Table of Content

30 January 2015, Volume 49 Issue 01 Previous Issue    Next Issue

Metallography and Metallurgical Technology

Select

Design of Principle and System of Large Rotating Conicoid Intelligent Precision Grinding HU Dejin 2015, 49 (01):  1-6.  Abstract ( 715 )   Save Abstract： The precision grinding principle of the spherical, aspherical and other large two revolving curved surface was analyzed. Besides, a novel method for grinding large rotating conicoid with two linear motion and a rotation was introduced. Moreover, an approach for a realtime detecting surface precision based on normal tracking was proposed, and the intelligently precisely grinding system was designed. The results show that with the application of this method, the grinding spindle rotation center line coincides with the normal line of the ground point on the quadratic rotated conicoid, thereby, improving the grinding accuracy and grinding efficiency. References | Related Articles | Metrics

Select

Establishment of Strain Rate Dependent Constitutive Model for Roll Forming Process YAN Yu,WANG Haibo,ZHAO Wei 2015, 49 (01):  7-11.  Abstract ( 1115 )   Save Abstract： The strain rate ranges were determined and the uniaxial tensile tests of DP 980 steel sheet under three strain rates were performed. With the nonlinear fitting of the experiment data, the strain rate dependent JohnsonCook constitutive model was established. Meanwhile, an finite element model of roll forming process with the established constitutive model was constructed, and the corresponding experiment was conducted. The resrults indicate that the established constitutive model is reliable, and can be used in further study of roll forming process optimization. References | Related Articles | Metrics

Select

Experimental Study of Hot Stamping Process of B1500HS Ultra High Born Steel ZHANG Lei,ZHAO Yuzhang,WANG Wurong,WEI Xicheng 2015, 49 (01):  12-18.  Abstract ( 1139 )   Save Abstract： In order to determine the heating specification of coldrolled boron steel B1500HS with a thickness of 1.8 mm, the effect of austenitizing temperature and soaking time on the quenching microstructures, original austenite grain sizes and mechanical properties were investigated. The Vshaped bending die with a cooling channel was used to conduct the hot stamping experiment of B1500HS steel and cold stamping test of M1200 fully martensite steel. The results indicate that the tensile strength of hot stamping part is up to 1.530 GPa, and the profile has a perfect precision with almost no springback. Compared with the hot stamping process of B1500HS, the cold stamping process of M1200 martensite steel requires much higher forming load, approximately 750 kN, which is twice as much as that of hot stamping process. In addition, the part of cold stamping obviously has springback and the springback angle is approximately 9°. Key words： References | Related Articles | Metrics

Select

Whole Lifecycle Reliability Assessment of Multiple NC Machine Tools with Minimal Repair REN Lina,RUI Zhiyuan,LIU Jun,LEI Chunli 2015, 49 (01):  19-23.  Abstract ( 819 )   Save Abstract： Based on superposed loglinear process (SLLP), a whole lifecycle reliability assessment method for multiple numericallycontrolled (NC) machine tools with minimal repair was proposed. A bathtub curve model, which includes early failure period and wear failure period, was presented. The lasting time of early failure period was quantitatively analyzed, and the point maximum likelihood and interval estimators of model parameters and reliability indices were given. An example of real data with failure truncation from multiNC machine tools was taken to prove the proposed method. The results of AIC and goodnessoffit show that the SLLP model is better than that of the superposed powerlaw process model, which is suitable for whole lifecycle reliability assessment of NC machine tools. References | Related Articles | Metrics

