Table of Content

25 October 2020, Volume 31 Issue 20

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Design of High-resolution Satellite Micro-vibration Suppression System Based on COTS

GUO Jinsheng1;WANG Feng1;YUE Chengfei2

2020, 31(20):  2395-2042，2411.  DOI: 10.3969/j.issn.1004-132X.2020.20.001

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In order to solve the problems of micro-vibration suppression of small satellites with high-resolution optical loads，a system design method was proposed herein by modifying the parameters of COTS and optimizing the installation of the vibration components. Different from other methods based on the knowledges of vibration mechanism, the micro vibration characteristics of the vibration components and tuning the parameters were directly analyzed by the proposed method, and a reasonable location of the vibration components was obtained by analyzing the dynamics response of the honeycomb sandwich structure using Newmark method. The effectiveness of the proposed method was verified by simulations and ground tests. Results show that the micro-vibration of the vibrating components is suppressed by 90% in the sensitive frequency bands, and the secondary mirror displacements caused by the micro-vibrations of the whole-star ground measurement do not exceed 0.04″. Orbital experiments show that the satellite in-orbit micro-vibration environment meets the requirements of the camera. Thus the design method of the suppression system sets an example for other engineering practices in the future.

Multi-phase Material Topology Optimization Design of Heat Dissipation Structures Considering Topology-dependent Heat Sources

ZHAO Qinghai1,2;ZHANG Hongxin2;JIANG Rongchao2;HUA Qingsong1,2;YUAN Lin2

2020, 31(20):  2403-2411.  DOI: 10.3969/j.issn.1004-132X.2020.20.002

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Considering the topology-dependent heat source problems in the heat conduction topology optimization design, the mathematical model of multi-phase material topology optimization of heat dissipation structures was constructed. The objective function was assigned to dissipation of heat potential capacity, combined with volume fraction constraint conditions. The variable density theory was introduced to represent the multi-phase material interpolation model based on ordered-solid isotropic microstructures with penalization (Ordered-SIMP) methodology. Then the sensitivity analysis of topology-dependent and topology-independent heat sources was executed respectively, and the iteration format of design variables were solved by optimization criterion. The partial differential equation filter method was implemented to suppress numerical instability in the optimization processes. Through the 2D/3D numerical models, the meaningful conclusions of topology-dependent heat sources, topology-independent heat sources and coupled heat sources were illustrated under different boundary conditions. The proposed method is effective and feasible in solving the multi-phase material topology optimization problem of topology-dependent heat sources.

Optimal Design for Cutter-layout of Global Force Balanced PDC Bits

MA Yachao;ZHANG Peng;HUANG Zhiqiang;DENG Rong;YU Hongmei

2020, 31(20):  2412-2419,2428.  DOI: 10.3969/j.issn.1004-132X.2020.20.003

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For the problems of the well deflection, hole enlargement, bit whirl and vibration, and the bit early failures caused by the unbalanced forces on PDC bits during the drilling processes, the optimal design model of cutter-layout of global force balanced PDC bits and bending moment model were constructed based on the existing PDC bit cutting mechanics, and the corresponding solution method was proposed. Results of a cutter layout design example show that the global force balance cutter layout design method may keep the global force balanced status of PDC bits in different footages. In particular, the force balance state of PDC bit is greatly improved at small footage(<1 mm). The drilling stability of PDC bits is improved. The results are of great significance to amend the forces on drill bits, which may extend the service life of the drill bits and improve the drilling efficiency.

Fault Diagnosis for Rolling Bearings Based on Improved Singular Value Decomposition and Spectral Kurtosis

MENG Zong;LIU Zihan;LYU Meng

2020, 31(20):  2420-2428.  DOI: 10.3969/j.issn.1004-132X.2020.20.004

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For the problems that is difficult to determine the number of effective singular values of noisy signals, an improved SVD method—singular value accumulation method was proposed. The difference between the actual falling and the cumulative value of the average falling of the singular value was calculated, and the position of the maximum point of the difference was taken as the boundary point of the number of effective singular values to determine the effective singular value number. A fault diagnosis method for rolling bearings was proposed based on singular value accumulation method and fast spectral kurtosis. Firstly, the singular value accumulation algorithm was used to denoise the original signals and the center frequency and bandwidth of the filter was determined by the fast spectral kurtosis. At last, fault features might be diagnosed by analyzing obvious frequency components in envelope spectrum. The proposed method may effectively denoise the signals, so that the fault impacts reflected by the obtained kurtosis value are closer to the actual situation. By analyzing the experimental data of rolling bearings with inner and outer ring faults, the experimental results show that the proposed method has better fault identification effectiveness than that of the fault diagnosis method with the fast spectral kurtosis.

