Table of Content

25 November 2016, Volume 27 Issue 22

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Tolerance Analysis Based on Equivalent Kinematic Pair and Degradation of Kinematic Pair

Yin Liming, Ye Peiqing, Zhang Hui

2016, 27(22):  2983-2989. 

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Subject to the random characteristics in deformations, position and value of the features which were constrained by tolerance, a method to analyze the stack-up of tolerance by deeming tolerance constrains to equivalent kinematic pair was proposed herein. Under the situation of equivalent kinematic pair, the features constrained by tolerance were transformed to the features constrained by n-DOF of kinematic pair and the assembly would be transformed to a robot arm, which connected by the rigid parts and without any errors. As the results of the assembly processes, the affections of interaction among different kinematic pairs were the emerging problems after transformed. To deal with that problems, the method of degradation for kinematic pair was proposed herein. Then the formula to analyze stack-up of tolerance was established based on the method of equivalent kinematic pair and degradation for kinematic pair. Finally, those methods were used to analyze a realistic assemble product, and compared the calculated values with the experimental results.

Experiments on Laser Induced Precision Transfer of Cu Film

Huang Zhigang, Li Honghui, Yin Shihua, Guo Zhongning

2016, 27(22):  2990-2994. 

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The experiments on the LIFT of Cu film were carried out through changing pulse energy and defocus distances. The materials transferred on the quartz substrate and the restraint layers were investigated, and the effects of pulse energy and defocus distances were analyzed by the optical microscope and scanning electron microscope. The mechanism of LIFT was discussed based on the experimental results. A transfer dot of about 10 μm is found, and which is much smaller than the focal radius. The transferred materials are found on both of the substrate and the restraint layers, which means that there exists a backward transfer process along with forward transfer. With pulse energy increasing, the materials deposited on the substrate become more scattered, and the distribution of the deposition dots tend to form a ring. When the enlarging focal distances are enlarged, the ring disappears, and the deposition area shrinks below the foal radius. And a micro array was successfully fabricated using the LIFT method.

Prediction of Remaining Useful Life for Electrical Sliding Plug Door of Metro Vehicles

Wang Ling, Chen Changjun, Pan Jing, Xu Hong, Chen Xiai, Na Wenbo

2016, 27(22):  2994-3000. 

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To solve the problems of poor lubrication associated with elecrical sliding plug doors of metro vehicles, a prediction model of the remaining useful life was proposed herein based on self-organizing feature map(SOM), hidden Markov chain(HMC) and Monte Carlo(MC) simulation. Firstly, the motor current signals were collected and the features were extracted. Secondly, the SOM method was used to achieve data fusion and encoding for the multi-dimensional feature data. Then the results were used as input vector of the HMC in order to obtain state transition probabilities for the whole life. Finally, the MC simulation was used to predict the remaining useful life of the degradation process. The fault simulation experimental results show that the method can predict the remaining useful life effectively of the electrical sliding plug door with the consideration of the failure mode of poor lubrication.

Novel Technique for Electroforming with Flexible Compression

Qian Wanghuan, Qin Feng, Miao Xiaomei

2016, 27(22):  3001-3004. 

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A novel technique of flexible compression electroforming was described by the experiments of W fiber reinforced Ni， where the mechanism of the flexible compression was presented. Theoretical analysis and experimental results show that the friction and extrusion between the flexible compression wheel and the cathode may effectively remove the hydrogen bubbles which reduces the surface porosity; the effects of solution supplement by the flexible compression wheel may prevent the generation of the internal voids and raise the limiting current density which reduces the grain size significantly. When the volume fraction of tungsten wire is as 50%, the tungsten-Ni comqosite electroforming layer strength is up to 1597MPa， which improves by 21%.

Design and Parameter Optimization on Vertical Shallow-basin Type Composites Seed-plate Soybean Seed-metering Devices

Liu Hongxin, Xu Xiaomeng, Fu Lulu, Wang Chen

2016, 27(22):  3005-3011. 

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To meet the working requirements of mechanical precision seed-metering device at high speed, a vertical shallow basin-type composite seed-plate seed-metering device with double cavity was designed, the seed-metering device might utilize gravity, centrifugal force and interaction force among the seeds to increase the filling force, improve the filling performance of seed-metering device at high speed. And in order to obtain the structure parameters of seed-metering devices to further improve the quality of precision seeding, the software of EDEM was utilized to make the three factors and five levels of all factors rotational quadratic orthogonal experiments which took the diameter of seed-plate, folding angle, working speed as the influence factors, and filling rate as the performance index， the experimental scheme was designed. And Design-expert 8.0 software was used to deal with the simulation data, the optimal structural parameters of the seed plate were obtained, the physical prototype test was made to verify the values of simulation. The experimental results show that when the diameter of seed plate is as 234mm, folding angle is as 68°, qualified rate may be beyond 90% at the high-speed area(working speed in the range of 8km/h to 12km/h), the optimized parameters may meet the demands of high speed operations, which will provide the basis and references for the product approval.

