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Development Status and Prospect of Key Rail Grinding Equipment and Technology of Grinding Stone ZHANG Wulin, FANXiaoqiang, ZHU Minhao, DUAN Haitao China Mechanical Engineering    2022, 33 (19): 2269-2287.   DOI: 10.3969/j.issn.1004-132X.2022.19.001 Abstract （376）      PDF （17216KB）（536）       Knowledge map    Save  The rail grinding strategies and techniques were reviewed， and the key equipment of the grinding methods using grinding wheels（active grinding and high-speed passive grinding）and the milling and grinding compound process were summarized. Meanwhile， the research status of rail grinding stone（grinding wheel， equipped with rail grinding train and used for cutting tools）were reviewed from ingredients， forming processes， structural design and grinding performance evaluation criterions， etc. It was concluded that the fine formula design, scientific evaluation criterions, etc. were the main challenges for the development of high-performance grinding stones. Finally， it was pointed out that the greenization， standardization， and intelligence were the important directions for future development of grinding stone technology.  Reference | Related Articles | Metrics

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Development of Gear Measurement Technology during Last 20 Years SHI Zhaoyao, YU Bo, SONG Huixu, WANG Xiaoyi China Mechanical Engineering    2022, 33 (09): 1009-1024.   DOI: 10.3969/j.issn.1004-132X.2022.09.001 Abstract （316）      PDF （72652KB）（415）       Knowledge map    Save There were two forces that promoted the development of gear measurement technology. One was the continuous new requirements for gear measurement put forward by industrial development, and the other was the penetration of continuously improving related technologies in the field of gear measurement. Since the 21st century, the convergence of these two forces promoted the rapid development of gear measurement technology. Based on a brief review of the evolution of gear accuracy theory and gear measurement technology in the 20th century, the basic framework of gear generalized accuracy theory was put forward. The gear measurement technology during the last 20 years was systematically summarized from the aspects of gear full-information measurement technology, in-site rapid gear sorting and detection technology, extreme measurement technology for extra-large gears and micro gears, high-precision gear artifacts and traceability, etc. There is more than 100 years since the beginning of gear precision measurement, and it is currently in the critical stage of the transition from the 3rd generation to the next-generation of gear measurement. The overall technical concept of next-generation of gear measurement was presented, the basic theory and key technical problems that must be overcome were listed for realizing the next-generation of gear measurement, and the research focus and scientific issues of gear measurement in the next 10 years were prospected. Reference | Related Articles | Metrics

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Research Progresses on Surface Integrity of Bearing Grooves WANG Dongfeng, YUAN Julong, WANG Yanshuang, CHENG Yongjie, LYU Binghai China Mechanical Engineering    2022, 33 (18): 2143-2160.   DOI: 10.3969/j.issn.1004-132X.2022.18.001 Abstract （268）      PDF （5702KB）（201）       Knowledge map    Save Improving the surface integrity of bearing grooves was an important solution to solve technical problems such as low reliability life, high friction power consumption and unstable vibrations and noises of bearings. On the basis of comprehensive research of generalized surface integrity by domestic and foreign scholars, the definition and connotation of characteristic parameters of bearing groove surface integrity were proposed, and the significance of characteristic parameters and the influence mechanism on bearing performance were expounded. The influences of different processing processes such as forging, turning, heat treatment, grinding and ultra-precision on the surface characteristic parameters of bearing raceways were analyzed in details, and the corresponding control measures were given. The new technologies, new processes, and new methods for improving surface integrity were briefly introduced. Finally, the summary and prospect of improving the surface integrity of bearing grooves were made to provide some references for improving the contact fatigue lifes of bearings. Reference | Related Articles | Metrics

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Navigation Trajectory Prediction Method of Inland Ships Based on Multi-model Fusion ZHANG Yang, GAO Shu, HE Wei, CAI Jing China Mechanical Engineering    2022, 33 (10): 1142-1152.   DOI: 10.3969/j.issn.1004-132X.2022.10.002 Abstract （265）      PDF （2807KB）（103）       Knowledge map    Save  Inland waterway navigation was an important part of the modern comprehensive transportation systems. The real-time and high-precision ship trajectory prediction method was helpful to effectively avoid water traffic accidents and enhance the ability of automation and intelligent supervision. Aiming at the problems that the accuracy of the existing inland ship trajectory prediction was not high， in order to improve the short-term prediction accuracy of ship trajectory， comprehensively using the recent AIS (automatic identification system) data and historical AIS data of the ships， and based on the relationship among trajectory and speed， course， and the characteristics of inland waterway， the temporal convolutional network model for speed and course prediction， ship trajectory dynamics equation model and adaptive double-hidden layer RBF network were constructed. The ship trajectory prediction method based on multi-model fusion was proposed. Experimental results show that the proposed method has obvious improvement in trajectory prediction accuracy and may meet the real-time requirements.  Reference | Related Articles | Metrics

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Hydrodynamic Force Calculation Method of Tracked Equipment Based on Artificial Lateral Line#br# WU Jiaxiong, SHEN Yanhua , YANG Shudi, FENG Zhipeng China Mechanical Engineering    2022, 33 (10): 1135-1141.   DOI: 10.3969/j.issn.1004-132X.2022.10.001 Abstract （262）      PDF （7590KB）（294）       Knowledge map    Save  Aiming at the challenge that the hydrodynamic forces of underwater equipment could not be measured in real time， a method for calculating the hydrodynamic forces of track equipment was proposed based on ALL. Through the ALL system of the track equipment， the pressure values of different incoming flow speeds and angles were extracted， and the distribution law of pressure values was used to perceive the local flow field information of the track equipment. Through the hydrodynamic force restraint experiments of the track equipment combined with the computational fluid dynamics（CFD）simulation method， the functional relationship between the front surface shapes of the track equipment and the viscous coefficient was established. Based on the flow field perception results of the ALL， the hydrodynamic force empirical model of the track equipment was derived. The verification results show that the pressure distribution characteristics of the ALL may effectively identify the incoming flow velocity and angle. The hydrodynamic force empirical model combined with the results of ALL perception may be used to estimate the hydrodynamic force of underwater track equipment in real time， the water resistance calculation error of underwater track equipment model is within the acceptable range of the engineering application.  Reference | Related Articles | Metrics