Select

Design of a Wire Transport System and Position Fluctuations of Discharge Area in Wire Electrode in WEDG WANG Yanqing1,2，BAI Jicheng1，ZHU Guozheng1，ZHANG Heng1 2015, 49 (01):  23-30.  Abstract ( 174 )   Save Abstract： A multidegree of freedom vibration model for wire transport system was developed to analyze the effects of material and diameters of wire electrode, diameters and mass of wheels, and the length of wire electrode between two adjacent wheels on the natural frequency of the wire transport system. And the obtained conclusions through simulation analysis were used to increase the natural frequency of the wire transport system, thereby reducing the possibility of resonance and decreasing the position fluctuations of discharge area. The effects of wire running speeds, wrap angles of wire electrode on wheel guide, and wire electrode tension on the position fluctuation rang of discharge area were experimentally studied. Finally, a micro shaft with a diameter of (50±1) μm was successfully fabricated. The experimental results show that the designed wire electrical discharge grinding(WEDG) device and optimal parameters obtained through experimental study can be used to process micro shafts with high dimensional accuracy. References | Related Articles | Metrics

Select

Multi-Objective Optimization of Auto Inner Panels Based on Model-Based Calibration Toolbox XIA Yufeng,TIAN Yongsheng,YANG Jianbing,CHEN Banghua 2015, 49 (01):  31-36.  Abstract ( 142 )   Save Abstract： Taking auto inner panels as a research object, a mathematical model for studying the relationship among the friction coefficient, blank holder force, sheet size, the coefficient of drawbeads restraining force with springback and thickness of sheet metal was built based on modelbased calibration (MBC) toolbox using Matlab software in order to study the influence of process parameters on the springback and thickness of sheet metal. An multiobjective function was optimized to get the best combination of parameters by the CAGE optimization module in modelbased calibration toolbox, namely, the friction coefficient is 0.125, the blank holder force is 350 kN, the sheet size is 250 mm×360 mm, the coefficients of drawbeads restraining force are 20%, 10%, 6%, 35%. The numerical simulation and experimental results indicate that this method is feasible.   References | Related Articles | Metrics

Select

Influence of Equal Channel Angular Extrusion on Erosion Wear Resistance of Ti5553 LI Zhenhua1,MA Caiyun1,HUA Chen2,CHENG Xianhua2,3 2015, 49 (01):  37-43.  Abstract ( 130 )   Save Abstract： A novel method was proposed to improve the erosion wear behaviour of Ti5553 exposed to seawater with quartzes, in which the erosion performance of Ti5553 treated by equal channel angular extrusion (ECAE) was compared with that of counterpart without ECAE treatment. The results indicate that the sample treated by ECAE demonstrates a significantly improved erosion wear resistance due to the grain refinement introduced by ECAE, resulting in the improvement of tensile strength, ductility, toughness and microstructure of the sample. Scanning electron microscope (SEM), assisted by quantitative analysis utilising Matlab, was adopted to generate the surface morphology of the samples. With the exploration of the microstructure, mechanical properties and erosion mechanism evolution dependence of erosion wear behaviour, it is found that the erosion mechanism of the sample treated by ECAE has impact deformation and ploughing, accompanied by severe scratching and crater cracks while that of the sample without ECAE treatment has slight impact deformation and ploughing, with shallow scratching and crater cracks. Key words： References | Related Articles | Metrics

Select

An Evaluation Method of Weld Formation Based on Binocular Stereo Vision ZHANG Pengxian1,LI Ming1,FENG Yi2 2015, 49 (01):  44-48.  Abstract ( 94 )   Save Abstract： A new method was proposed to evaluate weld formation based on binocular stereo vision. First, visual images that contain all information of weld formation were seperated from the images acquiced. With similarity measurement function, and with the size of matching window and similarity threshold being confirmed, an area matching algorithms was established based on gray value to measure weld formation. Next, three dimensional coordinates of weld formation was established by means of matching disparity map, based on which the extraction of weld width and weld hight and the reconstruction of weld formation images were accomplished in three dimension. Finally, according to the requirement of Chinese Standard GB10854—89, for the size examination of steel structure, the indexes to evaluate weld external quality were set up. The four indexes are the difference between maximum and minimum of weld width, the difference between maximum and minimum of weld height, the full degree of weld filled and straightness of weld formation. Weld test results show that weld formation can be evaluated by means of visual measurement method and the indexes. Key words： References | Related Articles | Metrics

