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    25 July 2022, Volume 33 Issue 14
    Design and Performance Verification of Marine Intelligent Water-lubricated Stern Bearings with Temperature Sensing
    XUE Enchi, GUO Zhiwei, YUAN Chengqing,
    2022, 33(14):  1639-1645.  DOI: 10.3969/j.issn.1004-132X.2022.14.001
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    An innovative design of marine intelligent water-lubricated stern bearings was proposed to assist the tail shaft system for improving operating state monitoring and performance prediction in harsh environments. Based on the micro embedded self-powered monitoring systems and the water-lubricated bearing structures and material designs, some critical performance parameters of water-lubricated bearings in ship sailing were measured and analyzed in real-time, which were used for operating state identification, evaluation, and life prediction. As an example, the internal temperature of bearings was chosen for feasibility verification of the above intelligent water-lubricated tail bearings by CBZ-1 friction and wear tester. The results show that the internal temperature of the bearings may effectively reflect their lubrication and working conditions. Under water lubrication conditions, the initial period heating rate is as 0.1~0.4 ℃/min, the final period heating rate is as 0~0.01 ℃/min, and the temperature during the steady operations is as 29~33 ℃. Under dry friction conditions, the three data are 0.6~1.4 ℃/min, 0.03~0.25 ℃/min and 36~45 ℃, respectively. The huge temperature differences in different lubrication states make it possible to determine the bearing lubrication conditions, which means that temperature monitoring will greatly improve the reliability of water-lubricated bearings.
    Key Geometric Error Analysis and Compensation Method of Five-axis CNC Machine Tools under Workpiece Feature Decomposition
    LU Chengwei, QIAN Bozeng, WANG Huimin, XIANG Sitong
    2022, 33(14):  1646-1653.  DOI: 10.3969/j.issn.1004-132X.2022.14.002
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    A method was proposed to analyze and compensate the key geometric errors of five-axis CNC machine tools under workpiece feature decomposition. The complex workpieces were decomposed by the features, and the key geometric errors were identified and compensated through sensitivity analysis under the workpiece feature decomposition, so as to improve the overall machining accuracy of the workpieces. Taking a complex workpiece as an example, firstly, it was decomposed into four typical features: plane, inclined plane, cylinder and cone-frustum. Then, based on the sensitivity analysis, the key geometric errors corresponding to each typical feature were identified respectively. Finally, error compensation was made by feature decomposition. The experiments were carried out on an AC double-turntable five-axis machine tool, and the experimental results show that the sum proportion of key geometric error sensitivity coefficients obtained by identification are all more than 90%. After compensation, the machining accuracy of the four typical features of the workpiece is improved by 20%~30%. The results show that the proposed method may effectively identify the key geometric errors under different workpiece feature decomposition, thus improving the machining accuracy of complex workpieces.
    Research on Rocking Head Type Piezoelectric Motor with Double Annual Plate for Canard Control
    2022, 33(14):  1654-1660.  DOI: 10.3969/j.issn.1004-132X.2022.14.003
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    Aiming at the compact and direct drive requirements of rudder actuator for guided ammunitions, a hybrid piezoelectric stator with sandwich transducer inducing bending vibration of double annual plate was proposed. A novel rotary piezoelectric motor might be configured by the proposed stator to actuate the canard wings. Four pieces of piezoelectric ceramics were installed in the middle of the sandwich transducer to excite the bending mode of the stator and the output amplitudes were amplified by two annual plates. The rocking head type vibrations of sandwich transducer excited the fifth-order bending mode of the annual plates at both ends and the output amplitudes might be amplified. Two disk rotors were pressed on the driving surface of the hybrid stator and driven to rotate by the friction interface between the stator and rotors. The rocking head type motor with double annual plates was designed for the actuation of canard wings of a guidance system. The structural dynamics model of the hybrid stator was built, and the vibration mode of the stator was calculated by using the finite element method. Then a prototype of the rocking head type piezoelectric motor with double annual plate was produced. Finally, a test platform was built to study the output characteristics of the motor. Under the driving voltage of 300 V, the maximum speed may reach 190 r/min and the maximum output torque may reach 0.07 N·m.