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Progresses of Surface Engineering in Extreme Environments and Its Common Scientific Problems CHANG Keke, CHEN Leilei, ZHOU Ruonan, XIAO Xuelian, WANG Fangming, WANG Liping China Mechanical Engineering    2022, 33 (12): 1388-1417.   DOI: 10.3969/j.issn.1004-132X.2022.12.001 Abstract （255）      PDF （51339KB）（288）       Knowledge map    Save The strong coupling effects from multi factors in the typical extreme environments of “three depths and one pole” (deep space, deep sea, deep earth and polar) led to the coexistence of multimode damages and failures, such as material corrosion, wear, fatigue, and fracture， which bringed severe challenges to the high precision, high reliability, and ultralong service life of mechanical systems. Surface engineering technology was one of the most effective ways of surface strengthening and life extension. The researches of relevant methods and basic scientific problems were important supports for structural optimization and material designs of highsafety and highreliability mechanical engineering equipment in extreme environments. The general methods of surface engineering technology and their applications in the fields related to extreme environments were introduced, the common basic scientific problems of surface engineering in extreme environments were analysed, focused on the implements of theoretical calculation methods in solving problems, and the development directions of surface engineering in extreme environments were commented. Reference | Related Articles | Metrics

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Design and Performance Verification of Marine Intelligent Water-lubricated Stern Bearings with Temperature Sensing XUE Enchi, GUO Zhiwei, YUAN Chengqing, China Mechanical Engineering    2022, 33 (14): 1639-1645.   DOI: 10.3969/j.issn.1004-132X.2022.14.001 Abstract （243）      PDF （3728KB）（137）       Knowledge map    Save 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. Reference | Related Articles | Metrics

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A New Method for Optimal Distribution of Kinematic Accuracy of Mechanical Transmission Systems LI Jian, RAN Yan, ZHANG Genbao, WANG Yongqin China Mechanical Engineering    2022, 33 (09): 1034-1043.   DOI: 10.3969/j.issn.1004-132X.2022.09.003 Abstract （236）      PDF （2446KB）（145）       Knowledge map    Save In order to distribute the kinematic accuracy of mechanical transmission system reasonably, a new method for optimal distribution of kinematic accuracy of mechanical transmission system was proposed with the meta-action theory. Firstly, the “function-kinematic-action” structural decomposition tree was used to decompose the mechanical system, and then the basic meta-action and meta-action chain were obtained. Secondly, taking the meta-action chain as research object, the formation mechanism of kinematic accuracy was analyzed, and the kinematic error transfer model was established. Considering cost factors and sensitivity factor of kinematic errors, cost function and robustness function were established. Then the optimal distribution model of the kinematic accuracy of the meta-action chain was established, and the kinematic errors of the meta-action were obtained. An engineering example proved the effectiveness of the method. Reference | Related Articles | Metrics

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Research Progresses of Modeling and Optimization Methods for Multi Domain Behavior Processes of Human-Machine Environmental Systems#br# DONG Yuanfa, ZHANG Wenli, XIAO Renbin, TIAN Qihua, DU Xuan, China Mechanical Engineering    2022, 33 (08): 929-942.   DOI: 10.3969/j.issn.1004-132X.2022.08.007 Abstract （223）      PDF （1784KB）（171）       Knowledge map    Save  Due to the immaturity of intelligent technology in universality， robustness and security， intelligent interactive products were prone to “behavior conflict” due to the mismatch with user behavior patterns in intention expression， information processing， decision logic， interaction timing and action intensity. Unified modeling and optimization of multi domain behavior processes of human-machine environmental systems were the key to realize behavior characteristic regulation and forward design of intelligent interactive products. This paper systematically reviewed the research progresses of multi domain behavior process representation model， modeling language and tool， model validation and behavior process optimization of human-machine environmental systems from four dimensions：how to represent， what to represent， how to verify and how to optimize. The existing problems and limitations in this field were analyzed， and the future research focus and development trend were prospected.  Reference | Related Articles | Metrics

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Design of Soft Robots for Hand Function Rehabilitation Training CONG Ming, BI Cong, WANG Minghao, LIU Dong, DU Yu China Mechanical Engineering    2022, 33 (08): 883-889.   DOI: 10.3969/j.issn.1004-132X.2022.08.001 Abstract （216）      PDF （7250KB）（129）       Knowledge map    Save In order to solve the problems such as poor fit between soft robot and human hand， insufficient DOF and low driving force， a kind of soft robot with bi-directional bending module and elongation module was designed， which might realize independent or coupled motions of multiple DOF. Using FEM analysis， a soft driver model was established and a variety of flexible materials were fused to ensure that might provide sufficient driving forces. The sensors were used to track the bending characteristics. Experimental results verify that the soft robots may complete grip training and gesture training， etc.， and meet the training requirements of patients at different rehabilitation stages. The fingertip force may reach 5.1 N， and it may play an auxiliary role in the daily hand rehabilitation training of patients.  Reference | Related Articles | Metrics

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China Mechanical Engineering    2022, 33 (12): 1-.   Abstract （216）      PDF （181211KB）（506）       Knowledge map    Save Related Articles | Metrics

