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Table of Content

    25 February 2007, Volume 35 Issue 2
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    Mechanics
    Effect of Environmental Temperature on Load-Carrying Capacity of RC Beam Strengthened with CFL
    Huang Pei-yαn Zhang Bo-lin Yang Yi Zhou Zhi-lin
    2007, 35(2):  1-5. 
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    The load-carrying capacity of the reinforced concrete( RC) beam strengthened with carbon fiber laminate (CFL) under different failure modes in the temperature field was theoretically analyzed. The results show that the environmental temperature affects the load-carrying capacity of the strengthened RC beam to a certain degree , and the details are: (1) when the CFLs are in the thickness of o. 1 , o. 2 , o. 3 and o. 4 mm , the cracking loads of the strengthened beams respectively increase by 5.37%, 10.46%,15.9% and 20.94% at a temperature increase of 30 K; (2) the strengthened RC beams with the CFL thickness of o. 1 and o. 2mm are of a failure mode of tension fracture and a decreasing extreme load-carrying capacity in an increasing temperature field , the decrease being less than 3.5% ; and (3) the strengthened RC beams with the CFL thickness of 0.3 and O. 4mm are of a failure mode of concrete crush and an increasing extreme load-carrying capacity with the environmental temperature , the increase being less than 3. 5 % .

    Investigation into Arc Windshield of Aircraft Subjected to Bird Impact
    Yao Xiao-hu Han Qiang Zhao Long-mao Yang Gui-tong
    2007, 35(2):  6-12. 
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    An experimental investigation into the arc windshield of a homemade aircraft subjected to bird impact was performed. The critical velocity of the arc windshield , the history curves of displacement and strain of the key point were all obtained. On the basis of the experimental investigation , a finite element model for the full-scale cir-cular arc windshield and the related parts of the aircraft was established. The whole process of bird impact was then numerically simulated using the nonlinear finite-element software LS DYNA3D. A comparison between the wind-shield and the bird in the deformation process and the dynamic history curves of displacement and strain was made ,showing that the experimental results accorded well with the simulated ones. Moreover , the impact force-time curves under different impact velocities were presented. The possible location where failure occurred was finally analyzed.

    Analysis of Multiple Cracking of Carbon Fiber Sheet-Reinforced RC Beam Under Four-Point Bending
    Zeng Qing-dun Chen Xi-long Tan Cha-sheng
    2007, 35(2):  13-17,22. 
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    With the aid of the analytical methods of composite mechanics , a layered shear-lag model is established to investigate the multiple cracking of reinforced concrete (RC) beam reinforced with carbon fiber sheets under four-point bending. The relationships between the crack items and the applied load as well as the number of carbon fiber sheets are then obtained , where the crack items include the crack density and the maximum crack width in the reinforcement cover under the pure bending part of the beam. The calculated results are in good agreement with the xisting experimental ones , showing that (1) the crack density and width increase with the applied load; (2) with the increase of the number of carbon fiber sheets , the crack spacing obviously becomes small , while the maximum crack width almost remains constant; and (3) in the case of a small number of carbon fiber sheets , a cluster of sa-turation cracks emerge in the reinforcement cover under the pure bending part of the beam when the applied load reaches or exceeds a certain value.

    Fatigue Damage Behavior of Steel Fiber-Reinforced and Polymer-Modified Concrete
    Liu Yi-ping Tang Li-qun HuαngXiao-qing Liu Ze-jia
    2007, 35(2):  18-22. 
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    The bending fatigue damage behaviors of a new kind of material-steel fiber-reinforced and polymer-modified concrete was experimentally and theoretically investigated , and the results were compared with those of steel fiber-reinforced concrete. Then , by reasonably defining damage factors , the fatigue damages and the corre-sponding evolution principles of the new material and the steel fiber-reinforced concrete were measured by experiments.A new fatigue damage evolution equation was proposed according to the fatigue accumulative damage theory ,the effectiveness of which was verified by experimental results. Finally , the fatigue damage evolution behaviors of the two above-mentioned materials under the same stress were analyzed and compared. The results show that the steel fiber-reinforced and polymer-modified concrete is of better fatigue resistance than the steel fiber-reinforced concrete.

