Table of Content

10 December 2010, Volume 21 Issue 23

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Reliability Guiding Principles for Research and Development of Mechanical Products

ZHANG Xi-Min, HUANG Xian-Zhen

2010, 21(23):  2773-2785. 

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The primary purpose of reliability guiding principles for the research and development of mechanical products is to sum up the reliability experiences, and make them organized, systematic and scientific. Then, the guiding principles may be the necessary foundation for the research and development of mechanical products in enterprise. According to the developing progression of mechanical products,the authers formulated the guiding principles for the gathering and processing reliability date, the establishment of reliability database, reliability analysis, reliability design and reliability management. In the research and development of mechanical products, if the guiding principles are followed, the reliability can be integrated into the mechanical products, and then improve and guarantee the reliability of mechanical products.

Position Analysis of a 3-DOF PKM Module for a 5-DOF Hybrid Robot Exechon

LI Ban, HUANG Tian, LIU Hai-Chao, DIAO Xin-Hua

2010, 21(23):  2785-2789. 

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This paper dealt with the inverse and forward position analyses of a 3-DOF parallel mechanism module, which formed the main body of a 5-DOF hybrid robot named Exechon. In the forward position analysis, a twenty-four order polynomial equation was derived, leading to 4 sets of mirror poses associated with 8 real solutions of the polynomial. In the inverse position analysis, an explicit equation was formulated to determine 2 poses associated with 2 solutions. Consequently, the entire set of solutions for the forward and inverse position analyses of the mechanism were found.

Control Strategy of Hybrid Excavator Based on Condition Recognition and Hybridization Optimization

WANG Dong-Yun, GUAN Cheng

2010, 21(23):  2790-2793. 

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The hybrid technology brought new opportunity to energy saving of a hydraulic excavator.However, the control strategy is hard to be determined because of the complexity of working condition and cyclic fluctuation of the load. As the dynamic-work-point control strategy can not optimize the main power source and the auxiliary one simultaneously, a new control strategy based on condition recognition and hybridization optimization was presented. It optimized the power distribution rate between the two power sources according to the load condition and the SOC(state of charge) of the battery. Experimental results show that the control strategy ameliorates the speed fluctuation of the engine, optimizes the working points of the engine and SOC of battery. Ultimately it improves the fuel economy of the hybrid hydraulic excavator.

Modeling and Simulation of Valveless Hydraulic Impactor

LIU Zhong, BANG Jin-Yan, LIANG Cheng-Jie, LI Wei

2010, 21(23):  2794-2798. 

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A new type valveless hydraulic impactor was proposed，and its structure, operational principles and characteristics were analyzed. The mathematical models of return stroke and impact stroke were established respectively. By means of AMESim, the simulation model was obtained and the dynamic simulation was carried out. The influence of the providing flow rate and the initial pressure of the nitrogen chamber on the working performance was studied. While the initial pressure of the nitrogen chamber is constant, the hydraulic impactor will be started only the providing flow rate reaches to a certain value. And in certain limits, the providing flow rate which can make the impactor works under the best performance is found. And when the providing flow rate is constant, the impactor energy and efficiency are low while the initial pressure of the nitrogen chamber is rather low; but when the initial pressure of the nitrogen chamber is too high, the impactor cannot be started. Through the simulation, a conclusion is reached: the impactor working performance is the best when the providing flow rate is 75L/min and the initial pressure of the nitrogen chamber is 2.0MPa. The above work can make the hydraulic impactor design become more exact and proper.

Coupling Analysis of Vibration Fatigue Crack Growth for Breathing Cracked Beam

LIU Wen-Guang, CHEN Guo-Beng

2010, 21(23):  2798-2802. 

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A method for coupling analysis of vibration fatigue crack propagation was proposed to improve the analysis precision of fatigue crack growth for breathing cracked beams. Double linear spring was used to depict breathing crack and the modified Forman equation was employed to simulate crack propagation. And cracked beam was simplied to single degree of freedom system through Galerkin method and the coupling relation between vibration and fatigue crack growth was considered through vibration analysis instead of crack propagation estimation cycle by cycle. Results indicate that breathing crack can depict the vibration course and the phenomenon of fatigue crack growth objectively, excitation frequency and damping has important influence on the fatigue life, especially obvious on resonance fatigue.

Research on Mining Method of Perceptual Needs of Product Form in Commercialization of New Technology

CHEN Li, SHU Ru-Feng, ZHOU Hai-Hai

2010, 21(23):  2803-2808. 