Research on Normal Random Micro-vibration of Restrictors in Ultra-precision Gas Static Pressure Systems

SHEN Xiaoyan;DING Jiawei;YU Jing;LI Dongsheng

2020, 31(20):  2429-2436.  DOI: 10.3969/j.issn.1004-132X.2020.20.005

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College of Metrology & Measurement Engineering，China Jiliang University,Hangzhou,310018
Abstract: Taking the airless cavity planar restrictor as the research object, the theoretical simulation and experimental research were carried out on the flow-solid coupling normal random micro-vibrations of the restrictors. Constrained by the differences between the restrictor thickness and the film thickness and the initial boundary conditions of the input, a simplified COMSOL simulation model of the restrictor was established. Bidirectional fluid-solid coupling numerical simulation of the restrictor-gas film microfluidic field was carried out. The simulation results show that the amplitudes of the normal random micro-vibrations of the restrictor are symmetrical about the center of the restrictor. In addition, the amplitudes of the vibrations gradually increase from the center to the edge of the restrictor and increase as the flow rate of the inlet gas increases. A nano-scale laser vibrometer was employed to test the normal vibrations of several different positions of the HEXAGON double-ring type restrictor. The size of the restrictor was 75 mm×50 mm×14 mm, and the supply pressure was 0.1～0.5 MPa. The results show that the amplitude distribution characteristics of normal random micro-vibrations are consistent with the simulation results. The amplitudes are symmetric with respect to the center of the restrictor and gradually increase from the center to the edge, verifying the “seesaw” vibration forms of the normal vibrations of the restrictor. At a supply pressure of 0.5 MPa, the edge vibration amplitude reaches 1 nm or more. While the results of power spectral density analysis show that the normal random micro-vibrations of the restrictor carry a large power at 9.4 kHz and 10.6 kHz. It can be considered as the natural frequency of the restrictor-gas membrane fluid-solid coupling systems. The experimental results demonstrate the normal random micro-vibration characteristics of the restrictor effectively, and provide theoretical guidance for the design of the gas static pressure systems to avoid the stochastic resonance region and optimize the gas static pressure systems.

Tribological Properties and Corrosion Resistance of MoS2-based Composite Coatings with Different Graphene Additions

LI Yingchun1,2;CHENG Bei1;QIU Ming1,2;GU Shouxu1;FAN Henghua1

2020, 31(20):  2437-2444.  DOI: 10.3969/j.issn.1004-132X.2020.20.006

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In order to improve the friction and wear performance and corrosion resistance of MoS2-based solid lubricating coatings, MoS2 composite coatings were prepared with different amounts of GE additions. The friction and wear performance of the composite coatings was tested using a HSR-2M friction and wear tester and the wear mechanism was also analyzed. The electrochemical corrosion behavior of the coating when placed in 3.5% NaCl solution was studied by means of polarization curves, the electrochemical impedance spectroscopy. The results show that the 0.8-GE/MoS2 composite coating has the best friction and wear and corrosion resistance: its friction coefficient and wear rate are as 0.232 and 2.379×10-13 m3/(N·m) respectively, which are 49.56% and 43% lower than those of the MoS2 coating without graphene; and the corrosion rate(1.96 ×10-8 A/cm2) is reduced by nearly two orders of magnitude compared with the pure MoS2 coating (5.54×10-6 A/cm2). Results indicate graphenes two-dimensional sheet structure has good self-lubricating properties and may effectively block the penetration of corrosive media when it is uniformly distributed in the coating. Therefore, the addition of graphene improves the tribological properties and corrosion resistance of MoS2-based composite coatings and the optimal amount of graphene is as 0.8%.

