Table of Content

10 May 2023, Volume 34 Issue 09

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Failure Mechanism on Touchdown Bearings of Heavy Maglev Rotor Drop

LI Zilin, SHI Zhengang, TIE Xiaoyan, YANG Guojun, REN Wenliang, YAO Jiakang, WANG Yuming, WANG Zixi

2023, 34(09):  1009-1018.  DOI: 10.3969/j.issn.1004-132X.2023.09.001

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For the national key R&D program “high-speed precision suspension bearing”, the requirements for the drop capacity of TDBs were: rotor mass ≥3000 kg, drop speed ≥3000 r/min, and successful drops ≥10 times. Based on this, the research and development of TDBs drop failure mechanism were carried out. Two hybrid TDBs with ceramic balls suitable for drop conditions were proposed: full complement ball without cage scheme and non-full complement ball with cage scheme. A rotor drop simulation model was built including dynamics and thermal. The force and heating processes of the drop processes were simulated. The effectiveness of the simulation model was verified by mounting the TDBs in the test bench for experiments. TDBs without cage are found to have failed severely. The damages of the failed bearing are detected, and it is observed that due to the large friction coefficient between the rolling elements, the rolling elements are seized up, resulting in continuous dry friction between the rolling elements and the raceways, and between the inner ring and the rotor, and serious burns and wear of the inner rings.


Research Progresses of Super-hard Abrasive Grain Controllable Arrangement Grinding Wheels

CHEN Bing, GUO YeDENG Zhaohui

2023, 34(09):  1019-1034.  DOI: 10.3969/j.issn.1004-132X.2023.09.002

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In the grinding processes, the distribution and arrangement of the abrasive grains on the grinding wheel affected the form of interaction between the abrasive grains and the workpiece materials, the order of grinding trace distribution and the material removal characteristics, which determined the grinding surfaces, sub-surface quality, grinding forces, et al. Compared with the grinding wheel with random distribution of abrasive grains, the ordered grinding wheel helped to reduce the grinding forces and grinding temperature during processing and improve the life and grinding performance of the grinding tools by reasonably adjusting the positions and distribution modes of abrasive grains on the grinding wheel surfaces, which helped the abrasive grains on the grinding wheel surfaces to have uniform forces and reasonable size of chip holding spaces. At present, the research on super-hard grain ordered grinding wheels was a relatively mature research direction with earlier development and more related theories than that on ordered grinding wheels such as abrasive clusters and structured grinding wheels. The research status of super-hard abrasive ordered arrangement wheel preparation was reviewed herein. Then, the theory and application status of super-hard abrasive wheel with directional arrangement, phyllotactic arrangement and other arrangement were discussed. Finally, the future research directions of super-hard abrasive grain controllable arrangement grinding wheels was discussed.

Research on Path Tracking Control Method of Distributed Drive Electric Vehicles with Integrated Stability

WANG Shu, ZHANG Haichuan, ZHAO Xuan, SONG Hankun

2023, 34(09):  1035-1044.  DOI: 10.3969/j.issn.1004-132X.2023.09.003

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 A path tracking control strategy with integrated vehicle stability was proposed to improve the path tracking precision and vehicle stability of distributed drive electric vehicles under dangerous driving conditions such as high speed and low adhesion conditions. The hierarchical structure path tracking control strategy with vehicle stability, including the path tracking control layer, the stability controller decision layer and the drive wheel torque distribution layer. To solve the problem of the lower accuracy of LQR path tracking controller under high-speed and large curvature conditions, a closed loop PID correction driver model was used to compensate the front wheel angle of the vehicles. In addition, the stability controller was designed to track the ideal reference model of the vehicles. The controller developed the model predictive control algorithm to generate additional yaw moment. Meanwhile, the controller realized the optimal distribution of the wheel drive torques with the objective of minimizing tire load rate. Based on the independently designed distributed drive electric test vehicle, the double lane change tests were carried out on high-speed high adhesion road surfaces and high-speed low adhesion road surfaces respectively. The results show that, when driving on dry concrete pavement at 90 km/h speed, the lateral root mean square errors of the path tracking precision with integrated dynamics stability reduce by 29.7%, compared to the LQR path tracking controller using only closed-loop PID correction for path tracking. When driving on wet asphalt pavement at 70 km/h speed, the lateral root mean square errors reduce by 10.3%. Therefore, the proposed path tracking control strategy with integrated vehicle stability of distributed drive electric vehicles may improve path tracking accuracy, ensuring yaw stability under extreme conditions effectively. 