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Aiming at the complexity and uncertainty of consumers' needs in commercialization of new technology, the detection and mining methods of the perceptual need of product form were improved. The target images of new product style and the representative samples of each image were acquired by research on products of the same trade, the representative disagree of each sample to each image was calculated by semantic differential scale and factor analysis. The key form features of the products of the same trade were extracted and the association between the target images and the form features were analyzed by multivariate regression analysis. The method was validated by an example of finance equipment. Finally, the application problems of this method in general products of new technology were discussed. 

Research on Joint Torque Optimization of a Soft-finger Dexterous Hand

MENG Qiang-Xin, GU Feng, GONG Hai-Xia

2010, 21(23):  2808-2811. 

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Linearzing the constraints of a soft finger contact model, the linear inequalities of joint torque vector as the variable were derived, which was fulfilling the balance and friction constraints at the same time, and the objective function of the smallest sum of output torque squares was built.The torque optimization in the joint force space was translated into quadratic programming with linear constraint, acquiring the best optimization results of the torque. Using linearization of the soft finger contact model, the non-linear calculation amount was reduced visibly. The quadratic programming with linear constraint can be resolved with the simplex method quickly. The proposed algorithm was implemented on a two-fingered dexterous hand with soft finger contact model for grasping a plane object, and the correctness and real-time capacity of the proposed algorithm were verified．

Structure and Kinematics Analysis of a Novel 4-RPTR Parallel Mechanism

LIU Yan-Bin, ZHANG Shu-Chao, HAN Jian-Hai, GU Xin-Jie

2010, 21(23):  2812-2815,2820. 

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A novel 4-RPTR parallel mechanism was presented,which can perform three-dimensional translations and rotation about X axis. Based on screw theory, the principles that the mechanism can perform the above motions were analyzed, the mobility of mechanism was calculated, and the drive input joints was chosen and discussed, the singularity of the parallel mechanism were analyzed. By use of multi-body system kinematics theory, the kinematics equation was set up, the forward and inverse position kinematics solutions were discussed and proved by use of numerical simulation. The 4-RPTR parallel mechanism replenishs four-DOF parallel mechanism family, its four branch

is the same, and its structure is semi-symmetric and simple, and the parallel mechanism can be applied in the fields of industrial assembly robots, coordinate measuring machines, posture adjusters, parallel machine tools, work platforms.

A Finite Element-Least Square Point Interpolation Method for Acoustic Numerical Computation

TAO Ling-Yun, XU De-Ge, CANG Xian-Guo

2010, 21(23):  2816-2820. 

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The finite element method (FEM) is unreliable to compute approximate solutions of Helmholtz equation for high frequencies due to the numerical dispersion. This paper introduced a hybrid FE-LSPIM to solve the 2D acoustic problem. The quadrilateral elements were used to discretize the problem domains and the shape functions of the quadrilateral element and the least square point interpolation method were used for local approximation. The present method inherited the compatibility properties of finite element method and the quadratic polynomial completeness properties of LSPIM.The FE-LSPIM greatly reduces the numerical dispersion errors and obtaines accurate results for acoustic problems. Numerical examples were studied and the results show that the FE-LSPIM achieves more accurate results and higher convergence rates as compared with the corresponding finite elements, especially for high wave number and irregularity meshes. Hence the FE-LSPIM can be well applied in solving two-dimensional acoustic problems, which has more application foreground in practice.

Research on Trajectory Tracking in Virtual Sculpture Based on Machine Vision

TUN Dan-Ni, WU Tie-Jun

2010, 21(23):  2821-2825. 

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For the low accuracy and limit application feature which is becaused by force feedback devices and data gloves in the virtual sculpture in order to track cutting trajectory, machine vision was introduced into the field of virtual sculpture for the first time. According to the application requirements of this method, an experimental system and a tracking algorithm were designed. The algorithm has improved the detection of connected region in dynamic determining search area based on Kalman filtering, which makes the accurate positioning more efficiently. At last, the tracking speed and accuracy was validated to prove the method’s probability. 

Study on Pose Detection Algorithm for Specific Object Based on Monocular Vision

LIU Ling-Yun, JIAN Xin-En, LUO Min

2010, 21(23):  2825-2829. 

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This paper brought forward a monocular vision detection algorithm in allusion to a specific object's pose based on Hausdorff Distance. At first, according to the established mathematic model, a 2D template sequence was generated by projecting the specific object in different poses into the image plane of a virtual camera. Then, in order to predigest calculations and accelerate the matching speed during the image matching, the algorithm adopted the local-mean Hausdorff Distance as matching estimation and adopted the search strategy based on hiberarchy which reduced the searching rang by the threshold method before accurate match. The experiments that measured the poses of the clamp via the different clamp images respectively were given to testify the validity and speediness of this algorithm. 

