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Research Status and Development Trends of Large Wind Turbine Main Shaft Sliding Bearings ZHU Caichao1, ZHANG Ronghua1, SONG Chaoshen1, TAN Jianjun1, YANG Liang2 China Mechanical Engineering    2024, 35 (10): 1711-1721.   DOI: 10.3969/j.issn.1004-132X.2024.10.001 Abstract （850）      PDF（pc） （4422KB）（458）       Knowledge map    Save The pace of large wind turbine units was accelerating, and the reliability of core components was increasingly important for wind turbine operations. Sliding bearings had the advantages of high load capacity, long life, easy maintenance, scalability and small size, and they had advantages and great potential for the reliable replacement of wind turbine main bearings key components produced at home. The problems of main shaft rolling bearings in high-power wind turbines and the advantages of using sliding bearings on the main shaft were analyzed herein. The technical methods and application status of wind turbine main shaft sliding bearing design, materials, lubrication, and experimental verification were present in detail, and the existing problems of high-power wind turbine main shaft sliding bearings and future development trends were summarized. It is expected to provide reference for the digital design and industrial development of high-power wind turbine main bearings. Reference | Related Articles | Metrics | Comments（0）

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Lubrication Characteristics of Gear End Face Friction Pairs of Aviation High-speed Gear Pumps CHEN Yuan1, XIONG Dianfeng1, LI Yuntang1, GAO Yongcao2, LI Chuancang2, WANG Bingqing1, JIN Jie1 China Mechanical Engineering    2024, 35 (07): 1178-1187.   DOI: 10.3969/j.issn.1004-132X.2024.07.005 Abstract （334）      PDF（pc） （9034KB）（240）       Knowledge map    Save Aiming at the serious wear problems of gear end face friction pairs of aviation external gear pumps, a new compound texture combining Tesla valve groove type and elliptical shape was opened on the gear end faces to improve lubrication performance. Based on hydrodynamic lubrication theory and finite element simulation calculation method, a theoretical analysis model of gear textured end face friction pair lubrication was established. Pressure distribution and velocity distribution of fluid within the end face liquid films were simulated and analyzed under conditions with and without texture, and the effects of operating and structural parameters on the openness and sealing performance of gear end faces were studied. The results show that the hydrodynamic pressure generated by the texture may make the gear end face friction pairs run non-contact, which has a positive effect on reducing friction and increasing efficiency. With the comprehensive consideration of the openness and leakage control performance of gear end face friction pairs, groove depth is as 7~9 μm, height difference is as 5~6 μm, inclination angle is as 0°~10°, and shape factor is as 0.4~0.5 are the optimal structural parameters for the texture structure. Reference | Related Articles | Metrics | Comments（0）

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Robust Control of High-pressure Pneumatic Pressure Servo Systems ZHANG Dijia1, 2, GAO Luping2, ZHOU Shaoliang2, GAO Longlong2, LI Baoren2 China Mechanical Engineering    2024, 35 (07): 1141-1150.   DOI: 10.3969/j.issn.1004-132X.2024.07.001 Abstract （450）      PDF（pc） （7020KB）（229）       Knowledge map    Save Parameter uncertainty and unmodeled dynamics of HPPS restricted the improvement of the control accuracy. An adaptive robust control method was proposed and applied to control the HPPS based on RISE. This paper considered the influencs of HESV control performance on the high-precision control of HPPS, and a cross-comparison test was designed. The results show that the HESV position control method may avoid sinusoidal signal distortions and reduce steady-state pressure jitter, and the HPPS pressure control method may improve the response speed and dynamic tracking capability of the systems. Reference | Related Articles | Metrics | Comments（0）

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Design of Twisting Climbing Wheeled Inspection Robot for Mining Wire Ropes TANG Chaoquan, TONG Binghang, TANG Wei, ZHANG Gang, WANG Siyuan, TANG Hongwei, LIU Bei, ZHOU Gongbo China Mechanical Engineering    2024, 35 (10): 1732-1739.   DOI: 10.3969/j.issn.1004-132X.2024.10.003 Abstract （405）      PDF（pc） （6279KB）（216）       Knowledge map    Save In response to the unmanned inspection requirements of mining wire ropes, a rope-twisting climbing inspection robot was designed and developed. Compared to traditional axial climbing robots, which required approximately 91.5% of the driving force. When carrying a load of 3 kg, the robot may overcome obstacles with a height 0.6 mm higher than that of axial climbing robots. With an obstacle height of 3 mm, the maximum load capacity exceeds that of axial climbing robots by 0.4 kg. Climbing experiments were conducted under simulated deep mine conditions with wire rope vibrations. The results show that the climbing robots exhibite stable climbing performance when the wire ropes are stationary, achieving a maximum climbing speed of 8.25 m/min and capable of continuous climbing for 500 m. Under low-frequency large-amplitude vibration conditions, the climbing speed of the robot is higher than that when stationary, while under high-frequency small-amplitude vibration conditions, slight fluctuations in climbing speed are observed due to wire rope vibrations. Reference | Related Articles | Metrics | Comments（0）

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Research on Compound Wave Propulsion Performance Improvement for Bionic Fish Robots LUO Zirong1, XIA Minghai1, YIN Qian2, LU Zhongyue1, JIANG Tao1, ZHU Yiming1 China Mechanical Engineering    2024, 35 (11): 1901-1908.   DOI: 10.3969/j.issn.1004-132X.2024.11.001 Abstract （378）      PDF（pc） （8473KB）（190）       Knowledge map    Save Motivated by the profound impacts of longitudinal and transverse waves of earthquake, a novel underwater bionic propeller that utilized longitudinal and transverse compound wave patterns was proposed and designed. A kinematic model incorporating the composite waves was theoretically established, alongside the development of a physical prototype and testing platform. The propulsion performances of the propeller were systematically compared and analyzed through CFD simulations as well as prototype tests under varying amplitudes of longitudinal wave superposition. Simulation results show that both the thrust and velocity generated by the undulating fin may be significantly enhanced, with mean thrust increasing by 27.6% and peak thrust exceeding 200%. Experimental results reveal that under a frequency of 2 Hz with a longitudinal-wave amplitude of 20°, the steady-state average velocity achieved by the propeller reaches 0.761 m/s, which is approximately 14.7% greater than that of without longitudinal wave. This paper demonstrates that composite wave bionic fins exhibit superior thrust and velocity performance compared to single sinusoidal wave configurations, thereby offering an innovative propulsion mechanism for advancing high-performance bionic fish robots. Reference | Related Articles | Metrics | Comments（0）

