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Research Progresses for Machining Characteristics and Field-assisted Techniques of γ-TiAl Alloys FAN Tao1, 2, YAO Changfeng1, 2, TAN Liang1, 2 China Mechanical Engineering    2025, 36 (04): 636-645.   DOI: 10.3969/j.issn.1004-132X.2025.04.001 Abstract （1502）      PDF（pc） （25931KB）（73）       Knowledge map    Save γ-TiAl alloys, due to their low density, high specific strength and excellent high-temperature oxidation resistance had broad application potentials in the aerospace fields. However, due to their high brittleness and low room-temperature plasticity, they were considered typical difficult-to-machine materials, with challenges such as high cutting forces, rapid tool wear and surface defects during the machining processes. In recent years, field-assisted machining technologies provided new solutions to these issues. The material properties, machining characteristics, and surface integrity of γ-TiAl alloys were systematically analyzed, with a focus on the research progresses of field-assisted machining technologies, including their applications in reducing cutting forces, extending tool life and improving surface quality. Additionally, the current research limitations and future development trends were sorted out, aiming to provide theoretical and technical references for the efficient machining of γ-TiAl alloys.  Reference | Related Articles | Metrics | Comments（0）

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Effects of Forced Positioning&Clamping on Geometric and Physical Assembly Performances for Composite Structures and Collaborative Guarantee Strategies GUO Feiyan1, ZHANG Yongliang2, LIU Jialiang1, ZHANG Hui2 China Mechanical Engineering    2025, 36 (04): 655-670.   DOI: 10.3969/j.issn.1004-132X.2025.04.002 Abstract （1341）      PDF（pc） （7015KB）（64）       Knowledge map    Save The large-size & thin-walled aviation composite structures had low forming accuracy and huge in-plane warping deformation. The accumulation of assembly errors, unexpected geometric gaps and shape deviations were prone to occur at the joining areas. In engineering, passive reduction actions, such as applying local clamping forces was usually applied, but uneven internal stress distribution and even internal damages would be occurred, which affected the mechanical performances of the structures in service directly. Firstly, the principle of forced positioning clamping was explained, and the affection on geometric accuracy and mechanical properties of weak rigid composite parts was analyzed. Secondly, starting from the analysis of two main aspects, i.e. optimization on forced clamping process parameters before assembly, and flexible positioning force&position adjustment of fixtures during assembly, five key technologies were solved with detailed technical solutions, i.e. setting forced assembly force limits, reduction of geometric gaps, prediction of stress/damage evolution, reverse optimization of forced clamping process parameters, and precise measurement of assembly stress&damage. Then the active control of shape&force coupling and macro & micro collaborative guarantee in the clamping processes for assembly performance, could be achieved. Finally, for the composite assembly structures, from the perspective of practical engineering applications, the future working focus towards high assembly quality and efficient, and low-cost assembly goals were proposed. Reference | Related Articles | Metrics | Comments（0）

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Study on Lubricating Performances and Mechanism of Nano-carbon Balls Cutting Fluids SUN Hao1, LAN Qixin2, YAO Bin2, LU Jingjing1, ZHANG Jinhui2, PAN Zhirong2, ZHAO Kexin2 China Mechanical Engineering    2025, 36 (04): 715-723.   DOI: 10.3969/j.issn.1004-132X.2025.04.008 Abstract （1304）      PDF（pc） （8056KB）（28）       Knowledge map    Save Nano-carbon balls cutting fluid was applied to the cutting processes of difficult-to-machine aerospace gear steels(15Cr14Co12Mo5Ni2W), and the lubrication enhancement effects of nano-carbon particles on the cutting fluid were investigated. Firstly, a cutting force model for metal cutting was established to analyze the relationship between cutting lubrication and cutting forces. Furthermore, through combined friction-wear tests and milling experiments, the lubrication performance of nano-carbon balls cutting fluid was evaluated in terms of friction coefficient, wear volume, friction surface quality, and cutting forces. Compared with the base cutting fluid, when the mass fraction of nano-carbon is reached 0.02%, the milling forces for the gear steels are decreased by over 10%, and surface roughness is reduced by more than 15%. Experimental observations reveal that nano-carbon particles on the friction contact surfaces preferentially are adsorbed onto micro-peak regions with higher surface free energy, forming a nano-carbon adsorption film. Lubrication mechanism analysis indicates that this adsorption film may exert a friction-reducing “micro-bearing” effects. Reference | Related Articles | Metrics | Comments（0）