Comparison of Three Methods for DEM Modeling of Brittle Materials Cutting Processes

XIE Yong, XU Xi-Feng

2010, 21(23):  2830-2835. 

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A new method (improved ORC method) of constructing irregular particle shape was proposed based on traditional discrete element method and ORC method. Discrete element model of silicon nitride was modeled and cutting simulations was conducted by using above three methods. The relationships among the three methods were discussed from surface quality, distribution state of chips, values of the main cutting force. The advancements of improved ORC method were analyzed. A series of bending and cutting simulations of grain-refining granite and coarse-grained granite were carried out and verified under different parameters, and the values of the bending strength and the horizontal cutting force were calculated. The experimental and simulation results show that the traditional discrete element method is suitable for the modeling of homogeneous and discontinuous materials, the traditional element method and improved ORC method are suitable for the modeling of fine grain granite, whereas the modeling coarse grain granite has to be finished by the improved ORC and ORC methods. 

Output Torque of Double-acting Multi-pump and Multi-motor

WEN De-Sheng, GAO Dun, WANG Zhi-Li, LV Shi-Jun, ZHU De-Che-Gao

2010, 21(23):  2836-2838. 

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A series of novel kind of pumps and motors were designed, which were based on a new structure called by double-stator. For double-stator, one rotator corresponds two stators and more than one pump or motor can work alone or be combined just in one shell. After introduced the working principle of double-acting double-stator motor and the definition of symbols, a novel theory named multi-pump and multi-motor hydraulic transmission was proposed. The output torque in a variety of connection for double-acting multi-pump and multi-motor transmission was discussed in details. The results show that this new kind of hydraulic components can better meet the actual requirements and has broadly potential applications.

Large-caliber Optical Surface Cleanliness Testing System Based on Multi-disciplinary Optimization

LI Meng-Ai, LI Dong-Yang, XIE Zhi-Jiang

2010, 21(23):  2839-2842,2851. 

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Image processing methods based on machine vision meet the needs of large-caliber optical surface by breaking the detection of regional size limits, but with coupling of light, mechanical and electrical elements. The coupling relations of different subsystems were treated with multi-disciplinary design optimization approach, by establishing the coupling relation of disciplinary, the coupling analysis model, to achieve subject co-ordination. The key points of optical subsystem design, movement subsystem and structural design, image mosaic, image processing and cleanliness calculated were systematically represented. The testing system was built to meet the testing requirements.

Accurate Modeling and Tool Orientation Compensation for Nonlinear Errors in Multi-axis NC Machining

CHEN Wei, BANG Fang-Yu, YAN Rong, YANG Jian-Zhong, LI Bin

2010, 21(23):  2843-2847. 

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Nonlinear errors during machining process were analyzed for multi-axis NC machining. Based on the nonlinear relationship between machine-axis space and cutter space, an accurate nonlinear error model for sculptured surface machining was established, which reflected the geometry of complex surfaces. In case that nonlinear error exceeds permissible limit, adaptive linearization control strategy was adopted to smooth the tool orientation. The control module for nonlinear errors was developed. At last,a large-scale propeller blade was machined by 5-axis machine tools to validate theory mentioned herein, of which the results indicate the strict control of precision has come true.

Research on HEV Planetary Mechanism Coupling Device Control

JU Ai-Wei, WANG Qiang-Nian, LIU Jin-Gang, WU Mo-Jiang, GU Yuan-Hua, LEI Wei

2010, 21(23):  2847-2851. 

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This paper introduced a planetary mechanism coupling device for HEV, which used two-degree of freedom structure of planetary mechanism, through two sets of clutches and a set of brakes to restrict one degree of freedom, so that the issue how to make HEV “multi-power input single-power output” was solved.A mathematical model of planetary mechanism dynamic coupling device was built after analyzing the characteristics of motion to planetary mechanism. The control requirements of planetary mechanism coupling device for HEV under all working conditions were researched, and a fuzzy control strategy was established for control of dynamic coupling device clutches and brake. Finally, the work results of planetary mechanism coupling device were verified by tests.

A Training and Test System for Shape Memory Alloy Wires

WANG Zhen-Long, LI Jian, WANG Yang-Wei, GAO Fei

2010, 21(23):  2852-2856. 