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Design of Scale-changeable Pantograph Legs for Heavy-duty Robots SUO Zhe, LI Xiang, LIU Jianfeng, WANG Jixin China Mechanical Engineering    2025, 36 (02): 191-196.   DOI: 10.3969/j.issn.1004-132X.2025.02.001 Abstract （243）      PDF（pc） （7951KB）（176）       Knowledge map    Save The motion characteristics of the 2 DOF(degree-of-freedom) scale-changeable pantograph leg mechanisms were analyzed, different designs for scale change were compared. A scale-changeable pantograph leg with a nonlinear length adjustment mechanisms was proposed. The length of the thigh and shank link could be adjusted with a single driver according to the nonlinear proportion relation. Thus, the scale could be changed while preserving the pantograph mechanism properties. The scale-changeable pantograph leg may change the scale without disassembling, adjust the foot working space and the carrying capacity of the robots. Reference | Related Articles | Metrics | Comments（0）

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Design and Analyses of a Novel Two-axis Flexure Hinge with Elliptical Transverse Cross-sections WEI Huaxian1, 2, ZHAO Yongjie2, YANG Nan2, WANG Fengtao2, NIU Xiaodong2 China Mechanical Engineering    2024, 35 (08): 1348-1357.   DOI: 10.3969/j.issn.1004-132X.2024.08.002 Abstract （385）      PDF（pc） （12837KB）（170）       Knowledge map    Save  Two-axis flexure hinges with orthogonally-collocated notches comprised rectangular transverse cross-sections which increased the stress concentration on the sharp edges. In addition, such effects could not be avoided through notch optimization. Consequently, a novel kind of two-axis flexure hinge with elliptical transverse cross-sections was developed herein. Firstly, the parametric model of the flexure hinges with circular notches was established. Then, the compliance and stress models of the flexure hinges were developed based on the Castiglianos second theorem. The analytical models were verified through finite element analyses and the parametric simulations were performed to evaluate the characteristics of compliances and stress concentration. Finally, the compliances of a flexure specimen were tested through experiments. The results show that the ETC flexure hinges have two-dimensional anisotropic compliances. The sharp-edge structures are avoided. Therefore, the stress concentration effects are reduced and the motion capability is increased. Compared to exiting two-axis flexure hinges with identical notch profiles but rectangular transverse cross-sections, the motion capability of the ETC type flexures hinges is increased by 47.9%. The ETC type two-axis flexure hinges expand the design spaces of the primary flexure structures. Reference | Related Articles | Metrics | Comments（0）

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China Mechanical Engineering    2025, 36 (04): 1-.   Abstract （195）      PDF（pc） （293186KB）（169）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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China Mechanical Engineering    2024, 35 (09): 0-.   Abstract （83）      PDF（pc） （364KB）（166）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Research Progresses of Mechanical Dressing for Arc Diamond Grinding Wheels CHEN Bing1, QING Guangye1, GUO Ye1, DENG Zhaohui2 China Mechanical Engineering    2024, 35 (08): 1331-1347.   DOI: 10.3969/j.issn.1004-132X.2024.08.001 Abstract （355）      PDF（pc） （13816KB）（164）       Knowledge map    Save The arc diamond grinding wheels had unique arc profile and commonly used for precision and ultra-precision grinding of optical components made from difficult-to-cut materials such as ceramics, optical glass, and cemented carbide. However, during the grinding process of optical elements, the interaction between the grinding wheel and the workpiece surface caused the abrasive grains on the grinding wheel to be squeezed and damaged. Then, this led to issues such as grinding wheel blockage, wear, reduction in size and shape accuracy, ultimately affecting the surface roughness, shape accuracy, and damage thickness of the optical elements after grinding. To address these problems, dressing the arc-shaped diamond grinding wheel was an effective solution. Among the various dressing methods, mechanical dressing remained the primary approach in production due to the high dressing efficiency and ease of implementation. This paper provided a comprehensive review of the mechanical dressing methods for arc diamond grinding wheels. The truing mechanism and characteristics of different methods were explored, the evaluation method for truing effectiveness was analyzed, and a future outlook for the mechanical truing of arc diamond grinding wheels was presented. Reference | Related Articles | Metrics | Comments（0）

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A Review of Mechanics Property Studies of Retracting and Releasing Cables for Marine Exploration Equipment WAN Buyan1, 2, PENG Fenfei1, 2, 3, JIN Yongping1, 2, LIU Deshun1, 2, PENG Youduo1, 2 China Mechanical Engineering    2024, 35 (09): 1521-1533.   DOI: 10.3969/j.issn.1004-132X.2024.09.001 Abstract （337）      PDF（pc） （8520KB）（155）       Knowledge map    Save The retracting and releasing cables were the only link between the submarine exploration equipment and the ship, had the functions of power, information transmission and load-bearing, and were widely used in all kinds of launch and recovery systems. The safety and reliability of retracting-releasing cables were of the core functional requirements. Therefore, conducting experiments on mechanics properties of retracting-releasing cables was the foundation of retracting-releasing cable research. Starting from the types and failure modes of ocean winches and retracting-releasing cables, the state of experimental studies of the mechanics properties of retracting-releasing cables was systematically summarized, and an outlook on future research directions was provided. Firstly, the functions of ocean winches and retracting-releasing cables were categorized, followed by a detailed analysis of the forms and reasons for their failures. Secondly, the operating conditions, mechanics performance requirements of retracting-releasing cables, and experimental researchs current status were described. Lastly, the research directions for the mechanics properties of retracting-releasing cables in ocean detection equipment were discussed, including the impact and mechanism of extreme operating environments on mechanics properties of synthetic retracting-releasing cables, the behavior and mechanism of synthetic retracting-releasing cable damage under multiple load couplings, and the technology and integrated simulation devices for retracting-releasing cable mechanics properties. Reference | Related Articles | Metrics | Comments（0）

