Table of Content

    25 December 2021, Volume 32 Issue 24
    Research on Traveling Wave Resonance Characteristics of Spiral Bevel Gears and Its Influence Laws under Parameter Adjustment
    LUAN Xiaochi, ZHAO Yu, SHA Yundong, LIU Gongmin, ZHAO Qian,
    2021, 32(24):  2899-2908,2914.  DOI: 10.3969/j.issn.1004-132X.2021.24.001
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    Aiming at the driven bevel gear fracture failure of a certain type of aero-engine central drive bevel gear due to traveling wave resonance in actual processes, combination of simulation analysis and test verification was used to study the traveling wave resonance characteristics and influence laws of spiral bevel gears under parameter adjustment. The modal analysis of the driven gears was carried out based on finite element method, and the relationship between the thickness of the spoke plate and the working temperature with the gear traveling wave resonance characteristics was discussed. Transient dynamic analysis of meshing gears was carried out based on Hertz contact theory, and the influences of load power, operating temperature and damping factor on the stress distribution of driven bevel gears under traveling wave resonance were discussed. The comparison of simulation and test results shows that the errors of simulation results of modal calculation and dynamic analysis are within a reasonable range. Under the premise of meeting the relevant requirements of gear design, the resonance speed or resonance frequency may be avoided by adjusting the thickness of the spoke plate. In terms of the sensitivity of the resonance parameters of the vibration stress distribution, the analysis shows that when the gear is working in the third or fourth nodal diameter traveling wave resonance states, the stress values at the tooth roots are the largest, and the stress values on the front surfaces of the spoke plate are the smallest; when the temperature and damping factor changing, the change of stress values at front of the driven bevel gear spoke plate is small, and the change of stress values at the back of the spoke plate and tooth root is big. Therefore, in improvement and optimization designs of the gears, it is necessary to deal with the third or fourth nodal diameter traveling wave resonance.
    Research on Preparation and Performance of Graphene-Polymer Flexible Capacitance Sensors
    YAO Fangping, LI Xiangmeng, SHI Qiangshengjie, ZHANG Xiao
    2021, 32(24):  2909-2914.  DOI: 10.3969/j.issn.1004-132X.2021.24.002
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    In order to study the influences of different microstructures on the performance of flexible capacitive pressure sensors, a low cost spin coating technique was used to prepare flexible capacitor pressure sensors with no microstructure, single layer microstructure, double layer and occlusal microstructure were comparatively analyzed in terms of the sensitivity of sensors. Meanwhile, the response characteristics, repetition characteristics and hysteresis characteristics of the single-layer microstructure sensors were tested and analyzed. The test results reveal that the flexible capacitive pressure sensor with single-layer duplicated sandpaper structure has higher sensitivity than that of the other two sensors, with sensitivity of 0.451 kPa-1 for the pressure range of 0~4 kPa, 0.14 kPa-1for the pressure range of 4~6 kPa and 0.03 kPa-1 for the pressure range of 6~25 kPa, under the load of 20 kPa. The prepared sensors are endowed with high response characteristics, good recovery and stability, and they may adapt to the application requirements in flexible or wearable electronics.
    Flow Field Analysis of a Centrifugal Rotary Blood Pump under Active Speed Modulations
    HUANG Feng, WANG Chuchen, RUAN Xiaodong
    2021, 32(24):  2915-2923.  DOI: 10.3969/j.issn.1004-132X.2021.24.003
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    In order to study the effects of active speed modulation on the internal flow field and blood damages in the blood pumps, the CFD method was adopted to simulate the full flowpath internal flow of a blood pump under speed modulations. The combined numerical simulation of the lumped cardiovascular system mathematical model and the rotary blood pump model was used to obtain the ventricular and aortic pressures under the assisting of the blood pump, which were then set as the inlet and outlet boundary conditions of the blood pump in CFD simulations. The flow fields of blood pump under the constant speed and three types of asynchronous speed modulation waveforms, including sine, square and triangle waves, were analyzed, and the velocity distribution and shear stress distribution of the rotary blood pumps were obtained. The results show that the flow pulsation of blood pump is enhanced under speed modulations, which is a feasible scheme to restore the pulsation of the blood flow. Among the three speed modulation waveforms, the blood pump flow pulsation index is high and the shear stress in the blood pump is small under the sinusoidal speed modulation, which is a relatively ideal speed modulation waveform.