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Research and Applications of Condition Monitoring and Predictive Maintenance of Marine Diesel Engines CHEN Dongmei, ZHAO Siheng, WEI Chengyin, CHEN Yajie China Mechanical Engineering    2022, 33 (10): 1162-1168.   DOI: 10.3969/j.issn.1004-132X.2022.10.004 Abstract （212）      PDF （3080KB）（318）       Knowledge map    Save Based on the four dimensions of thermal-pressure parameters， lubricant oil conditions， vibrations and cylinder pressures， data acquisition and feature extraction were carried out， and a method for diesel engine condition monitoring was proposed based on OCSVM anomaly detection algorithm and Fisher discriminant analysis.  The CUSUMMR was used for parameter trend detection and the D-S evidence theory and weight of evidence method were used for multi-source information fusion. the RUL(remaining useful life) of diesel engine lubricating oil was predicted by LSTM. The Paper solves the problems such as low early warning rate， poor adaptability of the model under diesel engine dynamic conditions.  Reference | Related Articles | Metrics

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Effects of Laser Cladding Process Parameters on Microstructure and Residual Stresses of Fe-based Double Layer Coatings ZHOU Jiali, CHENG Yanhai, CHEN Yongxiong, LIANG Xiubing, BAI Chengjie, DU Wang China Mechanical Engineering    2022, 33 (12): 1418-1426，1434.   DOI: 10.3969/j.issn.1004-132X.2022.12.002 Abstract （209）      PDF （13411KB）（260）       Knowledge map    Save  Aiming at the problems that the components had high crack sensitivity due to the intense temperature field changes accompanied by stress and strain evolution in laser cladding processes. The evolution of residual stresses under different laser scanning paths and processing parameters was studied. Fe-based multilayer coatings were prepared by laser cladding on Q345 steels. The residual stress distribution along the coating depth was measured by X-ray diffraction method combined with electrochemical corrosion stripping method. The effects of laser scanning path, power and scanning speed on the microstructure and stress distribution of the coatings were investigated. The results show that the residual compressive stress occurs on the surface and inside of the coatings, the residual stresses changes at the coating-substrate fusion line, and the heat-affected zones are of the residual tensile stress. Laser cladding processes have significant influences on the size and distribution of residual stresses for coatings. When laser scanning path is contour bias, power is as 1.8 kW and scanning speed is as 0.02 m/s, the coatings have the best residual stress distribution and forming quality. The residual stress is mainly related to the impacts of laser beams on the molten pool and the non-equilibrium solidification characteristics of the cladding layers. Reference | Related Articles | Metrics

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Applications of Microfluidic Technology in Cross-domain of Mechanical Engineering and Life Science MAN Jia, HUA Zesheng, XIA He, LI Jianyong, LI Fangyi, LI Jianfeng, China Mechanical Engineering    2022, 33 (15): 1857-1868.   DOI: 10.3969/j.issn.1004-132X.2022.15.012 Abstract （209）      PDF （9998KB）（42）       Knowledge map    Save Taking microfluidic technology as the research object， the preparation materials and technology of microfluidic chips were introduced， and the applications of microfluidic chip technology in the cross fields of life science were emphasized. It was mainly introduced from three aspects：biological detection， bionic fabrication of in vitro structure and preparation of controllable drug carriers， and the key technologies involved were discussed from the aspects of chip structure design and preparation， functional module integration， process regulation and so on. The application prospect of microfluidic technology in the fields of cross-domain between mechanical engineering and life science was prospected.  Reference | Related Articles | Metrics

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Metal Defect Image Recognition Method Based on Shallow CNN Fusion Transformer TANG Donglin, YANG Zhou, CHENG Heng, LIU Mingxuan, ZHOU Li, DING Chao China Mechanical Engineering    2022, 33 (19): 2298-2305，2316.   DOI: 10.3969/j.issn.1004-132X.2022.19.003 Abstract （209）      PDF （8847KB）（120）       Knowledge map    Save Aiming at the problems of large amount of parameters and calculation in the field of metal defect recognition， a metal defect recognition method was proposed based on shallow CNN and Transformer model. The shallow CNN was used to learn the local information and position information of the images， and the Transformer was used to learn the global information of the images. At the same time， the channel attention module SE was introduced to pay attention to the important feature channels to realize the defect image recognition. The effectiveness of this method was verified by introducing the open defect data set， and the universality of this method was verified by using the self-built defect ultrasonic data set. The experimental results show that the proposed method has strong universality and may effectively identify metal defect images on small and medium-sized data sets.  Reference | Related Articles | Metrics

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Scale Optimization of Humanoid Robotic Arms Based on Kinematic Performance Analysis SUN Peng, LI Yanbiao, ZHANG Cong, SHAN Xiaohang, YUE Yi, WEI Baochen China Mechanical Engineering    2022, 33 (19): 2331-2340.   DOI: 10.3969/j.issn.1004-132X.2022.19.007 Abstract （193）      PDF （10626KB）（290）       Knowledge map    Save  Aiming at the problems that the coupling effect of multi-joint series mechanisms on the kinematic performance of the end-effector， the kinematic characteristics of series-parallel hybrid mechanisms were analyzed， and a multi-parameter plane model was proposed to realize visualized design. Based on screw theory， the kinematics transfer matrices of serial and parallel joints were established respectively， and the corresponding performance indexes were set up. According to the multi-parameter plane model， the coupling relationship among parameter scale， orientation workspace， and performance indexes were further revealed through a three-dimensional visualization graphics. Finally， the values of parameters， the range of high-quality orientation workspace， and the distribution of indexes were confirmed. The results show that the global performance indexes of the shoulder and wrist joints are as 0.78 and 0.67， respectively， and the global condition number of the elbow joint is as 2.38. The hybrid configuration has functions similar to that of the human arm joints， and gives full play to the comprehensive advantages of series and parallel mechanisms.  Reference | Related Articles | Metrics