Select

Analysis of Strength of Adhesive Bonding of Single Lap Joints of Metal with Reinforcements Based on OneDimensional Beam Theory WANG Yuqi,HE Xiaocong,DING Yanfang,XING Baoying 2015, 49 (01):  49-55.  Abstract ( 136 )   Save Abstract： In order to enhance the strength of adhesive bonding of single lap joints (SLJs), the adhesive bonding of SLJ with reinforcements was designed based on Goland and Reissner’s onedimensional beam theory model. The adhesive bonding of SLJs whose adherends were aluminum alloy 5052 (Al5052), Al5052 with pasting aluminum and Al5052 with pasting copper were separately tested under tensionshear loading, and stress distributions were acquired by means of finite element analysis. The results show that the strength of joints and the state of stress in the adhesive layer are influenced by the stiffness at the end of the overlap region. The strength of adhesive bonding of SLJ whose adherend is Al5052 with pasting copper is stronger than that of other kinds of joints. The feasibility and validity of adhesive bonding of SLJ with reinforcements are verified by these analysis results. Key words： References | Related Articles | Metrics

Select

Finite Element Method Simulation of  Stagger Power Spinning Forming of Automobile Spoke LU Ping1a,1b,ZHANG Yunkai1a,1b,CHEN Bo2 2015, 49 (01):  56-61.  Abstract ( 55 )   Save Abstract： In order to make an indepth research on stagger spinning process of automobile spoke with three rollers, the elasticplastic finite element simulation model was established and the forming process was analyzed based on ABAQUS. The methods for imposing boundary conditions and trajectory curves of rollers were introduced. The correctness of the simulation model was verified by calculating the ratios of kinetic energy and pseudo strain energy to internal energy and by comparing simulation results with production parts by using the reverse technique and experimental measurement. The results show that the material does not produce plastic deformation in the central area of the blank contacting with tailstock. Plastic deformation distributes homogeneously in the circumferential direction of the spoke and changes in the radial direction. Thus equivalent plastic strain rings and thickness rings are formed. Plastic deformation is severe when forming curved fillet areas and outer edge regions of the spoke. Material accumulation defect is likely to occur when forming outer edge regions of the spoke. The thickness of the spoke is different along the generatrix direction, and it changes in accordance with the sine law. References | Related Articles | Metrics

Select

Creep Life of Babbitt ZChSnSb11-6 of OilFilm Bearing WANG Jianmei,XUE Yawen,CAI Min 2015, 49 (01):  62-66.  Abstract ( 135 )   Save Abstract： Aimed at the creep damage problem of bushing Babbitt ZChSnSb11-6 of oil-film bearing in operation, the creep test equipment was designed, and a creep test of ZChSnSb11-6 was conducted. Two kinds of steady-state creep constitutive equations based on Dom theory and the constant speed theory were respectively established by using the creep test data. The experiment indicates that the steadystate creep constitutive equation based on Dom theory has a higher calculation accuracy, with a relative error of 1.52%. Besides, a creep life calculation model of ZChSnSb11-6 of oil-film bearing based on steady-state creep constitutive equation of ZChSnSb11-6 was established. The service life of alloy under any working condition could be predicted. Moreover, the resistivity and hardness of alloy after creep were measured, and their relationship was analyzed. Furthermore, the creep life evaluation model of ZChSnSb11-6 based on the resistivity was established, and a method measuring the resistivity of alloy to evaluate the service life of bearing was proposed. References | Related Articles | Metrics

