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Table of Content

    25 September 2015, Volume 26 Issue 18
    Parameterized Modeling and Modal Analysis of High Speed Grinding Machine  Structure
    Chen Guiping, Wen Guilin
    2015, 26(18):  2415-2418. 
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    The entity parameter model of high-speed  grinder machine parts  was built based on the dynamic sub structure method,the finite element model of the high-speed  grinding machine mechanical structure was established with MSC.Patran/Nastran software,and  modal analysis for the spindle,bed and workbench-bed combination structure was finished.Using the LMS vibration and dynamic signal acquisition and analysis system,the modal experiments were completed.Experiments show that the combining part simulation technology based on the assumed material can make the dynamic test result of  grinder structure and finite element modal analysis result be consistent,the experimental dynamic characteristics of high speed grinding machine are consistent with the finite element analysis ones,and the parametric solid model based on substructure method is correct and feasible for the high speed grinding machine.

    An Assessment Model of Energy Consumption for NC  Turning  Process Based  on   Principle  of  Conservation  of  Energy
    Huang Zhengtao, Zhang Chaoyong, Luo Min, Xie Yang, Zhou Zhiheng
    2015, 26(18):  2419-2426. 
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    Based on the principle of conservation of energy,an accurate assessment model of energy consumption for NC turning operation was presented. According to the energy flow of machine tool system, the power of each energy branch was  separated. After modeling every branch, a function was built  among  energy consumption and spindle speed, feed rate and material removal rate.Because of the independence of these branches, the energy consumption model suited  to the stable cutting stage,and to the stable standby and idle and  cutting-free  stages.The accuracy of  this method  is confirmed over 98% by a series of  turning experiments.On the strength of this method, an improved model of specific energy consumption was developed.

    Study  on  an Improved Trot Gait for Quadruped Robot
    Chang Qing, Han Baoling, Luo Qingsheng
    2015, 26(18):  2426-2431. 
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    The classical trot gait for quadruped robot was planned in the body coordinate of robot, and there exist some problems which might decrease the stability and accuracy of the locomotion in practical applications.For example, the swing legs could  not  land the ground simultaneously,and the rolling-over of the body  could  not  be suppressed effectively. To overcome the problems,an improved trot gait for quadruped robot which was considered in the world coordinate was proposed  herein.The swing phase was planned via kinematics with floating base, and the term related to the body's position and attitude was introduced in the foot's Jacobian matrix to ensure the swing legs could  land the ground simultaneously. The adjustment phase  was introduced between the support phase and swing phase  when the four legs got in touch with ground. The body' posture might  be adjusted in the adjustment phase. Finally, the results of simulation and prototype experiments show  that, the proposed method can improve the stability and accuracy of the robot's locomotion.

    Cylindricity Error Inspection and Evaluation Based on CMM and QPA
    Zhao Yibing, Wen Xiulan, Xu Youxiong
    2015, 26(18):  2432-2436. 
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    A mathematical  model of the minimum zone cylindricity error inspected on QPA  was proposed  to compute the minimum zone cylindricity error.QPA employed  real coding, the initial positions and velocities of particles were generated by quasi random Halton series and particles' velocities were modified based on constriction factor approach (CFA). In order to verify the proposed method, the cylindricity error of the measurement data from the reference was computed and was compared with the results by other methods.Besides, lots of shafts were machined on  CNC  machining center and measured on CMM. The cylindricity errors of the shafts  were computed  by the proposed method and the results were compared with those from CMM. The experimental  results verify that QPA  has the advantages of fast optimization speed and high computation accuracy,as well as the  algorithm is simple and few parameters need to be set. It is easy to be popularized and applied.

    Research on Phased Array Ultrasonic Methods for Defect Detection of Compressor Impeller Blade Root
    Zhu Xuegeng, Dong Shiyun, Xu Binshi
    2015, 26(18):  2436-2441. 
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    Compressor impeller blade root was easy to occur fatigue cracks, holes and other internal defects.Based on the principles  of ultrasonic pulse reflection and phased array ultrasonic method,the testing positions of blade root defects were  analysed by  voice model,and the experimental  plan was optimized with sound field simulation and  defect testing simulation.An experiment of artificial flat bottom hole defect testing was made by focus scanning.The results  show  an evident defect signal of blade root is found  by phased array  ultrasonic  testing when scanning through impeller internal.The defect location error is only 0.19% which shows a high accuracy.