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Core-problem Oriented System Cause Identification Method and Innovative Design Research  YANG Guang, LI Wenqiang, WAN Changfu, China Mechanical Engineering    2022, 33 (15): 1810-1820.   DOI: 10.3969/j.issn.1004-132X.2022.15.007 Abstract （193）      PDF （6499KB）（57）       Knowledge map    Save  Aiming at the facts that traditional innovative design methods might only solve one pair of conflicts when solving multi-conflict problems, a core problem-oriented system cause identification method was proposed, which might solve multi-conflict problems. The conflict relationship in product design was obtained through the house of quality and the core problems were selected. The root cause analysis method was used to obtain the system causes of each core problems, and the relationship network diagram between the core problems and the system causes was established. The best worst method was used to obtain the importance degree of each system causes and carry out innovative design in order of importance. The solution of the system causes may realize the solution of multi-conflict problems. Moreover, the design of floating plate vibration isolator is taken as an example to verify the feasibility and effectiveness of this method. Reference | Related Articles | Metrics

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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 China Mechanical Engineering    2022, 33 (14): 1646-1653.   DOI: 10.3969/j.issn.1004-132X.2022.14.002 Abstract （192）      PDF （5495KB）（181）       Knowledge map    Save 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. Reference | Related Articles | Metrics

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Influence Law and Mechanism of Texturized Controllable Interfaces on Leakage of Steam Turbine Regulating Valves LIAO Yihong, ZHANG Guiming, XU Jing China Mechanical Engineering    2022, 33 (12): 1427-1434.   DOI: 10.3969/j.issn.1004-132X.2022.12.003 Abstract （190）      PDF （5452KB）（85）       Knowledge map    Save Based on the theory of fluid lubrication, the pressure distribution and leakage of steam turbine control valves were calculated by finite element method, the influence law of textured controllable interface on the leakage of the control valves was analyzed, the action mechanism of textured control valves was clarified, and the interface regulation was realized. The results show that the designed hydrophilic and hydrophobic textures meet the expected wettability, the hydrodynamic lubrication of micro pits is poor. The dynamic pressure balance texture has dynamic pressure wedge effect and obvious eddy currents, which may effectively improve the hydrodynamic lubrication of clearances between valve stem and valve sleeve. However, the dynamic pressure balance texture increases the connecting area of upper and lower walls, which is not conducive to sealing. The influences of leakage reduction rates of texture from large to small is hydrophobic texture, combined texture, hydrophilic texture and dynamic pressure balance texture. When the pressures on the regulating valves exceed 3.5 MPa, the leakage reduction rate changes gently. Hydrodynamic lubrication, sealing dam effect and the synergy of eddy current energy exchange and energy dissipation in the grooves make the combined texture superior to other textures in improving the stability of valve stems and reducing leakages. Reference | Related Articles | Metrics

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Industrial Engineering and Lean Management for Smart Manufacturing QI Ershi, HUO Yanfang, LIU Hongwei China Mechanical Engineering    2022, 33 (21): 2521-2530.   DOI: 10.3969/j.issn.1004-132X.2022.21.001 Abstract （187）      PDF （4622KB）（153）       Knowledge map    Save This paper reviewed the development routes of developed countries such as the United States， Japan， and Germany since the emergence of industrial engineering for more than 100 years， discussed the regular characteristics of enterprise management innovation， and drew the conclusion that smart manufacturing also needed IE/LM to provide management support. According to the smart manufacturing project cycle， the functions of IE/LM in smart manufacturing engineering were analyzed from the perspectives of basic preparation， scheme selection， and integration development. The framework of lean smart management system for smart manufacturing transformation of Chinese enterprises was given， and the improvement ideas and methods of smart-lean integration were explained based on a case. Finally， some key technologies of smart manufacturing management facing transformation and upgrading of Chinese enterprises were presented based on the actual needs of China.  Reference | Related Articles | Metrics

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Adaptive Control Research and Quantitative Evaluation of Resistance Spot Welding Expulsion Based on Electrode Displacement LI Huan, LYU Tianle, XIA Yujun, LI Yongbing China Mechanical Engineering    2022, 33 (09): 1025-1033.   DOI: 10.3969/j.issn.1004-132X.2022.09.002 Abstract （185）      PDF （8186KB）（82）       Knowledge map    Save Expulsion was a common problem in resistance spot welding, which seriously affected the welding quality. Aiming at the typical abnormal conditions, through the quantitative analysis of expulsion metals and expulsion sudden stop experiments, it is shown a strong linear correlation between the sudden of electrode displacement signal and the total mass of expulsion metals is found, and the sudden of electrode displacement signals is basically the same as the reduction of nugget thickness before and after expulsions. Therefore, the sudden of electrode displacement signals may characterize the degree of expulsion. Based on this, the adaptive control strategy of spot welding expulsion was proposed based on quantitative statistics. The fuzzy control strategy was formulated with expulsion degree and expulsion probability as inputs and current amplitude modulation parameters such as amplitude modulation coefficient, amplitude modulation time and amplitude modulation duration time as outputs. The time compensation parameters such as time compensation length and time compensation current were determined according to the time compensation strategy of constant energy and constant power. The effectiveness of the strategy was verified by using two kinds of strength sheets. Experimental results show that compared with constant current welding, the method herein may effectively suppress expulsion, reduce indentation depth and increase nugget diameter. Compared with the traditional short-time current amplitude modulation strategy, the method reduces the number of amplitude modulation and the time of time compensation, and effectively improves the welding efficiency. Reference | Related Articles | Metrics