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Spiral Machining Trajectory Planning Method Based on Discrete Point Cloud Construction of Radial Lines WU Jiangsheng, CHAI Xingliang, BO Qile, LIU Haibo, WANG Yongqing China Mechanical Engineering    2025, 36 (04): 697-702,714.   DOI: 10.3969/j.issn.1004-132X.2025.04.006 Abstract （1142）      PDF（pc） （7105KB）（33）       Knowledge map    Save Aiming at the problems that it was difficult to directly generate efficient and accurate continuous smooth tool path trajectories based on discrete point clouds, a method to directly construct radial lines on point cloud and generate spiral machining trajectories through radial line interpolation was proposed herein. For the construction of radial lines, a boundary recognition method was proposed based on feature descriptors to extract boundary points as two end points of the radial lines. Taking the optimal discrete geodesics between two end points on the point cloud as the radial point set, the curvature minimization problems of discrete geodesics were proposed and solved by Newton iteration method. The B-spline curves were used to fit and resampling according to the residual height based on the radial point sets. The radial line interpolation algorithm was proposed to generate the spiral machining trajectory with equal residual height. Finally, an example was given to demonstrate the spiral machining trajectories directly generated by the point cloud data, which fully verified the effectiveness of the proposed method. Reference | Related Articles | Metrics | Comments（0）

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Design of Jig and Fixture for Machining Precision Forged Blade Tenons of Aeroengine ZHANG Shen1, LIANG Jiawei2, WU Dongbo3, WANG Hui4, ZHAO Bing1, XU Lijun5, ZHOU Fen5 China Mechanical Engineering    2025, 36 (04): 703-714.   DOI: 10.3969/j.issn.1004-132X.2025.04.007 Abstract （1038）      PDF（pc） （9510KB）（52）       Knowledge map    Save Precision forged blades of aeroengine were a typical thin-walled parts with complex curved surface. When milling the blade tenons, it was difficult to locate and easy to produce deformations and vibrations. Aiming at the above problems, a design method of multi-point clamping fixture for precision forged blades was proposed, and a low stress hard clamping fixture was designed. Static analysis was used to optimize the clamping position, select the coping element materials and optimize the clamping method. The effectiveness of the fixture was tested by modal tests and vibration tests. The results show that the low-band amplitude of the system is reduced by 50%, the high-band amplitude by 75%, the first-order resonance frequency is increased from 210 Hz to 402 Hz, the damping ratio under the peak value is increased from 17.4% to 25.9%, the effective value of vibration displacement signals is reduced by 35%, and the machining error margin is reduced by 59%. Reference | Related Articles | Metrics | Comments（0）

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Depth of Cut Control for Thin-walled Parts in Robotic Milling Based on FLADRC SHI Long, ZHOU Hexiang, LI Zhoulong China Mechanical Engineering    2025, 36 (04): 671-680.   DOI: 10.3969/j.issn.1004-132X.2025.04.003 Abstract （946）      PDF（pc） （8675KB）（56）       Knowledge map    Save Weakly rigid large thin-walled parts had large deformations and vibrations during robotic thinning machining, which led to a degradation of the surface quality of the workpieces and difficulties in ensuring the accuracy of the remaining wall thickness. To this end, a VCM-driven follower support head was used for vibration and deformation suppression, and a FLADRC based control strategy was proposed for depth of cut of robotic milling thin-walled parts. In order to verify the effectiveness of the control strategy, the system control models were firstly established based on the MATLAB/Simulink simulation and experimental platform, and the simulation analysis was carried out, then experimental verification was carried out on the thin-walled parts robotic milling experiment platform. Both of the simulation and experimental results show that the depth-of-cut control strategy based on the follower support head may significantly suppress the vibrations and deformations during the machining processes of thin-walled parts and effectively ensure the accuracy of the remaining wall thickness. In addition, compared with the traditional fuzzy PID control, the FLADRC has a better control effectiveness and exhibits higher robustness in the presence of external disturbances. Reference | Related Articles | Metrics | Comments（0）

