Table of Content

10 November 2017, Volume 28 Issue 21

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Stability Analysis of Disc Friction Pairs Based on Stribeck Model

WANG Yanzhong1;GUO Chao1;JIA Shuwang1;NING Keyan2;LAN Hai2

2017, 28(21):  2521-2525. 

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In order to obtain system stability of friction pairs under sliding and analyze instability of the system, a multiple-degree-of-freedom and velocity-related sliding stability analysis model was established based on Stribeck friction model herein. The dynamics differential equations were established for the disc-friction pairs and the Coulomb friction formula was expanded with Taylor method. Then the system stability and the effects of key parameters on the system characteristics were analyzed depending on Liapunov's stability criterion. The results show that the system stability may be intensified by decreasing Stribeck coefficient, ratio of static friction and sliding friction and load, or increasing the system damping etc.

Semi-active Suspension System with Novel Permanent Magnet-solenoid Valve Type MR Damper by Artificial Fish Swarm Optimization Algorithm

HU Hongsheng1;XIAO Ping2;JIANG Ming2;OUYANG Qing1

2017, 28(21):  2526-2533. 

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A semi-active suspension control system with MR damper was studied in order to improve the performances of automobile suspension systems. Firstly, a new type of MR damper with permanent magnet and solenoid valve structure configuration was designed according to the MR fluid theory. The theoretical dynamics model of MR damper was established and verified with high credibility by F-v experimental curves. In addition, the F-S indicator diagrams of damper show that it may satisfy the operating requirements of vehicle suspensions. Secondly, a 7-DOF mathematical vibration model of vehicle suspensions was set up according to the principles of vehicle system dynamics. The LQG controller using the improved artificial fish swarm algorithm was proposed to reduce the structural responses in the vehicle suspension system. Finally, the simulation experiments of vehicle suspension systems were carried out. Compared to the passive systems, the semi-active suspension systems based on the artificial fish swarm algorithm may be significantly improve the vehicle dynamics performance, where the vehicle body centroid vertical acceleration, pitching angular acceleration and vehicle roll angle are decreased by 38.95%、35.12%、35.98% respectively.

Aircraft Assembly Material Delivery Path Planning Based on Normal Fuzzy Time Window Constraints

ZHU Yongguo1;LI Junjie2;LIU Chunfeng3;SONG Likang4

2017, 28(21):  2534-2541. 

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Required time of assembly position material requirements was fuzzy during aircraft assembly. A time parameterization method for work station material demands was proposed based on normal fuzzy time window constraints. The membership degree of normal fuzzy numbers was used to represent the satisfaction of stations. Based on the presented normal fuzzy time window constraints, a mathematical model of path planning was established for aircraft assembly material delivery. The presented mathematical model was solved by genetic algorithm. During solution, roulette and best reservation strategy were used as selection operator. Niche selection mechanism of double selection crossover strategy was used as crossover operator, and mutation operator was used to achieve better solutions. MATLAB simulation results show that the presented path planning method has better economic performance.

Simulation Design and Experimental Analysis of Commercial Vehicle Cab Suspensions

HUANG Jigang1;LI Lin1;LI Kaiqiang2

2017, 28(21):  2541-2546. 

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A dynamics simulation model was established and testified by bench test researches for the development of a cab suspension and based on which the vibration isolation was optimized. A finite element model was also built and validated using the boundary conditions extracted from the dynamics model. Several limiting conditions were analyzed, which gave back necessary informations for modifying the structures of cab suspensions. The fatigue characteristics of the cab suspension was also tested by the fatigue tester. The results show that the difficulties encountered in researches and developments of cab suspensions may be solved efficiently by the method of simulation design and experimental analyses.

Load Spectrum Compilation of Damper Durability Tests Based on Multi-axial Loads

ZHENG Songlin1,2;WANG Shuo1;FENG Jinzhi1,2;CHEN Tie1;YU Jiawei1

2017, 28(21):  2547-2552. 