    Deployable Waterbomb Wheel Structure Analysis and Optimization of Mine Rescue Robots
    SHANG Zuen, ZHAO Lijuan, LIU Xionghao, JIN Xin
    2021, 32(24):  2924-2933.  DOI: 10.3969/j.issn.1004-132X.2021.24.004
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    A waterbomb wheel structure used in the coal mines rescue robots was designed to improve working reliability under complex conditions and adaptability to unstructured environments. A structural radial kinematics modeling method of the waterbomb wheel structure with the parallelogram as basic units was proposed to study the influences of different basic units on the waterbomb wheel structure's load-bearing characteristics. Based on the theory of continuum damage mechanics, the fatigue life of the parallelogram waterbomb wheel structures under axial compression loads was predicted. The design parameters of the waterbomb wheel were optimized by multi-objective optimization using the folding ratio as restrictions, with ultimate bearing capacity and fatigue life as evaluation functions. The research results show that the parallelogram waterbomb wheel has a better ultimate bearing capacity under the same mass. The optimized waterbomb wheel's folding ratio, the ultimate bearing capacity, the fatigue life prediction value has increased by 15.8%, 40.7%, 55.4% respectively, the working reliability of the waterbomb wheel structure is improved, and the actual fatigue life failure area is consistent with the theoretical calculation result. The experimental results verify the accuracy of the analysis processes and the effectiveness of the optimization method.
    Torque Fluctuation Behaviors under Continuous Shears of a Novel Confined Granular Media Coupling
    LEI Gang, OUYANG Hongwu, YU Hailiang, TANG Xin,
    2021, 32(24):  2934-2943.  DOI: 10.3969/j.issn.1004-132X.2021.24.005
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    The aims of this work were to study and utilize the mechanics response characteristics of granular media under continuous shear. For this purpose, a novel type of coupling(containing confined granular media/filled with steel balls)was designed to study the torque fluctuation behaviors, and a method then was developed to regulate and control the torque transmission characteristics. A specially-designed continuous shear device with pressure applied in the axial direction was adopted, and a series of experiments with different settings of low shear speed, initial normal stress, and packing height were carried out on the torsion testing machine to obtain the torque transmission characteristics of the coupling. The experimental results show that under continuous shear, the evolution of shear deformation of the granular media has a close relationship with the jamming density φJ, where the novel experimental device may provide a theoretically viable measuring method. Further insights from the study suggest that: by selecting an appropriate set of shear speed, initial normal stress, and packing height, the expected speed-sensitive torque transmission characteristic may be achieved in the confined granular media coupling. Controlling of φJ enables the regulation of torque fluctuation behaviors within the coupling.
    Research on Single Envelope Forming for CP Type Single Screw Gullets
    CHEN Jiu, XIA Linhai, SHA Feng, WU Changbo, CHEN Jianping
    2021, 32(24):  2943-2949.  DOI: 10.3969/j.issn.1004-132X.2021.24.006
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     The single envelope forming method was one of the most main machining methods for the parts with tooth characteristics. According to the structural characteristics of CP type single screw gullets and the principles of space meshing, a calculation method of single envelope forming for CP type single screw gullets was studied. The method included the section edge shape calculation of rotary cutters, the equations of theoretical and envelope forming screw gullets creation, and single envelop forming errors analysis. The single envelope forming model of a common single screw gullet was calculated and optimized by using this method, the single envelope forming errors of the optimized reference tooth profile were calculated. The results show that error values are large, it indicates that the single envelope forming method may not be applied to the one-step forming of CP type single screw gullets. 
