Loading...

Table of Content

    25 August 2018, Volume 29 Issue 16
    Reliability Evaluation of Accumulator in Single Failure Data
    GUO Rui1,2;ZHANG Rongbing1,3;ZHAO Jingyi1,2,4;WANG Jinfeng1,3
    2018, 29(16):  1891-1899. 
    Asbtract ( )   PDF (3831KB) ( )  
    References | Related Articles | Metrics
    The single failure data were obtained by means of no replacement  time truncation test method,the reliability curves of the reliability  model under the xponential distribution and the reliability function,the  failure probability density function and the failure rate function under  the Weibull distribution were obtained respectively.Through the analyses  of the reliability life of the accumulators,Weibull distribution took  into account the influences of experimental data before failure,failure  time and failure on reliability evaluation,in terms of experimental data  integrity,it was superior to the exponential distribution,which failed  to take into account the failure data.The reliability data are closer to  reality,and have more theoretical and engineering significances to  evaluate the reliability of small data and small sample.
    Study on Influence Factors of Chip Deformation and Breaking for Staggered Teeth BTA Deep Hole Drilling
    LI Xubo;ZHENG Jianming;KONG Lingfei;XIAO Shiying;LIU Chi;GUO Bian
    2018, 29(16):  1900-1906. 
    Asbtract ( )   PDF (1318KB) ( )  
    References | Related Articles | Metrics
    The influence factors on chip breaking were analyzed by using the chip bending deformation rules of staggered teeth BTA deep hole  drilling. The varation rules of deformations and breaking along with  drilling radius, drilling process parameters and chip breaker dimension  parameters were studied. The results show that the drilling radius has a  great influence on the chip thickness. With the drilling radius increasing, the chip thickness increases.The maximum chip thickness is located on  the teeth periphery, and the external tooth chip thickness is the  smallest. Compared with drilling speed, drilling feed has a greater  impact on the chip deformation and breaking. With the increases of the  feed, chip thickness increases, chip strain increases. As the  chip-breaker width decreases and the height increases, the chip strain  increases and the chip breaking conditions improve.
    Fault Diagnosis Method of Resonance Demodulation under Compressive Sensing Frameworks
    WANG Ke1,2;LYU Yong1,2;YI Cancan1,2
    2018, 29(16):  1907-1911. 
    Asbtract ( )   PDF (1158KB) ( )  
    References | Related Articles | Metrics
    In the early fault diagnosis of wind turbine rolling bearings,the compressive sensing algorithm might denoise the noisy signals  utilizing the signal sparsity,but the selection of sparseness had a great  influence on the denoising effectiveness.Since the sparseness of signal  fault components was known in the Fourier domain,the envelope feature of  wind turbine signals might be reconstructed by Fourier transform basis and   compressive sensing subspace pursuit(CS_SP)algorithm.As a result,the  effects of noises and other irrelevant informations would be reduced,and  the fault characteristic frequency might be extracted from the signal  components directly reflecting fault characteristics.The results  demonstrate that the resonance demodulation technique under compressive 
    sensing frameworks may effectively acquire the fault characteristic  informations of wind turbine rolling bearings.The effectiveness of the  proposed method was verified.
    A Merged Binding Modeling Method for Contact Fields of Bolted Joints
    CUI Fangyuan;HUA Dengxin;LI Yan;KONG Lingfei;LI Pengyang
    2018, 29(16):  1912-1920. 
    Asbtract ( )   PDF (1357KB) ( )  
    References | Related Articles | Metrics
    A merged binding modeling method for contact areas of bolted joints was presented in order to improve the accuracy of on-line dynamic monitoring and real-time updating of large-scale complex structures' models.During the modeling processes,the contact field elements were  constructed by separating a part of elements from the two mating substructures at each side of the interfaces.The elements in the contact  regions would meet the isotropic conditions after a equivalent treatment,and a merged binding contact relationship was established among the  elements.The greatest advantage of this modeling method is timesaving because it may effectively avoid increasing the numbers of degrees of  freedom in the joint model.Moreover,this method is more universal with advantages of convenience in parameter identification.In the interest of  the consistent accuracy between the calculation model and the physical model,the effects of additional masses of bolts,nuts and sensors on  modeling accuracy were taken into account together with an optimization and identification of physical characterization parameters of bolted  joints based on multi-objective genetic algorithm.The results show that the first six order theoretical mode shapes are in excellent coherence  with their experimental counterparts,and the absolute values of the relative errors of corresponding natural frequency are less than 10%, which shows the proposed modeling method may effectively solve the dynamic modeling problems of joints in engineering practices.