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Traditional damper durability tests only took the vertical loads into consideration and without unified standard for horizontal force loading, which led to inaccurate results. Given this situation, combined with actual user road load, this paper proposed a new method considering load spectrum with the multi-axial loads. With sine on sine method to compilation the load spectrum in order to analyze the failure reason of damper. The half-power bandwidth method and the maximum line velocity principle were employed to determine the low frequencies and high frequencies respectively, then establish durability bench test with multi-axial loads. The test results show that damper's failure lifes reduce greatly with the horizontal forces and the failure mileage consisted with survey results. It turns out that the spectrum compilation method may be more accurate to reappear the actual working status, and may provide technical support for the damper designs and improvements.

Fault Data Set Dimension Reduction Method Based on Schur Decomposition and ONPE Algorithm

LIU Yunjia;ZHAO Rongzhen;WANG Xuedong

2017, 28(21):  2552-2556. 

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Aiming at dimension reduction of fault data set，a novel method in dimension reduction was proposed based on the combination of Schur decomposition and ONPE algorithm. Firstly wavelet packet decomposition was used to extract the fault signals of different frequency band energy features，then Schur decomposition and ONPE algorithm were used to project the high-dimensional data sets to lower dimensions. After the transformation, the considered pairwise samples within the same class were as close as possible, while those between classes were as far as possible. Finally, the lower dimension was collected and the K nearest neighbor classifier was input to recognize the different patterns. The fault characteristic data sets from a double span rotor test-rig were used to validate the proposed algorithm performances. The results show that this method may solve the problems of reducing the dimension of rotor fault features sets effectively.

Theoretical Design and Modeling of a Novel Piezo-driven Rhombic Flexure Mechanism with Double Beams

JIANG Zhou1;CAO Junyi1;LING Mingxiang1,2;ZENG Minghua1;LIN Jing1

2017, 28(21):  2557-2561,2566. 

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Design and modeling of a new diamond micro-displacement mechanism with double flexible beams was presented to overcome the issue that the output stiffness, natural frequency and displacement amplification ratio of the traditional diamond displacement amplification mechanism might not be improved at the same time. The static analysis model of displacement amplification ratio and input/output stiffness of the mechanism were derived based on Castigliano’s second theorem. Analytical model of natural frequency was also deduced by further employing the Lagrange equation .The finite element analysis was used to verify the accuracy of the analytical models. A prototype of the proposed compliant mechanism was machined by means of electric spark cutting processes and the performance measurement was performed for comparative analysis with the traditional mechanism with the same dimensions. Experimental results show that the natural frequency of the composite compliant mechanism is as 1330Hz and displacement amplification ratio is as 4.2. In addition, the modeling method and the corresponding theoretical formula proposed herein may provide a useful reference for the optimal design and development of similar displacement amplification mechanisms.

Structure Optimization Design of Robot Arm Based on Flexible Multi-body Dynamics

LIANG Mingxuan1,2,3;LI Zhenggang2;TANG Renzhong1;CHEN Li2;HUANG Chuan2

2017, 28(21):  2562-2566. 

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Aiming at the influences of the flexible joints on the dynamics of industrial robots, the effect laws of the joint stiffness on the natural dynamics characteristics of the robot arm were investigated based on the rotor-torsional spring model and the finite element method. A flexible multi-body dynamics model of robot arm was established by considering the flexible characteristics of the arms and the joints. The topology optimization on the robot arms was carried out by taking the lightweight as the design goal and the total displacement as the constraints. The results indicate that the tare-load ratio of the optimized robot arm increases, the stiffness and strength of the robot arm enhances, and the overall dynamics performance improves significantly.

Design and Experiment of Piezoelectric Actuator Based on Diaphragm Type Hydraulic Amplification

WANG Jianhong1;ZHOU Hao2;XU Youxiong1; LIU Di1

2017, 28(21):  2567-2572. 