Description of Nonlinear Characteristics of Piezoelectric Micro-manipulation Stage Based on SVM

Hu Junfeng, Zheng Changhu, Cai Jianyang

2016, 27(22):  3012-3019. 

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The nonlinear characteristics of micro-manipulation stage would be occurred due to the hysteresis of piezoelectric actuator, which might seriously affect the movement precision and repeated positioning accuracy of the stage. In order to solve the issue, a hybrid modeling method was proposed to describe the hysteresis characteristics based on Preisach and SVM. As for a one dimensional micro-manipulation stage, the sample points were chosen as the piezoelectric driving voltages and corresponding output displacements of the stage. The regression model of the hysteresis loop of the PEA was established by using SVM theory. The model might be used to predict the displacements corresponding to the voltages not at sample points. Combined with the Preisach model, the output displacement corresponding to any voltage sequence might be obtained. The experimental studies were carried out in order to verify the validity of the presented model. Arbitrarily selecting two sets of input voltage sequences, and the prediction value of the output displacements corresponding to the selected voltage sequences might be obtained by using the regression model and Preisach model. The measured values were obtained under the same voltage sequences by experimental tests. Comparing the measured values and predicted values, the results show that the relative error ranges of the two sets of the measured and predicted values are as 0.6%～2.1% and 0.02%～2.1%, respectively. Therefore, the predicted displacements are very close to the measured ones. It illustrates that the proposed model may accurately describe the nonlinear characteristics of the micro-manipulation stage in order to realize its precise movements.

Design and Implementation of Fretting Fatigue Test System for Curvic Couplings

Cui Haitao, Li Aimin, Wen Weidong

2016, 27(22):  3020-3024,3031. 

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A two-dimensional loading scheme for curvic couplings fretting fatigue test was designed and manufactured to reduce the costs and the technical difficulties which the three-dimensional loading scheme could bring about. A two-dimensional fretting fatigue test model was provided and tests which employing typical two-dimensional curvic couplings fretting specimen were conducted. In all of  the tests, fatigue cracks initiated on the edge of the contact surface and massive abrasive dust appeared on the contact area, which indicated the typical failure mode of the fretting fatigue occured to the contact area. The results show that this kind of loading scheme can meet the requirements of the curvic couplings fretting fatigue tests and may provide test data for the predictions of fretting fatigue life and further research on damage mechanism of fretting fatigues.

Optimization Design of Low Noise Circular Saw Parameters Combining Response Surface Model with Hybrid Optimization Algorithm

Tian Yongjun, Duan Guolin, Xia Xiaoguang, Zhang E

2016, 27(22):  3025-3031. 

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Focusing on inherent limitations in the traditional optimization methods for structure parameters of low noise circular saw, an optimization combining response surface model with hybrid algorithm was proposed to optimize the design of dynamic rotating blades. Firstly, a set of experimental design data points were extracted by D-optimal experimental design scheme，then the points were calculated respectively by display algorithm for acoustic, stress response and implicit algorithm for deformation saw blades.Then the corresponding response surface models were set up by the points' responses. Finally, these second-order regression models were optimized by adaptive simulated annealing and leapfrog algorithm. The results show that under the conditions of safety, by a limited number of value analysis after the optimization, the final structure may reduce the idle noise 4~7dB.Numerical example indicates that this method is suitable for the optimization design of acoustic properties of rotating cutting tools.

Mechanism of Defect Detections for Rectangular Differential Probes of Pulsed Eddy Current Testing

Zhou Deqiang, Wang Jun, Pan Meng, Li Ke, Su Lei, Hua Chunjian

2016, 27(22):  3032-3037. 

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To further improve the detectability of defects of pulsed eddy current testing (PECT), the methods of rectangular differential probes of PEC were put forward. A three-dimensional testing model of the PEC rectangular probes was established, and the distribution of induced current on samples under a rectangular testing coil was analyzed. The distribution and value of induced current were compared between ferromagnetic and non-ferromagnetic materials. According to the symmetric distribution of X and Y components, two design methods of metals for PEC rectangular probes were put forward. The relative differential rectangular probes of PEC were designed to obtain different magnetic components. The simulation and experimental results show that X and Y components of magnetic fields may lead higher testing sensitivity than Z component for the ferromagnetic and non-ferromagnetic materials respectively.