Research on Far-focused Pixel-based Imaging Method of Defects inside Multilayer Media

DU Wenjie, ZHENG Huifeng, ZHANG Kaisheng, TANG Jiaxuan

2023, 34(09):  1045-1051.  DOI: 10.3969/j.issn.1004-132X.2023.09.004

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To address the problems of unclear imaging and inaccurate positioning of defects in the conventional ultrasonic imaging methods for the detection of defects inside multilayer media, the research of the imaging of defects inside multilayer media was carried out based on the far-focused pixel-based imaging algorithm. The changes of acoustic propagation characteristics caused by multilayer media were analyzed, and the results of acoustic propagation path calculation were compared based on the ray-tracing method and Snells theorem by simulation analysis with the three-layer media model. Through the theoretical derivation, a multilayer medium propagation attenuation model was established to determine the transmission compensation coefficient, diffusion attenuation compensation coefficient and directivity calibration coefficient. The experimental results show that the imaging amplitude of the defect center is improved by 6.3 dB after the attenuation compensation, and the optimized imaging method may achieve the detection of defects inside the multilayer media with the defect localization errors less than 0.4 mm and the dimensional measurement errors less than 0.35 mm2.

Dry Mirror Grinding Technology of Coarse Diamond Grinding Wheel Based on Electrical Discharge Dressing

LU Yanjun, GUAN Weifeng, SUN Jiajing, MO Rui, WU Xiaoyu

2023, 34(09):  1052-1060.  DOI: 10.3969/j.issn.1004-132X.2023.09.005

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 In order to solve the problems of low efficiency and environmental friendliness of ultra-hard diamond grinding wheels, ECD dressing method was used to dress coarse diamond grinding wheels to obtain high micro grain protrusion to realize efficient and precise mirror grinding of high strength and hard materials such as cemented carbide and die steel. The 46# metal-bonded coarse diamond grinding wheels were dressed by mechanical dressing and dry ECD dressing. The dressed diamond grinding wheels were used to dry axial grind cemented carbide and die steels. The influences of grinding parameters on dry grinding force, ground surface roughness and grinding force ratio of cemented carbide under mechanical and dry ECD grinding conditions were compared and analyzed. The experimental results show that the dry axial grinding forces and surface roughness of cemented carbide decrease with the increase of wheel speed, and increase with the increase of feed speed and cutting depth. Compared with mechanical dressing, the dry ECD dressing may achieve higher micro grain protrusion and better ground surface quality, as well as produce little grinding force and grinding force ratio. The dry ground surface roughness Ra of cemented carbide and die steel are as 0.058 μm and 0.022 μm, respectively.

New Definition of Basic Loop Set of Kinematic Chain and Its Generation Method

SUN Liangbo, HONG Xixi, LIU Xiaocui, LIU Xin

2023, 34(09):  1061-1066，1076.  DOI: 10.3969/j.issn.1004-132X.2023.09.006

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Loops were an inherent feature of kinematic chain structures, and most of the existing researches and applications were focused on configuration synthesis, isomorphism determination and rigid sub-chain elimination based on loops. A new definition of basic loop set was proposed, and the dendrogram expression of kinematic chain and related theories were proposed, as well as the basic loop set extraction principles based on the holographic matrix expression of inter-component connection relations and complex hinge determination. The proposed method is simple in rules, easy to implement by computer programmatically, and may obtain the basic loop sets of kinematic chains with complex structures quickly, and the correctness and validity of the above theory were proved by examples.

Two Stage Wiener Modeling and Reliability Analysis Considering Measurement Errors

GAO Xin, YE Nan, ZHOU Kun, TAO Yourui,

2023, 34(09):  1067-1076.  DOI: 10.3969/j.issn.1004-132X.2023.09.007

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In the existing multi-stage Wiener degradation modeling and reliability analysis, most of them ignored the measurement errors and did not consider the differences of change points in the degradation processes. Considering measurement errors， a two-stage Wiener model was established and the maximum likelihood estimation method and multidimensional search algorithm were combined to obtain the estimated values of measurement errors. Considering the differences of change points, the change point interval was estimated based on BIC minimum criterion, at the same time, the estimated values of drift coefficient and diffusion coefficient were determined according to the positions of change points, and then the estimated values of change points were obtained by using SSE minimum criterion. A reliability evaluation method was given based on the distribution interval of change points. Finally, based on the established model, an example of RV reducer transmission accuracy degradation data was analyzed. Considering the uncertainty impacts of measurement errors and change point positions on degradation modeling, the reliability evaluation accuracy of the products is further improved and the life of the products may be predicted more accurately.