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In order to solve the problems of the stack piezoelectric ceramic minute output displacements, which might not meet the practical applications, a piezoelectric actuator was proposed based on diaphragm type hydraulic amplification and the statics and modal analyses of the rubber diaphragm were analyzed by finite element analysis method. The analysis results show that the rubber diaphragm has sufficient safety strength and good working bandwidth. Then, the physical prototype of a piezoelectric actuator was developed and its control platform was built. Finally, the experimental research on the piezoelectric actuator was done. The open-loop experimental results show that the output displacement range is as 0～24mm under the control voltage of 0~100V and the actual amplification ratio is as 5. The closed-loop control experimental results show that the control effectiveness of the segmented PID is better than the conventional PID ,and the steady-state errors are about ±0.5μm.

Simulation on Grind-hardening Layers Based on Piecewise Variable Grinding Forces

HUANG Xiangming;LI Tong;REN Yinghui;WU Wei;HE Zhijian

2017, 28(21):  2572-2576. 

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The actual grinding time and the variation of grinding forces during the grinding processes were analyzed. A grinding temperature simulation was put forward to predict the distribution of grind-hardening layer depths based on piecewise variable forces. Firstly, the grinding forces were discretized, and the corresponding heat flow density was calculated. Then, according to the actual contact length between the grinding wheel and the workpiece, the heat flow density was loaded onto the grinding surface, and the temperature field of the workpiece was simulated and analyzed. So the distribution of the grind-hardening layer was obtained. Finally, the comparison and analysis were carried out by the experiments and the traditional simulation method. The results show that the simulation may be more accurate to simulate the distribution of the grind-hardening layers along the grinding directions.

Investigation of Interaction between Lift-type VAWTs

ZHANG Zhouzhou;CHEN Jian;XU Hongtao;LIU Pengwei

2017, 28(21):  2577-2581,2587. 

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The transient computational fluid dynamics (CFD) was carried out to study the interactions between two vertical axis wind turbines(VAWTs) at different distances. The pressure fields and the vorticity fields of the two wind turbines in one-third rotation period were also analyzed. The results indicate that the unsteady wake flows of the rotor No.1 will affect the pressure fields and vorticity fields of the rotor No.2 significantly. This wake flow effects on the rotor No.2 are weakened with the increasing of the distances. That is the reason why the power coefficient of the rotor No.2 is increased with the distance increasing. When the distance is equal to 6D(D is the diameter of the rotor),the maximum power coefficient of the rotor No.2 is approximately equal to that of the rotor NO.1.

Air-coupling Ultrasonic Testing of Defects in LY12 Duralumin Alloys

WANG Xingguo;WU Wenlin;CHEN Zhenglin;WU Nanxing

2017, 28(21):  2582-2587. 

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To deal with problems of traditional ultrasonic testing by liquid or semi-solid couplant caused corrosions of tested materials, a method of air coupling ultrasonic testing for duralumin LY12 defects was proposed. An air coupling ultrasonic control equation for the duralumin LY12 was established by transfer matrix method. Dispersion characteristic curves of ultrasonic wave propagation were obtained due to solve this equation. These results show that all the models shift toward right by comparison with that of existing conventional couplant. The results provide suitable parameters for the air coupling ultrasonic testing. Through analyzing time domain signals of different defects in the LY12 duralumin alloys, it may be obtained that transmission wave amplitude decreases with the increases of defect diameters.

Automatic Fault Recognition for Key Parts of Train Based on Multi-feature Fusion and BP-AdaBoost Algorithm

SUN Guodong1;TANG Hanbing1;LIN Kai1;ZHANG Yang2;ZHAO Daxing1

2017, 28(21):  2588-2594. 

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An automatic fault recognition method was proposed for the fault detection of the fastening bolts and dust collectors based on multi-feature fusion and BP-AdaBoost algorithm. Firstly, the local binary pattern (LBP), histogram of oriented gradient (HOG) and Haar-like features of the faulty and non-faulty areas were extracted. Then, the principal component analysis (PCA) was used to define the contribution of different features to the fault recognition accuracy, the three features metioned above were fused, and the dimensionality reduction was conducted to the fusion feature. Then the BP-AdaBoost classifier was trained by the fusion features. Finally, the trained classifier and the recognition algorithm were used to detect the dust collector and fastening bolt faults. The experimental results show that the algorithm may adapt to the recognition of two different faults. High recognition accuracy rate, low false ratios and low omission ratios are obtained, and the algorithm is robust to light unevenness and occlusion.