    Multi-stage Noise Reduction Method with ESMK for Adaptive Feature Extraction of Rolling Bearings
    ZHANG Long, CAI Binghuan, XIONG Guoliang, WANG Chaobing, HU Junfeng
    2021, 32(24):  2950-2959.  DOI: 10.3969/j.issn.1004-132X.2021.24.007
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    The rolling bearing fault signals contained both of the high quality factor oscillation components and low quality factor periodic transient impact components. The method of multipoint optimal minimum entropy deconvolution adjusted(MOMEDA) was adopted to weaken the influences of interferences such as transmission path firstly, and the weak transient impact components were enhanced initially. Furthermore, the problems of quality factor determination in resonance-based signal sparse decomposition(RSSD) method and the strict periodicity of fault frequency components in the envelope spectrum were considered and the PSO was used to optimize the quality factors based on proposed novel index called envelope spectrum multi-point kurtosis(ESMK). In consequence, a new self-adaptive transient impact extraction method called PSO-RSSD was proposed, which might effectively eliminate the impacts of high amplitude interference and background noises. Bearing simulation and measured signal analysis results show that, compared with minimum entropy deconvolution(MED)-RSSD method, ESMK may effectively measure periodic transient impacts under strong impact interference, and PSO-RSSD may separate adaptively the optimal low quality resonance components, which verifies the effectiveness and superiority of the proposed method. 
    Research on Gas Path and Sensor Coupling Fault Diagnosis Model for Gas Turbines
    YAN Liping, ZHANG Hualiang, DONG Xuezhi, CHEN Haisheng, TAN Chunqing,
    2021, 32(24):  2960-2966,2974.  DOI: 10.3969/j.issn.1004-132X.2021.24.008
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     If the sensors of gas turbine fail during operations, and the measurement deviation would seriously affect the accuracy of gas path diagnosis results. In order to solve the above problems, a gas path and sensor coupling fault diagnosis model for gas turbines was proposed. In this model, the measurement variations caused by the changes of working conditions were used instead of the conventional measurements, to reduce the interferences of sensor bias faults. Then, the unscented Kalman filter was adopted to estimate the gas path health parameters by tracking the residual errors between the measured variation and predicted variation caused by different working conditions. Each filter in the sensor diagnosis systems was updated, and the sensor faults were isolated according to the weighted square sum of the residual sequence of the filters. Finally, a simulation example of a typical three-shaft gas turbine was carried out, which shows that the proposed model may reduce the coupling effects between gas path faults and sensor faults, and may realize accurate diagnosis of gas path fault and sensor fault. 
    Prediction of Surface Roughness of Rubber Soft Die End Face Polishing Based on GRA-RSM
    SHI Qiangsheng, ZHANG Xiaojian, CHEN Wei, YANG Zeyuan, YAN Sijie,
    2021, 32(24):  2967-2974.  DOI: 10.3969/j.issn.1004-132X.2021.24.009
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    In order to solve the problems of uneven fitting clearance between rib strip and skin on the composite reinforced siding plates, a rubber soft die should be pasted on the surface of rigid die. The rubber soft die should be polished to eliminate fitting clearance. However, if polishing parameters were not proper, the surface of rubber soft mold was easy to get hairy, and the roughness value was too large, which was easy to absorb polishing dusts. Aiming at the above problems, a set of robot-based polishing and dust removal system was built for end face polishing of rubber materials. The influences of polishing parameters, such as abrasive particle size, polishing rotation speed, polishing pressure and edging distance on the surface roughness were explored. A method was proposed to predict the surface roughness of rubber polishing by robot based on GRA-RSM, which might be used to establish the prediction model of roughness(Ra) of the rubber materials after polishing. The fitting coefficient R2 value of the model is as 0.9878, which indicates that the model fits well. The root mean square error between the predicted value of Ra calculated by the model and the observed value is as 0.014 47, which verify the validity of the prediction model. Based on the prediction model, the parameter combination with the minimum roughness Ra value(3.3 μm) is obtained(polishing rataion speed 4158.9 r/min, polishing pressure 38.4 N, and edging distance 30 mm).
