Table of Content

25 February 2006, Volume 34 Issue 2

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Electronics, Communication & Automation Technology

Process Analysis and Experimental Investigation of Multi·Pass Ofset Spinning

Kuang Wei-hua Xia Qin-xiang Ruan Feng Wang Yu-hui

2006, 34(2):  12-16,21. 

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The difference between the offset spinning and the conventional symmetric spinning is analyzed.The numerical simulation based on a 3 D FEM (Finite Element Method)model is then carried out for the offset tube neck·spinning by using ANSYS,and the dynamic boundary and the frictional contact problems during the simu-lation are also solved.The transient stress distribution in the contact area,the deformed workpiece mesh,the distributions of stress& strain and the axial extension are thus obtained. Moreover.some common phenomena and defects in the offset spinning are analyzed.Simulated results indicate that the offset spinning with obvious non-ax isymmetric form ing parameters is different from the conventional symmetric spinning and the correspon-ding deform ation mechanism is influenced by many parameters such as the spinning style,the offset distance,the feed rate,the roundness radius of the roller,the namely pass reduction and the tube thickness.Experimen-tal results show that form ing parameters greatly influence the spinning force and workpiece quality of the conven-tional symmetric spinning.The influences of various parameters on the spinning force and workpiece quality of the offset spinning are finally discussed based on the experimental results.

Mechanical Engineering

M andreless Neck-Spinning Technology Based on Numerical Simulation

2006, 34(2):  1-7. 

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In order to further investigate the neck-spinning mechanism and conduct practical manufacturing,the mandreless neck-spinning with a single roller is simulated based on the 3 D elastic-plastic FEM (Finite Element Method)model by means of the FEM software MARC.The deformation mechanism and the distributions of stress and strain in the process of the mandreless neck-spinning are also analyzed.The results show that(1)the deformed metal in the contact zone between the roller and the blank is in a 3 D compressive stress state;(2)the axial tensile strain is gradually transformed into the compressive strain from the deform ed zone to the undeformed zone. while the radial compressive strain is transformed into the tensile one;(3)with the increment of the reduction of blank radi-US,the equivalent stress increases,and the maximum radial stress appears at the opening and the inner wall of the transitional circular zone;and(4)the thinnest area,namely,the dangerous position at which crack may occur.appears at the transitional circular zone.The simulated results accord well with the actual spinning process,which lays a theoretical foundation for the establishment of neck-spinning technology.

Integrated Hydrocylinder-Driven Multi-Platen Adapter for Powder Press

Zhou Zhao-yao Huang Chun-man He Hui Shao Ming

2006, 34(2):  8-11. 

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In order to press complex green compact with two upper levels and three lower levels,a set of multi-plat-en adapter driven by integrated hydrocylinder is designed and manufactured according to the characteristics of existing adapters for powder press.It is compatible with precise powder-metallurgy equipment and can be used to press complex green compact with two upper levels and three lower levels.The three lower platens are separately driven by four uniformly distributed hydrocylinders to balance the force,which means that the integrated hydrocylinder consists of twelve platen-used hydrocylinders.Moreover,the operation data about the location of each platen are collected by a grating ruler,and the displacements of punch heads in the pressing process are precisely controlled by a closed-loop hydraulic system .with an axial position accuracy at the punch head being ±0.01 mm.Thus,complicated powder-metallurgy green compacts with homogeneous density distribution can be pressed via the coordi-native movement of the platens.

Form ation Process of Three-Dimension Fin for Stainless Steel Packings by Plowing/Extruding

Wan Zhen-ping Tang Yong

2006, 34(2):  17-21. 

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To fabricate high-performance stainless steel packings,a new fin-form ing technology named plowing/ex-truding is proposed to machine three.dimension downy fins on the surfaces of stainless steel laminas that are used as packings.The formation process of three-dimension fin by plowing/extruding is analyzed,and the influences of the tool and process parameters on the form ation of the fin are investigated. It is shown that the whole fin-form ing process can be classified into three stages:plowing,extruding and fin forming.and that the extruding obliquity,the extruding edge width and the plowing/extruding depth are the main factors influencing the fin forming. Moreo-ver,within a certain range,the height of fin increases with the extruding edge width and the plowing/extruding depth,but the extruding obliquity has no obvious infl uence Oil the height.

Digitalized Synchronized Control of Twin-W ire Pulsed Gas M etal Arc W elding

Li Yang Huang Shi-sheng Lu Pei-tao Li Yuan-bo

2006, 34(2):  22-26. 