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State-of-the-art and Trend of High Loading Capacity Plastic Gear Drives LIU Huaiju, LU Zehua, ZHU Caichao China Mechanical Engineering    2025, 36 (01): 2-17.   DOI: 10.3969/j.issn.1004-132X.2025.01.001 Abstract （339）      PDF（pc） （15004KB）（153）       Knowledge map    Save Focusing on the loading capacity and applications in power transmission of plastic gears, the failure modes and loading capacity under the current materials and technology levels were introduced. The strengthening measures for improving loading capacity of plastic gears were elaborated from the application of new materials, lubrication improvement, collaborative design, and so on. The applications and potential of plastic gears scenarios in power transmissions such as automobile engines, vehicle reducers, and aeroengine accessory gearboxes were introduced, which has important reference significance for promoting the development of high load plastic gear technology and applications. Reference | Related Articles | Metrics | Comments（0）

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Visual Detection of Subsurface Corrosions in Ferromagnetic Metal Plates Using Pulsed Eddy Current Based on Dual-sensor Differential Mechanism WANG Jin1, LI Yong1, SU Bingjie1, GAO Wenlong1, XIANG Yi1, 2, LIU Zhengshuai1, CHEN Zhenmao1 China Mechanical Engineering    2025, 36 (03): 381-390.   DOI: 10.3969/j.issn.1004-132X.2025.03.001 Abstract （233）      PDF（pc） （17686KB）（151）       Knowledge map    Save A pulse eddy current visual detection method was proposed based on a dual-sensor differential mechanism for subsurface corrosions in ferromagnetic metal plates. In this method, a dual-sensor differential probe was used to pick up the pulsed eddy current testing signals, and the slope of the logarithmic curve along the falling edge of the testing signals and the peak value of the normalized differential signals were extracted as signal features, which were used for visual detection of defects of different sizes. Through simulation and experimental research, the correlation laws between the proposed signal features and the sizes of defects were established, and it is verified that the dual-sensor differential probe has the advantages of reducing noise interference and improving the detection sensitivity compared with traditional single-sensor probes. In addition, a method was proposed to fuse the two signal features, and the results indicate that the defect images using fused signal features have a higher image signal-to-noise ratio. The research method proposed herein provides an effective and reliable solution for the visual detection of subsurface corrosions in ferromagnetic metal plates. Reference | Related Articles | Metrics | Comments（0）

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Research on Driving Style Classification and Recognition Methods Based on Driving Events QIN Datong, CHEN Moji, CAO Yuhang, GAO Di China Mechanical Engineering    2024, 35 (09): 1534-1541.   DOI: 10.3969/j.issn.1004-132X.2024.09.002 Abstract （454）      PDF（pc） （6584KB）（150）       Knowledge map    Save Aiming at the problems that, based on data statistical characteristics, the classification and recognition method of driving style was easy to ignore the diversity of driving style during driving, a classification and recognition method of driving style was proposed based on driving events, spectral clustering and random forest. Experiments were designed to collect driving data, and the data were preprocessed to extract turning events and braking events. After standardization and dimensionality reduction, the spectral clustering algorithm was used to cluster the driving style of turning events and braking events respectively. The entropy weight method was used to obtain the driving style weights of each driver, and the accuracy of five machine learning algorithms was compared for driving style recognition. Results show that the accuracy of driving style recognition is as 92.73% based on random forest, which significantly improves the accuracy of driving style recognition. Reference | Related Articles | Metrics | Comments（0）

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Research Progresses on Reliability Analysis and Optimal Design of Automobile Structures ZHANG Lei1, 2, 3, SUN Xuetao1, 2, CHEN Jie1, 2, SUN Yuanbo3, GUO Jiajia1, 2, ZHENG Jie1, 2 China Mechanical Engineering    2024, 35 (11): 1948-1962，1970.   DOI: 10.3969/j.issn.1004-132X.2024.11.006 Abstract （315）      PDF（pc） （2504KB）（146）       Knowledge map    Save In order to study the reliability of automobile structures, the uncertainty of mechanical structure analysis and design was summarized, and the uncertainty of design variables and parameters of automobile structures was analyzed from three aspects: structural parameter uncertainty, material performance parameter uncertainty and load uncertainty. The research progresses of probabilistic reliability analysis and non-probabilistic reliability analysis methods were reviewed and summarized. The applications of reliability analysis method in automobile structures were listed. The mathematical model and algorithm of reliability were sorted out, and the applications of reliability optimization design in lightweight and crashworthiness of automobiles were studied, and the development trends of reliability analysis and optimization design of automobile structures were presented.  Reference | Related Articles | Metrics | Comments（0）

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China Mechanical Engineering    2024, 35 (07): 0-.   Abstract （98）      PDF（pc） （350KB）（138）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Geometric Design and Performance Analysis of Multi-closed-loop Deployable Honeycomb Mechanisms with Thick Panels CHANG Boyan1, 2, GUAN Xin1, JIN Guoguang1, 2, LIANG Dong1, 2 China Mechanical Engineering    2024, 35 (07): 1156-1167.   DOI: 10.3969/j.issn.1004-132X.2024.07.003 Abstract （350）      PDF（pc） （14153KB）（135）       Knowledge map    Save A new type of space mechanisms with single-closed-loop was proposed according to thick-panel origami teory, and the mobility was analyzed by using screw theory. The degree of freedom of mechanism was reduced to 1 by the introduction of Myard constraint and Sarrus constraint, and the corresponding deployable units were obtained with the names of Myard deployable honeycomb unit and Sarrus deployable honeycomb unit. M-type honeycomb mechanism and S-type honeycomb mechanism were proposed based on kinematic analysis and planar mosaic array of deployable honeycomb units. The influence regularity of various factors on folding ratio was analyzed, and the deployable honeycomb units  were optimized with the rising of folding ratio index. The results show that M-type honeycomb mechanism may achieve flat surface, and S-type honeycomb mechanism may achieve higher folding ratio index. Reference | Related Articles | Metrics | Comments（0）