    Effects of Tooth Surfaces of Topographic Profile Errors in Double-sided Grinding on Gear Transmission by Forming Method
    LI Yan, WANG Zhonghou, LIU Lei, DIAO Xinwei, WANG Xuejun
    2022, 33(14):  1661-1669,1679.  DOI: 10.3969/j.issn.1004-132X.2022.14.004
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    The double-sided grinding method of helical gears with additional radial motion had the advantages of small-lot and multi-variety machining and reliable mechanisms, but the unavoidable tooth surface distortion phenomenon occured during machining, resulting in the principle errors between the machined tooth surface and the theoretical tooth surface, and the impacts of this phenomenon on the performance of helical gears were quantified. The error tooth surface model of the double-sided grinding method was calculated numerically, and the error tooth surface was compared with the theoretical tooth surface; the transmission errors and contact spots under different tooth surfaces were calculated by the tooth surface contact analysis (TCA) method. The results show that the distortion of tooth shape has less influences on the performance of the left tooth faces, and the left tooth face may basically achieve the theoretical reshaping effect, while the tooth distortion phenomenon causes significant deterioration of the right tooth face performance; the appropriate reshaping method and shaft intersection angle may reduce the transmission error difference between the left and right tooth faces to about 15%.
    Research on Durability Test Specifications of User-association Drive Axle Test Fields
    ZOU Xihong, LING Long, CHEN Jing, WANG Chao, GOU Linlin, JIANG Mingcong, YUAN Dongmei
    2022, 33(14):  1670-1679.  DOI: 10.3969/j.issn.1004-132X.2022.14.005
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    To realize the correlation between drive axle user and test field durability, a method was proposed to develop test field durability test specifications based on users and test field road measurement data. Based on the collected user torque loads, combined with the gear and speed signals, a model of the Total load (including axle load and tooth load) distribution of the drive axles was predicted under different gears based on the rotational rainflow counting and nonparametric kernel density estimation methods. The multi-objective optimization model of “user-test field” was established by correlating the damage matrix of the coefficients of each characteristic working condition in the test site. The non-dominated sorting genetic algorithm with elitist strategy(NSGA-Ⅱ) was applied to solve the multi-objective optimization model and select the optimal solution by setting constraints based on the actual use of the test site. The validity of the optimized model solution set was verified from the perspective of relative damage and load distribution for loads. The results show that the total mileage of the developed test range test specification is about 46 133.3 km equivalent to 200 000 km of actual driving by users, and the road reinforcement factor is as 4.34. The study provides a reference and basis for more effective development of the drive axle test field durability test specification and reasonable evaluation of the durability and reliability for the whole vehicles and their components. 
    Dimensional Design and Performance Analysis of a 6-DOF Parallel Manipulator with Two Limbs
    XIE Zhijiang, CHENG Qing, DING Jun, HE Miao, FAN Naiji, WU Xiaoyong
    2022, 33(14):  1680-1690.  DOI: 10.3969/j.issn.1004-132X.2022.14.006
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    A novel 6-DOF parallel manipulator was proposed. The manipulator was composed of two kinematic subchains, each subchain contained an active spherical joint. Compared with the conventional 6-DOF parallel manipulators, the reduction of subchains might increase the workspace of manipulator. The closed-loop vector method was presented to determine the inverse position of the proposed manipulator. Then, the velocity mapping relation between the input and output of the manipulator was analyzed and the Jacobian matrix was established. The workspace and global conditioning index were used as performance evaluation indexes, and the dimensional design of the proposed manipulator was completed with the performance atlas method. Based on the dimension parameters, the workspace, dexterity, load capacity and stiffness capacity were comprehensively analyzed under certain posture. Finally, a 3D printing prototype was built, and the practical applications were illustrated.
    Air-bag Tactile Sensor with Pressure and Position Detection Functions
    WANG Ding, WU Deyu, YANG Daliang, CHEN Liting, YE Jinhua, WU Haibin
    2022, 33(14):  1691-1696,1706.  DOI: 10.3969/j.issn.1004-132X.2022.14.007
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    In order to improve the safe interaction between the robot and the external environment, a tactile sensor model for the curved surface of the robot was proposed based on the theory of electric potential distribution on the conductive surface and the closed gas compression law. The sensor might detect contact positions and contact pressures. Three-layer structure was adopted, including conductive layer, compressed gas isolation layer and signal extraction layer. In order to adapt to arbitrary surface shapes and reduce the influences of nonlinear electric potential distribution of conductive layer, a machine learning algorithm was used to reconstruct the electric potential distribution model. The conductive layer of the sensor was modeled and simulated by COMSOL software, and the sensor sample was prepared. Simulation and experimental results show that the proposed tactile sensor may be customized to the curved surfaces of the robot, and may realize the real-time detection of contact positions and contact pressures, which may be used for human-machine information interaction.