    Modeling and Natural Characteristic of Non-sinusoidal Oscillator of Continuous Casting Molds
    ZHOU Chao1,2;ZHANG Xingzhong1;LIU Pingfei1;GUAN Jie3
    2018, 29(16):  1921-1926. 
    Asbtract ( )   PDF (1385KB) ( )  
    References | Related Articles | Metrics
    To realize modification ratio of non-sinusoidal oscillation  adjusted on line for mold driven by mechanisms,a non-sinusoidal  oscillator driven by double servomotors was proposed.Firstly,working  principles of the oscillator were described.3D model of the system was  established,which was analyzed by simulation software.Secondly,the  torsional-translational coupling dynamics model was created,and the  dynamics equations of which were deduced.The results show that mass matrix  of non-sinusoidal oscillation is constant,stiffness matrix and damping  matrix change with time.At last,based on instantaneous  mechanism-solidified method,natural frequency of the system was analyzed ,which was influenced by rotational angles of eccentric shaft,amplitudes,inertia parameters and stiffness.
    Flow Filed Analysis and Performance Evaluation on Axis-in Dual-Stage Tandem Hydrocyclones
    XING Lei1,2;ZHANG Yong1,2;JIANG Minghu1,2;GAO Yang3
    2018, 29(16):  1927-1935. 
    Asbtract ( )   PDF (1522KB) ( )  
    References | Related Articles | Metrics
    To solve the problems of oil/water separation in narrow spaces  might not keep high precision,axis-in dual-stage tandem hydrocyclone was  designed according to theory of cyclone separation.Flow field  characteristics and separation efficiency of the hydrocyclones were  analyzed.The distribution rules of velocity field,pressure field, concentration field and separation efficiency influenced by inlet flow  rates and split ratios were obtained.Results show that as the increasing  of inlet flow rates,maximum pressure drop grows exponentially,tangential  velocity increases as well;tangential velocity of ring runner and second  hydrocyclone are gradually decreased with the split ratio of first  hydrocyclone increases.The effects of split ratio of second hydrocyclone 
    in separation efficiency of first hydrocyclone are very little.First  hydrocyclone plays main role in separating oil and water,second  hydrocyclone plays main role in removing oil from water.Research results  identify that the best split ratio of first hydrocyclone is as 20%,to the  second hydrocyclone is as 15%.The best inlet flow rate is as 4.8 m3/h,and  the best total flow rate of hydrocyclone is as 32%.The axis-in dual-stage  tandem hydrocyclone accommodating to variable processing and split ratio  completely meets the requirements of practical applications,the maximum  separation efficiency reaches 99.6%.
    Simulation and Verification of Hydraulic Control Systems for Continuous Lifting
    ZHOU Yuwei;ZHANG Qing;SHI Yunfei
    2018, 29(16):  1936-1942. 
    Asbtract ( )   PDF (1410KB) ( )  
    References | Related Articles | Metrics
    By the large scale structure continuous synchronous lifting technology,the supporting structure with four jack-up points and each  point with four jack-up hydraulic cylinders was used for the system.The  volume synchronization control mode was applied in the single jack-up  point based on synchronous split-flow hydraulic pump.The multi-point  master-slave control mode was used between the jack-up points based on  displacement fuzzy control.The system based on synchronous split-flow  hydraulic pump and displacement fuzzy control was modeled and  simulated.The system prototype tests and the data analysis were 
    completed.The results show that due to the various factors in the actual  conditions,the actual errors are bigger than the simulated one but still  meet the requirements of synchronization.The results validate the  application feasibility of the hydraulic control systems.
    Analysis and Extraction Technology in Frequency Domain for Phase Angles of Shafting Vibration Dampers
    ZHANG Xin1;SONG Xuan1;JIANG Li2
    2018, 29(16):  1943-1946. 
    Asbtract ( )   PDF (1184KB) ( )  
    References | Related Articles | Metrics
    In order to prevent the harms caused by too large ship shafting vibrations when the performances of vibration dampers declined during the  ship moving,an algorithm of analysis and extraction of the phase angles  of ship shafting vibration dampers in frequency domain was proposed herein,a twist vibration meter  was used to constantly measure and compute the  inner and outer angular velocities of vibration dampers,the phase angles  and damping coefficients of the vibration damper were obtained and error  reasons were analyzed,large error data were excluded ,then the fitted  curves were compared with standard curves to estimate the performances of  vibration dampers.The prototype test results show that the algorithm may  accurately calculate the phase angles of the vibration dampers,and the  fitted curves are of high accuracy,which satisfy the design requirements  on ship shafting performances of vibration dampers.