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To overcome the un-stabihty and low effectiveness during the twin-wire gas metal arc welding(GMAW) process,a digitalized synchronized control system consisting of a dual-microprocessor- 80C320 and 80C552 highspeed single chip processom-is developed.By means of the CAN(Controller Area Network)communication protocol and the related software,the system can synchronize two soft-switch inverter power sources to produce pulsed welding current with ahem ating peak and constant frequency. So,the interference between two arcs is efectively reduced,and the welding process becomes stable with a fine welding seam. In addition,the arc lengths are controlled by a close-loop fuzzy control program. Experimental results show that the digitalized synchronized control scheme is very flexible and that it can help stabilize the twin-wire GMAW process.

Algorithm of Topology Optimization Criteria for Heat Conduction Structure Based on Density Approach

Li Jia-chun Ye Bang-yan Tang Yong Guan Qi-ming Liu Wei

2006, 34(2):  27-32. 

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The existing methods for the optimal design of heat conduction structures mainly focus on the optimiza-tion of the shape and the size.But the obtained topology may not be the optimal one due to the absence of the initial optimal topology.To seek the optimal topology for heat conduction structures,the well-rounded topology methodolo-gY and algorithms in structural mechanics are adopted in the optimal design of heat conduction structures,with the least dissipation of heat transport potential capacity as the optimal objective.Then the topology optimization model of heat conduction is established and the corresponding optimization criteria are proposed based on the density ap-proach.Moreover,during the calculation process,a filtering technique based on the convolution is employed in density field to eliminate numerical instability.Numerical examples in different conditions are finally presented to demonstrate the corectness and validity of the proposed method,with the results laying a reliable foundation for the subsequent shape and size optimizations in thermal engineering.

Measurement of Residual Stress Distribution in Thick Pre-Stretched Alum inum Alloy Plate

Guo Hun Zuo Dun-wen Wang Shu-hong Wang Min

2006, 34(2):  33-36. 

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In order to overcome the distortion of the airplane monolithic structure parts caused by residual stresses,the modified layer··removal strain method was used to measure the residual stress in thick pre··stretched aluminum alloy plates by considering and analyzing the characteristics of the aluminum alloy plate.The stress-strain relation matrix was then deduced according to the elasticity theory. Moreover,the residual stress in a typical navigationused 7075T7351 aluminum alloy plate was measured by the proposed method,with the results being finally analyzed and compared with the data obtained by other methods.The results indicate that the proposed method is effective in measuring the residual stress in thick pre-stretched aluminum alloy plates.

Interelectrode Gap Control in Electrochemical M achining Based on Neural Network and Fuzzy Control

Wang Xi Zhao Dong-biao Yun Nai-zhang

2006, 34(2):  37-40,46. 

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In this paper,the force resulting from the electrolyte and loaded on the cathode surface is used to express the size of the interelectrode gap in ECM (Electrochemical Machining).The nonlinearity mapping between the force and the interelectrode gap is first implemented by a BP neural network.and a fuzzy controller is then de-signed to control the gap,with the voltage increment as the output and the force eror transferred from the eror of the interelectrode gap and the change of force eror as the inputs.Moreover,a simulation model is set up based on the theoretical expression of the interelectrode gap.An intelligent control system consisting of the BP neural net-work,the fuzzy controller and the ECM system is finally tested based on the Simulink module of Matlab to adiust the three increment parameters of the fuzzy controller.Simulated results show that the interelectrode gap can be well controlled by the proposed method,with high speed,good robustness and with no stable ero

M odeling and Re-Engineering of Design Process for Products

Tang Ting-xiao Liao Wen-he Huang Xiang Liu Yong

2006, 34(2):  41-46. 

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The design process of products is a complex systematic engineering integrating multifold knowledge. In this paper,by an integrated analysis of existing modeling methods of the design process for products,a novel ap-proach to information modeling is proposed based on the expanded directed graph and the fuzzy design structure ma-trix,and the inform ation dependence of activities is quantitatively described.Then.process re-engineering is im-plemented by the decomposition,tear and partition of activities.Moreover,a fuzzy order based on the inform ation correlation grade of coupling activities is carried out to guide the activity decomposition,with the coresponding al-gorithm being also provided.A case of punch die design is finally presented to verify the efectiveness and feasibili-ty of the proposed method.

A Roboticized M ulti-Function Nursing Bed and Its Control System

Zhang We Xie Cun-xi Zhou Hui-qiang Xiong Wei

2006, 34(2):  47-51. 