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Research Progresses on Incremental EMF Technology for Thin-walled Components CHENG Xiao1, LI Rui2, ZOU Guisheng2, LIN Junfeng1, 3, YU Haiping1, 3 China Mechanical Engineering    2024, 35 (12): 2092-2105.   DOI: 10.3969/j.issn.1004-132X.2024.12.001 Abstract （705）      PDF（pc） （12617KB）（135）       Knowledge map    Save With the development of Chinas high-end manufacturing industries, the demands for thin-walled components in many industrial fields such as aerospace were increased dramatically. The high-speed forming characteristics, traditional EMF was successfully applied to the production of thin-walled components of some key lightweight materials. However, due to the limitations of forming coil and discharge equipment, it was difficult to process large-scale and complex structure parts. In the past decade, incremental EMF technology was developed and gradually applied to the large thin-wall components processing, where a large number of research results were emerged. On the basis of briefly describing the principle and characteristics of EMF technology, the existing incremental EMF technology was divided into two categories according to the processing form: incremental electromagnetic composite forming and incremental electromagnetic direct forming. The research status of each processes was expounded from the aspects of basic principle, technical scheme and application results. Thus the main problems existing in the incremental EMF technology were analyzed, then the future development prospects and research direction of the incremental EMF technology were prospected. Reference | Related Articles | Metrics | Comments（0）

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Rolling Bearing Fault Diagnosis of Wind Turbines Based on Frequency Domain Group Sparse Model with Graph Regularization Constraints LI Jimeng, WANG Ze, SHI Qingxin, MENG Zong China Mechanical Engineering    2024, 35 (11): 1909-1919.   DOI: 10.3969/j.issn.1004-132X.2024.11.002 Abstract （1010）      PDF（pc） （11269KB）（134）       Knowledge map    Save Due to effects of the non-stationary operations, noisy working environment and strong electromagnetic interference for the wind turbines, the fault impulses of rolling bearings were submerged by strong noise, and the weak features were difficult to accurately identify. To solve the above problems, a frequency domain group sparse model with graph regularization constraints was proposed, which might effectively extract fault features of rolling bearings without periodic prior knowledge. Firstly, vibration signals were converted into graph signals to construct the graph regularization constraints, and the structured information was utilized to guide the penalty strength to improve the accuracy of sparse reconstruction. Secondly, the frequency domain group sparse model with graph regularization constraints was constructed, the method was given to determine the shrinkage threshold of the in-group components, and the objective function was simplified with the proximal mapping to optimize the solution. Finally, the parameters of the model were optimized by using the constructed comprehensive index and the moth flame optimization algorithm, and rolling bearing faults were identified by the envelope spectrum analysis of the reconstructed signals in the time domain. Numerical simulation and experimental results demonstrate that the proposed method has good anti-noise performance and may effectively extract weak fault features of rolling bearings under strong noise interference. Reference | Related Articles | Metrics | Comments（0）

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Research on Geometric Parameter Constraints of Swing Roller Movable Tooth Transmission Systems WEI Rui1, JIN Herong1, 2, 3, YANG Zeyu1, CHEN Tao1, YI Yali1 China Mechanical Engineering    2024, 35 (10): 1722-1731,1739.   DOI: 10.3969/j.issn.1004-132X.2024.10.002 Abstract （309）      PDF（pc） （9450KB）（131）       Knowledge map    Save Aiming at the problems such as long dimensional chain and weak structure of key components for the traditional swing movable tooth transmission, a new type of swing roller movable tooth transmission configuration and the tooth profile design method and parameter selection strategy were proposed. The swing roller movable tooth transmission mechanism was equivalent treated, and the equivalent connecting rod vector transfer model was constructed by topological analysis. According to the principle of conjugate meshing, the conjugate tooth profile vector equations of wave generator and ring gear were derived. Based on the constraint conditions of avoiding motion interference and top cutting of tooth profiles, the selection strategies of swing coefficient and base circle radius of the wave generator were developed with the transmission pressure angle as the evaluation basis. The tooth profile design and performance analysis were carried out according to the optimized parameters and the two groups of comparison parameters. The results show that the designed swing roller movable teeth transmissions have continuous tooth profiles and are able to run without stalling. Under the same load conditions, the peak value of engagement force of the wave generator and movable teeth with the optimized parameters is 37.09% and 28.28% lower than that of the comparison groups, which verifies the effectiveness of the design strategy. The research may provide theoretical reference for the tooth profile design and parameter selection of swing roller movable teeth transmission. Reference | Related Articles | Metrics | Comments（0）

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Study on Dynamic Mechanics Characteristics and Fatigue Life Prediction of Single PCPs ZU Haiying, SUN Jinshan, YE Weidong, LI Daqi China Mechanical Engineering    2024, 35 (08): 1358-1365.   DOI: 10.3969/j.issn.1004-132X.2024.08.003 Abstract （227）      PDF（pc） （6691KB）（124）       Knowledge map    Save Aiming at the rubber fatigue failures of the stator of conventional production PCPs, the fatigue test of stator rubber material under 50 ℃ oil immersion condition was carried out with GLB120-27 type single PCP as the research object, the fatigue performance parameters of rubber material were obtained, and the fatigue life prediction model was established. The dynamic mechanics characteristics of PCPs were analyzed by finite element method with ABAQUS software. Based on the stress-strain response results obtained by numerical simulation and the stress-strain fitting expression of stator rubber materials in uniaxial tensile tests, the range of strain energy release rate at fatigue danger points was calculated. The fatigue life prediction of PCPs under different interference conditions was studied by using the established fatigue life prediction model. The results show that the fatigue life decreases exponentially with the increase of interference. Compared with the average working life of a single PCP in recent 5 years, based on crack propagation method the fatigue life of the stator rubber may meet the requirements of engineering prediction accuracy. Reference | Related Articles | Metrics | Comments（0）

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Influences of Strain Rate on Plastic Deformations and Martensitic Transformation Behaviors of 304 Stainless Steels ZHAN Lihua1, 2, ZHAO Shuai1, YANG Youliang1, 2, CHANG Zhilong3 China Mechanical Engineering    2024, 35 (12): 2132-2138，2168.   DOI: 10.3969/j.issn.1004-132X.2024.12.005 Abstract （334）      PDF（pc） （5871KB）（124）       Knowledge map    Save To investigate the plastic deformation behaviors and martensitic transformation rules of 0.5 mm thick 304 stainless steels at room temperature, uniaxial tensile tests were conducted at five different strain rates of 0.000 67 s-1, 0.002 s-1, 0.01 s-1, 0.1 s-1 and 1.0 s-1, with subsequent X-ray diffraction(XRD) analysis for phase analysis. The results reveal a notable increase in yield strength with rising strain rate, indicating strain rate strengthening effects. Additionally, due to plastic work converting into heat during tensile processes, martensitic transformation was inhibited, resulting in a slight tensile strength reduction. Below a true strain of 0.27, work hardening rates decrease under varying strain rates. However, beyond this threshold true strain, significant secondary hardening occurs under low strain rates, which is attributed to the internal martensitic transformation.To address this phenomenon, the Olson-Cohen equation was integrated into the traditional Johnson-Cook model to characterize secondary hardening during tensile processes across different strain rates. The improved Johnson-Cook model achieves high accuracy in predicting rheological stress changes, with deviations of 3.23%, 3.42%, 4.13%, 4.09%, and 5.14% respectively compared to experimental values, effectively capturing the secondary hardening stage at various strain rates. Reference | Related Articles | Metrics | Comments（0）