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Generation Method of Milling Paths of Open Blisk Channels Based on Parameter Mapping HAN Jiang1, 2, ZHANG Wenqiang1, 2, TIAN Xiaoqing1, 2, XIA Lian1, 2 China Mechanical Engineering    2025, 36 (04): 688-696.   DOI: 10.3969/j.issn.1004-132X.2025.04.005 Abstract （883）      PDF（pc） （9035KB）（30）       Knowledge map    Save A machining strategy for variable layer thickness with layered surfaces was proposed to address the rough machining issues of the channels across the entire blisk components. Considering the characteristics of the variation in the width of the channels across the entire blisk components, the geodesic offset was used to determine the toolpath boundaries on both sides of the channels, and the step size and the number of paths were determined. A planning method for the longitudinal milling path along the channels was proposed, and then the tool axis vector of the channel boundaries is calculated, and the tool axis vector of the middle cutter positions of the channel boundaries is calculated by quaternion interpolation. The calculation results show that, compared with the conventional uniform layering method using the blisk hub rotary surface offset or the blisk covering rotary surface offset, the variable layer thickness surface delamination may better adapt to the surface changes from the covered rotary surface to the hub rotary surface, the surface quality of the blades is ensured, with the advantage of a uniform machined blade surface allowance, and the feasibility of the algorithm was verified through machining examples.  Reference | Related Articles | Metrics | Comments（0）

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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 （808）      PDF（pc） （4422KB）（454）       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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Instantaneous Milling Force Modeling and Coefficient Calibration Method of Variable Helical Circular-arc End Mills with Unequal Rake Angle QI Shutao, LI Jiaqi, ZHENG Shucai, XU Jinting, SUN Yuwen China Mechanical Engineering    2025, 36 (04): 681-687,696.   DOI: 10.3969/j.issn.1004-132X.2025.04.004 Abstract （807）      PDF（pc） （5531KB）（29）       Knowledge map    Save Variable helical end mills with unequal rake angle maight effectively suppress milling chatters, which significantly improved the machined surface quality and simultaneously reduced the risk of tool breakages, however, due to the unequal geometric parameters of each cutting edge, the existing models had difficulty to accurately predict the cutting forces, hence, a new instantaneous milling force modeling and coefficient calibration method were proposed. Firstly, the geometry and position relational expression of the cutting edges for variable helical circular-arc end mills were given, then considering the tool runout and variation of geometrical parameters of cutting edges, an instantaneous uncut chip thickness calculation and element cutting force prediction model was established; Subsequently, a nonlinear optimization method to simultaneously calibrate the cutting force coefficients and tool runout parameters was proposed, and an efficient algorithm for solving the model parameter initial values was also given based on linear least squares and oblique cutting theory. The experimental results show that the amplitude and waveform of predicted cutting forces are consistent with the measured ones with errors of less than 15%, verifying the effectiveness of the proposed model. 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 （683）      PDF（pc） （12617KB）（134）       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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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 （564）      PDF（pc） （4789KB）（92）       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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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 （429）      PDF（pc） （7020KB）（227）       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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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 （421）      PDF（pc） （6584KB）（149）       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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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 （382）      PDF（pc） （6279KB）（215）       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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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 （363）      PDF（pc） （12837KB）（169）       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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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 （361）      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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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 （334）      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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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 （334）      PDF（pc） （13816KB）（161）       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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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 （329）      PDF（pc） （14153KB）（133）       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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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 （319）      PDF（pc） （5871KB）（122）       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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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 （313）      PDF（pc） （8520KB）（152）       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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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 （311）      PDF（pc） （9034KB）（239）       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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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 （298）      PDF（pc） （15004KB）（151）       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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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 （298）      PDF（pc） （12715KB）（109）       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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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 （296）      PDF（pc） （9159KB）（109）       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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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 （295）      PDF（pc） （2504KB）（143）       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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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 （286）      PDF（pc） （9450KB）（130）       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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Fault Diagnosis of Rotating Machinery Bearings Based on Multi-source Wavelet Transform Neural Network GUO Haiyu1, ZOU Shenggong1, ZHANG Xiaoguang2, 3, 4, LU Fanfan2CHEN Yang2, WANG Han2, XU Xinzhi2 China Mechanical Engineering    2024, 35 (11): 2026-2034.   DOI: 10.3969/j.issn.1004-132X.2024.11.014 Abstract （285）      PDF（pc） （5837KB）（63）       Knowledge map    Save  A multi-source wavelet time-frequency transform convolutional neural network was proposed to address the issues of limited fault samples in rotating machinery bearing fault diagnosis, along with the vulnerability to overfitting and the poor generalization ability of traditional models when dealing with small datasets. Initially, for high-frequency data obtained from a single vibration sensor, a wavelet transform-based time-frequency convolutional layer was formulated to integrate both the real and imaginary components of wavelet coefficients. Here, the real component represented the amplitude information of vibration signals, while the imaginary component depicted phase information. Compared with a convolution layer that only considering real part, this convolutional layer may extract comprehensive time-frequency features. Subsequently, the time-frequency convolutional layer was employed to independently extract features from high-frequency data acquired by multi-sensors on a single device, and these features were then concatenated. Lastly, a dense module utilizing lightweight depth-separable convolution was developed to conduct further feature extraction from the concatenated features, facilitating fault classification. The effectiveness of the model was confirmed through experimentation using Case Western Reserve University rolling bearing dataset, achieving an accuracy of 98.5%.Additionally, the model was deployed for fault diagnosis in rotary kilns, belt conveyors, and grate coolers, demonstrating an average accuracy of 97.19%. 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 （284）      PDF（pc） （28888KB）（113）       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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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 （281）      PDF（pc） （8799KB）（106）       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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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 （280）      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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Deep Reinforcement Learning Method for Flexible Job Shop Scheduling ZHU Zhengyu1, GUO Jutao2, LYU Youlong3, ZUO Liling1, ZHANG Jie3 China Mechanical Engineering    2024, 35 (11): 2007-2014，2034.   DOI: 10.3969/j.issn.1004-132X.2024.11.012 Abstract （277）      PDF（pc） （4565KB）（76）       Knowledge map    Save Aiming at the flexible job shop scheduling problems under the mode of multi variety and small batch production, an intelligent scheduling method was proposed to minimize the total tardiness of orders based on combination rules and reinforcement learning. Transforming the flexible job shop production scheduling problem into a Markov decision process, according to the characteristics and optimization objectives of the problems, seven features were used to represent the workshop states, and six combination rules were designed as an action library. The problem was solved by using the improved DQN algorithm. Taking the aerospace structural parts machining workshop as a case study, the feasibility and effectiveness of the proposed method in shortening task delivery time are verified by comparing with other common rule-based methods in five different scale calculation examples. Reference | Related Articles | Metrics | Comments（0）