Research on Wall Effect of Abrasive Flow Machining

TANG Lubin, WEN Donghui, KONG Fanzhi, YUAN Qiaoling,

2023, 34(09):  1077-1085.  DOI: 10.3969/j.issn.1004-132X.2023.09.008

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Effects of initial surface roughness, inlet flow velocity and hole diameter on flow field pressure, local pressure difference and shear force of cylinder inner wall were simulated by numerical method. Formation processes of flow field velocity and shear force at the cylinder entrance were detected, then over-polishing phenomenon accrued at the entrance of cylinder inner surfaces was deduced according to the abrasive forces action. Effects of all parameters on wall effect during abrasive flow machining was revealed by abrasive flow machining experiments and simulation. Theoretical analysis and experimental results show that, increasing diameter of round hole or reducing inlet flow rate may improve pressure uniformity of abrasive flow field effectively, initial surface roughness has a weak effect on flow field pressure value and the local pressure difference. Sharp transition of wall surface velocity at the entrance causes a sudden change of shear force, then leads to over-polishing phenomenon of abrasive flow machining. Initial surface roughness Ra=0.296 μm is conducive to weakening wall effect of abrasive flow machining and Ra=4.273 μm is conducive to increasing material removal rate.

Optimization of Multi-objective Grinding Process Parameters to Suppress Chatter Marks

LI Guolong, ZHU Guohua, JIANG Lin, TAO Yijie, JIA Yachao

2023, 34(09):  1086-1092.  DOI: 10.3969/j.issn.1004-132X.2023.09.009

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Aiming at the problems of chatter marks frequently occurring in gear grinding with worm-shaped grinding wheel, the effects of grinding process parameters (linear speed of grinding wheel, axial feed speed of abrasive wheel, radial feed of grinding wheel) on machining vibrations and tooth surface roughness were investigated by orthogonal design experiments of helical gears used in a certain type of new energy vehicles. A multi-objective optimization mathematical model was established with multiple quadratic regression method to reduce vibrations and tooth surface roughness, and genetic algorithm was used to optimize grinding parameters. The results show that the optimized processing parameters may greatly reduce the vibrations in grinding while maintaining the stable roughness value of tooth surfaces, effectively prevent the generation of chatter marks and prolong the working life of the machine tools.

Adaptive Fractional Order Sliding Mode Control for PMSMs Based on NDO

ZHAO Ximei, WANG Chao, JIN Hongyan

2023, 34(09):  1093-1099,1119.  DOI: 10.3969/j.issn.1004-132X.2023.09.010

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The feed system of CNC machines driven by PMSM servo system was susceptible to parameters variation, external disturbances and other uncertain factors, an AFOSMC scheme was designed based on NDO. First, the dynamic mathematical model of PMSM with uncertainties was established. Then, FOSMC and adaptive control were combined to suppress the chattering phenomenon of integer order sliding mode control, and the switching gain might be adjusted in real time to improve the control accuracy of the system. However, external disturbances would have a great impact on the system. Therefore, NDO was used to identify the external disturbances in real time, and the observed values were introduced into AFOSMC as feedforward compensation to improve the anti-interference ability of the controller. Finally, the experimental results show that the designed AFOSMC may weaken the chattering phenomenon effectively based on NDO, improve tracking performance and anti-interference ability of the feed systems.

Research on Underwater Gliders Path Tracking Based on Reinforcement Learning Algorithm

SHI Qingqing, ZHANG Runfeng, ZHANG Lianhong, , LAN Shiquan,

2023, 34(09):  1100-1110.  DOI: 10.3969/j.issn.1004-132X.2023.09.011

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Aiming at the large deviations between the actual paths and the predetermined ones of underwater gliders affected by ocean current, a neural network ocean current prediction model with long-term and short-term memory and attention mechanism was established based on the traditional long-term and short-term memory network model.The dynamic Q-table of underwater glider motions was generated by depth neural network, and the optimal motion attitude was selected by reinforcement learning algorithm. Considering the influences of ocean current, an underwater glider path tracking algorithm was constructed based on depth reinforcement learning. The results show that the long-term and short-term memory network based on attention mechanism has less mean square errors and root mean square errors in ocean current prediction than that of the traditional integrated moving average autoregressive model and long-term and short-term memory network.Compared with the traditional PID control, the deep reinforcement learning model may reduce the root mean square errors of the underwater glider trajectory by 50.9%, and significantly improve the path tracking accuracy.