    Fatigue Açcumulative Damage Model of RC Beam Strengthened with Carbon Fiber Laminate
    Niu Peng-zhi Huang Pei-yαn yao Guo-wen Yang Yi Zhao Chen
    2007, 35(2):  23-26. 
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    The three-point hending experiments of the reinforced concrete (RC) heam strengthened with carbon fi-her laminate (CFL) were carried out , and the corresponding fatigue life curve was ohtained. Moreover , the evolu-tion histories of midspan flexihility and hending rigidity of the strengthened heam were descrihed. The residual ben-ding rigidity was then used to define the damage of the strengthened heam. Thus , a fatigue accumulative damage model was proposed to analyze the damage and fracture process of the strengthened heam. The evolution of the fa-tigue damage of the RC heam strengthened with CFL was finally calculated and discussed. The results show that the proposed model can correctly descrihe the damage and failure processes of CFL-strengthened RC heam , including the concrete cracking , the CFL dehonding from the concrete and the yielding of the steel har.

    Traffic & Transportation Engineering
    Boundary Pre-Adjustment Method for Finite-Element Mesh Generation of Closed Surface
    Du Qun-gui Liu Sheng Huang Xiao-dong
    2007, 35(2):  27-32. 
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    In order to guarantee an integrated boundary relationship between a closed surface and its parameter field , and to ensure the reliability of the advancing front technique (AFT) in mesh generation , a boundary pre-ad-justment method of closed surface is developed , in which new edges related to the boundaries of the parameter field and the virtual boundaries inside the parameter field are formed and defined as the additional boundaries of the closed surface. As a result , the closed surface is divided into a series of slices with open surface. Therefore , me-shes can be simultaneously generated via the AFT on each slice with open surface. The proposed method for bound-ary pre-adjustment makes the AFT suitable to the mesh generation of various closed surfaces.

    Analysis on AMT Shifting Process of Hybrid Electric Vehicle
    Luo Yu-tao Zhou Si-jia Zhao Ke-gang
    2007, 35(2):  33-36,42. 
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    A method to synthetically control the motor working together with the automatic mechanical transmission (AMT) is put forward based on the fast rotating-speed adjustment response of the speed loop in the motor control-ler.In this method , the shifting process is adjusted by the motor speed and the shifting time of joggled gears is shortened. The GZ6110HEV hybrid electric bus is then used as a control target to build a dynamic model of the
    driving line. Simulated and experimental results indicate that the proposed method is effective and practicable due to its advantage in shortening the shifting time.

    Structure and Simulation of Electromagnetic Continuously -Variable Transmission System
    Li Yu-zhou Luo Yu-tao Zhao Ke-gang Li Jun
    2007, 35(2):  37-42. 
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    The electromagnetic continuously-variable transmission (EMCVT) system is a system that works as a continuously variable transmission and possesses the functions of the clutch and the starter motor of a vehicle. In this paper , the structure and operation principle of the EMCVT system are discussed , and some of its models inclu-ding the power-flow mathematical model are then constructed. By analyzing the established model , it is shown that the EMCVT system can enable the engine to work on an optimal fuel-economy point , with a higher efficiency than the conventional cascade system. The feasibility of the EMCVT system is finally verified by the Matlab/Simulink simulation of a vehicle.

    Expert System for ßus-Styling Appraisement ßased on Neural Network
    Zhao Ke-gang Luo Yu-tao Pei Feng
    2007, 35(2):  43-46. 
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    A bus-styling appraisement method by constructing an expert system based on the artificial neural net-work (ANN) is presented in this paper. The key techniques of the expert system for quasi-three-dimension bus-sty-ling appraisement are then investigated , including the data collection , the graph pre-processing , the database con-struction and the design and training of ANN model , etc. Moreover , an expert system software is developed to app-raise bus styling. The effectiveness of the software is finally verified by a practical bus-styling task.