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Machine Learning and Finite Element Simulation and Experimentation for Springback Prediction of Al-Li Alloys HUI Shengmeng1, MAO Xiaobo4, ZHAN Lihua1, 2, 3 China Mechanical Engineering    2024, 35 (12): 2114-2121.   DOI: 10.3969/j.issn.1004-132X.2024.12.003 Abstract （287）      PDF（pc） （4522KB）（119）       Knowledge map    Save Creep aging tests were conducted on the 2195 Al-Li alloys under various stress conditions at temperatures of 180 ℃, 190 ℃, and 200 ℃ respectively. Constitutive equations were derived using MATLAB software and incorporated into the nonlinear finite element software MSC.Marc to build a finite element model for the creep aging forming of 2195 Al-Li alloy spade segments. The model utilized time, stress, and temperature as input parameters, with the springback radius being the critical output parameter. To enhance the accuracy and efficiency of predictions, a comparative analysis of various machine learning regression models was conducted, leading to the selection of the ridge regression model as the predictive tool, which facilitated the rapid and precise prediction of the springback radius under diverse processing conditions. The high predictive accuracy and practical utility of the model were validated through 1∶1 experimental verification, demonstrating a relative error of 0.9% between the experimental components springback profile and the target profile.  Reference | Related Articles | Metrics | Comments（0）

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Friction Reduction Mechanism of MoSe2/Graphene-Stainless Steel Self-lubricating Materials YAN Songshan1, XIAO Zhengli1, MAO Ya1, HU Rui2 China Mechanical Engineering    2024, 35 (07): 1151-1155.   DOI: 10.3969/j.issn.1004-132X.2024.07.002 Abstract （299）      PDF（pc） （9756KB）（119）       Knowledge map    Save In order to overcome the shortcomings of high friction coefficient and easy wear of stainless steel friction pair parts， based on the through-hole characteristics of powder metallurgy stainless steel porous matrix and the super sliding effect of heterojunction nano lubricants, a two-step preparation process of vacuum impregnation and hydrothermal synthesis were used to preduce MoSe2/graphene-stainless steel self-lubricating materials. The tribological properties and friction reduction mechanism of the composites were studied. The results indicate that the MoSe2/graphene lubricants in the matrix pores form a uniform lubricating film on the friction surfaces under the dragging effect during the friction processes, and significantly reduce the friction coefficient and wear rate of the friction pairs. At room temperature, load of 40 N, and speed of 100 r/min, the friction coefficient drops to 0.106, and the wear rate drops to 6.45×10-5 m3/(N·m). Compared with the stainless steel matrix, the friction coefficient and wear rate are reduced by 86% and 93% respectively.  Reference | Related Articles | Metrics | Comments（0）

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Thin Wall Metal Material Laser Cutting Process Optimization Based on Orthogonal Experiments ZHAI Zhaoyang1, LI Xinxin1, ZHANG Yanchao1, LIU Zhongming2, DU Chunhua1, ZHANG Huaming3 China Mechanical Engineering    2024, 35 (07): 1279-1289.   DOI: 10.3969/j.issn.1004-132X.2024.07.016 Abstract （303）      PDF（pc） （28888KB）（116）       Knowledge map    Save After laser cutting, the material substrates of thin wall metal components and the support plates below were prone to adhesion, which seriously affected the cutting quality. Fiber laser cutting experiments were conducted on 304 stainless steel and GH605 high temperature alloy thin plates, and the formation mechanism of the adhesion in laser cutting of different materials was analyzed. The single factor experimental method was used to analyze the influences of laser cutting process parameters on the HAZ and burr accumulation. The processing results show that with the addition of a micro-connection process, when the laser power is as 165 W, the cutting speed is as 5 m/min, and the auxiliary gas pressure is as 1.2 MPa, the cut edges are smooth and without deformation and residual adhesion. Reference | Related Articles | Metrics | Comments（0）

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Ultrasonic Vibration Softening Johnson-Cook Modeling and Validation of Thin Tube Curling Experiments SONG Pengfei1, 2, CAO Miaoyan1, 2, FU Min1, 2, CUI Yashuo1, 2, LI Yunfeng1, 2, LIU Zheng1, 2 China Mechanical Engineering    2024, 35 (12): 2106-2113，2121.   DOI: 10.3969/j.issn.1004-132X.2024.12.002 Abstract （354）      PDF（pc） （6974KB）（114）       Knowledge map    Save In order to accurately describe the deformation behaviors of lightweight thin-walled components during ultrasonic vibration-assisted forming, ultrasonic vibration normal excitation-assisted uniaxial tensile experiments were carried out with TU1 oxygen-free copper and 316L stainless steel. Considering the ultrasonic vibration softening effects, an ultrasonic vibration Johnson-Cook model was developed by introducing a new ultrasonic softening function. A subroutine was developed and embedded into finite elements for simulation, and was validated by comparison with unidirectional tensile and curling experiments. The results show that the numerical model may effectively capture the ultrasonic vibrational softening behaviors of the materials with an average absolute percentage error as low as 0.97%. Although different materials have different sensitivities to ultrasonic vibration, the ultrasonic softening rates all follow an Allometricl functional relationship with the ultrasonic energy field density. Reference | Related Articles | Metrics | Comments（0）

