China Mechanical Engineering

Research Progresses of Micro-area Induction Heating Technology in Micro/Nano Systems

WU Dezhi, CHEN Zhuo, HAI Zhenyin, CHEN Liang, YE Kun, WANG Lingyun, ZHAO Libo

2022, 33(01): 2-14，23. DOI: 10.3969/j.issn.1004-132X.2022.01.001

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Micro-area induction heating(MIH), as a localized heating technique with characteristics of non-contact, controllable, and fast thermal-response, was shown numerous potentials in microsystems, such as microelectromechanical systems and microfluidic chips. The fundamentals of MIH were introduced herein, and the research progresses of MIH in the fields of packaging, driving, material growth, et al， was presented systematically. Furthermore, some existing technique problems needed to be solved were analyzed, and several prospective research directions of MIH were pointed out.

Prediction and Experimental Study of Critical Cutting Speed of White Layer Formation in LAT Hardened Steels

XIE Xingjie, ZHANG Xiaojian,

2022, 33(01): 15-23. DOI: 10.3969/j.issn.1004-132X.2022.01.002

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It was easy to produce a white layer on the machined surfaces of hardened steels, which had a serious impact on service performance of parts. To solve the problems of white layer formation, LAT was therefore proposed to replace conventional turning for hardened steels. FEM of thermal-mechanical coupling LAT processes was established by VDFLUX user subroutine. Based on simulation results of FEM and prediction model of critical cutting speed of white layer formation, the influences of different laser preheating parameters on critical cutting speed of white layer formation were analysed. The results show that the upper limit of the critical cutting speed of white layer formation may be increased by appropriately reducing laser power, increasing laser spot radius, and shortening the distance from laser spot to tool tip within the ranges of laser preheating parameters selected, such as laser power P is as 200~600W，laser spot radius R is as 0.5~0.9 mm，distance between laser spot and tool tip L is as 5~15 mm. Under the optimized laser preheating parameters(P=200 W, R=0.9 mm, L=5 mm), the critical cutting speed of white layer formation on the machined surfaces of hardened steels is higher than that of conventional cutting to about 26.09%.

Suppression Effectiveness of NES for Vehicle Body Vertical Vibrations

ZHEN Dong, LI Kun, LIU Xiaoang, ZHANG Jiaqi,

2022, 33(01): 24-33. DOI: 10.3969/j.issn.1004-132X.2022.01.003

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In order to control the vertical vibrations of the vehicle body caused by the excitation of powertrain, 3-DOF vehicle powertrain-body-tire models with cubic stiffness NES and negative stiffness NES on body were established. Based on the complex-averaging method, the slow-varying equations of the two systems were deduced, the saddle-junction bifurcation boundary conditions of the system were studied, and the stability of the equilibrium point was analyzed. Numerical analysis shows that the optimized cubic stiffness NES may effectively reduce the vibrations of the vehicle body at the natural frequency; the negative stiffness nonlinear energy sink has a better damping effect than that of the cubic stiffness nonlinear energy sink.

Synchrosqueezing Algorithm for Window Extension and Compression Optimization and Its Applications in Instantaneous Frequency Estimation under Variable Speed Conditions

WU Hongan, , LYU Yong, , YI Cancan, YUAN Rui,

2022, 33(01): 34-44. DOI: 10.3969/j.issn.1004-132X.2022.01.004

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The fixed window of traditional time-frequency analysis method had the problems of low time-frequency aggregation when analyzing nonlinear frequency modulation signals.The synchrosqueezing theory was introduced on the basis of short-time Fourier transform, and a time-frequency synchrosqueezing transform algorithm for window scaling optimization was proposed by using the local information characteristics of the signals, and the second-order and high-order synchrosqueezing transform algorithms for window scaling optimization were deduced. This method might take into account the advantages of synchrosqueezing transform and reassignment method, and further sharpen the time-frequency ridges, thereby enhancing the energy concentration level of the time-frequency representation and improving the signal time-frequency resolution. In view of the unknown prior knowledge of the signals, the minimum information entropy criterion was used to optimize the window width of the intercepted signals, and the entropy values were used to estimate the time-varying window parameters to determine the optimal window parameters at each moment. The effectiveness of the method was verified through the analysis of the simulated signals and the actual signals.