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To provide an automatic training equipment and measure the stress, strain and electric resistance in the action process for shape memory alloy wires, a stepping motor driven SMA wires system based on labVIEW and an Advantech data acquisition card was developed. SMA wires with different diameters can be trained conveniently by the present system. The performance of SMA wires in different electric currents and external forces can also be measured. The experimental results show that the acquired data of SMA wires is highly exact and can be displayed and saved in real time. These data provides an experimental basis for the SMA wires’ further application and control.

Modeling and Experimental Study on a New Electric-thermal Heating Method for Shape Memory Alloy Wire Actuators

DONG Er-Bao, HU Min, LI Yong-Xin, YANG Jie

2010, 21(23):  2857-2861. 

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Aimed at the electric-thermal heating difficulties of thick SMA wire actuators for their small resistance, a new type of composite electric-thermal heating method by winding the enameled wire around the SMA wire was presented. Using the lumped parameter method and simplifying characterization of the complex heat exchange process between the enameled wire and the SMA wire to an equivalent thermal conductivity, a thermodynamic model of this electric-thermal heating process was built. And comparative analysis between the numerical solution of this theoretical model and the experimental results demonstrates that this thermodynamic model can describe accurately the heating and cooling process of this electric-thermal heating method. Further experiments show that this electric-thermal heating method can increase greatly the thermal heating velocities of thick SMA wire actuators.

On Mechanism of Magnetic Field Induced Compressive Modulus of Magnetorheological Elastomers Based on Dipole Model

SHU Xu-Li, MENG Yong-Gang, TIAN Yu

2010, 21(23):  2861-2864. 

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The mechanism of magnetic field induced compressive modulus of magnetorheological elastomers was analyzed by dipole model herein. The results show that particle chains are curved or curved and elongated simultaneously when magnetorheological elastomers are compressed. The compressive force of curved particle chains increases because of the moment on them induced by external magnetic field. When particle chains are curved and elongated, the matrix material is pressed by the chains at the presence of magnetic field, and the deformation of magnetorheological elastomers perpendicular to the direction of compression is constrained, so the compressive force increases. Therefore the compressive modulus of magnetorheological elastomers is enhanced by external magnetic field.

Effect of Ultrasound and Electromagnetic Field on Microstructure of Cast-rolling Magnesium Strip

TAN Xiang-Fu, MAO Da-Heng, CHOU Ling, ZHANG Sheng-Fang

2010, 21(23):  2865-2867,2876. 

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Experimental study on ultrasonic and electromagnetic roll-casting of AZ31B magnesium alloy was carried out using a self designed and installed twin roll continuous horizontal caster. 3mm thickness and 200mm width of AZ31B magnesium alloy casting strips were produced successfully. The results show that the ultrasonic and electromagnetic field is transferred into roll-casting zone and results in a great decrease of the grain size,the average grain size has decreased to 10～20μm from 30～60μm; and also improved the mechanics properties of the AZ31B magnesium alloy sheet, the tensile strength and yield strength and elongation and hardness are improved by 23.6% and 43.2% and 107.2% and 10% respectively. On this basis, the mechanism of grain refinement during cast-rolling process with ultrasonic cavitation and electromagnetic field effect were discussed.

Research on Molding and Experiment of Heat Transfer in Injection Molding of the Wrapped Plastic for Vehicle Glass

WANG Gan-Ting, CHEN Wen-Zhe, HUANG Yong-Hua, LIU Yi, LIU Xian-Beng

2010, 21(23):  2868-2872. 

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In the injection molding process of wrapped plastic in vehicle safe glass, the flaws always appear in the surface and the plastic may fall off from the glass because of the untight adhesion. The heat transport phenomenon was analyzed in the injection molding of wrapped plastic. First, a simplified model and the equations of heat transfer from the cavity to glass and mold walls were set up. Then the temperature curves from filling to the ejection of plastic were obtained by experiments. The results show that the temperature distribution of the plastic surfaces, moveable mold and stationary mold is different somewhat in time domain, with temperature rising in small amplitude. The enthalpy of the molding process of wrapping plastic calculated by the heat transfer model show that the temperature rising delay is in coincidence with the enthalpy distribution. This heat transfer analysis discloses the mechanism that the wrapped plastic fall off from the mold and surround the glass tightly, which can be used as the reference for the mold structure design and processing design.

Research on Key Technologies for Forging Stepping Shaft between Upper Flat and Lower V-shaped Anvil

WANG Lian-Dong, LIANG Chen, WANG Jin-Bao, LIU Wei-Wei

2010, 21(23):  2872-2876. 