    Vibration Prediction of Power Transmission Device Based on Elastic Vibration of Crankshaft
    Yu Xue-hua Zhang Jia-dong
    2007, 35(2):  47-49,78. 
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    In this paper , the dynamic stiffness matrix method is used to predict the vibration of the crankshaft sys-tem and to calculate the input exciting force from the crankshaft to the slide rod. Then , a finite element model of the whole power transmission device system is established. The proposed model is finally adopted to forecast and calculate the vibration. The calcu1ated results accord well with the experimental results , verifying that the proposed method is correct and practicable

    Vehicle Positioning ßased on CDMA and GSM Networks
    Shi Sheng-li Xu Jian-min Qin Zhong
    2007, 35(2):  50-53. 
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    The positioning methods based on widely-used CDMA and GSM networks are analyzed , and a vehicle-positioning algorithm combining CDMA and GSM networks is presented , which recalculating vehicles' localization using the measured positioning information from CDMA and GSM networks. The proposed algorithm can make use of the services provided by common network operators. It is simple , accurate and reliable with low time cost , and is adaptive to the update of positioning method. Tested results indicate that the proposed algorithm is feasible and helps to improve the positioning accuracy and the reliability.

    3D Hydrodynamic Response Analysis of Underwater Towed Vehicle Under Joint Manipulations of MuItiple Controls
    Wu lia-ming Xiong Xiao-hui
    2007, 35(2):  54-58. 
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    In this paper , a self-stable controllable underwater towed vehicle was taken as the research object , and the 3D hydrodynamic response perlormances of the vehicle with a constant velocity under the joint manipulations of a depressing wing and a twin-stern thruster were discussed. In the investigation , a numerical hydrodynamic model was established based on the LMBP algorithm of neural network theory. The experimental data for training the pro-posed model were provided from those of 2D vehicle prototype towing experiments conducted in a towing tank under the manipulation of single control mechanism such as a depressing wing or a twin-stern thruster , respectively. The 3 D hydrodynamic perlormances of the vehicle under the joint manipulations of the two above-mentioned control mechanisms were then analyzed based on the proposed model. The results of numerical simulation indicate that , by using the proposed model , the 3 D hydrodynamic perlo口nances of the towed vehicle under the joint manipulations of multiple controls can be effectively simulated.

    Simulation of Temperature Field of Bridge Deck Pavement with ANSYS Software
    Lu Yan-qiu Zhang Xiao-ning Tang Wei-xia
    2007, 35(2):  59-63. 
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    This paper aims to reveal the temperature distribution in the bridge deck pavement and to provide some theoretical guidelines for the calculation of temperature stress and the material design of the bridge deck pavement. In the investigation , the atmosphere factors that affect the temperature field of the bridge deck pavement are first an-alyzed based on aerography and calorifics theories. A two-dimension calculation model of the transient temperature field is established according to the Fourier heat-transfer law. Then , the proposed model is simulated using the fi-nite element software ANSYS. The obtained results are finally compared with those of the on-the-spot survey. It is concluded that , given the correct boundary conditions and thermo-physical parameters of the pavement material , the proposed model helps to obtain precise numerical solution.

    Calculation of Low-Temperature Relaxed Modulus of Elasticity for Bitumen via Creep Test
    Xue Zhong-jun Zhang Xiao-ning Zhan Xiao-li Wang Jia-ni Zhao Ying
    2007, 35(2):  64-68. 
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    In order to obtain the low-temperature relaxed modulus of elasticity for bitumen by tests with easy manipu-lation, the blending beam rheometer (BBR) was used to measure the creep compliance. The experimental data of BBR were then discretized in time domain. According to the constitutive relationship between the creep and the re-laxation, a numerical iteration expression was thus proposed to describe the relationship between the relaxed modu-lus of elasticity and the creep compliance. By the proposed expression , the relaxed modulus of elasticity for bitumen at the fiducial temperature was further calculated. Moreover , the main curves of the relaxed modulus of elasticity at different temperatures were drawn via the time-temperature equivalent principle. The characteristics of the main curve were finally analyzed and were used to evaluate the low-temperature performance of bitumen , thus providing some references for making the right choice of bitumen in practical engineering.