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Automated Grinding System and Method for Robotic Weld Seams Based on Point Cloud GE Jimin1, DENG Zhaohui2, WANG Shuixian1, ZHUO Rongjin1, LIU Wei1, Chen Xi3 China Mechanical Engineering    2024, 35 (07): 1253-1262，1268.   DOI: 10.3969/j.issn.1004-132X.2024.07.013 Abstract （320）      PDF（pc） （9159KB）（111）       Knowledge map    Save Service life and dynamic performance of structural components were affected by the accuracy and surface consistency of weld grinding. Currently, weld grinding mainly relied on manual or trajectory teaching methods, which had problems such as poor uniformity, low efficiency and high cost. So, a point cloud-based automated grinding system for robotic weld seams was proposed. A quadratic streamlining method for weld seam point cloud was proposed to obtain the global information of the weld seam surfaces accurately, and the weld seam width, height, and centerline features were extracted based on the distances between sampling points and neighborhood center of gravity points. The errors of height and width of the extracted weld seams are as 0.09 mm and 0.2 mm respectively, and the minimum residual height of the weld seams after grinding is as 0.17 mm, and the vlaue of surface roughness Ra is up to 0.498 μm. Reference | Related Articles | Metrics | Comments（0）

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Development and Applications of Aero-engine Accessory Gearbox Gear Transmission Design and Analysis Softwares LIU Guiyuan1, WANG Zeng2, YANG Ziyi2, HU Mingzhu1, LIU Huaiju1 China Mechanical Engineering    2024, 35 (11): 1938-1947.   DOI: 10.3969/j.issn.1004-132X.2024.11.005 Abstract （318）      PDF（pc） （12715KB）（110）       Knowledge map    Save The accessory gearbox gear transmissions were pivotal components for power transmission of the aero-engine accessories. The configuration and structure design of the accessory gearbox transmissions for aero-engines were complex, involving many parameters of components and system. Traditional design methods based on empirical formulas and scattered software programs could not meet the more efficient design requirements of advanced aviation equipment for high load capacity, long service life, lightweight, high performance transmission systems. Therefore, a “configuration design—component design—system analysis—system optimization” method for aero-engine gear transmission design was established, and the aero-engine accessory gearbox gear transmission design and analysis softwares were developed based on the C++/Python. According to the design requirements, four configuration schemes were generated applying the software, and a coaxial multiple-output non-symmetric power split configuration scheme was selected by comparison. A multi-objective optimization model for the transmission system was developed based on the NSGA-Ⅱ algorithm. With lightweight and high load capacity as the optimization goals, a reduction of 15.81% in gear transmission weight and an improvement of 2.98% in weak gear transmission safety are achieved. This provides theoretical methods and software tools to the research of gear transmissions for new generations of advanced aviation equipment. Reference | Related Articles | Metrics | Comments（0）

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Structure Optimization of Load Port Independent Double Spool Electro-hydraulic Valves CHEN Junxiang1, 2, QI Fanyu1, JIANG Hongda1, 2, KONG Xiangdong1, 2, JIN Zhenlin1, AI Chao1, 2 China Mechanical Engineering    2024, 35 (10): 1747-1761.   DOI: 10.3969/j.issn.1004-132X.2024.10.005 Abstract （269）      PDF（pc） （10594KB）（108）       Knowledge map    Save In order to study the influences of load port independent electro-hydraulic valve system parameters on the main valve fretting characteristics, a state space equation of electro-hydraulic valve systems was established based on the power bond graph theory, and the first-order sensitivity method was used to analyze the influences of system parameters on the main valve fretting characteristics. The pilot structure parameters of the feedback control systems were very important to the movement characteristics of the main valve, the dead zone width of the pilot stage, the form of the valve port and the matching coefficient of the inlet and return oil valve port were studied under the constraint conditions of no self-excited oscillation and the best damping ratio, the best match between the lead stage and the main stage was achieved. The results show that the main valve fretting characteristics are greatly affected by the friction force of the main valve core, the liquid capacity of the non-spring control chamber, the liquid capacity of the pipeline from the pilot valve inlet to the main valve control chamber(non-spring side) and the preload force of the main valve spring. While optimizing the above influencing parameters, the dead zone width of the pilot valve δ≤0.25 mm, the U-shaped valve port, and the matching coefficient of the inlet and return oil valve ports η=0.53, the overall performance of the system is effectively improved. Reference | Related Articles | Metrics | Comments（0）

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Design and Research of Variable Instantaneous Center Exoskeletons Driven by Pneumatic Artificial Muscles LI Chaoyang1, LUO Tianhong2, MA Xiangyu2, FANG Shangchen1, WANG Ke3 China Mechanical Engineering    2024, 35 (10): 1783-1792.   DOI: 10.3969/j.issn.1004-132X.2024.10.008 Abstract （293）      PDF（pc） （5557KB）（108）       Knowledge map    Save Aiming at the problems of low matching between the existing lower limb exoskeleton structure and the body, a new variable instantaneous center artificial knee joint driven by pneumatic artificial muscles was proposed by introducing additional degrees of freedom on the existing anti-quadrilateral joints. Combined with the kinematics analyses of the variable instantaneous center exoskeleton, the instantaneous center trajectory equations were solved, and the particle swarm algorithm was used to optimize the design of the knee joint structures. At the same time, the PID controller was used to simulate and analyze the motions, and experimental research was carried out. The results show that the instantaneous center trajectory of the proposed new variable instantaneous center artificial knee joints has a better match with the ideal instantaneoust center trajectory of the human joints, which provides reference and empirical support for the optimal design of the human-machine compatible structures. Reference | Related Articles | Metrics | Comments（0）

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Simulation and Experimental Study of Deformation Control of Large-size and Thin-wall Parts by SLM ZHANG Luo1, LIU Mingming2, CHEN Ruimin1, DAN Peng1, GUO Nan1 China Mechanical Engineering    2024, 35 (09): 1653-1658，1709.   DOI: 10.3969/j.issn.1004-132X.2024.09.015 Abstract （304）      PDF（pc） （8799KB）（108）       Knowledge map    Save Simulate Additive software was used to simulate and analyze the additive manufacturing processes of a typical large-sized thin-walled component—exhaust pipe. The results show that the SLM formed exhaust pipe parts without constraints have high residual stress and significant deformation. The post-processing releases residual stress in the parts, but the overall deformation of the parts further increases to 3.5 mm, with a maximum deformation of 9 mm. A lattice structure was introduced with high specific strength and stiffness as an auxiliary structure for controlling deformations, and a lattice processing scheme was designed with sufficient resistance to deformation and may be removed through post-processing. The cell type is QuadDiamond, the rod diameter is  as 1.3 mm, the rod length is as 19 mm, and the width of the lattice region is about 60 mm. The SLM test results of the exhaust pipe parts under lattice constraints are quite consistent with the numerical simulation results. The cloud image results of the three-dimensional scanning show that the overall deformation of the part is about 1 mm, and the maximum deformation does not exceed 2.5 mm, meeting the requirements for the part use. The above results show the effectiveness of using lattice structure in deformation control of large-sized thin-walled parts formed by SLM.  Reference | Related Articles | Metrics | Comments（0）