Studies and Applications of Resonance Demodulat Based on Three-dimensional Kurtogram

Ma Xinna, Yang Shaopu

2016, 27(22):  3038-3042. 

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Aiming at the features of periodicity impulsion of vibration signals from rolling bearings with faults, a three-dimensional kurtogram algorithm was proposed, which used the dichotomy of bandwidth and center frequency to search the optimal band with fault signals. The method was applied to select the parameters of band-pass filter in resonance demodulation. Thus, the resonance demodulat was brought forward based on three-dimensional kurtogram. With the running-in test-bed of railway wheel-set, experiments were carried out on rolling bearings with natural faults. The proposed method was used to fault diagnosis. Compared with the resonance demodulat based on fast kurtogram, the proposed method has better identification ability of faults. Finally, time complexity of three-dimensional kurtogram algorithm shows its higher efficiency and value for engineering applications.

Four-way Valve Automatic Brazing Positioning System  Based on Machine Vision

Kong Ming, He Chuhong, Wang Yingjun, Huang Wei

2016, 27(22):  3043-3047. 

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To improve the speed and precision of four-way valve brazing, an automatic brazing inspention system was proposed. Based on machine vision the four-way valve brazing coordinate was located accurately. Using near-infrared backlight source for lighting the automatic dectections of four-way valve center and side heigh were realize. Using near-infrared backlight the image edge might make more clear and easy to argue, with the advantages of environmental protection and energy saving, long life, et al. The system might achieve the level projection of four-way valve circle contour extraction and column height mainly through threshold segmentation and PCA algorithm respectively. Through shape matching and linear fitting the center of circle relative coordinate and height were obtained to achieve the four-way valve brazing inspectiong system.The four-way valve brazing inspection has the advantages of high speed, high accuracy, stable system operation and so on. It has good applications and broad development prospects in industries.

Bearing Fault Diagnosis Method Based on EEMD Approximate Entropy and Hybrid PSO-BP Algorithm

Zhang Shuqing, Huang Wenjing, Hu Yongtao, Su Xinshuang, Lu Chao, Jiang Wanlu

2016, 27(22):  3048-3054. 

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According to the non-stationary and nonlinear characteristics of mechanical faults, a new method for bearing fault diagnosis was put forward based on EEMD approximate entropy and hybrid PSO-BP algorithm. EEMD might resolve the end effects of the EMD, improving the limitations of EMD when dealing with nonlinear signals; the random weights and the compression factors were introduced to improve particle swarm optimization(PSO) algorithm so as to optimize BP neural network, realizing fast convergence to optimal solution effectively of neural network. Signals were first decomposed by EEMD to get the instrinsic mode function(IMF) components, and to construct feature vectors together with the approximate entropy and the constructed feature vectors were put into the PSO-BP neural network for pattern recognition. The experiments and the engineering tests demonstrate the efficiency and superiority of this method.

Simulation on Depths of Roll-beating and Springback Rules of Cold Roll-beating Forming

Liang Xiaoming, Li Yan, Wei Fanzhi, Yao Yuan, Wu Xueliang, Yuan Qilong, Yang Mingshun

2016, 27(22):  3054-3060. 

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In order to effectively control the effects of springback on formed part precisions, the relation between deformation and springback was studied. According to basic principles of cold roll-beating, a finite element dynamic simulation model was established by ABAQUS software, through simulations forming gullet section deformation laws and springbacks under of different roll-beating depths wre obtained in tangential direction, axial direction and radial direction. Because inner forces of workpiece in results of dynamic simulation were at unbalance states, the springbacks could not be directly solved, so a static simulation model was established based on results of dynamic simulations, and the depths of different roll-beatings of forming gullet section springback rules in tangential direction, axial direction and radial direction were determined by static analysis. Cold roll-beating experiments were carried out by using refit experimental equipment and workpiece profile shapes were obtained, compared with simulation results under the same processing conditions, and the results of simulation were validated, thus it provides references to effectively control the springback influences on forming precisions.

3D Unsteady Numerical Simulation of Magnetostriction-induced Ultrasonic Cavitation Flow

Xia Dongsheng, Sun Changguo, Yu Yan, Zhang Huichen

2016, 27(22):  3061-3067. 