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Active Order Noise Control of Hybrid Electric Vehicles Based on Variable Order Notch Filter Algorithm ZHOU Xuelian1, HE Yansong1, SU Hongjian2, LIN Weixiong2, GUO Lin2, FU Xiaoyu1 China Mechanical Engineering    2024, 35 (11): 2082-2089.   DOI: 10.3969/j.issn.1004-132X.2024.11.020 Abstract （275）      PDF（pc） （5720KB）（48）       Knowledge map    Save  For the issues of decreased effectiveness in active noise reduction under acceleration conditions with rich and varying orders in the working speeds of hybrid electric vehicle engines, a variable order notch filter-x least mean square(VOFxLMS) algorithm was proposed, and a corresponding multi-channel active engine noise control system was established. In MATLAB/Simulink, the multi-channel active engine noise control simulation model was constructed for a seven-seat hybrid multi-purpose vehicle(MPV), by utilizing the actual vehicle acoustic path, in-cabin noise, and engine speed signals, two algorithms were employed for noise reduction simulation and comparison. Simulation results indicate that the proposed VOFxLMS algorithm may effectively reduce noise for specific orders at various charging speed points. Compared to the traditional notch FxLMS algorithm, the proposed VOFxLMS algorithms overall noise reductions at the left and right ears of the drivers seat and the third-row left seat are increased by 28.5%, 60%, 50% and 50%, respectively. The noise reduction effectiveness of the active engine noise control system employing the VOFxLMS algorithm was verified through on-road tests during acceleration conditions at speeds ranging from 70 to 100 km/h, and the system demonstrates effective suppression across various engine orders, including 2nd, 5th, 5.5th, 6th, 6.5th, 7th, and 8th orders. 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 （272）      PDF（pc） （4522KB）（118）       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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Multi-objective Scheduling Optimization for Hybrid Flow Shops with Limited Waiting Time and High Energy Consumption CHANG Daliang1, 2, 3, SHI Haibo1, 2, LIU Chang1, 2 China Mechanical Engineering    2024, 35 (07): 1269-1278.   DOI: 10.3969/j.issn.1004-132X.2024.07.015 Abstract （271）      PDF（pc） （2723KB）（86）       Knowledge map    Save In order to solve the hybrid flow shop scheduling problems with tight time and high energy consumption process characteristics, a hybrid flow shop scheduling model was established with the objectives of optimizing product exposure time, maximum completion time, and energy consumption. An improved multi-objective particle swarm optimization algorithm was proposed to optimize the hybrid flow shop scheduling problems effectively. Firstly, based on ISDE indicator and a local neighborhood search strategy the archive maintenance strategy was constructed to assist the algorithm to jump out of local extreme values and reduce production congestion. Then, based on fuzzy theory a decision analysis method was proposed to select the optimal scheduling. Finally, by simulation experiments, the feasibility and superiority of the proposed multi-objective scheduling model and optimization algorithm were verified.  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 （270）      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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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 （267）      PDF（pc） （9660KB）（89）       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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Performance Comparison of High-speed Laser Cladding Martensitic  Stainless-steel Coatings and Electroplating Coatings WANG Jing1, 2, AI Chao1, YUAN Xiao2, ZHU Xun2, GUO Fei2 China Mechanical Engineering    2024, 35 (08): 1480-1488.   DOI: 10.3969/j.issn.1004-132X.2024.08.016 Abstract （263）      PDF（pc） （15117KB）（83）       Knowledge map    Save  In order to compare the feasibility of high-speed laser cladding coatings replacing electroplated hard chrome coatings under different service conditions of hydraulic cylinders, martensite stainless steel cladding layers XG-1, XG-2 and electroplated hard chrome coatings were prepared respectively. The microstructure, hardness, corrosion performance and wear performance under simulated different conditions(scratch wear, dry sand grinding wear, sliding friction wear) of the three coatings were tested, and the coating failure behavior and application conditions were discussed. The results show that the microstructures of XG-1 and XG-2 coatings are dense and uniform, with an average microhardness of 720.5 HV and 653 HV, respectively. The electroplated hard chrome coatings contain defects such as pores and cracks, and the self-corrosion current density is about 10.45 μA/cm2, indicating the worst corrosion resistance. Under the three wear modes, the electroplated hard chrome coatings have cracked and peeled off, while the high-speed laser cladding coatings exhibit better wear resistance, which are suitable for the service conditions of hydraulic cylinders such as piston rod easily to be scratched, surrounding environment being rich in hard particle pollutants, and large lateral loads. Reference | Related Articles | Metrics | Comments（0）