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In order to meet the increasing requirement of family nursing at present in China,a roboticized multi-function nursing bed controlled by sound or keyboard is developed by applying the multi-shaft coordinating control technology in robotics.Different nursing poses are implemented by the coordinative motions of bed boards in single acting or cooperative acting modes.The control system of the nursing bed consists of two modules:the main control module and the assistant control module.The former uses a single chip to reduce the cost and ensure the flexibility and reliability of the nursing bed,and the latter possesses the functions of sound identification and playing-back.Practical application shows that the proposed nursing bed is of practicability and efectiveness.

Hardware Design of Automobile Electric Power Steering System

Li Wei-guang Lin Ying Wang Yuan-cong

2006, 34(2):  52-56. 

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The power condition of a motor in an automobile EPS(Electric Power Steering)system can be adjusted according to road condition and automobile condition,So that the energy consumption can be reduced and the steer-ing characteristics and driving safety can be improved.In this paper,an embedded EPS system is designed,,with a DSP(Digital Signal Processor)chip as the core of the system.By analyzing the choice of DSP,the structure and control principle of EPS,and the system circuit module,this paper further describes the process of designing the layered structure of the system hardware,the signal processing circuit of EPS,the power steering motor and the power-driven control circuit of the electromagnetic clutch. Moreover,the characteristics of the torque sensor and some data of the signal processing circuit are obtained. Experimental results indicate that the essential functions of EPS can be optimally realized with the proposed control system.

Development of Drawing Die for Heat-Shield Panel of Autom obile Engine Based on Finite Element

Wu Chun-ruing Ruan Feng Qiu Hong-yang

2006, 34(2):  57-61. 

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A finite element model describing the drawing process of the heat-shield panel of automobile engine is established by using the commercial dynamic explicit code LS-DYNA.By the established model,the effect of BHF(Blank Holder Force)on the drawing process is analyzed,with the results showing that no appropriate BHF can effectively restrain the severe wrinkling and folding as well as the tearing.Therefore,drawbead is em-ployed together with BHF to control the drawing process,and several typical layouts of drawbead are analyzed and compared via FEA (Finite Element Analysis),with the most effective one then being applied to stamping experiments.The results indicate that the results of FEA accord well with those of the experiments,and that the proposed drawbead layout can eliminate the severe wrinkling and folding as well as avoid the excessive thinning.By the FEA,engineers can make correct decisions at the early design stage,and the development cycle of the drawing die for the panel shortens to 4 weeks fron the past 1 2 weeks.

Potential Model of Contact Surfaces for Calculating Static Friction Force

Xu Zhong-ming Huang Ping

2006, 34(2):  62-66,72. 

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A simplifted potential model of contact surfaces,which is based on the strong volume-dependent charac-teristic of metal.is established to caleulate the static friction force and the coefficient of two flat surfaces made of the same metal and to exDlain the origin of static friction force.The static friction force and the coefficient are then calculated according to the principle of energy,and the potential change of the contact surfaces is obtained by a universal adhesive energy function. Moreover,the relationships between the static friction force and the parameters of a tribo-system.such as the surface energy,the micro-stru ctural parameters of material,etc.,are revealed.The resuIts of the calculation using some known experimental data demonstrate apparent regularity and are proved to be consistent with the experimental results of copper specimen carried out by an ultra high-vacuunl atomic-force micro-scope,thus illustrating the feasibility of the proposed method.It is concluded that,as the surface energy can reflect the status 0f contact surfaces sensitively,the proposed method may improve the accuracy of friction calculation.

Computer-Assisted Orthopaedics Surgery Navigation Model Based on Binocular Vision Sensing

Jiang Li-jun Can Dong-bing Wang Guo-rong

2006, 34(2):  67-72. 

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ln order to meet the requirements of tracing the pose and orientating the position of operation instruments in computer-assisted orthopaedics surgery navigation,a passive optical stereoscopic orientating and tracing model IS devel0Ded based 0n the area CCD (Charge Couple Device) binocular vision sensing,and then the corresponding svstem is investigated.Experimental results show that the spatial object in depth direction ranges from 700 to 1 000 mm.and that the maximum path deviation of the spatial object can be controlled within 0.3 mm when the sDeed 0f the operating mechanism is 1 00 mm/s．It is shown that the proposed system is precise enough to satisfy the demand of orientating and tracing operation instru ments in orthopaedics surgery navigation·

Agent Model of Distributed M anufacture Inform ation System Unit

Zhang Kai-sheng Chen Wei Sun Yan-ming Zheng Shi-xiong

2006, 34(2):  73-76,117. 

