development system of the virtual instruments,the systematic input and output determining, and finally employing the neural network to implement automatic assembling of virtual instruments.The automatically assembling of virtual instruments reduces the demand of experience and knowledge for virtual instrument development, and promotes the wide use of virtual instruments.

Compositive Characteristics of Vibration and Current of the Generator Air-gap Eccentric Fault

Wan Shuting;Kong Jiangsheng

2008, 19(3):  347-350. 

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The generator stator winding parallel branches circulating current characteristics on air-gap eccentric fault were analyzed. Firstly, the expressions of electromotive force difference between stator winding parallel branches were gotten on generator normal operation conditions. Then through analyzing the parameter changing on air-gap eccentric fault, the circulating current characteristics were gained based on the expressions, which were that fundamental circulating current will increase on air-gap eccentric fault, and the compositive characteristics of vibration and current of air-gap eccentric fault were gained. Finally, the data of a type SDF-9 generator on the fault was measured in laboratory to verify the theoretical analysis presented above. On the other hand the relationship between mechanical fault such as air-gap eccentric fault and electric characteristic was found out, and electric signals can be as the symptom of mechanical faults，and the new idea and method for study the mechanical fault was provided.

Real-time Identification and Prediction for Intelligent Control of Rectangular Box Drawing

Su Chunjian;Zhao Jun;Guan Yingping;Ma Rui

2008, 19(3):  351-354. 

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In the four basic factors on the intellectualization of sheet metal forming, the real-time identification of the material performance parameter and the prediction of the optimum technological parameter are the most complicated ones. The accuracy of identification and prediction will have direct effect on the success of the intelligence control. Taking the intelligence control of rectangular box as an object of study, feed forward neural network model based on LM algorithm had been established to realize material properties and friction coefficient for deep drawing of rectangular box. By means of real-time monitoring and measuring to identify the material performance parameters and to predict the optimum technological parameters, and a satisfied accuracy of convergence is achieved.

Brazing of Diamond by Ag-Cu-Zn Alloy with Cr Powder and the Microstructure of the Interfaces

Zhou Yumei;Zhang Fenglin;Wang Chengyong

2008, 19(3):  354-357. 

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Cr powder was added between Ag-Cu-Zn alloy and diamond grits to braze diamond on the steel substrate by means of high frequency induction heater. Brazing alloy has well wet ability to diamond and the high bonding strength can be achieved between diamond and brazed alloy. By observation of optical microscopy，scanning electron microscopy，electron energy spectrum analysis and X-ray diffraction, the microstructure of the interfaces on steel substrate- brazed alloy-diamond were investigated. Two transition layers are found in the places which the Ag-Cu-Zn alloy is near the steel substrate and the diamond respectively, another transition layer is found on diamond itself. Main reactive phases between Ag-Cu-Zn alloy and diamond are Cr₇C₃ and lead to the high bonding strength between them.

Study on Metal Crack Mode under Laser-shock Processing

Ren Xudong;Zhang Yongkang;Zhou Jianzhong;Gu Yongyu;Zhou Lichun

2008, 19(3):  358-360. 

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The relationship of the tip of the crack dynamic stress intensity factor and the velocity of the crack propagation in the metal sheet and laser shock parameters were investigated. A new mode of the tip of the crack was put forth by the theory of fracture dynamics, and then the dynamic stress intensity factor of the crack under the laser shock wave was also obtained. And superposition method was adopted to add dynamic stress intensity factor arisen by the external load and dynamic stress intensity factor arisen by the remains residual stresses. Transformation on the characteristics of aerial alloy Ti6Al4V by laser shock processing and influence on the fatigue life with these transformations were studied.The influence of surface residual stress by laser shock processing and the outer load on crack propagation velocity was discussed. Utilizing these solutions the crack initiation life were developed to evaluate exactitude.

Auto-body NVH Structure Sensitivity Analysis Based on Modal Analysis Method

Yang Bo;Zhu Ping;Yu Haidong;Han Xu

2008, 19(3):  361-364. 

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A SUV auto-body noise,vibration,and harshness(NVH) structure sensitivity was analysed,considering the structure-acoustic coupling based on the modal analysis method.The structure and acoustic vibration mode were gained from coupling analysis while inner noise level from frequency analysis.The given methods reduce noise by identifying the main source to the noise through structure sensitivity analysis.

Dynamics Model and Braking Performance Analysis of Multi-axle Vehicle

Wan Zhen;Gao Feng;Ding Jing;Wu Xuelei

2008, 19(3):  365-369. 

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Through discussing the problems of calculation for the braking of multi-axle vehicle, which was based on the classical model and described the general dynamics models for the line braking of multi-axle vehicle. The models reserved the constrain of the suspension and introduced the suspension distortion harmonizing equations. Based on the models, it deduced the general formulas for calculating the vertical counterforce from road. Then it put forward a method for getting the lock sequence of multi-axle vehicle, which is easy to be implemented with computer language, and deduced the general calculation formulas for the brake power，braking acceleration and braking distance of the line braking.

Investigation and Test Validation of Vehicle Reference Speed Algorithm for ABS Based on the Information of Wheel Speeds and Pressure Control States

Wang Weida;Ding Nenggen;Xu Xiangyang;Yang Lei

2008, 19(3):  370-373. 

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Based on the existing algorithms of vehicle reference speeds for ABS, an improved self-adaptive algorithm was investigated. This algorithm distinguished every control cycle exactly according to the information of wheel speeds and pressure control states. The vehicle deceleration was estimated at the end of each control cycle, and the reference speeds during the next cycle were determined according to the estimated value of deceleration. The codes of this self-adaptive algorithm was written and tested as part of the self-developed ECU of ABS through road tests. Test results show that this algorithm of reference speed is valid and can meet the demands of ABS control.

Lightweight Design Study of Automotive Front Rail with TWB Structure

Shi Yuliang;Zhu Ping;Shen Libing;Lin Zhongqin

2008, 19(3):  374-377. 

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A method of redesigning the front rail using tailor-welded blanks was studied, in order to reduce the weight of front rail and enhance its crashworthiness on conditions of satisfying strength and stiffness requirements. By CAE analysis of stress distribution in the rail in the case of self-weight, the number of parent sheets and weld line distribution were determined. By establishing the constraint inequalities of strength, bending stiffness and torsion stiffness, the thickness determination was performed. The full-width frontal impact simulation of the whole car after redesign in the front side rails shows that the front rail of tailor-welded blanks has a better crashworthiness in comparison of original design, while it has a lightweight effect of 17.7%.