    Improved RSSD and Its Applications to Composite Fault Diagnosis of Rolling Bearings
    ZHANG Shoujing, SHEN Mingjun, YANG Jingwen, WU Rui
    2022, 33(14):  1697-1706.  DOI: 10.3969/j.issn.1004-132X.2022.14.008
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    Due to the influences of transmission paths and various interference sources, the individual defect-induced fault features of bearings simultaneously arising from multiple defects were difficult to extract from vibration signals, an improved RSSD method was proposed, which was combined with dual-parameter optimization and subband reconstruction. Firstly, the Q factor of RSSD and the number of decomposition layers were adaptively selected using the artificial fish swarm algorithm to construct the optimal wavelet basis matching the fault features and to obtain the low resonance components containing transient components. Secondly, the optimum sub-band which carried transient feature information, was selected and reconstructed using the proposed subband screening principle. Finally, the periodic impulses of the composite fault signals were identified and extracted by MOMEDA method. The analysis on the simulated signals and the experimental composite fault signals in the bearing life cycle shows that the proposed method may effectively extract each fault feature from the composite fault signals, and accurately realize the composite fault diagnosis compared with RSSD-maximum correlation kurtosis deconvolution(RSSD-MCKD) method.
    Unsupervised Transfer Learning with Residual Convolutional Autoencoder Networks for Bearing Fault Diagnosis
    WEN Jiangtao, ZHANG Pengcheng, SUN Jiedi, LEI Ming
    2022, 33(14):  1707-1716.  DOI: 10.3969/j.issn.1004-132X.2022.14.009
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    Intelligent fault diagnosis was widely studied based on deep learning for rolling bearings, and most researches assumed that the training and test data possessed identical distributions and there were sufficient samples of typical faults. However, considering complicated and variable operating conditions, it was difficult to obtain the real fault samples in large quantities in practical applications. Introducing residual learning into convolutional auto-encoder and combining with transfer learning, the paper proposed an unsupervised domain adaptive transfer learning method based on residual convolutional auto-encoders. Firstly, multiple one-dimensional convolutional auto-encoders were stacked to extract fault features, which adopted residual learning to avoid over-fitting and improved learning efficiency; secondly, integrated multi-layer multi-core probability distribution adaptation to constrain the domain learning of invariant features. Finally, the unsupervised and domain adaptation transfer learning were realized and good diagnosis results were obtained. The effectiveness of the proposed method was verified on bearing datasets from the bearing datasets of Case Western Reserve University. And the effects of the main parameters were discussed and comparisons were also presented.
    Non-contact On-line Inspection Method for Surface Defects of Cross-rolling  Piercing Plugs for Seamless Steel Tubes
    YU Hao, HUANG Huagui, ZHENG Jiali, ZHAO Tielin, ZHOU Xinliang
    2022, 33(14):  1717-1724.  DOI: 10.3969/j.issn.1004-132X.2022.14.010
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    A non-contact measurement method was proposed based on laser scanning, spatial point cloud data processing and depth learning to meet the practical requirements of on-line inspection for the surface defects of cross-rolling piercing plugs for seamless steel tubes. According to the characteristics of seamless steel tube production lines, the detection positions, system structures and data acquisition schemes of plug contours were determined, and the iterative closest point(ICP) registration method was introduced to achieve the registration of the measurement point cloud with the standard CAD model. The corresponding classification number set and gradual shape were designed for the head defects, and the point cloud depth learning method was used to realize the defect accurate classification and quantitative early warning. Aiming at the surface wear defects, the upper threshold of wear depth was set to monitor the wear degree accurately. In order to verify the reliability of the system, a physical simulation platform was built for plug inspection, and a plug model with different defects was customized by using 3D printing technology. The testing results show that the contour inspection errors are less than 0.06 mm, the classification accuracy of head defect may reach 97.7%, and the accuracy degree may reach 98.1%, which meets the requirements of on-line inspection.