    Angular Acceleration Measuring System with High Accuracy Based on FPGA and Pulse Counting
    Zhou Yijun, Xu Lijiao, Ji Xiaojun
    2015, 26(18):  2442-2447. 
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    An angular acceleration measuring system using FPGA was presented herein. The principles of measurement were based on pulse counting. Instantaneous angular acceleration might be measured with high accuracy and high resolution, where a compensation method was applied to compensate the errors caused by the inaccuracy of rotary encoder. In order to ensure the precision and validity in the process of pulse counting, a mechanism of ping-pang pipeline was employed. At the same time, a serial of scale factors were defined in the compensation module. Experiments prove the usability and reliability of this system. 

    Design and Test of Separable Supporting Structure Based on Clamp Band
    Cao Nailiang, Yang Liwei, Li Zhilai
    2015, 26(18):  2447-2451. 
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    In order to meet the requirements of complicated kinetics during the launch phase of space payload, and to realize separation between payload and satellite after in orbit, a separable clamp-band supporting structure was designed. The separation was driven by explosive bolts, and the relation between axial force of the bolts and tightening torque was analyzed. The contact model of finite-element for the structure was established and then the analyses for pre-tightening force and axial loading were conducted respectively. The analyses show that the stress in the bands decreases gradually away from the tightened bolts, the larger the coefficient of friction of the contact region, the smaller with maximum stress of clamp band. Two failure modes were analyzed. The results of the vibration show RMS acceleration magnification in three directions is very small, all of the first-order modes are greater than 200Hz, which meets the requirements of stiffness and load capacity, the device is unlocked with high reliability, and have good attenuation characteristics of impulse response.

    Numerical Simulation of Chip Thickness and Tool Tip Path in Two Dimensional Vibration Milling
    Li Dongming, Tian Ye
    2015, 26(18):  2452-2455,2465. 
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    Through the analyses of the characteristics of tool tip path in two dimensional vibration milling, a mathematical model of maximum contour line of tool path was built by using elliptic equation and rotation matrix.In the same tool angle,chip thickness could be calculated by using the distance formula. The tool tip paths of two dimensional vibration milling with different vibration parameters were simulated and analyzed.According to the results,the conditions of realizing the ideal tool path and chip thickness curve were summarized,which provides a good basis of the theory research in two dimensional vibration milling.

    Quick  Vision  Inspection for Large Number of Small Size Guide Holes on Complex Aircraft Parts
    Tang Junping, Zhang Liyan, Liu Shenglan, Ye Nan
    2015, 26(18):  2456-2465. 
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    A  quick vision inspection system MBMS for the large number of small size guide holes on complex aircraft parts was designed and implemented. The key techniques concerned were studied and discussed in details. The system combined  a visual sensor with a multi-axis CNC equipment. A method to calibrate the system's internal and external parameters was proposed.The programming method to generate NC inspection program  was discussed in detail, and the guide holes' inspection order was optimally planned. An accurate and stable method was proposed to locate the guide hole in the image. Finally, the evaluation of the guide hole's machining precision was achieved by comparing the real image with the underlying virtual image. The proposed method provides an approach to quick and accurate inspection of the large number of small size guide holes on complex aircraft parts.

    Visual Monitoring Platform of Manufacturing Process Based on Real-time Information Driven
    Liu Mingzhou, Wang Qiang, Ma Jing
    2015, 26(18):  2466-2472. 
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    In  order  to deal with the low visibility for manufacturing processes,the time-lag  effects of  the  information,and  other problems,which were caused by the lack of  the efficient measurements  in the real-time monitoring of the discrete manufacturing process status,an  object-oriented modeling approach was adopted to establish the resource ontology model(ROM) and the interface model for manufacturing  process  visibility(IMPV).Further,the data model,the visualization model,the operation model and the information interface model  of  IMPV were proposed and defined.Based on that,a framework of the real-time visual monitoring for manufacturing processes was designed,and the instantiation method of IMPV and the information integration mode  were  discussed  based on mapping rules.Finally,the results  of the visual monitoring  system's applications  on an engine assembly line demonstrate that the proposed system  can improve the productivity and efficiency.