Select

Microstructure Simulation of Q550D Ultra Low Carbon Bainite Steel DONG Hongbo,YU Xinping,ZHANG Wei 2015, 49 (01):  67-73.  Abstract ( 113 )   Save Abstract： The experimental data obtained by hot compression experiment were used to establish a Q550D low carbon bainite steel dynamic recrystallization model and a cellular automata model. The microstructure evolution on the hot deformation process was simulated by using DEFORM3D finite element software. The simulation results show that the strain rate at a temperature of 1 150 °C for the 0.05 s-1 sample in the process of hot deformation microstructure have dynamic recrystallization and the grain size is refined. At a temperature of 1 050 °C when the strain rate is increased, the dynamic recrystallization austenitic grain size decreases. The simulation results agrees with the experimental results. References | Related Articles | Metrics

Select

Correlation Analysis of Process Parameters and Arc Stability of Underwater Welding SHI Yonghua,LI Zhihui,LIN Shuiqiang,ZHENG Zepei 2015, 49 (01):  74-79.  Abstract ( 100 )   Save Abstract： Underwater wet fluxcored arc welding (FCAW) experiments were conducted in a hyperbaric chamber which was used to simulate different water depths. Relative standard deviation reciprocals of arc voltage were used as an index of welding arc stability. The influences of correlations between arc voltage and welding current at different water depths on arc stability were analyzed. From the point of view of the wire feeding  melting system, the influences of voltage and current correlations on arc stability were analyzed. The correlations of arc stability and arc voltage were numerically fitted by a second order function and then the optimal correlations of arc voltage and welding current were obtained. The results show that the optimal correlation curves of arc voltage and welding current for underwater wet welding are a series of ascending curves, which go upward with the increase in water depth. The arc stability depends on the correlations of arc voltage and welding current, and does not simply decline with the increase in water depth. The arc voltage corresponding to a single welding current of underwater wet welding should be increased as the water depth increases. Key words： References | Related Articles | Metrics

Select

Numerical Simulation of Projection Welding Between Hot-Stamped Steel and Low-Carbon Steel WAN Zixuan1,WANG Min1,JIAO Hailun1,GAO Boen2,LU Xinting2 2015, 49 (01):  80-85.  Abstract ( 63 )   Save Abstract： A kind of software named SORPAS has been applied in this paper to simulate the formation process of nugget in projection welding between hotstamped steel and low-carbon steel. Through the simulation, some changing rules about the temperature field and stress field during the formation process of nugget have been discovered both qualitatively and quantitatively, and the diameter of the final nugget has also been obtained. The results of the simulation show both the shift of nugget to the hotstamping steel sheet of the welding assembly and the change of nugget size with different welding currents applied correspond well with the results obtained by experiments. References | Related Articles | Metrics

Energy and Power Engineering

Select

An Experimental Study of Formation and Flow Charactristics of Droplets in a Rectangular Microchannel QU Jian，WANG Qian，HE Zhixia，HAN Xinyue，HU Zicheng，LIU Tao，WANG Chao 2015, 49 (01):  86-90.  Abstract ( 61 )   Save Abstract： With the aid of a highspeed CCD camera, the droplet formation and flow characteristics in a  polydimethylsiloxane (PDMS) rectangular microchannel with a width of 125 μm and a depth of 300 μm were experimentally investigated. By changing the volumetric flow ratios of water (dispersed phase) and silicon oil (continuous phase), the experimental data on droplet length, velocity, and generation frequency were obtained. Experimental results show that the dimensionless length of droplet in the microchannel can be well determined by the water/oil flow ratio, and a linear relationship is established between them. It is found that the velocity of droplet is larger than the twophase mixture superficial velocity. Besides, a simplified correlation for the precise prediction of the velocity of droplet was developed. In addition, a model predicting the generation frequency of droplet was proposed. The predicted values agree well with the experimental data within a deviation of approximately ±12%. References | Related Articles | Metrics

