Table of Content

25 November 2011, Volume 22 Issue 22

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Structure Optimization of Energy Recovery Turbines Based on Inner Flow Field

LI Ren-Nian-1, JIANG Dui-Jun-1, 2, HAN Wei-1, LIU Yu-Ying-1

2011, 22(22):  2647-2650. 

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A type of horizontal double-channel francis hydraulic turbine was designed based on the working principle of vane hydraulic machinery.In order to optimize its structure,ensure the performances and maximize the efficiency of water-power recovery,a three-dimentional tubulence numerical simulation was performed for the inner flow field of the turbine with and without guide vanes under clear water medium,based

on the Navier-Stokes equation and the standard two-equation turbulent model of κ-ε，using the body-fitted coordinates,unstructured-tetrahedron grid and SIMPLEC algorithm.The research indicates that compared to the turbines without guide vanes,the velocity circulation and pressure distribution in the runner's blade inlet,the velocity and pressure distribution in the blade surface and the internal flow state of the draft tube are more uniformity when the guide vanes exist,which increases the energy conversion index of the runner and provides a theoretical and practical reference for the further researches on the structure of energy recovery turbines.

FEM Simulation for Pipe MFL Inspection under Circumferential Magnetization

SONG Xiao-Chun-1, 2, YANG Lin-1, 2, HU Zheng-Wang-1

2011, 22(22):  2651-2653,2706. 

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In order to optimize the magnetizer of the circumferential MFL(C-MFL) detector for pipe inspection, the distribution of magnetic induction field in pipe wall under circumferential magnetization was simulated and studied based on 3D finite element method.The influences of such pipe parameters as diameter and wall thickness on the circumferential magnetic induction in pipe wall were analyzed,and the effects of the applied circumferential field on the induced field, the magnetic leakage field and the background magnetic field were also investigated.The simulation results show that the increase of the pipe diameter will increase the effective detected area, and the increase of the pipe thickness will also increase the effective detected area but decrease the induced magnetic field clearly. Moreover, the increase of the magnetization field is beneficial to testing the axial defect of pipes. However, some effective signal processing algorithms should be developed to eliminate the background magnetic field from the acquired magnetic leakage field.

Research on Surface Roughness Based on SPSO in High Speed Milling of GH4169

LIU Wei-Wei, LI Feng, LIN Jun-Hua, WEI Yuan

2011, 22(22):  2654-2657,2771. 

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Using single factor and orthogonal experiment,the effects of the carbide tool cutting parameters on superalloy GH4169 surface roughness were stuided under the high speed conditions.The research results indicate that feed rate have obvious influence on surface roughness, followed by cutting speed and cutting depth;An experience formula between the surface roughness and cutting parameters was built by SPSO and the confirmation tests were carried out to make a comparison between the experimental results and ones predicted by experience formula.The comparison results show that the experience formula established based on SPSO can predict the surface roughness of superalloy GH4169 in high-speed milling processes effectively. It also can provide the references for optimizing the milling parameters and the control of surface quality. 

Structure Design and Steady-state Thermal Analysis of ITER Poloidal Field Cryostat Feeder-though

CHEN Ke-1, JIANG Xin-Feng-1, SONG Yun-Chao-2, LIU Su-Mei-2, LIU Kun-2, CHEN Yong-Hua-2, ZHANG Shan-Wen-3

2011, 22(22):  2658-2661. 

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According to the ITER design requirements for Feeder, and simultaneously considering the complexity of CFT structur, all components of CFT were designed and modeled based on CATIA software. In order to simulate the steady heat transfer of the system in the vacuum and cryogenic environment, finite element analysis (FEA) thought was employed. A typical FEA model of CFT was established based on ANSYS software. The internal component temperature distribution and the cryogenic pipeline thermal load were obtained, which lay an important foundation for further structural optimization and prototype trial.

Research on a Kind of New Structured 3-RRRRR Parallel Micromanipulator

LI Shi-Hua, GOU Pan-Ru, WANG Zhi-Song, SUN Long-Qiang, LI Fu-Juan

2011, 22(22):  2662-2666. 

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This paper put forward a new structured parallel micromanipulator driven by piezoelectric ceramic, which was based on 3-RRRRR parallel mechanism.The corner formula of single flexibility revolute pair and the driving force formula were deduced.The relationship between driving force and output displacement of the mechanism end was also established, and then the maximum driving force and working space of the mechanism were obtained;A relationship between input voltage and output displacement was set up,and a 3-RRRRR parallel micromanipulator prototype was produced and tested.The foundation was layed for applications of this parallel micromanipulator.