    A Comprehensive Trust  Evaluation Model for Cloud Manufacturing Service Based on Service Satisfaction
    Tan Mingzhi, Yi Shuping, Zeng Rui
    2015, 26(18):  2473-2480. 
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    To effectively monitor the trust relationship of inter-enterprises cooperation on service-sharing platform of cloud manufacturing,a model of service comprehensive trust evaluation with comprehensive consideration of service satisfaction and its volatility    was developed,which was suitable for the operation mode of sharing platform.Firstly,an evaluation index  system  was  designed to quantize service satisfaction by introducing the used time  decay function to express  the varying trend of service satisfaction with time.Secondly,a computation method of  global service satisfaction was  put forth using the history informations  of service satisfaction of virtual package.Lastly,service comprehensive trust values of virtual resource package   was  the modification value of global service satisfaction by using volatility value of service satisfaction as the mechanism of rewards and punishments.Computational experiments  confirm    the used time decay function and mechanism of rewards and punishments are feasible, and they also prove the model is valid to monitor the unstable services provided by enterprises.

    Lubrication Analysis of Vane-stator Pair in a Variable Vane Pump Based on Different Apical Radius of Vane
    Zhang Guotao, Yin Yanguo
    2015, 26(18):  2481-2485,2490. 
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    Aiming at the direct contact between vane and stator in pre-lower pressure area which will aggravate the wear conditions, lubricating state and elastohydrodynamic lubrication model of vane-stator pair in vane pump were discussed.Then pressure distribution in contact area was studied  by numerical simulation.Through  analysing  the effects of apical  radius and bearing area of vane on mechanics  property,the influences of them on the hydrodynamic  lubrication performance of vane-stator pair were  investigated.Results show that poor lubrication performance occure near the end of pre unloading zone. The effects of the change of bearing area on mechanics and lubrication performance can not be ignored. Increase of  the apical radius can improve the lubrication condition and lead the distribute of pressure more uniformity. Therefore the lubricating condition is more stable and reliable.

    Parameter Identification of High-speed HSK Shrink Tooling System Coupling Portion
    Zheng Dengsheng, Chen Jian, Tao Defei, Wang Guicheng,
    2015, 26(18):  2486-2490. 
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    The dynamic characteristics of HSK tool system affected  the machine processing  efficiency and the workpiece surface quality,The basis of accurate  prediction of  the dynamic characteristics of HSK tool system was  for  obtaining coupling portion precise parameters of tool system.This paper  simplified coupling portion of HSK shrink toolholder as spring-damping model,based on Timoshenko beam theory a  finite element model of the HSK shrink-tool   coupling portion was established,the stiffness and damping of coupling portion was identified by using elastoplastic theory,stiffness and damping of HSK shrink-tool coupling portion was got  at different axial locations.And   dynamics finite element model of HSK shrink tool system was  established,frequency response function(FRF) of system tool tip point was analyzed.And  experimental measurements of HSK shrink tool system FRF were  made,which was  compared with the theoretical FRF.Equivalent to a spring-damping  the reasonable and effective identification method of coupling portion was validated.

    Energy Transfer and  Dissipation  in  of   Hydraulic  Wind   Turbines
    Ai Chao, Yan Guishan, Kong Xiangdong, Dong Yanwu
    2015, 26(18):  2491-2496. 
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    Taking a hydraulic wind turbine as the  research object, the energy transfer and dissipation were  studied  for energy conversion mechanism in hydraulic wind turbine. The entire unit was divided into several key sub-units. The energy transfer models were established, and the variation of energy transfer was analyzed. The energy dissipation was derived and analyzed based on energy transfer models, and mathematical models of energy dissipation were obtained. Using 30kVA hydraulic wind turbine simulation platform as the simulation and experimental foundation, simulation and experimental researches  of  energy transfer and dissipation were carried out.The accuracy of theoretical analyses was verified. The results show that energy feature state is changed during operation, containing a certain energy dissipation, and the overall efficiency is about 65.7%.