Design and Experiments of Special Rim Assembly for Intelligent Tire Development Platform

TAO Liang, ZHANG Dashan, ZHANG Xiaolong, PAN Deng, ZHAN Qingliang

2023, 34(09):  1111-1119.  DOI: 10.3969/j.issn.1004-132X.2023.09.012

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The paper focused on the design and experimental study of the special rim assembly, which consisted of the special rim, the elastomer and the special slip ring. Firstly, the functions of the intelligent tire development platform and the design requirements for the special rim assembly were clarified, and the structural design was carried out according to the requirements of air tightness, dynamic balance, safety, et al. Then, the finite element model of the special rim assembly was constructed based on ABAQUS software. A passenger car steering emergency braking condition was simulated and two times of the front wheel load was setup into the model. The strength and stiffness of the special rim met the design requirements. Finally, the 7075 aerospace aluminum alloy ingot materials were used for the overall processing of the special rim, and verification tests such as air tightness, dynamic balance and signal transmission were conducted. The tire pressure of the special rim assembly is set to 0.24 MPa and left for 5 days, but the tire pressure droppes only about 0.8%, so the air tightness is great. The special rim assembly was mounted on the Flat-trac bench for testing at different speeds, and the images of the slip ring stator end motion and the in-tire sensor output signals were collected simultaneously. The image sub-pixel matching method was used to obtain the displacement of the stator end of the slip ring. When the vehicle speed is as 50 km/h, the displacement is about 0.5712 mm, which meets the test requirements of the rim dynamic balance and slip ring. At different test speeds, the signals from multiple sensors inside the tire are output steadily through the special rim assembly, and the signals may effectively characterize the tire-road contact characteristics. The special rim assembly designed herein meets the requirements for building an intelligent tire development platform and provides an effective means to research on the tire-road contact mechanism.

Measurement Method of Cabin Automatic Docking Based on 2D Laser Displacement Sensor

SUN Luping, ZHANG Wenchang, WANG Zhihua, WANG Zhenwen, REN Zhimo, ZHANG Qian,

2023, 34(09):  1120-1125,1133.  DOI: 10.3969/j.issn.1004-132X.2023.09.013

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In view of the docking and assembly requirements of the cabins, a method for automatic docking measurement was proposed based on 2D laser displacement sensor in combination with the docking processes of the cabins. The displacement sensors detected the 2D contour deviation of the three points at the docking points of the two cabins, and calculated the pose of the cabins to be docked with 5 degrees of freedom except for the rotation angle; The positions of the flange gap in the cabins were calculated to obtain the rotation angle of the cabins to be docked. Finally, the results are fed back to the control system to drive the actuator to adjust the pose. The proposed method was verified by introducing error simulation and combining with docking experiments. The results show that the automatic docking method has high measurement accuracy and good docking effectiveness, which may meet the needs of cabin automatic docking, and improve the efficiency and stability of the automatic docking systems effectively.

Study on Engagement Characteristics of Gear Overrunning Clutch of Aquatic-aerial Amphibious Propellers

XU Long, HU Zhiqiang, YANG Yi, WANG Chao,

2023, 34(09):  1126-1133.  DOI: 10.3969/j.issn.1004-132X.2023.09.014

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 Based on the application requirements of aquatic-aerial amphibious propellers for the clutch, a gear overrunning clutch was designed. The engagement characteristics of clutch under different structure parameters were optimized for analysis through simulation. The effects of end face chamfer and displacement coefficient of gear tooth on engagement processes, disengagement speed and contact impact force were discussed. The simulation results show that increase of the angle of end face chamfer and displacement coefficient may accelerate engagement and disengagement speed and reduce contact impact force. When the number of chamfers and the coefficient of displacement are as 44° and 0.84 respectively, the engagement characteristics are optimal. If they continue to increase, the engagement and disengagement speed becomes slower and the contact impact force becomes larger. Finally, the gear tooth structure parameters with the optimal engagement characteristic index are obtained, and the correctness and validity of the simulation analysis results were verified by experiments. And the relative errors of the engagement characteristic index of simulation and experiments are less than 10%. The effectiveness of the optimized design process is proven, and the design results meet the requirements for the use of the propellers.