General Industrial Technology

Select

Performance and Optimization of a Refrigerant Distributor XU Bo1,ZHANG Chi1,CHEN Jiangping1，SUN Xihui2,MA Xiaokui2 2015, 49 (01):  91-95.  Abstract ( 74 )   Save Abstract： This paper studied the distribution performance of a reservoir distributor with complex inlet tube under different conditions. The result shows that the performance is improved with the increase of mass flow rate or the decrease of quality. The average STD is 2.8%. A simulation modeling was made. A new double-barrels distributor was proposed to reduce the influence of the complex inlet tube. The average STD is 2.36%, which is 15.7% better than the original sample. References | Related Articles | Metrics

Select

Prediction Method for Longitudinal Tensile Modulus of Short-Fiber-Reinforced Rubber Sealing Composites ZHANG Bin,GU Boqin,YU Xiaoming 2015, 49 (01):  96-100.  Abstract ( 53 )   Save Abstract： A model was established to predict the longitudinal tensile modulus of short-fiber-reinforced rubber (SFRR) sealing composites, which incorporated the interphase, the fiber and the matrix. The Mori-Tanaka method was employed to calculate the longitudinal tensile modulus of SFRR and the calculation results were compared with the experimental data. Moreover, the effects of fiber volume fraction, interphase thickness and interphase modulus on the longitudinal tensile modulus were discussed. The results show that calculation results of the longitudinal tensile modulus are in good agreement with the experimental data and the relative error is less than 11.2%. The longitudinal tensile modulus of SFRR increases as the fiber volume fraction increases. The interphase modulus has a significant effect on the longitudinal tensile modulus of SFRR. The longitudinal tensile modulus of SFRR increases as the interphase thickness increases when the interphase modulus is less than the matrix modulus, and decreases when the interphase modulus is larger than the matrix modulus. References | Related Articles | Metrics

Select

Effect of Bimodularity on Failure Behaviors of Pinned-Joint Composite Laminates LI Xuan,CHEN Xiuhua,SHI Xiaohui,WANG Hai 2015, 49 (01):  101-108.  Abstract ( 51 )   Save Abstract： A numerical simulation method considering the effect of bimodularity was proposed for the failure analysis of pinnedjoint composite laminates. Owing to different modulus in tension and compression for composite materials, an appropriate stiffness matrix was chosen according to the stress condition. The onset of damage at each ply was predicted by 3DHashin initiation criterion together with Camanho degradation rule. Three sets of composite laminates with different thicknesses and stacking sequencees were studied. Comparison studies were conducted between experimental results and those obtained from the finite element calculations using bimodular and/or tension modulus. The results show that the finite element model considering the effect of bimodularity can more accurately predict the ultimate failure load of pinnedjoint composite laminates. References | Related Articles | Metrics

Mechanical instrumentation engineering

Select

Measurement of States of Cellular Manufacturing Systems Based on Entropy Models ZHANG Zhifeng1,2，DAVID Janet2 2015, 49 (01):  109-115.  Abstract ( 117 )   Save Abstract： The states of manufacturing resources can be monitored and assessed through the amount of information needed to describe their technological structure and operational state from an information-theoretic perspective. The amount of information needed to describe cellular manufacturing systems was investigated by two measures, the structural entropy and the operational entropy. The structural entropic model and the operational entropic model were developed based on the Shannon entropy, respectively. Scheduling was introduced to measure the entropy models of cellular manufacturing systems and the feasible concepts of maximum schedule horizon and schedule adherence were advanced to quantitatively evaluate the effectiveness of schedules. The conclusion shows that the states of cellular manufacturing systems can be measured and monitored and effective ways can also be provided for improving operational efficiency of the systems by the entropy models built. References | Related Articles | Metrics