    Research on Hot Stamping-Joining Integrated Process Feasibility of High-strength Steel/CFRP and Sample Bending Performance
    ZHU Bin, LIU Wang, TIAN Feng, LIU Yong, ZHANG Yisheng,
    2021, 32(24):  2975-2980.  DOI: 10.3969/j.issn.1004-132X.2021.24.010
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    A joining and forming integrated process for high-strength steel/CFRP multi-material parts was developed, where the hot stamping technology was used to join the high-strength steel and CFRP prepreg. The preparation processes of multi-material composite parts under different quenching temperatures during hot stamping were studied and microscopic observation of the steel sheets was conducted. Then the three-point bending tests for the multi-material composite parts were carried out. The microscopic observation results show that the microstructure of the steel sheets is full martensite. The three-point bending tests indicate that the bending angles of the samples with no CFRP, with two layers CFRP, and with four layers CFRP are as 130°, 110° and 104°, respectively. Besides, the force-displacement curves of the bending tests were integrated to calculate the energy absorption of the samples. The results show that the energy absorption of the samples with no CFRP, with two layers CFRP, and with four layers CFRP are as 9410 J, 9692 J, and 10050 J. The energy absorption of the samples with two-layer CFRP and the samples with four-layer CFRP increase by 2.9% and 6.8% compared with the samples without CFRP.
    Feedforward Control Technology for Flatness and Sectional Shape of Ultra-high Strength Steel in Six-stand Tandem Cold Mill
    LIU Yaxing, GU Qing, QIAN Cheng, BAI Zhenhua ,
    2021, 32(24):  2981-2988.  DOI: 10.3969/j.issn.1004-132X.2021.24.011
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    In the production processes of ultra-high strength steel in six-stand tandem cold rolling mill, due to the number of stands, complex control processes and insufficient control ability of each stand, the flatness and cross-sectional shape of the finished products were out of tolerance. Based on the prediction model of strip flatness and sectional shape of ultra-high strength steel in cold rolling processes, a feedforward control strategy of strip flatness and sectional shape of ultra-high strength steel in cold rolling processes was analyzed. Then, the method of setting the target flatness curve of each stand was proposed based on the incoming materials, and the feedforward control technology of ultra-high strength flatness and sectional shape of six-stand tandem cold mill was developed. And, the control method was applied to a six-stand tandem cold rolling mill in a steel plant. The control ability of each stand is fully developed, and the flatness of the finished products is 12.5% higher than that before the application of the technology, and the sectional shape distribution is more uniform, which has the values of further promotion and applications.
    Test and Numerical Study for Buckling Performances of Segmented Toroidal Pressure Hulls
    DI Chenyang, ZHANG Jian, WANG Weibo, TANG Wenxian
    2021, 32(24):  2989-2994.  DOI: 10.3969/j.issn.1004-132X.2021.24.012
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    The buckling performances of stainless segmented toroidal pressure hulls were studied under uniform external pressure. The adopted segmented toroidal pressure hulls used was as 70.5 mm, the wall thickness was as 1.319 mm and the circumferential radius of rotation was as 134 mm. Six segmented toroidal models were manufactured and the geometric measurements, hydrostatic external force tests and numerical calculations were carried out. Then, the buckling behaviors of segmented toroidal pressure hulls were analyzed, along with the effects of the segmented angles and ring parameters on the buckling were investigated. The results show that the segmented angle is not influential on the buckling loads of segmented toroidal pressure hulls. The critical buckling load value remains constant and close to that of the connecting elements when the width and thickness of the segmented ring reach a certain threshold value.
    Ultra-thin Diamond Wire Tension Control System Based on Adaptive Backstepping
    ZHOU Feng, ZHENG Lixia, SHEN Yechao, JIN Bo
    2021, 32(24):  2995-3000,3007.  DOI: 10.3969/j.issn.1004-132X.2021.24.013
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    An adaptive backstepping control method was proposed based on the facts that the tension control systems of the multi-wire saw had the control characteristics of strong nonlinearity of Coulomb friction and the swing angle coupling, parametric uncertainties susceptible to diameter changes of the winding reel. The controllers combined with experimental identification method and the adaptive controller design method to simplified analyse multi-axis motor synchronization control system and estimate unknown parameters online, the globally asymptotic stability and boundedness of the control systems was guaranteed by using Lyapunov stability theory. The experimental results indicate that the proposed adaptive controller may achieve multi-axis synchronous control with small swing angle and better tension control accuracy. 