Applications of Generalized Morphological Closed and Open Margin Operation to Diagnose Weak Faults of Rolling Bearings

GU Xinglong;WANG Kai;LI Lulu;ZHAO Hongwei;XIE Ruidong

2017, 28(21):  2595-2600. 

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According to local extreme step and kurtosis criterion, an adaptive method was suggested to select structure elements of morphology operations herein. Fault diagnosis results of acquiring bearing weak fault was improved with the modified generalized morphological closed and open margin operation algorithm. The analyses of the simulated signals and the measured vibration signals show that the proposed method is superior to the traditional generalized morphological analysis in the diagnosis of weak faults of rolling bearings. The analysis method suggested herein may obtain rolling bearing weak fault features quickly and accurately.

Creative Design of Lock Cylinder Mechanisms Based on Regeneration Movement Chain Method

SONG Mengmeng1;XIAO Shungen1,2;LIN Shibin1

2017, 28(21):  2600-2607. 

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On the basis of analyses of the existing lock mechanisms, mechanism was restored the regenerative institutions using regeneration movement chain method to identify different kinematic chain mechanisms to meet topology requirements and constraint requirements in order to achieve mechanism innovation of new locks. First, existing Yue Ma idling cylinder body was transformed for corresponding generalized chain by using the principles of generalization; then a prototype kinematic chain was restored using the number synthesis theory in order to find all possible generalized kinematic chain patterns that had the same numbers of components and kinematics; then the movement chain identified the components according to design requirements and constraints , thus a viable specific chain was obtained, and finally the specific chain was transformed into a new organization sketch of lock cylinder. A new 3D model of lock mechanisms was established by using 3D software, and the working principles were analyzed. The results indicate that the lock cylinder mechanisms designed are reasonable, and successfully apply two national invention patents.


Integrated Design of Non-sinusoidal Generator of Continuous Casting Mold

LIU Dawei1,2;LUO Linming2;WANG Guohui2;JIN Xin2

2017, 28(21):  2608-2613. 

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On the analyses of non-sinusoidal oscillator principles, a method was presented, where the mold was driven by a pair of speed integration gear instead of the two stage generator. According to the typical non-sinusoidal wave with constant speed, the inverse solution for the pitch curve equations of the speed integration gear was given, with the key technological parameters deduced. On the basis of steel mill production requirements, a design example of the integration generator and technology analysis were made. The integration design of the noncircular gear transmission system attains good processing results, and achieves high efficiency and light weight, which is of practical and popularization values.

High-speed Dry Gear Hob Life Prediction Model and Optimization Method

ZHANG Ying;CAO Huajun;ZHU Libin;LI Benjie

2017, 28(21):  2614-2620. 

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Because high-speed dry hobbing technology lacked cutting oil and lubrication for cooling under high cutting speeds, the high-speed dry gear hob should have very high cutting properties including good wear resistance, high temperature resistant which led to a complex and expensive manufacturing for the substrate material and coating of high-speed dry hobs. Therefore, it was necessary to optimize the high-speed dry hobbing technology to improve the hob tool life to reduce manufacturing costs and improve efficiency. Combining the experiments in production practices and theoretical analysis, the failure modes and wear principles of the high-speed dry hobs were analyzed. The cutting lengths of single blade were used as evaluation indexes of the high-speed dry hob tool life and the corresponding calculation model was established. Based on this calculation model'high speed dry hob life experiments were carried out in gear production line. In order to build the empirical formula for hob tool life, a multivariate linear regression model which solved by MATLAB was established. Based on these work，a way to optimize processing parameters and a new hob shifting strategy were put forward to improve high speed dry hob tool life.