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Dimensional Parameter Optimization of Planar Closed-loop Legged Mechanisms WANG Xianye, LIU Haitao, HUANG Tian China Mechanical Engineering    2022, 33 (11): 1261-1268.   DOI: 10.3969/j.issn.1004-132X.2022.11.001 Abstract （184）      PDF （6330KB）（167）       Knowledge map    Save Aiming at the foot trajectory outputs by Theo Jansens linkages, the dimensional parameters of a novel planar closed-loop legged mechanism were optimized. The kinematic models of the mechanism were derived using the Assur groups methods. According to the structural characteristics, the number of design variables was reduced to one by using the position limitation of a crank-rocker mechanism. A single-objective optimization problem was established by minimizing the minimal deviation of the foot trajectories of two mechanisms subjected to the geometric constraints of the dimensional parameters. This problem was solved by the one-dimensional search method, leading to the design and fabrication of an eight-leg mobile robot. The feasibility of the design was verified by experimental results. Reference | Related Articles | Metrics

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Reliability Analysis of Machining Accuracy and Processing Parameter Optimization for Thin-plate Parts YI Qian, LI Congbo, PAN Jian, ZHANG You China Mechanical Engineering    2022, 33 (11): 1269-1277.   DOI: 10.3969/j.issn.1004-132X.2022.11.002 Abstract （183）      PDF （5621KB）（113）       Knowledge map    Save To address the problems of low machining accuracy caused by cutting deformations during the machining processes of the thin-plate parts, a machining deformation prediction model was established by using the finite element method and Gaussian process regression algorithm. Then, the workpiece processing deformations and machine tool motion errors were considered comprehensively to analyze the reliability of the thin-plate machining accuracy. A milling process parameter optimization design model was established with machining efficiency and average machining deformation as the goal, and the machining accuracy reliability as the constraint. The multi-objective optimization algorithm was used to solve the model, determining the optimal combination of processing parameters for coordinated processing efficiency and processing deformations. The case study indicates that after the optimized design, the minimum machining accuracy reliability reaches 98.21%, the average machining deformations are reduced by 21.14%, and the machining efficiency is increased by 4.18%. A feasible method is provided for the selection of milling process parameters for thin plate parts. Reference | Related Articles | Metrics

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Drag Torque Algorithm of Wet DCT and Its ApplicationsLIU Bo ZHANG Xingui, SHI Xinglei, YU Zilin, ZHONG Zhenyuan, LI Jia China Mechanical Engineering    2022, 33 (15): 1882-1889.   DOI: 10.3969/j.issn.1004-132X.2022.15.015 Abstract （183）      PDF （5896KB）（41）       Knowledge map    Save One type of wet DCT was taken as research subject, and the mechanism of output torque variations of the DCT for cars was analyzed in neutral/park positions while creeping or idling respectively. By building the mathematical model of the output torque， theoretical calculation formulas of the equivalent radius of lubricating oil film between DCT plates， the max drag torque and the critical rotational speed were figured out， and the dynamic interactions of three elements were illuminated. The accuracy was proved by experimental data， which may be used to reduce output torque fluctuation， drag torques and critical rotational speeds.  Reference | Related Articles | Metrics

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Digital Verification Method of Ship EEDI WANG Zhifang, YANG Zixuan, CHEN Qingren China Mechanical Engineering    2022, 33 (10): 1189-1194.   DOI: 10.3969/j.issn.1004-132X.2022.10.007 Abstract （180）      PDF （2060KB）（63）       Knowledge map    Save  In order to promote the implementation of the EEDI of inland waterway ships and the improvement of EEDI level， a fast， efficient， and accurate digital forecasting method for EEDI of inland waterway ships needed to be developed. The paper collected a large number of tank test data samples about inland waterway ships and divided them into two parts. One part samples were used to analyze and improve the Ayre method resistance evaluation and calculation method， based on the research， an improved Ayre method was proposed, which was suitable for the resistance curve estimation and effective power calculation of the wide and flat inland waterway ships with twin-engine double-propeller and large square coefficient. The other part samples were used to verify the improved Ayre method， and the results show that the revised Ayre method has a much more lower forecasting errors than that of the original version from 9.4% to 3.4%， and then the ship speed forecasting method was proposed. Through testing and verification of the collected 32 real ship speeds， the results show that the method has high prediction accuracy with an average error of only 2.678%， which is far lower than the 5% error accepted by the shipowner. Finally， EEDI digital verification software was developed to meet the needs of economic and rapid verification of EEDI， and promote the green and efficient development of inland waterway ships.  Reference | Related Articles | Metrics

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Research Review of Error Compensation Technology for Ultra-precision Machining CHEN Qidi, HU Xiaolong, LIN Min, SUN Xiaoxia, ZHANG Tao, ZHOU Zhixiong China Mechanical Engineering    2023, 34 (03): 253-268.   DOI: 10.3969/j.issn.1004-132X.2023.03.001 Abstract （179）      PDF （8557KB）（170）       Knowledge map    Save  Ultra-precision machining technology was a key technology in high-end manufacturing fields. At present, ultra-precision machining has entered the nano scale. Mastering the key technology of ultra-precision machining error control, ensuring and improving the machining accuracy of CNC machine tools, become a hot research point to improve the machining and manufacturing levels. This paper systematically summarized the research status and development trend of ultra-precision machining error compensation technology, and focused on the geometric errors, force induced errors, thermal induced errors and their compensation methods, which had the greatest impact on ultra-precision machining. Then, a series of problems of ultra-precision machining in geometric error separation, cutting force, thermal induced error measurement and compensation were deeply discussed, and it is further pointed out that the ultra-precision machining error compensation technology should also pay attention to the development direction of high efficiency, high precision, generalization, modularization, intelligence and flexibility. Reference | Related Articles | Metrics