Study on Elevator Brake Performance Testing Methods

XIE Xiao-Feng-1, NIU Gao-Chan-1, PU Han-Jun-1, ZHANG Fu-Ji-2, CENG Zi-Feng-2

2011, 22(22):  2667-2671. 

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By studying the elevator industry safety standards and rules for type test of lift,the authors acquired elevator brake test conditions and established a dynamics model of the brake.A new method to implement the elevator brake performance testing was put forward.A performance testing prototype was designed

based on the new method.A mathematical model and algorithm of load torque were established,which ensures that the elevator braking law in the testing machine and lift is consistent.

Modeling for Viscoelastic Property of Honeycomb Paperboard and Dynamic Parameter Identification

SHU Da-Feng-1, 2, ZHOU Shi-Sheng-1

2011, 22(22):  2672-2677. 

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A model of viscoelastic property of honeycomb paperboard was presented,the relaxation kernel was expressed as the sum of exponentials.A model for the dynamic properties of honeycomb paperboard under shock condition was formulated.The signal poles and residues of free response data were obtained

by use of modified Prony method.A dynamic properties parameter identification method was presented based on the signal poles and residues.A shock response experimental system was set up to investigate the shock response of the mass loaded honeycomb paperboard, the free response data were recorded and the dynamic property parameters were identified and presented.

FBG Based Air-gap Magnetic Flux Density Dynamic Measurement and Analysis

DING Guo-Beng, ZHOU Jie-De, HU Ye-Fa

2011, 22(22):  2677-2681. 

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A FBG based magnetic bearing air-gap magnetic flux density measurement test system was constructed,air-gap magnetic flux density was measured through a FBG sensing component under 3 rotating speeds(1080r/min,1320r/min and 1500r/min) and 6 coil-currents(0.5A,1A,1.5A,2.0A,2.5A and 2.95A),

the measurement results were analyzed with FFT method.It is concluded that there is virtually consistency between the measurement results and finite element calculations and it is feasible to utilize the FBG sensing component for dynamic measurement of air-gap magnetic flux density.

Simulation Calculation and Verification of Initial Injection MAP Based on Two Stroke Engine Numerical Model

HU Shan-Zhen-1, 2, WEI Min-Xiang-1, CHEN Lin-Lin-3

2011, 22(22):  2682-2685. 

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To improve the power performance,fuel economy and reliability of a small two stroke engine,a numerical model of the prototype engine was created by utilizing the thermodynamic numerical calculation software.The model was verified by the pressure indicator diagram in the cylinder, total power and fuel consumption rate under full load conditions.Then, the air mass flow in the intake port was acquired by numerical computation,the data of the injection quantity of the engine was calculated,and the initial injection map was obtained.Based on the map,an electronic control fuel injection system was developed.The engine bench test runs smoothly, which is the verification of the numerical model of the engine. Thus, the foundation for injection calibration of the engine has been built.The development cycle of injection system will be shortened.

A Dynamic Continuous Track Control Method on NX100 MOTOMAN Manipulator

YANG De-Wei, FENG Jie-Ren, GUO Wen-Chao

2011, 22(22):  2686-2690. 

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The control methods of NX100 controller can control a manipulator to follow a given unchanged trajectory, but it has run-unsmooth and time-delay drawbacks to track a real-time changing trajectory.This paper proposed an online pre-updating JOB method to realize dynamic continuous control of MOTOMAN manipulator,which can move smoothly,and response within 375 milliseconds theoretically under this way.This method can be transplanted easily,and online track experiments were carried out on MOTOMAN IA20 manipulator and FANUC 2000i manipulator.This method suits dynamic changing trajectory control situations while continuity and realtime performance of manipulator are required.

Experimental Validation of Structural Vibration Reduction Using Piezoelectric Shunt Damping Approaches

MAO Qi-Bei

2011, 22(22):  2690-2693. 

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With an example of clamped rectangular panel, the vibration control performances of three different types of piezoelectric shunt damping approaches, such as RL series circuit, RL parallel circuit and RL-C circuit, were experimentally analyzed and compared. Experimental results show that the vibration of the structure can be reduced significantly by using these shunt circuits with optimal parameters. Furthermore, it is found that the RL series and RL parallel shunt circuits have the same control performances basically.The RL-C parallel circuit can reduce the value of the inductance L due to the insertion of an external capacitance C. However, the control performance will be reduced simultaneously. The experimental results also show that the shunt circuits are very sensitive to inductance tuning errors. The control performances of these shunt circuits may reduce significantly if the inductances are different with the optimal values.