    Study on Influence Factors of Connection Stiffness of Rocket Structure
    LI Cao;SHANG Xianyang;ZHOU Xin;LENG Yue
    2018, 29(16):  1947-1951. 
    Asbtract ( )   PDF (1241KB) ( )  
    References | Related Articles | Metrics
    The rocket cabin docking connection stiffness was one of the important factors that affected the flight safety.At the same time,due to  capacity constraints,the rocket structure was strict with the weight.The  finite element simulation analysis method was adopted herein.The influence  factors of the connection stiffness were analyzed and researched.The  influence factors included connecting bolt preload,the thickness and  distribution of bolts.The regular patterns of the influence factors on  connection stiffness were obtained.The rocket structure design may be  guided by these researches.
    Contact Performance Degradation Mechanism of Electrical Connectors under Vibration Conditions
    LUO Yanyan1,2;ZHANG Le3;MENG Fanbin4;HAO Jie5
    2018, 29(16):  1952-1957. 
    Asbtract ( )   PDF (1349KB) ( )  
    References | Related Articles | Metrics
    In view of the problems of stress relaxation and fretting wear  caused by metal contacts of electrical connectors under alternating  vibration stresses, the contact reliability of electrical connectors might  be reduced.Firstly, the mathematical model of electrical connector  contacts was established.Secondly, vibration test scheme of electrical  connectors and testing circuit were designed,and the tests were carried  out subsequently.During the tests, the contact resistances of the test  specimen increased slowly with the increases of the vibration frequency,  and the fluctuation of the contact resistances was related to the  vibration amplitude and frequency.After the tests, the pore sizes of jacks  increasess and the values of insertion and withdrawal forces increased or  decreased.It is concluded that the stress relaxation phenomenon in the  jacks and fretting wear phenomenon between the contacts of the electrical  connectors are two main factors leading to the contact performance  degradation of the electrical connectors.In addition, the decreases of the  crystal sizes and the increases of the slip line density are the  fundamental reasons for the stress relaxation phenomenon in the jacks of  the electrical connectors.
    Trajectory Tracking Control of Wheeled Mobile Robots under Longitudinal Slipping Conditions
    BEI Xuying1,2;PING Xueliang1,2;GAO Wenyan1,2
    2018, 29(16):  1958-1964. 
    Asbtract ( )   PDF (1219KB) ( )  
    References | Related Articles | Metrics
    An trajectory tracking control of mobile robots was presented  based on wheeled mobile robots with unknown longitudinal slip  parameters.Firstly,the kinematic model of the mobile robots under  longitudinal slips was established,and the sliding parameters were used  to express the slip degrees of the left and right wheels.Then,a  suitable sliding mode observer was designed to estimate unknown slip  parameters,and the influences of chatters on estimation of slip 
    parameters were reduced by using the low-pass filters.Finally,a  trajectory tracking control law was designed based on Lyapunov direct  method,and a method of determine the control parameters was proposed  according to the pole distributions of the control systems.Numerical  simulation results show that the proposed trajectory tracking control  method is accurate and effective.
    Recommendation Method and Applications for Personalized Product Service Plans
    YANG Zhen;GENG Xiuli
    2018, 29(16):  1965-1974,1983. 
    Asbtract ( )   PDF (1334KB) ( )  
    References | Related Articles | Metrics
    Traditional LFM didn't consider the database dynamic update which would affect the program recommendation results,so a weighted  LFM  was proposed based on the dynamic update mechanism to recommend the  personalized product service plans. Firstly,aiming at the problems of  cosine similarity neglecting individual differences,a comprehensive  similarity weighted by cosine similarity between cloud drop distance  measure and cloud was proposed to predict and fill vacancy data and reduce  data sparsity.Then,the difference of interests of new users could be  restrained and the recommendation accuracy could be improved by using the  weighted LFM recommendation service scheme. Finally,the proposed method  was updated with the method of difference averaging,and the efficiency of  different recommended algorithms was compared with mean absolute error  (MAE). The practicality and validity of the proposed algorithm were  verified by examples.
    Multi-objective Optimization Design of Small-centrifugal Compressor under Variable Flow Conditions
    TANG Xinzi;XIAO Peng;CAI Peng;PENG Ruitao
    2018, 29(16):  1975-1983. 