    Monitoring and Analysis of Temperature for Concrete Box Girder in Continuous Rigid Frame Bridge
    Wang Wei-feng Chen Guo-xiong Ma Wen-tian
    2007, 35(2):  69-74. 
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    In this paper , the general temperature distrihution principle and the temperature effect in the construc-tion of long-span continuous rigid frame hridges were investigated hy means of site measure , calculation and analy-sis, with the Guanyinsha Bridge as the research target. In the investigation , the finite-element software ANSYS was adopted to simulate the temperature field , and the effects of heat conductivity , specific heat and some houndalγ
    conditions such as sunlight radiancy and wind speed on the temperature field were analyzed. Some recommended valuefì were then presented. It is shown that the simulated temperature field accords well with the measured one ,and that the stress and deflection calculated according to the simulated temperature field match the measured values well. As a result , the temperature field and the corresponding temperature-effect analysis of reinforced concrete hox girder can he conducted in real time according to the weather data from the weather hureau.

    Control of Random Wave Response of Wave-Permeable Breakwater Using TLD
    Sun Shu-min Xu Li-ming
    2007, 35(2):  75-78. 
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    The tuned liquid damper (TLD) is app1ied to eontr世the structural vibration of a wave-permeable break-water, and the dynamic response equation of the TLD-equipped wave-permeable breakwater under random wave load is formulated. Then , the influences of TLD parameters on the control effect are discussed on the basis of some calculation examples. The calcu1ated results indicate that the random wave response of the wave-permeable break-water can be effectively controlled when proper TLD parameters are selected.

    Materials Science & Technology
    Isothermal Crystallization Behaviour of Ternary-Monomer Solid-Phase Graft Polypropylene
    Hong Hao-qun He Hui Jia De-min
    2007, 35(2):  79-84. 
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    Temary-monomer solid-phase graft polypropylene (PPTM) was synthesized by the solid-phase grafting of maleic anhydride , methyl methacrylate and butyl acrylate onto polypropylene (PP). Then , the structure of PPTM was investigated by means of Fourier infrared spectroscopy , the isothermal crystallization behaviour of PPTM was studied by using the differential scanning calorimetry and the polarizing microscope , and the isothermal crystalliza-tion kinetics of PPTM was revealed via A vrami equation. The results show that (1) the A vrami index n of PPTM ,which approximates that of PP , is within the range of 0 to 3 , indicating that PPTM has a complex nucleation; (2)the grafted branch chains act as the heterogeneous nuclei , thus increasing the nucleation rate and decreasing the ac-tivation energy of crystallization; (3) the grafted branch chains hinder the crystallization of the PP chains , thus de-laying the PPTM crystallization; and (4) the fitted isothermal crystallization parameters of PP and PPTM prove to be consistent with the experimental data , which indicates the effectiveness of A vrami equation in describing the iso-thermal crγstallization behaviour of PPTM.

    Melt Filling Ability and Cavity Pressure Under Pulsed VibrationField
    Wu Hong-wu Zhang Shao-dan XuHai-hang
    2007, 35(2):  85-88. 
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    By considering the fact that the cavity of the spiral flow mold is both long and narrow , the effect of the pulsed vibration field on the filling ability of the melt in the molding process was investigated by measuring the product length. The cavity pressure in the molding and packing processes was then measured and analyzed using a high-sensitivity melt pressure sensor and a data collection system. Experimental results indicate that the pulsed vi-bration field helps to improve the flow length as well as the filling pressure of the melt in the cavity. Analytical re-sults show that , in a pulsed vibration field , the melt viscosity and the pressure consumption decrease , while the fil-ling ability of the melt and the effective packing time increase. All these factors contribute a lot to the compression of the product.