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A new mechanics model was established for forging round shaft between upper flat and lower V-shaped anvil, the stress state and deformation were analyzed. The operation principles for forging round stepping-shaft were proposed, the matching relation between turning angle and compression ratio was determined. Aimed at forging the steps of 1365 bearing roller, the technological parameters were formulated, the numerical simulation was done with DEFORM soft. The results indicate that the stress state in the deformation zone is good and the deformation is homogeneous, and the axis deflection of deformation zone is small. Forgings which are made according to the new technology pass ultrasonic flaw detection, and the axis deflection of deformation zone is lower than the requirements during the drawing process.

Three-dimensional Finite Element Simulation of Constrained Groove Pressing

YANG Kai-Fu, TUN Yong-Quan, CHEN Wen-Zhe

2010, 21(23):  2877-2881. 

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Three-dimensional finite element simulation was carried out for analyzing the severe plastic deformation behavior during constrained groove pressing. The load variations and equivalent strain distributions were obtained. The results show that the required load for pressing during different passes is identical. The required load for groove pressing varies with increasing the displacement can be classified into three phases: rapid increase, slowly increase, another rapid increase. Whereas the required load for flatten pressing exhibits four phases: stabilizing, rapid increase, another stabilizing, and another rapid increase. The equivalent strain distributions are homogeneous along Y and Z axis but inhomogeneous along X axis. It is shown that the equivalent strain distribution along X axis can be classified into the lower regions located at both ends and the periodic variation region located at intermediate section. The different stages presented in the load versus displacement curves and the inhomogeneous distributions of equivalent strain are associated with deformation behavior.

Hardware-in-the-loop System of Vehicle Stability Control Based on LabVIEW

Chen-Mo-Wei, LIU Xiang-Yu, YANG Jun, HUANG He

2010, 21(23):  2882-2886. 

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A hardware-in-the-loop system of VSC was built based on LabVIEW. The sliding mode variable structure control strategy was employed for VSC, the VSC ECU was designed based on ARM7, and the program was designed based on LabVIEW. A nonlinear 7 DOF vehicle model and the brake system model were built based on LabVIEW. The signals from wheel cylinder power sensors and steering wheel angle sensor were collected through PXI I/O to compute the vehicle driving parameters by vehicle model. The parameter feedback from vehicle model was transported to ECU through CAN-bus. Based on the virtual reality technology, a 3D model of vehicle and environments were built, and connected to LabVIEW. The simulation results verify the effectiveness of the VSC hardware-in-the- loop system. 

Study on Optimal Design of B-pillar for Crashworthiness and Light-weighting

TAN Yao-Wu, YANG Ji-Kuang, WANG Si-Wen

2010, 21(23):  2887-2892. 

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In order to enhance crashworthiness of B-pillar in side impact and reduce its mass at the same time to achieve light-weighting, the safety performance of a car was analyzed according to the design parameters of the B-pillar in side impact firstly. It is identified that the intrusion and intrusion velocity at the middle of the B-pillar are too large and the mass of the B-pillar structure is rather high due to extra reinforcements. An improved design of the B-pillar was implemented using the tailor-welded blank structure. Furthermore the location of weld and thickness of this structure were optimized by using design of experimental method and multi-objective genetic algorithm, considering crashworthiness and light-weighting. A desired deformation mode of B-pillar was finally obtained. Its maximum intrusion is reduced by 10%. The intrusion and intrusion velocity at the middle of B-pillar are reduced by 18% and 12% respectively. The mass is reduced by 18%. The results indicate that optimal design of B-pillar structure with tailor-welded blank can effectively balance the requirements of crashworthiness and light-weighting.

Driving Cycle Construction Method of City Motors Based on Clustering Method and Markov Process

JIANG Beng, DAN Qin, CHEN Mo-Wei

2010, 21(23):  2893-2897. 

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Two factors(the mean speed and speed deviation)with the fuels of automobiles were extracted by the factor analysis, according to two factors a series of driving cycles were divided into 3 different clusters by the two-step clustering method. The first cluster represented driving patterns of moving vehicles under 20 km/h.The second cluster consisted mostly of data with average speeds between 20 to 40km/h. And the last cluster included data with average speeds greater than 40km/h. Every driving cycle was taken as a stochastic Markov process with time and the driving data for each cluster were divided into acceleration segments, deceleration segments, idling segments and cruise segments according to a new classification scheme and the transition probabilities of segments were calculated. According to this basis the selection method of candidate cycles was considered by combination the transition probabilities of segments and vehicle specific power of the engine, the evaluation criteria of 12 characteristic parameters of evaluating the representative driving cycle were established. The driving cycles for different clusters were constructed with an example of typical roads in Hefei. The results show that the driving cycles with emissions have high similarity with the experiments and accords with driving cycles of real roads.