    Asbtract ( )   PDF (1363KB) ( )  
    References | Related Articles | Metrics
    In order to improve the performances of centrifugal compressor  under variable flow conditions,the influences of geometric parameters on  aerodynamic performances of the centrifugal compressor were investigated  by three-dimensional computational flow analysis.The optimal design  variable space was established based on correlation analysis.By employing  the method of Latin hypercube test design,Kriging model and NSGA-Ⅱ  algorithm,the multi-objective optimization of a micro-centrifugal  compressor impeller was carried out under variable flow conditions.The  pressure ratio and the efficiency of the optimal impeller at the design  flow conditions increase by 6.43% and 3.99% respectively;the pressure  ratio and the efficiency at the lower-flow conditions increase by 5.62%  and 3.52% respectively.The internal flow loss is reduced,the stall flow  reduces by 2.7%,the blocking flow increases by 6.85% and the stable working ranges are widened.
    Path Planning for Dual-robot Coordinate Welding Based on Multi-objective Genetic Algorithm
    HOU Yangqiang;WANG Tianqi;YUE Jianfeng;JIA Zhenwei
    2018, 29(16):  1984-1989. 
    Asbtract ( )   PDF (1439KB) ( )  
    References | Related Articles | Metrics
    A welding path planning method was proposed by studying the path  planning problems of dual-robot coordinated welding of complex spatial  welds based on multi-objective genetic algorithm .Parameters of affecting  the weld's quality and the stability of robot's movement were analyzed, and the objective function of the evaluation of welding paths such as  welding quality function,collide with dual-robot and robot motion  stability function were established.A multi-objective genetic algorithm  was used to solve the coordinated welding paths,and the optimal welding  path planning of the dual-robot was realized.Taking the "saddle shaped"  space seam as an example,the welding paths of 2 robots were tested and  verified.The results show that the proposed scheme may realize the 
    planning of dual-robot coordinated welding paths.
    Hybrid Gray Wolf Optimization for Energy-efficient Type-II Robotic U-shaped Assembly Line
    ZHANG Zikai1,2;TANG Qiuhua1,2;ZHANG Liping1,2;LI Zixiang1,2
    2018, 29(16):  1990-1995. 
    Asbtract ( )   PDF (1217KB) ( )  
    References | Related Articles | Metrics
    Considering task assignment and robot assignment,gray wolf  algorithm was proposed based on random key code to minimize energy  consumption.Considering precedence relations and cycle time constraint, the algorithm allocated the tasks and robots into workstations in decoding 
    phase.Based on social hierarchy in the population of gray wolf,3 optimal  wolves were selected to guide other wolves to update the  population.Simultaneously,based on the task assignment and robot  allocation,2 crossover operators were designed to enhance the 
    communication among low-grade wolves.The proposed algorithm was proved to  have great performance under benchmarks of U-shaped assembly lines.
    Formability of HSS in Cold Stamping Based on Variable Friction Coefficient and Thermal-mechanics Coupling
    NIE Xin;TAN Guang;QIAO Xiaoyong
    2018, 29(16):  1996-2002. 
    Asbtract ( )   PDF (1296KB) ( )  
    References | Related Articles | Metrics
    Measured friction coefficient of DP780 dual phase HSS under  different temperatures,a novel variable friction coefficient model was 
    established,and the formability during room temperature cold stamping   was researched based on thermal-mechanics coupling and variable friction 
    coefficients.The results show that temperature is increased obviously in  some areas of sheet metal in heat variable(HV) groups,and comparing the 
    same places with compared groups,the thinning ratio is smaller,not easy  to crack,better ductility are showed.From spring-back displacement 
    contour,values in HV groups  are smaller than the measured values in  stamping experiments.However values in compared groups are bigger,and 
    compared with the experimental measured values,the errors of HV groups  are only 27.8%   of compared groups,and are agreed with stamping 
    experiments better.
    Magnetic Property Simulation of Defects in Ferromagnetic Pipes under Magnetization
    ZHANG Lipan1;MA Bingyang1;SONG Kai1;WANG Zhen2
    2018, 29(16):  2003-2009. 
    Asbtract ( )   PDF (1414KB) ( )  
    References | Related Articles | Metrics
    A 3D model of DC magnetization pipes was built with finite element method.Meanwhile  the ferromagnetic material magnetic properties 
    and the distribution of magnetic permeability around defect areas were  analyzed.The effects of magnetization intensity,the thicknesses of the 
    pipes and the depths of the flaws on magnetic permeability distribution  were studied.The results show that the magnetic permeability of the defect 
    areas is uneven distributed while saturation magnetized,and the internal  defects may  even cause the magnetic permeability of exterior surface 
    changing under magnetization.The mechanism of internal defects on the  ferromagnetic pipes is revealed,and the applications of the eddy current 
    testing method are expanded.