    Preparation and Properties of the Sensing Membranes Immobilizing Plant Esterase-Chromogenic Agent
    Ma Wen-shi wang Jun Luan Chong-lin
    2007, 35(2):  89-92. 
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    PV AlSi02 organic-inorganic hybrid sol was prepared by means of in-situ sol-ge1 method , with poly( vinyl alcohol) (PV A) and tetraethylorthosilicate (TEOS) as the materials. Then , the sol with the dispersion of chromo-genic agent and plant esterase was dried to form a kind of transparent sensing membrane with controllable hydrophi-licity-acetonephilicity and good storability. It is shown that , (1) when the membrane is soaked in α-naphthyl ace-tate solution , an absorption band occurs at 520 nm in the ultravio1et-visible spectrum; (2) the enzyme activity of the sensing membrane obviously decreases in 12 days until it reaches a constant value; (3) the decreasing rate of enzyme activity of the sensing membrane in cold storage is significantly smaller than that in room temperature storage; and (4) the stability of the enzyme immobilized in the hybrid membrane is greatly improved , as compared with that of the enzyme in solution.

    Investigation into Deformation Characteristics of Aluminum Foam Using Digital-Image Processing Technology
    Hu Ling-ling Huang Xiao-qing Tang Li-qun Qiu Yan-hong Zhang Hong
    2007, 35(2):  93-96,111. 
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    This paper investigates the deformation characteristics of cuboid aluminum foam under quasi -static com-pression.In the investigation , the variation of the current relative density , the porosity distribution and porosity va-riation in the vertical section were all analyzed by means of digital-image processing technology. Some data-proce-ssing methods were also adopted to quantify the image information. Thus , stable current relative density was ob-tained, which is in good agreement with the results in previous studies. The results show that (1) the porosity in each part of the vertical section decreases with the increase of strain during the compression; (2) the deformation occurs in the whole specimen; (3) due to the restriction from the loading plates , the porosity is of an uneven varia-tion in the whole vertical section; specifically , the porosity variation rate of the parts near the two ends is lower than that of the middle parts; and (4) with the increase of strain , the variation rate of porosity becomes even in the whole vertical section.

    Spectroscopic Properties of Er3+ /Yb3+Co-Doped Germanium Tellurite Bismuthate Potassium Glass
    Zhao Chun Zhang Qin-yuαn Chen Dong-dan Jiang Zhong-hong
    2007, 35(2):  97-101. 
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    A kind of Er3+ /Yb3 +co-doped TeO2 -GeO2 - Bi2 O 3 -K2 O glass was fabricated by means of the melting method , and the absorption and upconversion spectra of the glass were obtained by differential thermal analysis.Judd-Ofelt theory was then used to calculate the three strength parameters of the glass , the oscillator strength , the spontaneous radiated transition probability , the fluorescence-branching ratio and the radiation life of each energy level of Er3+. Moreover , the green fluorescent emissions centering at 522 and 546 nm and the red fluorescent emi-ssion at 658 nm were obtained under the laser diode excitation at 977 nm , which respectively corresponded to the transitions2H 11/2 →4I15/2、4S3/2→4I 15/2 and 4F9/2→4I15/2 of Er3 + .It is found that the strong green and red emissions all result from a two-photon absorption process.

    Numerical Simulation of NOx Formation in Kiln
    Zeng Ling-ke Deng Wei-qiαng Fang Hqi-xin Wang Hui Shui An-ze Liu Ping-pan Cheng Xiao-su Liu Yan-chun Zhang Hai-wei
    2007, 35(2):  102-106. 
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    In order to reveal the main factors that affect the NO x formation in the process of maturing , CFD ( Com-putational Fluid Dynamics) software Fluent was used to simulate the mechanism of NOx formation. The results show that the formation of NOx is mainly affected hy the rising-rate of temperature , the maturing temperature and the flow velocity of kiln gas. As a result , in allowahle processing conditions and output , the formation of NOx can he de-creased hy properly decreasing the rising-rate of temperature , improving the kiln structure , accelerating the flow of kiln gas , uniformizing the kiln gas and reducing the retention time of kiln gas in the high-temperature region.