Parameterization of Faceted Surfaces Based on Neighborhood Polygon Characteristics and Energy Optimization

BANG Wei, CHEN Wen-Liang

2011, 22(22):  2694-2699. 

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A new parameterization method based on neighborhood polygon characteristics and energy optimization was proposed for complex faceted surfaces. Firstly, a neighborhood polygon characteristics linear system was constructed using the corresponding angle and length ratio of two adjacent edges, and the faceted surfaces can be flattened by solving a constrained optimization problem; the deformation energy will be generated inevitably in the faceted surfaces flattening process, and then the energy will be released by energy optimization method. Finally, the faceted surfaces parameterization result can be obtained. The results show that good parameterization results can be obtained by this proposed method, and this method can be used in CAD areas, such as complex model remesh. 

Study on Part's Set-up Planning Algorithm in CAPP

HUANG Wei-Jun-1, HU Xu-Jin-1, CA Li-Gang-2

2011, 22(22):  2700-2706. 

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Aiming at the set-up planning problem in computer aided process planning, a novel automatic set-up planning model for the prismatic part was present on the basis of definition of machining element, and a fuzzy clustering method for solving the model was proposed. From the perspective of process decision-making, these related factors affecting the machining element clustering were analyzed, such as the processing equipment, tool approach direction, process constraints etc., then the fuzzy similarity among machining elements was calculated. A net-making method was applied to cluster the machining elements of a part in various set-ups based on the set-up similar relation matrix; following the principle of minimum number of cutter changes, the machining elements clustered in the same set-up were sorted according to precedence relationship graph. Finally several case studies show that the proposed method is feasible. 

Fillet Recognition and Suppression in CAD Model Based on Feature Chain(Ring)

CHEN Zhi-Yang-1, YU Gu-Ming-1, ZHANG Yin-2

2011, 22(22):  2707-2711. 

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The paper proposed an algorithm of fillet recognition and suppression based on feature chain. Firstly, all fillets of the model were recognized. Secondly, a face-edge graph was built based on fillets, the connected subgraph was taken out successively, and the feature chain(ring) was established. According to the feature chain, the features (fillet) in the chain was suppressed. The fillets not in chain were suppressed by connected graph of minimal and with same radius.In summary,the algorithm can suppress the fillets with variable and constant radius, and the model containing non-quadric surface fillets can be suppressed well.

Virtual Prototype Parameterized Modeling and Simulation Analysis of Cone Crusher

YUE Shuang-Jie-1, FAN Xiu-Min-1, 2, MA Pan-Jun-1, DONG Gang-1

2011, 22(22):  2712-2716. 

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In order to improve mechanical structure operational performance and dynamic performance of crusher in the design stage,a method of cone crusher virtual prototype parameterized modeling was proposed which was based on the main parameter of cone crusher and combined with ADAMS modeling language.Expressing relationship between elements by parameterized types and constraint types,a general parameterized model was simulated to obtain mantle rotation speed information and key moving pairs' kinetic information under different working conditions, those data would support the evaluation of cone crusher performance and the following finite element analysis.

Finally,taking PYG1100 cone crusher as an example,the parameterized modeling and simulation analysis were completed to verify the validity and reliability of the model.

Research on Master-slave Tele-operated Force Sense Bilateral Servo Control System by H∞ Control

Wen Guang1,Gong Mingde2,Zhang Hongyan2

2011, 22(22):  2717-2722. 

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Aiming to the problem about big impact feedback force and bad position tracking of parallel force feedback bilateral hydraulic servo control system, a novel force sense bilateral servo control strategy was presented, which regarded the force errors between the master's manipulative force and the slave's resistance as command signals, the position errors and force errors were fed back for driving movement of the master; combined the master-slave control characteristics of tele-operated construction robot. Based on characteristics of tele-operated construction, through carrying on H∞ control with state observer compensated to hydraulic servo control force feedback joystick system, dynamic characteristic difference of hydraulic motor was improved, and experimentation of force sense bilateral servo control were carried on. Experimental results show that the strategy improves manipulative capability of master-slave control system, manipulator can obtain true “force sense” tele-existence, and takes on characteristic of control briefness, constringency rate rapidness, real-time well.

Effects of Flow Field on Heat Transfer Characteristics for Periodically Impinging Jets

GENG Li-Ping-1, 2, ZHOU Jing-Wei-2, YANG Mo-1

2011, 22(22):  2722-2726. 