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Surface Crack Orientation Detection Method of Stainless Steels Based on Electromagnetic Field YAN Liang, WAN Benli, HU Bin, FAN Mengbao China Mechanical Engineering    2022, 33 (09): 1057-1064.   DOI: 10.3969/j.issn.1004-132X.2022.09.006 Abstract （178）      PDF （6902KB）（72）       Knowledge map    Save To solve the problems that traditional ACFM used to detect cracks in any directions was prone to miss the defects, the effects of eddy current orientation and crack orientation changes on the detection amplitude of flat plate surface cracks were studied under rotating magnetic field. The expressions of the relationship between crack direction angle and trough amplitude of plane magnetic field component were derived, the crack direction determination method and the influencing factors were proposed from the perspective of detection mechanism. ACFM finite element simulation model for the surface cracks of austenitic stainless steels was established. A metal plate surface crack detection system was developed based on double U excitation and high-resolution tunnel magneto resistance(TMR) sensor. Simulation and experimental results show that using the trough characteristics of magnetic field components, the crack direction may be determined and the judgment errors are less than 8.4°. Reference | Related Articles | Metrics

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Study on Crack Repair Performance of Si3N4/TiC/ZrSi2 Ceramic Tool Materials ZHANG Shuai, CHEN Zhaoqiang, XIAO Guangchun, YI Mingdong, ZHANG Jingjie, ZHOU Tingting, XU Chonghai China Mechanical Engineering    2022, 33 (19): 2288-2297.   DOI: 10.3969/j.issn.1004-132X.2022.19.002 Abstract （178）      PDF （14085KB）（176）       Knowledge map    Save To solve the problems that ceramic tools were sensitive to cracks， ZrSi2 crack repairing agent was added into Si3N4/TiC ceramic tool material matrix， which made ceramic tools have crack repairing ability. When ZrSi2 content was as 10% （volumn fraction）， Si3N4/TiC/ZrSi2 ceramic tool materials had better comprehensive properties， with flexural strength of 815 MPa， fracture toughness of 8.06 MPa·m1/2， Vickers hardness of 15.91 GPa and relative density of 99.72%. Cracks were introduced into the surface of ceramic tool materials by Vickers hardness tester， and the optimal repair parameters and repair mechanism of cracks in Si3N4/TiC-based ceramic materials with ZrSi2 as repair agent were studied. The research shows that the flexural strength of Si3N4/TiC/ZrSi2 prefabricated crack specimen with 10% ZrSi2 added may be restored to 92.02% of that of smooth specimen after heat treatment at 800 ℃ for 60 min in air atmosphere， and the crack with the surface length of 300～350 μm is completely repaired， and an oxide layer mainly composed of ZrO2 and SiO2 is formed on the surface of the specimen. The mechanism of crack repair of ceramic cutting tool materials is analyzed as follows：in the air heat treatment processes， ZrSi2， a healing agent at the crack and the surface of the material， preferentially reacts with oxygen to generate ZrO2 and SiO2， which heal the crack on the surface of the material and restore the strength of the crack sample. At the same time， during cutting， ZrO2 and SiO2， oxidation products of ZrSi2 at the cracks and material surfaces， may repair the crack in time and improve the wear resistance of the tool.  Reference | Related Articles | Metrics

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Research on Accelerated Life Test Method of Harmonic Reducers WANG Qiao, DU Xuesong, SONG Chaosheng, ZHU Caichao, SUN Jianquan, LIAO Delin China Mechanical Engineering    2022, 33 (19): 2317-2324.   DOI: 10.3969/j.issn.1004-132X.2022.19.005 Abstract （176）      PDF （5879KB）（93）       Knowledge map    Save At present， there was an urgent need for an accelerated life test method of harmonic reducer in engineering to replace the full life test in order to reduce the test cycles and costs. Based on the principles of accelerated life test， a constant stress accelerated life test program  was proposed based on the failure characteristics of the harmonic reducer. The flexible wheel that was most likely to fail in the harmonic reducers was taken as the object， and the definite failure judgment， acceleration stress， acceleration factor， method of accelerating model were pointed out. In the small sample test data processing， a more accurate Weibull distribution parameter estimation was obtained by using the maximum likelihood method and Markov Monte Carlo method. The experimental results of the prototype show that the scheme may effectively describe the life of the harmonic reducers. The reliability evaluation standard of the basic rated life is 62% higher than that of the evaluation standard of the median life. The life index of the harmonic reducers was effectively evaluated. The research results have certain engineering application values.  Reference | Related Articles | Metrics

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A Multi-agent-based Simulation Method for Health State Assessments of Naval Equipment DING Shanting, WANG Miao, DONG Zhengqiong, NIE Lei, China Mechanical Engineering    2022, 33 (10): 1169-1177.   DOI: 10.3969/j.issn.1004-132X.2022.10.005 Abstract （173）      PDF （5054KB）（95）       Knowledge map    Save  Considering that the sea conditions had a significant impact on the safe navigation and mission execution of ships， a multi-agent technology-based equipment health state simulation assessment method was proposed herein. Based on the analysis of naval equipment navigation task， the “task-equipment-maintenance-environment” equipment health state model was established， and the internal rules and communication mechanism of the environmental agents were formulated to realize the health state assessment of naval equipment under different sea conditions， in view of the influences of sea condition factors on equipment performance and maintenance capability. Taking a ships power system as the object， the health states of the cruising mission was evaluated under sea state 0， 5 and 7 level， respectively， and the simulation analysis results show that compared with sea state 0， the health and mission success rate of the power system under sea state 5 and 7 are reduced， and the quantitative evaluation results are consistent with the trend of expert qualitative evaluation results.  Reference | Related Articles | Metrics