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When establishing a multi-agent system model of distributed manufacturing information system (DMIS),it is necessary to study and analyze the control requirements and the functional requirements.In this paper,theflexible coupling automaton was adopted to establish the abstract model,the computational architecture and the al-gorithm of each DMIS unit in the multi-agent system model,The communication among the agents was then iustanti-ated bv the interaction between the machine and the material storage,and the interface based 0n the two-way au-tomaton with output was utilized during the interaction.The results indicate that the proposed Agent system can be used to analyze simultaneously the control requirements and the functional requirements of DMIS,and that it is con-venient for both the analysis and the design of the system.

A Fast Algorithm for Calculating the Contour Similarity of Stamped Parts

Zhou Chi Ma Kai Ruan Feng

2006, 34(2):  77-81. 

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In order to calculate contour similarity with high speed and less data transfer in network application,this paper proposes a fast non-discrete algorithm in which lines and arcs are used to represent a contour.During the investigation,the image is normalized first,and the contour to be matched is then rotated continuously with a fixed step length.The contour to be matched and the target contour are respectively set as the template in turn to calculate the average square distance between the ve~exes of the template and the expected ve~exes of the matched contour.Finally,the minimum sum of the average square distances in all rotation angles is defined as the matching degree of the two contours.This algorithm can be used for both the convex and the concave contours.As compared with the traditional discrete algorithms,the proposed algorithm is of less data transfer,but of higher calculation speed and good identification and matching accuracy.

Schemes of Software and Communication Interface Design for Computerized Numerical Contral System

Feng Shou-ring Li Di Gao Jun-li

2006, 34(2):  82-87. 

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In order to rapidly design a real-time multi-task software prototype of CNC r Computerized Numerical Control)system,the MDD(Model-Driven Development)method is applied to the modeling analyses of the require-ment,the structure and the behavior.Based on the requirement analysis.the functional requirements of CNC soft-ware are obtained,and these functional requirements are then mapped into classes or objects via the structure analv-sis.By the behavior analysis,the actions of these classes or objects are established. Moreover,the problems of communication interface between the host and the slave are solved in the designing of a real-time multi-task CNC system ,and the communication reliability is thus guaranteed.Moreover ,a communication interface scheme based on HPI(Host Port Interface)is presented by analyzing the communication management state machine.With the proposed method and scheme,a CNC system prototype is designed and tested ,and its feasibility is verified.

Direct Interpolation Algorithm for Projective Curve on Param etric Surface

Meng Shu-yun Zhao Dong-biao

2006, 34(2):  88-91. 

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The machining of sculptured surface by the traditional method may cause many problems because the exi-sting CNC(Computerized Numerical Control)system,which possesses weak control capability,depends too much on automatic programming.In order to solve these problems,a direct interpolation algorithm for the projective curve on parametric surface is proposed in this paper.It can directly carry out the interp olation of tool paths in local surface with improved control capability of CNC system.Moreover,an example of local machining is presented to veri-fy the proposed algorithm .Simulated results show that the proposed algorithm is simple,feasible and effective,and that it can be applied to the machining of the whole surface.

Architecture & Civil Engineering

Experimental Investigation into Unbonded Post-Tensioned PC Flat Plate-T-Shaped Column Connections

Cai Jian Li Guang-xing

2006, 34(2):  92-99. 

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Six full-scale PC(Prestressed Concrete)fiat plate-T-shaped column connections,of which five are post-tensioned with unbonded tendons and one is a parallel specimen constructed with normal bo nded rejnforcjng bars,are experimentally tested to reveal their punching shear performances when being subjected to gravitv loads.The failure modes of the connections are then investigated.The results show that a combined flexural and punching shear failure occurs for each connection ,and that,when the applied load approaches the failuI℃ load,the tendon stre~ greatly increases but does not achieve the ultimate strength. Moreover,the pr -compression stresses in slabs can improve the ultimate strength and stifness of the connection, with the ductility being fairlv kept.Th e profile of the critical section and the location of the flexural failure aIle also presented based on the experimental results,and,finally,the experimental ultimate strengths of the six connections aIle comDaIled with the results obtained according to the provisions in the ACI and the Chinese codes

Spectrum Analysis of Seismic Strength-Reduction Factor for RC Building

Zhou Jing Cai Jian Fang Xiao-dan

2006, 34(2):  100-106. 

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In order to quantify the relationship between the seismic capacity and the seismic strength demand of a structure,this paper theoretically analyzes the relationships between the strength-reduction factor on the one hand and the ground motion parameter& the structural characteristic parameter on the other.The great effects of site conditions,displacement ductility,self-vibration period and damping ratio on the strength-reduction factor of a sin-gle‘DOF(Degree of Freedom)system in earthquake action are investigated.Moreover,simplified expressions for the strength-reduction factor spectra of a single·DOF system are proposed by a nonlinearly regressive analysis of the
statistic averages of strength-reduction factors in different site conditions.The results of the present study provide a valuable reference for the displacement.based seismic design of building

Experimental Investigation into Square CFT Stub Columns with Binding Bars Under Eccentric Loads

He Zhen-qiang Cai Jian

2006, 34(2):  107-111. 