    Numerical Simulation of Spray Drying Process for Producing Ceramic Microsphere
    Cheng Xiao-su Fang Hai-xin Liu Ze-hao Zhang Ying-yuan Wang Yue Wang Yong-zhao Liang Zhi-xian Zeng Ling-ke
    2007, 35(2):  107-111. 
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    A mathematical model that describes the spray drying process for producing ceramic microsphere is pro-posed based on the analyses of mass-and heat-transfer processes. The corresponding boundary conditions of the model are also determined. The Fluent software is then used to simulate the size and moving trace of the spraying particles. By comparing the calculated results with the tested ones , suitable operation parameters of the spray dry-ing process are finally determined. When the inlet temperature of air is 573 K, the outlet temperature of exhaust gas is 388 K, and the outlet pressure of exhaust gas is - 350 Pa , the best rotating speed of spray head is 12000 r/min.

    Effects of Silane Coupling on Interface Between Asphalt and Granite or Cement Mortar
    Su Da-gen He Juan Zhang Jing-feng
    2007, 35(2):  112-115,124. 
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    The water solution of silane coupling A was sprayed to the surfaces of granite and cement mortar , and the effècts of silane coupling on the inte由ces between asphalt (or emulsificated asphalt) and granite (or cement mortar) were investigated by means of infrared spectrum analyses , strength determination and adhesion tests. The results show that (1) for the granite , sand powder and cement slurry powder treated by silane coupling A, there
    appear clear-CH2 absorption bands in the IR spectra as well as coupling layers on the surfaces , which enhance their cohesion with asphalt and emulsificated asphalt; (2) after the coating of cement mortar with O. 6% silane cou-pling A and after the connection to emulsificated asphalt and asphalt , the 28 -day flexural and tensile strengths of the spaceman increase by 20% and 60% respectively; and (3) after the soaking in silane coupling A solution , the granite is of a larger binding area with emulsificated asphalt and an increased cohesiveness grade with asphalt.

    Hydration Characteristics of Cement Kiln Dust as Cementitions Materials
    Jin Xue-li Zeng Ling-ke He Zhen Shui An-ze Luo Xiang-yu Li Ping
    2007, 35(2):  116-120. 
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    In this paper , cement kiln dust (CKD) , fly ash and slag were mixed with Portland cement to compose a complex system. The hydration characteristics of the system were then investigated using a non-contacting resistivi-ty meter and by means of hydration heat test and SEM. Moreover , the folding resistance and compressive resistance of the mortar were measured. The results show that the water-soluble alkali and sulfate compounds in CKD provide an alkali environment for the activation of the latent activity of fly ash and slag , and help to improve the early-stage strength of the blending system with large doping amount.

    Fractal Dimension of Pore Structure of Concrete
    Wei Jiang-xiong Yu Qi-jun Zeng Xiao-xing Bai Rui-ying
    2007, 35(2):  121-124. 
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    A fractal model is established to simulate the spatial structure of concrete slurry , and a formula that de-scribes the relationship among the fractal dimension D , the porosity P and the pore distribution is deduced. ßased on the proposed formula , a fractal dimension of concrete pore structure in the range of 0 to 3 is obtained , which in-creases with the decrease in porosity and with the widening in pore distribution. Moreover , a Mercury Intrusion Po-rosimeter (MIP) is used to determine the pore structure of ordinary Portland cement and to calculate the corre-sponding fractal dimension. The results indicate that the fractal dimension and the concrete strength are closely in-terrelated.

    Simulated Study on Corrosion Resistance of Guangzhou Metro Engineering Concrete
    Huang Wen-xin Yin Su-hong Liu Hang Wei Jiang-xiong Wen Zi-yun
    2007, 35(2):  125-130. 
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    The cOITosion resistance of Guangzhou Metro engineering concrete to groundwater was investigated bysimulated and accelerated corrosion tests. In the investigation , the specific specimen similar to the one in actual use was cured in the simulated groundwater solution with chlorine and sulfate ions at 20 ℃. The results show that (1) the ratio of the cured specimen to the standard specimen in compressive strength continuously decreases with the in-crease in curing time; (2) the Cl - content of the cured specimen is close to the criterion limit after 40 days; and (3) temperature rising and alternative wetting/ drying may affect the compressive strength and corrosion resistance of concrete in varying degrees.

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