    Optimization Design of  Liquid  Hybrid Bearing in Grinding Head of High-speed Roll Grinder Based on Genetic Algorithm
    Wu Huaichao, Linghu Kejun, Sun Guanchao, Li Zhe, Zhang Shunfeng
    2015, 26(18):  2496-2500. 
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    The performances  of liquid hybrid bearing affect directly grinding performances of the whole roll grinder.Aiming at a kind of adjustable liquid hybrid bearing in grinding head of high-speed roll  grinder,its structural characteristics and working principles were  analyzed, and its structural dimensions and working parameters  were  calculated.Then,the lowest total power loss per unit loading capacity was regarded as an objective function of optimization design, and optimization design of the bearing was performed  based on genetic algorithm.Optimization results are as follows:objective  function value decreases from 0.0808  to  0.0678,total power loss of the bearing decreases from 766.9W to 642.6W,and  power consumption is reduced about 16%;moreover,structural dimensions of the bearing are reduced,and its stiffness is obviously  improved.Therefore,through the optimization design,manufacturing cost of the bearing is reduced,and  its comprehensive performances are improved obviously.

    Servo Parameter Tuning Method for Direct Feed Drive Based on Dynamic Stiffness Evaluation
    Lin Xiankun, Li Peixiang, Zhu Lin
    2015, 26(18):  2501-2505. 
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    The purpose of this paper  is to explore a  method of tuning servo parameters for direct feed drive,which can finally improve the anti-interference  performance of direct  feed  drive.The main difficulty of using  the  Bode diagram to tune servo parametersis was that the resonance frequency could  not   be measured accurately and efficiently.A servo parameter  tuning method of direct feed drive  was proposed on the  basis of  dynamic stiffness evaluation.A  dynamic stiffness measurement scheme was  proposed and verified  based  on pulse excitation,which was  based on the kinetic model of direct feed drive.A dynamic stiffness spectrum diagram  might  be  measured by the measurement scheme which was useful in the tuning strategy.Then,a dynamic stiffness model of direct feed drive was built,which infered  the main factors of dynamic stiffness.According to the main factors and the dynamic stiffness spectrum diagram,the fast tuning strategy of servo parameters was concluded.The tuning strategy found  the resonance frequency by using the dynamic stiffness spectrum diagram, and inhibited the resonance frequency by the electronic filter. Finally, an experiment was conducted on a  self-construction linear feeding platform servo system of which was driven by SINUMERIK  840D.The  experimental data  shows that the method can find the resonance frequency directly. Also, the study shows that the 0dB frequency of speed loop increases to 58.6Hz and have a 11.7Hz-delay  compared with the tuning strategy which is on the basis  of Bode diagram.

    A  Life Prediction  Model  for  Low  Cycle  Fatigue  Based  on Continuum  Damage  Mechanics
    Chen Ling, Zhang Xianming, Ouyang Ping
    2015, 26(18):  2506-2510,2517. 
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    According to  the basic conservation law of continuous media and continuum damage mechanics,the decrease of effective bearing area caused by the material fatigue damage could be  expressed as a function of mean strain.The  low cycle fatigue damage evolution of the micro crack stage and the fatigue crack stage were  analyzed.And then,a model for the life prediction of low cycle fatigue was established.Through low cycle fatigue experiments with smooth specimens of 316L steel at 420℃ under stress control, the damage evolution were   described and the fatigue life prediction was carried out by the method mentioned above.Results show  that the micro crack stage  is the main stage of low cycle fatigue life consumption of material.And compared with the experimental data, it  is  found that the predicted results  which  are obtained by the sampling data of different life periods are in good agreement with the experimental ones.