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The magnetostriction-induced ultrasonic cavitation flow was numerically simulated by using a “Singhal full cavitation model” and SST k-ω turbulence model with the dynamic mesh technique. The characteristics of ultrasonic cavitation flow and the cavitation erosion mechanism were revealed. The computational results show that pressure and vapor volume fraction (VVF) vary periodically on the specimen with vibration of the specimen. The lowest value of pressure fluctuation reaches the vapor pressure at the local flow field proximity to the specimen, where cavitation can occur. Pressure fluctuation presents a distinct pulse feature on the specimen surface, due to cavitation. Moreover, pressure and VVF were annularly distributed around the center on the specimen. However, they have irregular and discontinuous pulse in the annular zones. At the center of specimen, bubbles collapse leads to intense pulse pressure after twice oscillation, which can reach about 14MPa. Pulse pressure was distributed in the interval annular zones and alternately occurs in the adjacent annular zones with vibration of the specimen. In the ultrasonic cavitation flow field, the specimen surface seems to be as several acoustic emission sources. The acoustic waves generate mutual superposition and interference. Pressure dramatically attenuates with increasing the distance to the specimen. The considerable pressure fluctuation occurs within the distance of about 20mm to the specimen.

Second Order Reliability Method of Structures Considering Parametric Correlations

Jiang Chao, Deng Qingqing, Zhang Wang

2016, 27(22):  3068-3074,3081. 

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A vine copula based second order reliability method(VC-SORM) was proposed to deal with reliability analysis problems with complex multidimensional correlated variables. The multidimensional probability distribution function was converted into two-dimensional copula functions using vine copula function. The maximum likelihood estimation method and the AIC information criterion(Akaike information criterion) were used to identify the optional two-dimensional copulas. Then the joint probability distribution function was built and the first order reliability results were obtained. Based on the first order reliability results, a reliability results with higher accuracy were obtained using the second order approximation. Finally, two numerical examples were provided to verify the effectiveness of the method.

Fault Diagnosis Method of Bearings Based on LMD and LE

Xu Qianqian, Liu Kai, Hou Heping, Xu Zhuofei

2016, 27(22):  3075-3081. 

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A new diagnosis method for feature extraction of non-stationary vibration signals and fault classification of rolling bearings was proposed  based on LMD and LE. Firstly, the non-stationary vibration signals of rolling bearings were decomposed into several product functions with LMD. Then, dimensional fault feature sets were established by the time-frequency domain features of product function, instantaneous frequency and amplitude. Secondly, LE was introduced to extract the sensitive and stable characteristic parameters to describe the running states of rolling bearings effectively and accurately. Finally, support vector machine classification model was built to realize the classification of fault bearings. For test samples classification, the average prediction accuracy is as 91.17%.It means that the fusion method of the LMD and LE is suitable and feasible for the bearing fault feature extraction.

Optimization Design and Experimental Analyses of Non-circular Gears for Constant Flow Pumps

Hu Ziyang, Yang Hui, Li Dazhu, Han Jiang

2016, 27(22):  3082-3087. 

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Through analyzing the principles of a constant flow pump, the output speed pulsations might be reduced in order to reduce the output flow pulsations. The serial mechanism of the non-circular gears and slider-crank mechanism was used in the pump, so the non-circular gears were the important factors to impact the composite speeds of the two plungers. Based on the expected speeds of the two plungers, the pitch curves were resolved. And then on the premise of overall consideration of the transmission characteristics and the mechanics characteristics, the pitch curves were optimized. Then the non-circular gears' profile were designed by the generating cutting principles. At last, virtual machine simulations and actual machine tests verify that the theoretical design is correct. And the results confirm that the optimization design is very effective to reduce the output speed pulsations.

Multi-physics Coupling Simulation of ECM Processes for Compressor Blade

Chen Yuanlong, Fang Ming, Pei Di, Chang Weijie

2016, 27(22):  3087-3092. 

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A temperature dependent multi-physics coupling model was developed to predict ECM process and shorten the period for modifying machining parameters. Based on COMSOL multiphysics software, ECM processes for compressor blades were simulated and influences of the applied potential and the inlet mass flow on the normal equilibrium gap were analyzed. The simulation results indicate that with the applied potential increasing, the gap is increasing and the distribution of gap is less and less uniformity. However, with the inlet mass flow increasing, the distribution of gap tends to uniformity. The ECM experiments were carried out according to a set of simulation parameters. Comparisons between simulation and experimental results indicate that the errors are small when the blade profile curvature changes slowly and the errors are relatively large, but variation trend of the gap is same when the blade profile curvature changes fast.