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A numerical simulation was carried out to study the effects of the flow field of periodically impinging jets on heat transfer characteristics. The numerical model was validated by experimental results. Numerical simulations were performed for typical periodical jets such as sinusoidal, triangular and rectangular jets. The history profiles of temperature, coefficient of heat transfer and turbulence intensity at stagnation point were numerically obtained and the different heat transfer chracteristics for the three periodical jets were analyzed. The investigation shows that turbulence intensities for the sinusoidal, triangular jets will have a suddenly augumentation, which is beneficial to heat transfer enhancement, when the velocities of these two periodical jets increase. However, the turbulence intensities change slowly in the rest time of a period. The turbulence intensity for a rectangular jet will have a sudden enhancement when the jet have a step change, no matter an increasing step or a decreasing step change. But the turbulence intensity enhancement happened in the velocity decreasing step change is much larger than another one. Such a turbulence intensity abrupt enhancement is obviously good for the rectangular impinging jet heat transfer. The influence of a periodical jet can be observed all over the flow field, although the oscillation of the velocity far from the stagnation point is very small. However, the average velocity of a rectangular jet is still significantly larger than those for sinusoidal, triangular jets.

Insulation Resistance Variation with Vacuum and Temperature for Aerospace Electrical Connectors

CHEN Wen-Hua-1, 2, GAO Liang-1, LI Xing-Jun-1, LIU Juan-1, LEI Xian-Biao-3

2011, 22(22):  2727-2732. 

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Taking Y11P-1419 electrical connector as the object,the variation of insulation resistance with vacuum and temperature for Y11 series of aerospace electrical connectors was researched.The influences of vacuum and temperature on the insulation resistance of aerospace electrical connectors were analyzed.Through testing and statistical analysis for the testing data,the variation of the insulation resistance with vacuum and temperature was revealed,and the test phenomena and statistical results were explained from mechanism.The research results show that the changes of vacuum and temperature exert significant influences on the insulation resistance of electrical connectors, there are interactive effects of vacuum and temperature.When the temperature remains constant, the insulation resistance of electrical connectors increases as the pressure decreases; when the pressure remains constant, the insulation resistance of electrical connectors decreases as the temperature increases.

Prediction of Laser Cutting Speed for Stainless Steel

CHEN Ying-Ying-1, 2, FENG Wen-Jie-1, 2, QIN Feng-Dong-2, HUANG Jiang-2, ZHANG Meng-Liang-3

2011, 22(22):  2732-2734,2738. 

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Based on the interaction principles between laser and material in laser cutting stainless steel,thermal conduction law was analyzed,and a thermal model of the cutting process was advanced.Through thermal balance equation,where the total heat absorbed was equal to the sum heat both absorbed by removed material and lost by conduction, the functional relationship about cutting speed was established,which can predict cutting speed. The technological tests indicate that the predictions are fit in the experimental results perfectly, and it can be used for the guidance of practical applications.

Optimum Plan of Reliability Evaluation of NC Machine Tools Based on Exponential Distribution

DAI Yi

2011, 22(22):  2735-2738. 

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A reliability evaluation test plan of NC machine tools based on exponent distribution was investigated. At first the evaluation test plan type was confirmed as timing censored lifetime test with replacement, secondly the minimum failure number was discussed to get certain confidence interval, and then the condition that the product of machine tool number and censored time should satisfied was analyzed to get the minimum failure number.At last, the optimum plan about machine tool number and censored time were put forward. 

Research on Tool Path Generation Algorithm and Improvement Based on Hilbert Space-filling Curves

LI De-Shen, JIAO Dun-Feng

2011, 22(22):  2739-2743. 

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A generation method of Hilbert space-filling curves was researched. It was established that the mapping relationship from Hilbert space-filling curves in plain to Bezier parametric surface. And then the mapping rules and the program were also proposed. Owing to frequently reverse, it was adopted that a chamfer or an arc on transition instead of the right angle，so the impact on the tool and the part in machining process was reduced. The optimization method of tool path generation was applied to generate tool path, and the length of tool path and time of the two methods were contrasted. The method was used for a specific surface, and the effectiveness of the method was verified.

Evolution of Microstructures and Inclusions of 82B Wire Rod during Drawing Process

XU Qiang-Bei-1, 2, SUN Ying-1, LIU Xiang-Hua-2, YU Hai-Liang-3, DIAO Pan-Jun-4, CAO Qi-4

2011, 22(22):  2744-2748. 