Optimization of Electrical Topology of Thermoelectric Converter for Automobile Exhaust

FANG Wei1;QUAN Shuhai1;TAN Baohua2,3;RAN Bin4;WANG Li1;JIAO Yatian1

2017, 28(21):  2620-2626. 

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Aiming at the differences among the temperature differences and different characteristics of the thermoelectric devices of an automobile exhaust thermoelectric generator,in order to maximize the power generation potential of each thermoelectric device,the thermoelectric module of the thermoelectric generator was optimized by an topological structure research method,and the serial and parallel problems of the thermoelectric module were abstracted as a mathematical problem based on the graph theory,then the algorithm was targeted designed .The experimental results show that,compared with other simple series or parallel structures, the electrical topology optimized by this method may fully utilize the power generation potentials of each thermoelectric devices under the same conditions and are improved the output powers of the automobile exhaust thermoelectric generators.


Cutting Parameter Optimization and Cutting Force Prediction for Fe-based Amorphous Alloy Spray-fused Coatings

WANG Min

2017, 28(21):  2627-2631,2638. 

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The RSM of Box-Behnken design (BBD) was adopted in cutting force experiments about Fe-based amorphous alloy spray-fused coatings. And then four factor and three level tests of Fe-based amorphous alloy spray-fused coating machining scheme were designed by means of BBD experiments. The influence laws of tool and cutting parameters (cutting speed，feed and cutting depth) on cutting force components were analysed and these influence reasons were discussed. Significant levels of factors affected the cutting force components were obtained by the applications of variance analysis method, which offered the optimum cutting parameters in lower cutting speeds. According to multiple quadratic fitting of testing data, the least square regressive method predictive formula for the cutting forces of Fe-based amorphous alloy spray-fused coating was established. Finally, the feasibility and practicability of the models for cutting forces was verified through practical examples.

Study on Crystal Characteristics of Aluminum Alloy Cutting Surface by X-ray Diffraction Profile Analysis

AN Zenghui1; LI Shunming1;FU Xiuli2

2017, 28(21):  2632-2638. 

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In order to obtain a better understanding of the mechanism of cutting surface microstructure in the high-speed cutting processes and meet the strict requirements of various components on the service performance, based on micro view, the 7050-T7451 aluminum alloy was studied. For solving the problems that traditional observation method was difficult to obtain the statistical rule of grain sizes and dislocation densities, based on X-ray diffraction profile analyses such as Modified Warren-Averbach and Modified Williamson-Hall the methods were introduced into analyzing the microstructure of cutting surfaces from materials science and physics. Quantitative studies on microstructure of cutting surfaces under different cutting speeds were achieved. The results show that the machined surface is dominated by edge dislocations under high speed cutting conditions. The dislocation density values and rules are obtained. The formation mechanism is explained from plastic deformation and energy. The grain size distribution curve is fitted. The uniformities of the grains on the cutting surface are analyzed by the distribution function. When the cutting speed is higher than 4500m/min, the cutted surfaces with relatively low dislocation density and uniform grain size may be obtained.

Fatigue Life Prediction Method Based on Weld Quality Parameter Interval Model

AN Xingqiang1;GU Zhengqi1,2;MA Xiaokui1;ZHANG Sha1;MI Chengji3

2017, 28(21):  2639-2645. 

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Weld quality parameter—elastic modulus E, fatigue strength coefficient σ'f and exponent b, fatigue ductility coefficient ε'f and exponent c were always of uncertainty in fatigue life prediction. A method of fatigue life prediction was proposed by interval model which combined random-GA method with Manson-Coffin formula. Firstly, the fatigue life tests of welding specimen were carried out on biaxial fatigue testing machines based on strain control. Then , for fatigue life test data, fatigue life interval prediction method was constructed by combining weld quality parameter interval solving model which was constructed by random-GA method with Manson-Coffin formula. Finally, the accuracy of this method and the rationality of considering the uncertainty of weld quality parameters were verified by the comparisons between the interval model predictive data and fatigue life test data.