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Generalization Method of Dynamic Movement Primitives Based on Weighting of Task Parameters ZHANG Lei, FANG Zaojun, WANG Juxing, HE Chen, GU Danning, China Mechanical Engineering    2022, 33 (10): 1226-1233,1243.   DOI: 10.3969/j.issn.1004-132X.2022.10.012 Abstract （173）      PDF （5037KB）（81）       Knowledge map    Save In order to improve the computational efficiency and generalization performance of robot learning from demonstration， a robot learning from demonstration model was proposed based on generalization of dynamic movement primitives weighted by task parameters. The main steps were as follows：the dynamic movement primitives model was used to extract the characteristic parameters of the multi teaching motion trajectories； Under the new task parameter， the extracted feature parameterswas used to reconstruct the feature motion trajectory； the approximate degree of the teaching task parameters and the new task parameters were usedto weight the feature motion trajectory to generate a new motion track. Experiments on Kukaiiwa robot show that the proposed method may quickly and effectively generalize the new trajectory in the new task scenario. Compared with the existing methods， the proposed method has a great improvement in computational efficiency and generalization performance near the teaching task parameters.  Reference | Related Articles | Metrics

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Design of Cross-spring Flexure Hinges WU Hao, LI Zongxuan, ZHANG Defu, LI Qingya, LI Yunfeng, China Mechanical Engineering    2022, 33 (10): 1203-1209.   DOI: 10.3969/j.issn.1004-132X.2022.10.009 Abstract （172）      PDF （4097KB）（98）       Knowledge map    Save To realize the requirements of a certain optical instrument for flexural hinges， a new type of cross-spring flexural hinge was proposed， and the design method was studied by using the Castiglianos second theorem. First， the Castiglianos second theorem was used to derive the flexibility calculation formula of the cross-spring flexural hinges to determine the axial rigidity and rotational rigidity of the hinges. Then， a case design was carried out and the finite element analysis was used for simulation. Finally， an optical test platform was set up and the rotation stiffness of the example was measured. The results show that the analytical solution， the simulation solution and the experimental data are in good agreement， and the relative error is as 8.7%. Using the Castiglianos second theorem as a design tool， the designer may determine the dimensional parameters according to the rigidity and structural requirements of the cross-spring flexural hinges， and the design of the cross-spring flexural hinges provides a new approach method for other hinges.  Reference | Related Articles | Metrics

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Establishment and Research of Prediction Model of Discharge Gap Voltages in Discharge Arc Milling ZHANG Jin, HAN Fuzhu, China Mechanical Engineering    2022, 33 (16): 1891-1896.   DOI: 10.3969/j.issn.1004-132X.2022.16.001 Abstract （170）      PDF （4167KB）（96）       Knowledge map    Save It was difficult to directly measure the discharge gaps during arc milling. The changes of the discharge gaps were judged by the changes of the discharge gap voltages. The system identification theory was used to determine the structure and model parameters of the discharge gap voltage prediction model. The method for establishing the prediction model was elaborated, and the degree of fit of the prediction model was verified by experiments. The experimental results show that the fit accuracy of the prediction model decreases with the increase of the fitting time. Therefore, the recursive least squares method was used to perform the online discharge gap voltage measurements. It is predicted that the average error of online prediction is as 6.82%. The results show that the discharge gap voltage prediction model may predict the discharge gap voltage stably and effectively one step ahead, with fewer model identification parameters and high prediction accuracy. Reference | Related Articles | Metrics

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Study on Leakage Characteristics and Dynamic Characteristics of New Type of Vortex Groove Seals JIANG Jinyu, SUN Dan, ZHAO Huan, ZHANG Guochen, LI Yu, WEN Shuaifang China Mechanical Engineering    2022, 33 (19): 2306-2316.   DOI: 10.3969/j.issn.1004-132X.2022.19.004 Abstract （170）      PDF （13329KB）（88）       Knowledge map    Save A new seal structure with vortex groove in the circumferential direction of the sealing inlet was proposed. The theoretical models of traditional labyrinth seal and the new type of vortex groove seal leakage characteristics and dynamic characteristics were established. Based on the model accuracy verification by means of experiments， the leakage characteristics and dynamic characteristics of the traditional labyrinth seal and the new type of vortex groove seal  were compared and analyzed under different inlet/outlet pressure ratios and pre-whirl ratios. The influence mechanism of the new vertex groove structure on the seal leakage and dynamic characteristics was studied. The results show that with the increase of the number of vortex groove， the leakage of vortex groove  seal decreases gradually. Under the same pressure ratio， the difference between the leakage of the new seal with different number of vortex grooves increases with the increase of the pressure ratio. When the pressure ratio is as 6， compared with the traditional labyrinth seal， the leakage of the 64 vortex grooves seal is reduced by 3.37%. Under the conditions of high pre-whirl ratio， the tangential airflow force of the seal with different number of vortex grooves is opposite to the direction of rotor vortex， which plays a role in inhibiting rotor vortex， the tangential airflow force increases with the increase of the number of vortex grooves. With the increase of rotor vortex frequency， the cross stiffness of seals with three different number of vortex grooves first decreases to negative value and then increases to positive value. The effective damping of the vortex groove seals is higher than that of the traditional labyrinth seals. The new vortex groove seal may improve the stability of the rotor systems.  Reference | Related Articles | Metrics

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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 China Mechanical Engineering    2022, 33 (14): 1680-1690.   DOI: 10.3969/j.issn.1004-132X.2022.14.006 Abstract （169）      PDF （11334KB）（93）       Knowledge map    Save 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. Reference | Related Articles | Metrics