Numerical and Experimental Investigations of Thermal Performance for Heat Pipe Ball Screws

HU Mian;DING Xiaohong

2020, 31(20):  2445-2453.  DOI: 10.3969/j.issn.1004-132X.2020.20.007

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A new type of ball screw with built-in heat pipes was designed to solve the problems of high temperature gradient, fluctuation on the surfaces of the screw and long time to reach the heat balance in the traditional liquid-cooled heat dissipation ball screws. The liquid filled medium of heat pipe ball screws was chosen and the structural dimensional parameters were calculated. To verify the thermal performance, the finite element model of the heat pipe ball screws with tube wall layer, liquid reflux layer and steam chamber layer was established, and the hierarchical equivalent model was used to simulate the heat pipe parts of the ball screws. The temperature distribution on the surfaces of the screws was analyzed when the nuts were located in different positions, and the thermal performance of the screws was compared with that of the traditional liquid-cooled screws. The heat pipe ball screw was prepared by boiling exhaust method. The experimental platform was built to test the surface temperature of the heat pipe ball screws and the results were compared with the simulation ones. The results show that the surfaces of the heat pipe ball screws have smaller temperature gradient, better temperature uniformity and shorter time to achieve thermal balance than that of the traditional liquid cooling heat dissipation ball screws. The simulation results are in agreement with the experimental ones, which verifies the effectiveness of the simulation method.

Bearing Life Prediction Method Based on PMCCNN-LSTM

2020, 31(20):  2454-2462,2471.  DOI: 10.3969/j.issn.1004-132X.2020.20.008

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Timing characteristics between data was an important hidden information that might be utilized while predicting the remaining life of the bearings. In order to better extract features with timing informations for prediction, a remaining useful life prediction model was proposed based on PMCCNN-LSTM. The model was consist of two parts. The front end was PMCCNN, which extracted the signal features, mined for the timing characteristics of the data, and used layer-by-layer training and fine-tuning to improve the convergence of the parameters. The back end was an LSTM network with remaining useful life prediction based on features, and the weighted average method was used to smooth the prediction results. The accuracy of the model was verified by using leave-one-out method on a public dataset of bearing accelerated life tests. The experimental results show that the mean errors and maximum errors of the proposed model are 23.38% and 15.84% lower than that of CNN, 24.14% and 19.01% lower than LSTM, 30.32% and 23.09% lower than that of CNN-LSTM respectively.

Rolling Bearing Fault Diagnosis Method Based on Generalized Refined Composite Multiscale Sample Entropy and Manifold Learning

WANG Zhenya;YAO Ligang

2020, 31(20):  2463-2471.  DOI: 10.3969/j.issn.1004-132X.2020.20.009

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Aiming at the difficulty of extracting fault features of rolling bearings, a feature extraction method was proposed based on GRCMSE and manifold learning. GRCMSE was utilized to extract the features of rolling bearings.DDMA method was employed to reduce the dimension of the high-dimensional feature sets. The low-dimensional fault features were input into particle swarm optimization support vector machine(PSO-SVM) multi-fault classifier for fault identification. The experimental results of rolling bearing fault diagnosis show that the features extraction effectiveness of GRCMSE is better than that of MSE, RCMSE and GMSE,the dimensionality reduction effectiveness of DDMA is preferable to Isomap and local tangent space alignment(LTSA),the fault recognition accuracy of rolling bearings reaches 100% by combining GRCMSE and DDMA.

Research on Cooperative Modes and Tipping Stability of Multiple Mobile Robots

XIE Dongfu1;LUO Yufeng1,2;SHI Zhixin1;LIU Yande2

2020, 31(20):  2472-2485.  DOI: 10.3969/j.issn.1004-132X.2020.20.010

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In view of the problems such as insufficient climbing ability and poor stability of single mobile robots in mountain orchard, a method of multiple mobile robot cooperative operation was proposed. The connectors for multiple mobile robot cooperative operation were added based on the original structure of hexapod robots, and the robot monomers for multiple mobile robot cooperative operation were obtained. And three typical cooperative modes of serial walking mode, parallel walking mode and triangle walking mode were obtained by the way of cooperative operation of three hexapod robot monomers. Finally, the static and dynamic stability of the single mode and three typical cooperative modes of the foot type mobile robot systems were analyzed under six typical terrain conditions by using the stable cone method respectively. Theoretical analysis and simulation results show that any two of the three typical cooperative modes may switch to each other, and the stability of the foot type robot systems may be improved by the way of cooperative operation and mode switching under six typical terrain conditions.

Modeling Method for Thermal Characteristics of Ball Screw Pairs

ZHANG Yaoman;BAO Fengxu;QI Peining

2020, 31(20):  2486-2490,2496.  DOI: 10.3969/j.issn.1004-132X.2020.20.011

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The thermal characteristics and modeling method of an external circulation ball screw pair were studied. Firstly, the mathematical model of steady temperature distribution of the ball screw was established based on the analysis of the heat source and boundary conditions of the ball screw feeding systems. The temperature field of the ball screw and the influences of raceway on the steady temperature of the screw were obtained by software programming. Secondly, the finite element analysis model of ball screw pairs including raceway influences was established, and the steady and transient thermal characteristics analysis results of the ball screw systems were obtained. Finally, the temperature and the changes of the key points of ball screw feed systems were obtained through the thermal characteristics tests of the ball screw pairs. The results show that the mathematical model of the ball screw pair thermal characteristic analysis may obtain the temperature field of ball screw accurately. Ignoring the influences of the raceway may cause a 15% to 20% errors in the simulation results of the temperature field of the ball screw pairs.