Simulation of Metal Bulk Forming Based on MPM

Xie Guilan, Yu Chao, Gong Shuguang, Tian Jie, Hu Jundi

2016, 27(22):  3093-3097,3102. 

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Aiming at the problems that mesh distortions in finite element method(FEM) and difficulties of applying the essential boundary conditions in the traditional mesh-less method when doing the analysis of metal bulk forming process, a simulation model of metal bulk forming process was presented based on MPM. Because the shape function of the finite element method was used on the background grid nodes, MPM might solve the difficulty problems in dealing with the boundary conditions effectively. Two metal bulk forming processes(heading of cylindrical billets and backward extrusion) were performed, compared the results of experiments with those of finite element method, it is shown that MPM may eliminate the mesh distortions, and may get more accurate results than that of the finite element method when large deformations occur. The conclusions may provide guidance for the MPM to be applied in the large elastic-plastic deformation analyses.

Stepping Press Forging Process for Uniform Thickness Parts of Sheet Metal with High Straight Arm and Small Spacing

Wang Kesheng, Han Yu

2016, 27(22):  3098-3102. 

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Stepping press forging(SPF) process was proposed to form parts with high straight arms and small spacing, which could not be formed by normal stamping because the interferes would happen when the straight arms were expanded before stamping. Parts with large space straight arms were formed by stamping initially and then by using several bending steps to narrow the distance between the two straight arms to the target value. Cold forging should be used after every bending step to flat the bending area and it was important to select the reasonable stepping coefficients to avoid the overlap, wrinkling and cracking during cold forging. Bending limit diagrams for every bending step were obtained based on the mathematical model of streamline bending. Numerical simulations together with experiments were used to determine the stepping coefficients with no process defects. The SPF process is a new way to form such parts which have excellent performance and high productivity.

Compliance of Self-adaption Suspension Group Systems in Selfpropelled Transporters

Zhao Jingyi, , Kang Shaopeng, , Cheng Fei, , Fan Liangzhen,

2016, 27(22):  3103-3110. 

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Through the descriptions and effect evaluations of the compliance of self-adaption suspension group systems in self-propelled transporters, a kind of self-adaption suspension group system was improved and designed in view of the present traditional hydraulic spring suspension system, and a nonlinear mathematical model of the transporter and self-adaption suspension group system was established. Based on the six axis of self-propelled transporter which was loaded 3200kN, the simulation model of hydraulic spring suspension system and self-adaption suspension group system was built with random road surface excitation for inputs under no-load and full load conditions. Simulation analyses and field tests show that the compliance coefficient of the improved self-adaption suspension group system is increased by 103.8% and 55.1% under no-load and full-load conditions respectively, the output forces of the system hydraulic cylinder are more gentle and the compliance performance of the system is better. The ability to resist shock vibrations and the performance to ride comfort improvements have remarkable effects in the self-propelled transporter driving processes using the improved self-adaption suspension group system.

Analysis for Effects of Transient Crosswinds with Different Wave-lengths on Vehicle's Aerodynamics Performance

Huang Taiming, , Gu Zhengqi, Feng Chengjie, Chen Zhen

2016, 27(22):  3111-3117,3123. 

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The large eddy simulation was used to investigate the vehicles subjected to transient sinusoidal crosswinds, and the transient crosswinds were changing in time and space, which was realized by the user defined function(UDF) to control the boundary conditions. The effects of the transient crosswinds with three different wave-lengths on the coefficient of the aerodynamic forces were analyzed, and the results were compared with the experimental and the quasi-steady simulation. The results show that: the coefficients of the aerodynamic forces are changing in periodic when the vehicles subjected to the transient sinusoidal crosswinds, but the change frequency of the coefficients of the drag forces is two times of the coefficients of lift and yawing moments. The changing range of the coefficients of drag forces are gradually decreased when the wavelengths of the crosswinds are reduced. The A-pillar has important influences on the vehicle aerodynamic performances in crosswinds.

Prediction of Internal States of Battery in HEV by BELM

Wang Qi, Sun Yukun, Ni Fuyin, Chen Taihong, Chen Lianyu, Luo Yinsheng

2016, 27(22):  3118-3123. 

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BELM was proposed based on approach to predict the battery's internal states of HEVs. The basic principles of BELM were described in detail, and the performance parameters of battery were collected under advanced vehicle simulator(ADVISOR) including voltages, currents, temperatures and so on. Then the BELM was used in the predictions of SOC and SOH, at the same time, the influences of aging battery were taken into account. The results of BELM indicate that the prediction model possesses higher prediction accuracy, and achieves real-time and accurate SOC and SOH predictions with high effectiveness.