Select

Normal Contact Stiffness Fractal Model Considering Asperity Elastic-Plastic Transitional Deformation Mechanism of Joints HE Liange，ZUO Zhengxing，XIANG Jianhua 2015, 49 (01):  116-121.  Abstract ( 69 )   Save Abstract： Based on the contact mechanics theory, the deformation behavior of a single contacting asperity was studied, a micro contact model was  proposed considering elastic-plastic transition deformation mechanism of rough surface joints, and a mathematical model of normal contact load and contact stiffness were established. Besides, the fractal model of mechanical joints normal contact load and contact stiffness were presented based on the fractal geometry theory. The results show that the plasticity index is lesser, the relationship between normal contact load and contact stiffness is approximately linear, and with the plastic index increasing, the relationship between normal contact load and contact stiffness is strongly nonlinear. The normal contact stiffness increases with increasing fractal dimension and normal contact load and decreases with increasing dimensionless fractal scale parameters. Moreover, the joints normal contact stiffness whose machining surface were milled and ground were calculated respectively by using the present model. The comparion of test results show that the present model is consistent with the experiment result. References | Related Articles | Metrics

Others

Select

An Experimental Study of Filtration Combustion of Gas and Liquid Fuel in Porous Medium LIU Hongsheng,XU Zhenjie,XIE Maozhao,JIANG Linsong 2015, 49 (01):  122-128.  Abstract ( 108 )   Save Abstract： An experimental study on the premixed filtration combustion of propane/air mixtures in a packed bed consisting of inert ball free accumulated with low velocity was conducted. The condition of combustion chamber temperature, combustion wave propagation speed, and emission load were analyzed, and the influence of gas flow velocity and equivalence ratio on the combustion and the emission characteristics were clarified. Based on the premixed filtration combustion, the preevaporated selfsustaining combustion of diesel in porous media at normal pressure was realized, and the temperature characteristics of liquid fuel filtration combustion were studied.Experimental results show that there are great differences between the combustion wave propagation speed and the region of hightemperature in various stages of combustion. With the increase of the equivalence ratio, the average speed of combustion wave is reduced, the combustion temperature is raised, and the emission load is increased. With the increase of the gas flow velocity, the average speed of combustion wave is increased and the emission load is reduced. The highest temperature for liquid fuel filtration combustion is lower than that of gas, and the central temperature of the burner is much higher than that on the wall. Key words： References | Related Articles | Metrics

Energy and Power Engineering

Select

Simplification of DME Combustion Mechanism and Validation with HCCI Combustion LI Pengfei,QIAO Xinqi,WU Zuozhu 2015, 49 (01):  129-134.  Abstract ( 131 )   Save Abstract： Based on the integration computational singular perturbation (ICSP), a reduced mechanism consisting of 24 species and 20 reactions was simplified from the skeletal mechanism. The reduced mechanism was validated using closed internal combustion engine simulator, and it was found that the reduced mechanism reproduced the important characteristics of dimethyl ether (DME) detailed chemical kinetic model, such as low temperature reaction, negative temperature coeffcient (NTC), the production and consumption of HCOOH and high temperature reaction. The results calculated from the reduced mechanism agree with that from the detailed one, which means that the reduced mechanism is suitable for the numerical simulation of homogeneous charge compression ignition (HCCI) fueled with DME. Besides, the poor applicability of reduced mechanism after trimmed by important index iuustrates the high simplicity of original reduced mechanism. References | Related Articles | Metrics

Select

Effect of Contact Angle on Nucleate Pool Boiling Heat Transfer CHEN Yanjun,LI Yuanyang,LIU Zhenhua 2015, 49 (01):  135-140.  Abstract ( 124 )   Save Abstract： Based on analysis of a semi-analytical heat transfer model with contact angle effect, it is found that the boiling heat transfer characteristics could be expressed as a function of wall superheat, contact angle and physical properties. A correlation for predicting the effect of contact angle on wall heat flux of pool boiling was deduced by using the graphical method. By analyzing the saturated water data on plane metal surface or its coated surface under different pressure conditions, an empirical correlation for predicting the wall heat flux of saturated water nucleate pool boiling under atmospheric pressure was obtained. Furthermore, a semiempirical nucleate pool boiling correlation applying to various liquids under wider pressures was also proposed. The results show that predicted values of saturated water nucleate pool boiling under atmospheric pressure are in good agreement with the experimental results. References | Related Articles | Metrics