    Research on Dry Etching Processes on PSSs
    HOU Xiang, LIU Yixin, ZHONG Mengjie, LIN Sai, LIU Yang, LUO Ronghuang, LUO Xuetao, ZHANG Sa,
    2021, 32(24):  3001-3007.  DOI: 10.3969/j.issn.1004-132X.2021.24.014
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    In order to shorten the etching time and improve the luminescence performance of the light-emitting diodes(LEDs), the dry etching processes of adding etching auxiliary gas trifluoromethane(CHF3) were studied. The effects of the bias power, the CHF3 flows and the degree of throttle butterfly pendulum auto pressure control valve(abb. APC) on the etch selectivity and the etch rate were investigated by orthogonal experiments during the inductively coupled plasma(ICP) dry etching processs. The experimental results show that the process has higher etch selectivity and etch rate when the bias power, the CHF3 flows and the APC is as 350 W, 15 sccm and 55%, respectively. The PSSs with large size, high pattern-sapphire ratio and small radian were obtained, compared with the conventional PSSs, the height and the pattern-sapphire ratio of optimized PSSs are improved by 5.6% and 4.6%, respectively.
    Analysis of Gear Bending Fatigue Test Based on Hierarchical Bayesian Model
    MAO Tianyu, LIU Huaiju, WANG Baobin, HOU Shengwen, CHEN Difa
    2021, 32(24):  3008-3015,3023.  DOI: 10.3969/j.issn.1004-132X.2021.24.015
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    The conventional gear bending fatigue test data processing method was based on the traditional frequency theory such as the LSE, and the probabilistic-stress-life(P-S-N) curve was prone to fitting distortion under the conditions of small samples. The bending fatigue tests of 8620H steel surface carburized gears were carried out based on the group method. Bayesian theory was applied to the analysis of bending fatigue test data under the conditions of small samples, and the HBM of the gear bending fatigue test data was established. Gibbs sampling was applied to acquire the posterior distribution of the parameters and the gear bending fatigue P-S-N curve. At the same time, the relative slope ratio of the S-N curve at 50% and 99% reliability was used as the evaluation index to compare the fitting effectiveness of the LSE model and the HBM model. The results show that the relative slope ratio α of the HBM model fluctuates with the change of the test sample data volume. The rate of change is 1/40 of that of the traditional LSE model, and the results of the HBM model are better than that of the traditional LSE model under the conditions of a small sample. This model may be extended and applied to data analysis such as gear contact fatigue tests.
    Research on Measurement Technology of Crankshaft Connecting Rod Journals Based on Non-equal Interval Sampling
    GU Tingting, LOU Peihuang, QIAN Xiaoming
    2021, 32(24):  3016-3023.  DOI: 10.3969/j.issn.1004-132X.2021.24.016
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    In order to meet the requirements of high accuracy in the synchronous measurement of the main journals and connecting rod journals of crankshaft measuring machines, a multi-probe measurement method and a Gaussian filtering with non-equal interval sampling were proposed. On the basis of synchronous measurement, a multi-probe measurement method was designed, which might add the measured data to eliminate the harmonics and achieve the goal of separating errors. According to the measuring processes of connecting rod journals, the real sampling angle distribution function was established, and the corresponding Gaussian weight function of each sampling angles was calculated. The weight function and the collected data corresponding to the angle were subjected to discrete cyclic convolution operation in the spatial domain to obtain the filtered effective circular contour data. Finally, the corrected measurement results were compared with the original measurement results. The measurement errors of the four connecting rod journals of the crankshaft is significantly reduced, and the accuracy is significantly improved.