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Optimal Design of Face-hobbed Hypoid Gear Meshing Efficiency in Drive Axles WANG Qin1, HE Di1, XUE Jianhua2, PENG Jin3, FAN Zijie1 China Mechanical Engineering    2024, 35 (11): 1920-1927，1937.   DOI: 10.3969/j.issn.1004-132X.2024.11.003 Abstract （238）      PDF（pc） （5325KB）（106）       Knowledge map    Save Based on the gear friction loaded tooth contact analysis(FLTCA) method, an optimal design method was proposed for the meshing efficiency of face-hobbed hypoid gears. Firstly, a method was employed to preset the peak-to-peak values of unloaded transmission errors and the positions of the contact zones, facilitating the modification design of the positive and negative tooth surfaces of face-hobbed hypoid gears. Then, building upon the modified tooth surface design, an optimization objective was set to maximize gear meshing efficiency under driving conditions. And the optimization analysis model was established by comprehensively considering factors such as the peak-to-peak values of gear pair loaded transmission errors, distribution of full-load contact pattern on both sides of the tooth surfaces and the maximum contact stresses. To enhance the solution speed of the optimization model, the Kriging surrogate model was employed in conjunction with a multi-island genetic algorithm to address and solve the optimization model. Finally, a case design and test validation were conducted on a commercial drive axle with a face-hobbed hypoid gear pair. The effectivenesses of the optimization method proposed were verified through unloaded contact pattern tests and whole-axle transmission efficiency tests. Reference | Related Articles | Metrics | Comments（0）

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A Multiaxial Fatigue Life Prediction Model for Notched Parts Considering Additional Damage and Notch Effect CHENG Qin1, GAO Jianxiong1, YUAN Yiping1, ZHU Pengnian2 China Mechanical Engineering    2024, 35 (07): 1194-1204.   DOI: 10.3969/j.issn.1004-132X.2024.07.007 Abstract （251）      PDF（pc） （8174KB）（105）       Knowledge map    Save To address the issue of significant errors in predicting the multiaxial fatigue life of notched components with local stress-strain method, a method for predicting the fatigue life of notched components under multiaxial loading was proposed based on the critical plane theory which toke the stress gradient and size of the notchs and influences of additional strengthening effects into account. The model was validated by experimental data from three different materials of notched specimens, and the prediction results of the proposed model were compared with those of two classic models. The results show that the prediction accuracy of the proposed model is higher than that of the other two models, and the prediction results are almost all within the double life error band. Reference | Related Articles | Metrics | Comments（0）

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Three-dimensional Positioning Guidance of Automobile Doors Based on Machine Vision NA Yiming1, HU Chao1, QIU Yeyu2, LU Libing2, SONG Kai1 China Mechanical Engineering    2024, 35 (09): 1677-1687.   DOI: 10.3969/j.issn.1004-132X.2024.09.018 Abstract （264）      PDF（pc） （13731KB）（100）       Knowledge map    Save At present, in workshops, parts fixed on fixtures were commonly guided and gripped by pre-teaching the motion trajectories of robotic arms, resulting in poor human-machine interaction and low levels of intelligence. Machine vision, as an effective means of non-contact sensing and measurement, was applied in industrial scenarios. Based on monocular vision pose measurement technology, a multi-camera PnP positioning model and robotic arm guiding model were established to achieve spatial perception and guided grasping of the parts. Additionally, a pre-calibration method was proposed using multi-zero anchors to compensate system errors between robotic arm and vision module, which effectively decreasing the positioning and guiding errors of large parts. Reference | Related Articles | Metrics | Comments（0）

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Low Carbon and High Quality Modeling and Processing Parameter Optimization of CNC Milling Machines LI Zeya1, LUO Min1, ZHANG Chaoyong2, XU Jinyu1 China Mechanical Engineering    2024, 35 (10): 1845-1851.   DOI: 10.3969/j.issn.1004-132X.2024.10.014 Abstract （241）      PDF（pc） （1871KB）（99）       Knowledge map    Save  Aiming at the problems of high carbon emission efficiency and poor surface quality caused by using unreasonable processing parameters during the working processes of CNC milling machines, an optimization method of CNC milling machine processing parameters oriented to low carbon and high quality was proposed. Initially, carbon emission factors in the milling processes were analyzed, and target functions of carbon emission efficiency, surface roughness, and processing time were defined. Prediction models for carbon emission efficiency and surface roughness for CNC milling machines were subsequently established, utilizing the support vector regression improved by grey wolf optimizer. Then, with spindle speed, feed rate, and cutting width designated as optimization variables, an improved egret swarm optimization algorithm was applied to optimize the cutting parameters. This resulted in obtaining Pareto front solutions for processing parameters that were low in carbon emissions, high in quality and efficient. Suitable processing parameters were selected using the EW-TOPSIS method. Finally, an experimental platform for monitoring carbon emissions in CNC milling machines was established, and the feasibility and validity of the proposed method were verified by the experimental results. Reference | Related Articles | Metrics | Comments（0）

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Probabilistic Fatigue Life Prediction Model for Filled Natural Rubber under Constant Amplitude Loading LIU Xiangnan1, 2, XU Jingwei1 China Mechanical Engineering    2024, 35 (08): 1366-1372.   DOI: 10.3969/j.issn.1004-132X.2024.08.004 Abstract （236）      PDF（pc） （3561KB）（98）       Knowledge map    Save A conditional probability distribution model was proposed to quantify the distribution law of rubber fatigue life under arbitrary strain levels. The uniaxial tensile fatigue tests of rubber under different strain levels were carried out. The distribution law of rubber fatigue life was analyzed, and the parameter values of the probability distribution model were determined by a great likelihood estimation method. The least squares method was used to fit the functional relationship between strain level and parameter values of the probability distribution model, and then the conditional probability distribution model was established. The rubber fatigue reliability assessment was carried out, and the rubber P-ε-N model was established. The validity of the rubber P-ε-N model was verified by comparison with the measured lifetimes. Reference | Related Articles | Metrics | Comments（0）