Phase Change Flow Characteristics of Double-row Spiral Groove Liquid Film Seals

CAO Shengzhao, CHANG Tao, HAO Muming, SUN Xinhui, WANG Zengli, REN Baojie

2022, 33(01): 45-53. DOI: 10.3969/j.issn.1004-132X.2022.01.005

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In order to study the gas-liquid two-phase flow phenomenon of liquid film seals under high-speed and low-temperature working conditions, a phase change model of liquid film seals was constructed based on the theory of homogeneous fluid, and two-phase flow characteristics of the fluid films and effects of operating parameters on phase change were analyzed. The results show that the divergence of the flow spaces is the main factor of the phase change of groove zones. The temperature field changes significantly due to heat absorption and heat dissipation of phase changes. With the increase in speed, the fluid dynamic pressure increases and the temperature rises, the phase change range expands and the phase change rate increases. The increase of the medium temperature weakens the fluid dynamic pressure, and the increase of vapor heat absorption and the decrease of viscosity heat dissipation are the reasons for the fluid cooling on the end surfaces.

Type Synthesis of Uncoupled Two-rotational Parallel Mechanism with One Pure Constraint Branch

ZHANG Yanbin, WANG Keming, LU Fenglin, WEI Xuemin, WANG Kefeng

2022, 33(01): 54-61. DOI: 10.3969/j.issn.1004-132X.2022.01.006

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In order to improve stiffness and loading capability of decoupled parallel mechanisms, a systemic method of type synthesis for the uncoupled two-rotational parallel mechanism with one pure constraint branch was proposed based on branch actuation wrench screw theory. The relationship between motion decoupling and branch actuation wrench of the uncoupled two-rotational parallel mechanism was analyzed, and the action forms of the branch actuation wrench screws were determined. Mapping relationship between input and output motions of the parallel mechanism was studied. According to the characteristic of Jacobian matrix which was a diagonal one, real forms of the actuation wrench screws and actuated twist screws of driving branches were derived. The law determining the non-actuated twist screws was established. As a result, structural synthesis of the driving branches was completed. Finally, type synthesis of the uncoupled two-rotational parallel mechanism with one pure constraint branches was realized and some new parallel mechanisms were obtained.

Road Roughness Recognition Based on Vehicle Body Dynamic Response of Tracked Vehicles

LING Qihui, DAI Juchuan, CHEN Shengzhao, SUN Feiying, WANG Guosheng, LIAO Lili

2022, 33(01): 62-69. DOI: 10.3969/j.issn.1004-132X.2022.01.007

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A model for road surface roughness recognition was established based on dynamic response of tracked vehicle body. NARX neural network structure was adopted in the model, and dynamic response signals of tracked vehicle body were taken as inputs and road surface roughness values were taken as outputs. Correlation coefficient, root mean square error, and absolute error cumulative probability density were proposed as indexes of recognition effectiveness evaluation, and the fusion method of the three indexes was proposed. Based on orthogonal experimental design, the balance between the number of input and the recognition effectiveness of road roughness recognition model was analyzed and realized, which simplified the layout of the sensor test system. The recognition effectiveness of road roughness under different road surfaces, different sampling frequencyies, and different speeds was analyzed. The results show that the proposed model may satisfy the practical engineering needs.

Temperature Distribution of Powder-gas-optical Coupling temperature field in Laser Cladding Processes

XU Mingsan, ZHOU Chunhui, ZHANG Zheng, ZENG Shoujin,

2022, 33(01): 70-77. DOI: 10.3969/j.issn.1004-132X.2022.01.008

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There was a powder-gas-light coupling temperature field before powders reachesd substrate surfaces in laser cladding processes. A 3D numerical model of the powder-gas-light coupling temperature field during the feeding processes was established. Research results of the coupling temperature field show that laser power is the main factor of coupling temperature, and the powder carrier gas is the main factor of coupling temperature field; the coupling temperature field of infrared thermometer is basically consistent with simulated temperature field.

Online Monitoring Method for NC Milling Tool Wear by Digital Twin-drivenLI Congbo

SUN Xin, HOU Xiaobo, ZHAO Xikun, WU Shaoqing

2022, 33(01): 78-87. DOI: 10.3969/j.issn.1004-132X.2022.01.009

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In order to solve the problems of large errors of tool wear prediction model caused by continuous aging of CNC milling machines and difficulties of on-line acquisition of dynamic data during machining, a digital twin-driven online tool wear monitoring method was proposed. Firstly, a neural network was used to extract features from multi-source data in the machining processes, and a quantitative model of tool wear time varying deviation was established considering machine aging. Based on this, an on-line prediction method of tool wear in CNC milling was proposed. Then, a numerical control milling digital twin system for tool wear was developed to online sense the dynamic data and simulate the tool wear processes in real time. Finally, this method was applied to actual machining and compared with other prediction methods. The results show that this method may reduce the prediction errors and realize the accurate prediction of tool wear value.