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Bearing Fault Diagnosis of Mining Drilling Rig with Time-frequency-fused Deep Network ZOU Xiaoyu1, 3, SUN Guoqing1, WANG Zhongbin1, 3, PAN Jie2, LIU Xinhua1, 3, LI Xin1, 3 China Mechanical Engineering    2024, 35 (08): 1405-1413，1448.   DOI: 10.3969/j.issn.1004-132X.2024.08.009 Abstract （261）      PDF（pc） （9001KB）（79）       Knowledge map    Save To solve the problems of weak and noisy bearing fault features caused by the low-speed and heavy-load operating characteristics of mining drilling rigs, a fault diagnosis method was proposed for mining rig bearings, named time-frequency-fused deep network. It considered the limitations of fault diagnosis with single modality, and then jointly characterizes two modal features of the time domain and time-frequency domain. The designed diagnostic network differentially embeded specific attention mechanism in different modules to extract multi-dimensional key fault features. Finally, the proposed method was validated on the experimental equipment and the Case Western Reserve University bearing dataset. The results show that the proposed method may automatically extract sufficient fault features combining two domains. It has higher accuracy and noise immunity than those with a single domain. Reference | Related Articles | Metrics | Comments（0）

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Study on Influences of Load on Oil Film Interface Slip and Elastohydrodynamic Lubrication Characteristics GUO Chuang, ZHAO Erhui, QUAN Long, WANG Chengwen China Mechanical Engineering    2024, 35 (09): 1567-1574.   DOI: 10.3969/j.issn.1004-132X.2024.09.006 Abstract （258）      PDF（pc） （9210KB）（70）       Knowledge map    Save In order to explore formation and evolution mechanism of lubrication failure of friction pair in mechanical transmission system under harsh working conditions, a point contact elastohydrodynamic lubrication model was established considering oil film interface slip, and simulation calculation was carried out. The two-color light interference elastohydrodynamic lubrication test was carried out to study the influences of load on oil film interface slip in elastohydrodynamic lubrication, and then variation characteristics of entrainment velocity, hydrodynamic pressure, oil film thickness and slip parameters with load were studied under interface slip state. The results show that with the increase of load, the slip amplitude and slip range of interface increase significantly and the entrainment velocity in slip region decreases obviously. The dynamic pressure distribution in slip region tends to be uniform. In addition, slip region produces film thickness accumulation and inlet depression characteristics. The shape of slip region gradually presents the characteristics of “half crescent”. Reference | Related Articles | Metrics | Comments（0）