    Numerical Analysis and Theoretical Studies of Axial Compression Behavior of A6061 Thin-walled Conical Tubes
    WEI Tieping, ZHOU Xingyang, GUO Jinquan, ZENG Shoujin, YE Jianhua, YANG Xiaoxiang
    2022, 33(14):  1725-1733,1750.  DOI: 10.3969/j.issn.1004-132X.2022.14.011
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    The axial compression simulation of conical tubes, which had cone inclination from 0° to 40° and wall thickness from 1mm to 2.5 mm, LS-DYNA software was applied to study the influences of cone inclination and wall thickness on the energy absorption characteristics and deformation law of conical tubes. In addition, the instantaneous load correction formula for the wide range of the cone inclination angle(15°~40°) was proposed based on the instantaneous load collapse model of Mamalis conical tube. The results show that the critical angle of the deformation mode is 15°, but the deformation mode is in the stacked mode when the cone inclination is less than 15° and it is in the nested mode when the angle is greater than 15°. Moreover, with the increase of the cone angle, the average load and the specific energy absorption decreases gently, while the initial peak load decreases significantly. It should be noted that with the increase of wall thickness, the crushing mode must transform from the diamond mode into the annular symmetry mode while the average load, the initial peak load and the specific energy absorption increase. The simulation results illustrate that the Mamalis instantaneous load formula is modified by the Pearson correlation coefficient analysis method and the maximum error is less than 10% between the modified value and the simulation value, In addition, the accuracy of the modified formula was verified by the experiments. In brief, the correction formula provides a theoretical basis for revealing the mechanism of crushing of thin-walled tubes with large-scale tapered inclination.
    Cracking Suppression and Lateral Bending Broadening Strategy of Fan-shaped Thin-wall Ribs during Extrusion
    HU Futai,
    2022, 33(14):  1734-1740.  DOI: 10.3969/j.issn.1004-132X.2022.14.012
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    Through numerical simulation and physical experiments on extrusion forming mechanism of fan-shaped ribs with large ratio of height to thickness, it is found that the main causes of corner cracking are local deformation disharmony and corner stress concentration. A stress transfer method was proposed, where the local incision was prefabricated in advance at the initial stage of the rib forming, which might effectively change the distribution pattern of tensile stress inside the ribs and reduce the tensile stress at the connection between the rib and the side wall from 120 MPa to 50 MPa or even lower. Experimental and simulation analysis show that the precast incision may release the deformation constraint of the rib itself, the rib deformation with the incision as the central boundary, the left part of the ribs in the plane bending towards left side, the right part of the ribs in the plane bending towards the right side. It is concluded that the length of ribs may be greatly increased by in-plane bending under the action of small tensile stress.
    Design and Steering Angle Control of Steering-by-Wire Hydraulic Systems for Multi-axle Vehicles
    LIU Jun, SHI Chaohuan, LIN Beiqing, HUANG He
    2022, 33(14):  1741-1750.  DOI: 10.3969/j.issn.1004-132X.2022.14.013
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    The angle of the third axle steering wheel under the cargo box and the front steering wheel under the cab of multi-axle vehicles were required to conform to Ackerman principle for reducing rear steering wheel wear. The steering-by-wire hydraulic system was designed and the dynamics model was established based on a certain 8×2 four-axle heavy truck for controlling the steering angle of the third axle steering wheel. The sliding mode controller based on the exponential approach law was simulated in the typical operating conditions, and vehicle experiments were carried out. The experimental results show that the sliding mode controller based on the exponential approach law has faster response, shorter approaching time and overshoot duration, and smaller steady-state difference, compared with the sliding mode controller based on the proportional switching function and open-loop controller. Installation of the steering-by-wire hydraulic system based on the controller may significantly improve the steering wear resistance of the third axle tire, and improve the steering performance of the vehicles, compared with the mechanical hydraulic steering systems.
    Research on Wake Characteristics and Output Characteristics of Umbrella Wind Turbines#br#
    LIU Dong, BAO Daorina, LIU Xujiang, LIU Jiawen, WU Shengsheng, WANG Peng, TANG Di
    2022, 33(14):  1751-1759.  DOI: 10.3969/j.issn.1004-132X.2022.14.014
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     In order to adapt to the harsh application environment of distributed wind turbines,while meeting the needs of power regulation and fan self-protection,a new type of umbrella wind turbine was proposed. In order to study the influences of the umbrella wind turbine wheel contraction angles on the wake characteristics and output characteristics,the numerical simulation and wind tunnel tests were carried out respectively. The results show that when the contraction angles of the wind turbine wheels increase,the swept areas decrease,the wake diameters decrease,the axial influence ranges of the wakes increase,and the speed recovery slows down. At the same time,the strengths of the tip vortex may decrease. The strengths of the central vortex first increase and then decrease. However,the strengths of the central vortex are always greater than those of the tip vortex,so the speed losses behind the blade roots are always greater than those of behind the tips. Besides,the wind tunnel tests also verify the effectiveness of the wind wheel contraction angles on power control.