    Useful Information Reconstruction-based Vibration Acceleration Signal Integral Method for Faulty Rotating  Machinery
    Zhu Yong, Jiang Wanlu, Zheng Zhi, Hu Haosong,
    2015, 26(18):  2511-2517. 
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    A faulty  rotation machinery vibration acceleration signal integration method  was proposed  based on useful information reconstruction.Firstly,ensemble empirical  mode decomposition(EEMD) was utilized to decompose the integral signals. Secondly, the values of kurtosis,mean square error and singular value were proposed to be combined into  a  feature vector, and further used to extract the effective feature for the decomposed signals.Then,the effective feature components were extracted by Euclidean distance search.Finally,the effective feature components were reconstructed by threshold limit,and the desired integral signals were obtained.The effectiveness and  practicability of  the method were testified by simulation analysis and measured data.Results indicate that this method is excellent at removing noise and reserving effective feature information,and possesses high precision and superiority.

    Rod Type Traveling Wave Ultrasonic Motor Based on Spiral-driving
    Hua Shunming, Meng Yuming, Li Zhiqiang, Lou Yinghou, Li Jialin,
    2015, 26(18):  2518-2524. 
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    A rod type traveling wave ultrasonic motor was designed based on spiral-driving and its working principles were  preliminarily analyzed.The relationship among thread angle and stator length as well as rotor diameter was discussed. And then,setting  efficiency   improvement  of screw transmission as object function, the main geometric parameters of stator could  be determined.The size of groove was also optimized,which was used to amplify vibration amplitude.Based on these analyses,a prototype motor was fabricated. The corresponding experimental platform was established, and the main performances of motor were tested.The experimental results indicate that the actual working frequency is as  24.5kHz, which is in accordance with simulation one. The motor can be controlled to run clockwise or counter clockwise through alternating phase difference, and on-off  operating characteristics are satisfied.Under driving voltage of  220V, the maximum rotary speed under no-load conditions  is as 40r/min,and the locked axial force is as 1.7N.

    Influences of Spark Plasma Sintering Process on Overall Resistance of Non-conductive Materials
    Luo Junting, Liu Yongkang, Shen Jianglong, Zhang Chunxiang
    2015, 26(18):  2524-2527. 
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    The overall resistance variation of  sintering system on  non-conductive materials  in spark plasma sintering was  studied based on experimental data of Si3N4  nano-ceramic.Results show that sintering temperature and the height of  the  initial  powder are the two key factors that affect the overall resistance.In  the heating stage,the overall resistance gradually decreases with the rising of  temperature and reducing of initial powder  height,but when the powder sintering,if the sintering temperature continues to raise,the overall  resistance increases gradually.According to the sintering test results,the curve of overall resistance with the initial powder height and the sintering temperature was
    obtained.And  with the SPS test data of SiC ceramic material on the fitting formula was verified,  the applicability of the formula for the spark plasma sintering of non-conductive material was demonstrated.

    Experimental Research on Deep Drawing Process Using Radial Segmental Blank Holders with Conical Die
    Kong Xiaohua, Qin Siji, Lu Hong, Zheng Xing
    2015, 26(18):  2528-2532,2538. 
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    The forming limit  could be improved by using the conical die in the deep drawing process when the blank  was drawn to the shape accordant to the inside surface of the die.And the blank wrinkled  easily  during the large deformation process.A  new technology combining  the conical die with  the radial segmental blank holding technique was proposed  to  improve the restrain conditions  between the blank holders  and the blank and to suppress the wrinkles.The drawing  die were designed with the conical die and the rigid-flexible composite segmental blank holders and the experiments for the cylindrical cup deep drawing process were  conducted using the conical dies with different die semi-cone  angles.The  results reveal that the wrinkles at the beginning of the drawing process can be  overcame  effectively by the new blank holding method with smaller conical angles. The forming limit  coefficients for AA5754, AA6061 and 08AL are  as 0.410,0.431 and 0.373 respectively, which are enhanced effectively, adopting the die with 45° die  semi-cone angle.The theoretical forming limit  calculation method for the deep drawing process with the conical die is given and the theoretical results are accordant with the experimental ones.