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Potential and Challenges for GPT Robots ZHANG Fan , TAN Yuegang China Mechanical Engineering    2024, 35 (07): 1241-1252.   DOI: 10.3969/j.issn.1004-132X.2024.07.012 Abstract （254）      PDF（pc） （11486KB）（96）       Knowledge map    Save The fusion of robots and ChatGPT might create “silicon intelligence entity” with human-like intelligence and advantages, defined as “GPT-R”. The characteristics, technological trends, and applications of GPT-R were explored in industrial and human life domains, with a focus on the integration of ChatGPT and robot intelligence. The challenges of GPT-R in physical abilities, intelligence, and coexistence with humans were analyzed, and the corresponding strategies from robotic body and intelligence of GPT-R, law and security issue, and social rules were proposed. The GPT-R, which integrated ChatGPT and robotics technology, will be expected to have increasingly broad applications and market potential, and will become one of the crucial directions in the future development of the integration of artificial intelligence and robotics. Reference | Related Articles | Metrics | Comments（0）

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Research on Station Optimization of Aircraft Assembly Laser Trackers Based on Digital Twins LI Hao1, JIAO Yanchao1, ZHANG Yuyan1, ZHANG Hao1, XING Hongwen2, WEN Xiaoyu1, WANG Haoqi1, YE Guoyong1, GUAN Xiao2 China Mechanical Engineering    2024, 35 (11): 1986-1994.   DOI: 10.3969/j.issn.1004-132X.2024.11.010 Abstract （583）      PDF（pc） （4789KB）（93）       Knowledge map    Save  Due to the large size of aircraft parts and the complex distribution of tooling on the assembly site, the laser tracker had poor visibility. During the guided assembly or off-rack inspection, it was necessary to adjust the laser tracker station repeatedly, which seriously affected the measurement stability and efficiency. To solve this problem, a method was proposed for optimizing the station of a laser tracker in aircraft assembly based on digital twins. A measurement constrained model of laser trackers for aircraft assembly was established. The digital twin environment was established based on an accurate simulation of aircraft assembly site elements. Then, the optimization of laser tracker station placement was completed. Finally, a measurement simulation of the laser trackers in the digital twin environment was conducted to verify the feasibility of the genetic algorithm in solving the optimal station of the laser trackers. The results show that the coverage rate of the optimized laser tracker to the measuring points is increased by 110%, and the coincidence rate of the measuring points is increased from 11.7% to 55.5%, both the coverage rate and the coincidence rate of the measuring points of the laser trackers are significantly improved. Reference | Related Articles | Metrics | Comments（0）

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Neural Network Sliding Mode Control of Bellows-type Pneumatic Soft Actuators Based on Improved Ternary Model LYU Boyang1, 2, 3, MENG Qingxin1, 2, 3, XIAO Huai1, 2, 3, LAI Xuzhi1, 2, 3, WANG Yawu1, 2, 3, WU Min1, 2, 3 China Mechanical Engineering    2024, 35 (08): 1414-1425.   DOI: 10.3969/j.issn.1004-132X.2024.08.010 Abstract （287）      PDF（pc） （9660KB）（91）       Knowledge map    Save A sliding mode control method was proposed based on an improved ternary model for a bellows-type pneumatic soft actuator, and an RBF neural network was used to compensate the aggregate set disturbance to achieve tracking control of the desired trajectory in the vertical direction of this type of actuators. Firstly, an experimental platform was constructed to test and analyse the dynamic characteristics of the bellows-type pneumatic soft actuators. Based on the above dynamic characteristics, an improved ternary model of the bellows-type pneumatic soft actuators was proposed. Meanwhile, the parameters of the proposed model were obtained by using the collected experimental data for parameter identification based on the least squares algorithm. Then, the sliding mode controller was designed in conjunction with the improved ternary model, and the RBF neural network was used to compensate for the aggregate set disturbance. The stability of the system was analysed by using the Lyapunov method. Finally, the effectiveness of the proposed method was verified through a series of experiments. Reference | Related Articles | Metrics | Comments（0）

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Reseach on Improvement of Creeping Phenomenon of Sliding Guideways by Composite Lubrication Texture FAN Yujie, CHEN Yuzhe, HAO Mengjie, WANG Suyang, DU Yuchen, XIA Jing, GUAN Xiaoyan China Mechanical Engineering    2024, 35 (10): 1740-1746,1761.   DOI: 10.3969/j.issn.1004-132X.2024.10.004 Abstract （214）      PDF（pc） （7624KB）（90）       Knowledge map    Save The creeping phenomenon of sliding guideways at low speed and heavy load seriously affected the machining accuracy of the machine tools. In order to improve the creeping phenomenon of the sliding guideways, the design of composite lubrication structure on the surfaces of sliding guideways and the characterization of friction force in stages were studied. The composite lubricating micro-texture was prepared by high temperature and high-pressure mosaic method based on the laser ablation micro-texture. The characterization methods of friction force in stages were proposed by friction tests. The influences of different composite lubricating structures on the friction characteristic parameters of each stage were explored. The theoretical models of the composite lubricating structures to improve the creeping phenomenon were established, and the composite lubricating structures with the best performance to suppress the creeping phenomenon were found. The results show that the surface micro-texture only affects the severe stick-slip and climb stages of friction force, while the composite lubrication texture has a significant effect on the entire start-up stage. The multi-stage composite lubrication texture(SF-3) with the combination of sinusoidal grooves and hexagonal pits filled with molybdenum disulfide (MoS2) was the most effective in improving the surface contact conditions and suppressing the creep phenomenon. Compared to the smooth surface(SS) sample, the creep time of the SF-3 sample is reduced by 72%, the instability force in the first stage is reduced by 69.83%, and the friction jump force in the second and third stages is reduced by 75.91% and 80.17%, respectively.  Reference | Related Articles | Metrics | Comments（0）