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High-performance Paper-based Electronic Fabricated by Electric-field-driven Jet Micro 3D Printing#br# ZHANG Yongxia, ZHANG Guangming, ZHOU Longjian, ZHOU Hefei, XU Quan, LAN Hongbo China Mechanical Engineering    2022, 33 (10): 1244-1259.   DOI: 10.3969/j.issn.1004-132X.2022.10.014 Abstract （169）      PDF （6248KB）（151）       Knowledge map    Save A novel method of the electric-field-driven（EFD）jet deposition micro-scale 3D printing for fabricating high resolution circuit on paper-based surface was proposed. The basic principles and process flows of the proposed method were presented. The effects and rules of the main processing parameters（e. g.， the voltage， back pressure， printing speed） on the accuracy and quality of silver wires fabrications were revealed by a serial of experiments. Then， by using optimized parameters and the nano silver paste（75% silver content and 35 Pa·s（at 25 ℃）dynamic viscosity）， the micro/nano-scale structure with high resolution and high aspect ratio was fabricated by multi-layer stacking on three kinds of paper substrates. For example， the line width with 15 layers stacking on RC photo paper may be kept at 10 μm， and the aspect ratio may be increased to 6.33， causing the 94.8% decrease of the resistance. Finally， flexible electromagnetic actuators（FEMAs） and complex conductive patterns were fabricated on different paper substrates to prove the printing ability. The results show that the new method of EFD 3D printing technology combined with high viscosity and low temperature sintering nano silver paste may provide an effective way for high-performance paper-based electronics.  Reference | Related Articles | Metrics

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Dynamics Modeling Method of Complex Rotors for Aero-turboshaft Engines WANG Longkai, WANG Ailun, YIN Yijun, JIN Miao, HENG Xing China Mechanical Engineering    2022, 33 (13): 1513-1520.   DOI: 10.3969/j.issn.1004-132X.2022.13.001 Abstract （167）      PDF （6544KB）（226）       Knowledge map    Save To establish the dynamics model of complex rotor systems in turboshaft engines，the complex structure was modeled by substructure method on the basis of finite element method and piecewise linear fitting. After reducing the degrees of freedom of the systems，motion equations of the rotor systems were derived. The validity of the model was verified by theoretical analysis and experiments，and the vibration characteristics of the gas generator rotors were analyzed. The results show that the established model may significantly reduce the complexity of the overall systems and greatly shorten the calculation time under the premise of ensuring the solution accuracy. Reference | Related Articles | Metrics

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An Unsupervised Bearing Health Indicator and Early Fault Detection Method ZHAO Zhihong, LI Lehao, YANG Shaopu, LI Qing China Mechanical Engineering    2022, 33 (10): 1234-1243.   DOI: 10.3969/j.issn.1004-132X.2022.10.013 Abstract （164）      PDF （7873KB）（59）       Knowledge map    Save A method of unsupervised bearing health indicator and early fault detection was proposed. A deep separable convolutional auto-encoder model was designed to effectively extract bearing state features， where the outputs of the encoder were used as bearing state features. Then， the Bray-Curtis distance was used to calculate the distance between the degenerated state features and the healthy state features as the bearing state health indicator（BC-HI）. An early fault detection method combined with Savitzky-Golay filter was proposed based on BC-HI. The abnormal threshold was obtained according to the trend of health indicators to judge the occurrence of early faults. In order to verify the effectiveness and generalization ability of the proposed method， the experiments were carried out on datasets of bearing accelerated life tests. The experimental results show that the health indicator proposed may reflect the degradation trend of bearings， and is sensitive to early faults， and has strong generalization ability. Compared with the methods such as isolated forest and support vector machine， the first fault detection time is earlier and the false alarm rate is lower， so it has certain application values.  Reference | Related Articles | Metrics

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Research on ECT for Online Detection of Defects in Wire Ropes XIA Hui, ZHENG Jun, QIU Jinchuan, WU Jianbo, WANG Jie China Mechanical Engineering    2022, 33 (09): 1044-1050.   DOI: 10.3969/j.issn.1004-132X.2022.09.004 Abstract （164）      PDF （6690KB）（131）       Knowledge map    Save In order to guarantee the safe operation of WR, an online detection method of ECT for defects in WR was proposed. Firstly, an image reconstruction algorithm was proposed based on the same heating time to get the reconstruction images that had the same heating time in the whole WR. Then, the column maximum normalization algorithm was proposed to eliminate the errors in temperature acquisition caused by inconsistent emissivity. Finally, an online ECT detection system was established, and the detection experiments were carried out for defects with a different number of broken wires and wear defects. The experimental results show that the novel method may effectively detect and identify 1~5 broken wires and wear defects of WR. Reference | Related Articles | Metrics

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Environmental Adaptability and Tribological Properties of MoS2/WS2 Composite Films FAN Xin, REN Siming, WANG Haixin , PU Jibin China Mechanical Engineering    2022, 33 (12): 1468-1476.   DOI: 10.3969/j.issn.1004-132X.2022.12.008 Abstract （163）      PDF （20638KB）（31）       Knowledge map    Save The hot and humid atmosphere had a serious deteriorating effect on the tribological properties of the MoS2 lubricating films. Unbalanced magnetron sputtering technology was successfully used to prepare WS2 doped MoS2 composite films, and the addition of a small amount of WS2 in the MoS2 matrix might induce the preferential growth of MoS2 along the(002) crystal planes, the film structure became denser, the penetration and diffusion of corrosive media were significantly inhibited, and the MoS2/WS2 composite film exhibited high salt spray corrosion resistance, low friction coefficient and wear rate. The composition-optimized MoS2-1.6at.%WS2 composite film was only oxidized on the surface layers after 4 days of salt spray, and still maintained a low friction coefficient of 0.16 and a low wear rate of 3.80×10-6 mm3/(N·m).  Reference | Related Articles | Metrics