    Experimental Study  of  Stainless  Steel  Alloy   Coating  Fabricated  by Laser Cladding onto Hydraulic Support
    Shen Weiguo, Fang Yan, Dong Ling, Cen Hu, Wang Chunxian, Gu Zhenjie
    2015, 26(18):  2533-2538. 
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    The stainless steel alloy coating was fabricated on the surface of silico-manganese steel specimen by laser cladding.The SEM and X-ray diffraction were used  to  analyze microstructure and composition of the clad  layers.The bending and impact strength experiments were carried out on the clad  specimen.The results show that the bright zone exits  in  the zone between clad   layer and matrix or the zone between clad layers,which forms metallurgical bonding when the laser power is as  6kW,the scanning speed is  as 8mm/s,the spot diameter is as 5mm and overlap rate is as  30%.The layer fabricated in the direction perpendicular to the observed surface shows honeycomb,and the layer fabricated in the direction parallel to the observed surface shows vertical bars.The  slag inclusion forms in the zone between layers during laser cladding when the laser power is as  6kW,the scanning speed is as 16mm/s,the spot diameter is as 5mm and overlap rate is as  30%.The impact strength of the specimen increases by 7.7%, the clad  layers have nice toughness and impact strength.

    Research on Near-Net-Shaping  Ti6Al4V  Alloy Parts  under  Two-Step Hot  Isostatic   Pressing
    Huang Jun, Xue Pengju, Wei Qingson, Shi Yusheng
    2015, 26(18):  2539-2544. 
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    Monolithic superalloy parts shaped by hot isostatic pressing may exist  low density region  which will cause  uneven overall performance.This  paper  proposed  a two-step hot isostatic  pressing method:at  low temperature  and pressure  original parts were shaped without connected pores from alloy powder,then  the low density regions were densed  at an appropriate temperature and pressure after removing  capsule and shape-control mold,which could guarantee uniform performance. Taking Ti6Al4V powder material  as an example,two-step HIP parameters were determined by combining finite element simulation and  experimental  tests,with which bladed disk parts  were made.The SEM results show that:it  is fine and  homogeneous  strip α+β   phase in the parts and there is no prior particle boundary or connected pores, which contribute to the good performance of parts.The fracture morphology  analysis shows that: the powder particles are metallurgically bonded firmly and no longer the crack source given appropriate processing parameters.Tensile strength of two-step HIP parts is slightly better than that of  conventional HIP and as same as the forging's.

    Fatigue  Life   Optimization for  Spot-Welded  Structures  of   Vehicle  Body Considering Uncertainty of Welding Spots
    Liu Zhicheng, Jiang Chao, Li Yuan, Bai Yingchun
    2015, 26(18):  2544-2549. 
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    Fatigue life interval  optimization  analysis model with two types of welded structures:tensile-shear(TS) and modified  tensile  shear(MTS)  spot welded joints would be  constructed  based  on  interval optimization method,considering uncertainty of  the  welding spots.Using the modified Manson-Coffin formula  as  fatigue  life  calculation method of spot welded structures,taking  consideration  of  the characteristics that the uncertainty of welding torch placement during the process,the positions of the welding spots  were treated as interval variables.By interval optimization of welding spot coordinates,maximum fatigue life and best welding spot coordinates of the two types of welded structures could be obtained.Further more,corresponding upper and lower fatigue life bounds of the standard sample  welded structures were also demonstrated.A computing tool with function of analysis and optimal design of the fatigue life was provided,which could be applied on spot welded structures in engineering practices.

    Research on Aerodynamic Characteristics of Vehicle with an Improved LRN k-ε Turbulence Model
    Gu Zhengqi, Chen Zhen, Huang Taiming, Feng Chengjie, Zong Yiqi
    2015, 26(18):  2550-2555. 
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    Since  the  LRN(low Reynolds number) k-ε turbulence model presented by Jones and Launder failed   to predict the laminar-turbulent transition,the streamline curvature factor and total stress limitation(TSL)  were  incorporated to improve the  turbulent dissipation rate  and  turbulence viscosity coefficient.Thus, a new modified LRN   k-ε  turbulence model was obtained for the prediction of the aerodynamic characteristics of vehicles.Computations were  carried out using the ISIS-CFD flow solver. The comparisons among  the results obtained by the modified LRN  k-ε  model with ones by  other commonly used turbulence models and wind tunnel experiments  show that the new model is more accurate and efficient to simulate the flow separation around the body surface and the wake vortexes.