Quality Prediction of Automotive Parts for Imbalanced Datasets

LI Minbo, DONG Weiwei

2022, 33(01): 88-96. DOI: 10.3969/j.issn.1004-132X.2022.01.010

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In response to the problems of imbalance between quantity of qualified and unqualified automotive parts for the product inspection datasets, a MCDC-MF-SMOTE oversampling method of quality inspection data was proposed based on density clustering and multi-process manufacturing features. Firstly, density clustering was carried out for the minority(unqualified) and the majority(qualified) samples respectively, and then oversampling weight was calculated by multi-process manufacturing data and cluster sample distribution. Data were generated in a few clusters according to oversampling ratio and cluster weights. The MCDC-MF-SMOTE method was used to generate a balanced quality dataset of automotive parts. Random Forest was used to rank feature importance to reduce feature dimension. LightGBM, XGBoost, SVM, and MNB models for Stacking were integration to predict unqualified products. After experiments, this method has higher stability and quality prediction performance. Compared with random sampling, the detection rate of unqualified products is increased by approximately 63%.

Clustering Genetic Algorithm for Multi-objective Integrated Scheduling of AGVs and Machine

ZOU Yuji, SONG Yuchuan, WANG Xinkun, WANG Yi

2022, 33(01): 97-108. DOI: 10.3969/j.issn.1004-132X.2022.01.011

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Aiming at the integrated scheduling problems of AGV and processing equipment and considering the conflict-free path planning of AGV, a scheduling optimization model was established based on the maximum completion time, AGV running time, and total machine load. And a scheduling optimization model was proposed based on time window and Dijkstra's multi-objective adaptive clustering genetic algorithm. According to the characteristics of the algorithm in different iteration periods, a cross-recombination strategy including adaptive individual cross-probability was proposed. Adaptive population mutation probability was designed. An environmental selection strategy was introduced based on the number of grid divisions and the distances of the expanded grid. The simulation results verified the feasibility and superiority of the algorithm.

Modelling and Control Optimization for Underwater Gliders of Variable Buoyancy Processes in Vertical Plane

YAN Sheng, ZHANG Runfeng, YANG Shaoqiong, , NIU Wendong, ZHANG Yuhang, LI Baoyu,

2022, 33(01): 109-117. DOI: 10.3969/j.issn.1004-132X.2022.01.012

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Based on the configuration and control characteristics of Petrel-Ⅱ UG， an accurate dynamics model of UG was established considering the influences of seawater density and pressure at different depths on UG motion. The seawater mass immersed into the front and rear noses of UG was viewed as part of the mass of UG. The model took the variation process of oil of UG as variable mass process， and the influences of seawater depth on the buoyancy as the variable buoyancy process. Besides， the model was numerically simulated for forward and back movements of battery pack as input parameters， and the pitch angles were adopted as output control parameters. Then simulation results were compared with the sea trial data collected in South China Sea. And the results demonstrate the validity of the model herein. Finally， the PID control simulation was conducted with a gliding angle as a control variable based on the model, and the results show that the motion performance of UG may be enhanced by the optimal control strategy.

Research and Verification of Control Parameter Automatic Optimization Calibration Simulation System for Electric Vehicles

GAO Jianping, YU Jiaheng, MENG Yao, XI Jianguo

2022, 33(01): 118-125. DOI: 10.3969/j.issn.1004-132X.2022.01.013

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In order to solve the problems that the control parameters of electric vehicles depended on manual experience and lack of validation for optimization models, firstly, three calibration parameters which had great influences on a comprehensive evaluation index were selected by orthogonal test, secondly, the platform of automatic optimization and calibration system for electric vehicles was developed by Isight, dSPACE, and other tools. An optimization algorithm was used to select parameters and analyze the results automatically. Finally, the optimization model was verified by a bench test. The simulation results show that the comprehensive evaluation index is improved 19.74%, the fuel saving rate is improved 11.95%, and all indexes of power performance are improved after optimization significantly. The simulation results are close to the test ones, which shows the correctness of the proposed automatic optimization calibration simulation system.

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