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An experiment was carried out that an 82B wire rod of 12.5mm in diameter was drawn nine passes. The evolution of the microstructures and inclusions of the 82B wire rod were observed by SEM after drawing at different strain, and the relation between pearlitic lamellar spacing and the drawing strain was investigated.The results indicate that the pearlitic lamellar spacing decreases as the drawing strain increases.And the drawn pearlitic layer distorted strongly and lamellar cementite deform along with the bending of lamellar ferrite, so they show good capability of plastic deformation. Moreover, the martensite formed owing to centre segregation is broken to pieces because of its weak plastic deformation capability in the drawing process and finally breaks away the matrix. In contrast to this, although a brittle inclusion of 10μm in diameter has also been broken to pieces in the drawing process, the crack around the inclusion is not formed.

Development of One Kind of FV520(B) Stainless Steel Matching with Alkalinity Welding Electrode Used on Fan Impeller 

ZHANG Min-1, LI Yan-1, 2, LI Ji-Gong-1, LV Jin-Bei-1

2011, 22(22):  2749-2753. 

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According to the mechanical property requirements of fan impeller welded joints to high-performance welding electrode and combination with principles of welding material designed to microstructure matching, a kind of welding electrode with good mechanical and processing properties was developed by using metallurgical analysis, mechanical property testing and fracture observation.The results show that the deposited metal of developed welding electrode with the alloy system Cr-Ni-Nb-Cu-Ti and mechanical properties of welding electrode developed is superior to the special welding electrode of

FV520(B) stainless steel. Mechanical properties of deposited metal were improved by carbides

rich of chromium and alloying.The carbides are Mo2C3,NbCrN and Ti(C,N) which

are composed by alloy element of Mo,Nb,Ti,Cr and so all.The welding zone and HAZ microstructure of FV520(B) stainless steel is composed of tempered sorbite, lath martensite,

residual austenite and quadratic precipitated phase. However, the fracture mechanism of No.1,No.2 and No.4 welding electrode is quasi-cleavage crack and the No.3 is complex fracture consisting of dimple and cleavage fracture. 

Modeling and Model Amendment for Welded Steel Tube with Modal Parameters Object

LI Yong-Jun, MA Li-Yuan, LI Shi-Long, WANG Tian-Hui

2011, 22(22):  2754-2757. 

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Modeling of the heat affected zone in welding is a difficult problem in dynamic analysis, while the consistent of modal parameters is a major objective of modeling and model amendment. The two key issues herein are the same approximation of the model and analysis of the sensitive parameters in model amendment. With the scale samples of a welded steel pipe for the object and experimental test results provided, the simulating process was studied so that the model can approach the two test targets, namely the natural frequencies and modes of the structure. And then the main sensitive parameters during the model amendment were analyzed. The results show that the weld thickness of the welded steel pipe, the elastic modulus of the welding line and heat affected zone should be considered as the main parameters in model amendment. 

Investigation of Microstructure and Superhardness Effect of TiAlN/SiO2 Tool Nanomultilayers

WANG Jun-Chao, LIU Beng, YANG Li-Gong, LI Wei, LIU Xin-Kuan, MA Feng-Cang

2011, 22(22):  2757-2761. 

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A series of TiAlN/SiO2 nanomultilayers with various SiO2 layer thicknesses were synthesized by reactive magnetron sputtering. The microstructure and mechanical properties were evaluated by X-ray diffraction (XRD), scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM) and nano-indentation. The results reveal that, under the template effect of TiAlN layers, amorphous SiO2 is forced to crystallize and grow epitaxially with TiAlN layers when SiO2 layer thickness is below 1nm, and the nanomultilayer appears superhardness effect with the maximum hardness and elastic modulus of 37GPa and 393GPa when SiO2 layer thickness is 0.6nm. As the SiO2 layer thickness exceedes 1nm, SiO2 transforms into amorphous state and breaks the coherent growth of multilayers, resulting in the decrease of hardness and elastic modulus. Therefore cutter protective coatings which possess better mechanical properties and good oxidation resistance at high temperature are synthesized by this mechanism to meet modern cutting.

Research on Gear's Contacting Fatigue Life Prediction of Side Reducer in Armored Vehicle

TANG Dong-Gong, CUI Yu-Lian, ZHANG Bing-Chi, DIAO Yong-Dong

2011, 22(22):  2762-2765. 

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By dealing with the load data from vehicle test on typical terrain, this paper obtains the torque and stress spectrum bearing by the side reducer gear in armored vehicle. Considering the influence of the residual stress on the contacting fatigue limit, the distribution of strength and contacting fatigue limits in different depths were obtained by means of the distribution of residual stress and hardness as well as the relationship between strength and hardness. The gear's fatigue life was predicted by combining the fatigue life prediction technique.The prediction result is accorded with the actual rule.

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HU Jin-Fang, CHEN Mo-Wei

2011, 22(22):  2766-2771. 

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