A Measuring Method for Radial Section Sizes of Ring Forgings Based on Laser Scanning

LI Qun1;LIU Yuanxi1;ZHANG Yucun2;NING Jian1

2020, 31(20):  2491-2496.  DOI: 10.3969/j.issn.1004-132X.2020.20.012

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 In the forging processes, the radial section size data greatly affected the forging accuracy of ring forgings. Because of the complexity of forging environments and the high intensity noise interference, the amount of scanning data was very large. The accuracy of the radial dimensions measured from these scanning data was low. Therefore, a new measuring method for radial section sizes of ring forgings was proposed based on laser scanning. Firstly, the information space sets of laser scanning data were established, then, this information space was divided by continuous concentric circles. Secondly, according to the information relationship between the various areas in the information space, the gradient descent method was combined with the uniform continuous coefficients to solve the undetermined coefficients. Thirdly, the reduction ratio was set according to the density of scanning data points. By combining the reduction ratio with the undetermined coefficients, the number of points needed to be reserved in each area of a concentric circle was determined. The remaining points and the repetitive points in the intersection of two concentric circles were deleted. Finally, the method was repeated to traverse the laser scanning data, so as to process the laser scanning data of the radial sections for the ring forging. The method was applied in the experiments. The dimension data of the radial sections were extracted from the processed data of the laser scanning radial section line. The dimensions measured from the unprocessed and processed data points were compared with the true values. The dimensions measured from the processed data have higher accuracy and smaller errors. The feasibility of the proposed method is proved.

Bionic Surface Abrasive Belt Grinding of Nickel-aluminum Bronze Alloy and Its Noise Reduction Characteristics

HUANG Yun;JIAHUA Suolang;XIAO Guijian

2020, 31(20):  2497-2504,2511.  DOI: 10.3969/j.issn.1004-132X.2020.20.013

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In view of the difficulty in machining bionic groove surfaces of nickel-aluminum bronze alloy to improve its noise reduction performance, the bionic grooves were grinded on the surfaces of nickel-aluminum bronze alloy by pyramid belt and hollow spherical belt, and a test platform was set up to grind the surfaces of nickel-aluminum bronze alloy with bionic groove structure. The characteristics of grinding surfaces were extracted and the finite element fluid noise analysis was carried out accordingly. The noise performance of pyramid abrasive belt grinding bionic surface and hollow ball abrasive belt grinding bionic groove surface was compared and analyzed. The results show that the average acoustic energy level of regular bionic groove surface grinded by pyramid abrasive belt is as 18.07 dB, and that of irregular bionic groove surface grinded by hollow ball abrasive belt is as 37.6 dB. In the experiments, the surfaces of nickel-aluminum bronze alloy grinded by two kinds of abrasive belt have bionic groove structure, and the regular bionic groove surfaces grinded by pyramid abrasive belt have better underwater noise reduction performance.

Precision Optimization of Driving Axle Parts for Low Cost and Low Noise

JIAO Dongfeng;LIU Zhifeng

2020, 31(20):  2505-2511.  DOI: 10.3969/j.issn.1004-132X.2020.20.014

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In order to achieve multi-objective optimization of automotive driving axle parts accuracy for low cost and low noise, a calculation model of correlation degree between influence factors and meshing noise was constructed. The correlation degree among influence factors and meshing noise was objectively obtained by combining the detection data of influence factors of market failure parts with the statistical results of unqualified rate of production processes. The orthogonal experimental method was used to carry out multi-level analysis of influence factors. Through bench noise test, the combination of the lowest noise factors was obtained, and the sensitivity and interaction analysis of the influence factors of noise was carried out. The multi-objective optimization function of vehicle-driven bridge noise with high performance and low cost was constructed, and the optimal combination of factors was obtained by combining the manufacturing cost and the orthogonal test results. The sound pressure level of commercial driving axles before and after optimization was compared by the method of vehicle NVH performance test. The validity of the optimization results was verified by the vehicle NVH performance test method.