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In order to investigate the mechanics properties of square CFT(Concrete-Filled Tubular)stub columns with binding bars under unilateral eccentric loads,14 specimens were tested by considering the parameters such as the steel ratio.the load eccentricity ratio and the location of the binding bars.Experimental results indicate that (1)the bearing strengths of the specimens decrease with the increase in the load eccentricity ratio while they in-crease with the increase in the steel ratio,and(2)binding bars help to improve the ultimate strength and the duc-tilitv 0f the eccentric-loaded specimens.The tested results were finally compared with the results calculated by the methods presented in the current specifications at home,showing that the curent specifications,in general,have undervalued the ultimate strength of the specimens with binding bars.

Novel Four．Node M embrane Elem ent with Rotational Degrees of Freedom

Shu Xuan-Wu Kang Lan Liu Qiang

2006, 34(2):  112-117. 

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For a traditional membrane element,the introduction of a vertical rotational freedom of degree may expo-nentially increase the displacement and greatly improve the calculation precision and the element performance.In this paper,two excellent four-node membrane elements are proposed for the membrane structure and the shear wall of high-rise structure.The results of theoretical analysis and numerical simulation indicate that the two membrane elements both possess a displacement field in which linear displacement and rotational displacement al e mutually in-dependent,which results in an easy transition between one-dimension element and two-dimension element and makes the program realization rather simple.Numerical results show that the proposed displacement field not only accords with the practical situation better than others.but also reduces the calculation time.

Integrity Theory and Its Application of Structure Reinforcing / Retrofitting and Disease Treatment Techniques

Zheng Hua-bin Han Da-fian Lu Rui-ming

2006, 34(2):  118-123. 

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The integrity theory is applied to the research on structure reinforcing/retrofitting and disease treatment techniques based on the revivification theory.This paper integrates the interactions and requirements of such vari-ables as the safety,applicability and durability of a stru cture and achieves the whole grasp from individual and par-tial levels.Therefore,a new approach is proposed to reinforce/retrofit building structure and treat disease.Further-more,the corresponding procedure and the synthetic integration method based on the integrity theory are presented.Finally,a project example is given,proving that the proposed method is effective and feasible in practice.

Optimal Design and M onitoring of Steel Sheet Pile Coferdams of Xinguang Bridge

Luo Guan-yong Cao Ho Pan Hong Zhou Hong-xing

2006, 34(2):  124-129. 

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The 5^# and 6^# cofferdams of Xingguang Bridge are retained by steel sheet pile walls and steel struts struc-ture.Rock powders are used to resist the seepage force.In this paper,the optimal design of the retaining structure is introduced.A comparison between the designed results and the monitored results is also carried out to investigate
the main causes of the obvious differences in pile deformation.It is found that(1)during the initial loading of steel sheet pile walls,the slippage of piles occurs,which results in a great decrease in the total rigidity of the walls and brings about a deform ation larger than that of the designed value;while in the later loading phase,the interaction between piles increases and the relative slippage is restricted,thus resulting in a recovery of the total rigidity and a deformation increment similar to the designed one;and(2)the deformation mainly centers around the joints be-cause the rigidity of longitudinal joints between piles is weaker than that of piles.It is thus concluded that,when designing a retaining system,the wall module should be varied according to the loading phases of piles,and that the safety coefi cient of steel struts should be larger than that of steel sheet piles.

Dynamic Properties of Stoneley W ave in Elastic Half-Space-Ideal Fluid Layer

Xiong Yu-chun Fang Ying-guang

2006, 34(2):  130-134. 

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In order to reveal the dynamic properties of the Stoneley wave in elastic half-space-ideal fluid layer and further to provide a surveying method for exploring oceanic resources, a characteristic equation expressing the Stoneley wave in half-infinite solid-ideal fluid layer is derived based on the dynamic equations of elastic solid and i-deal fluid.According to the proposed characteristic equation,the influences of the physical characteristics of the solid and the fluid on the dynamic pressure of the fluid are analyzed,and the displacement distribution in the solid and the fluid are described.The results show that(1)the displacement distribution of the Stoneley wave in the solid is similar to that of the Rayleigh wave in half-space,while that in the fluid is obviously regular;and(2)the Stoneley wave in elastic half-infi nite solid-ideal fluid layer is dispersive,with a velocity less than that of the Rayleigh
wave in elastic half-space.