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Bearing Fault Data Generation Method Based on WLT-ACGAN JIAO Huachao, SUN Wenlei, WANG Hongwei China Mechanical Engineering    2025, 36 (03): 546-557.   DOI: 10.3969/j.issn.1004-132X.2025.03.018 Abstract （1670）      PDF（pc） （7836KB）（57）       Knowledge map    Save Using data generation method to generate high-quality data which made time-domain and frequency-domain features consistent with the real signals of bearing faults, and constructing balanced dataset, were of great significance for the establishment of an efficient diagnostic model of bearing faults in the case of data imbalance. In order to address the limitations of the existing data generation methods, which focused on a single feature in time or frequency domains, WLT-ACGAN was proposed herein. Firstly, a WLT network was constructed with a multi-layer neural network based on the principle of wavelet transform. The wavelet transform and inverse transform were simulated, and the mapping relationship between time-domain signal and frequency-domain signal was established. Secondly, the WLT network was embedded into ACGAN model as the primary component of model generator. Finally, two discriminators were constructed with different functions, enabling the improved ACGAN to learn time-domain and frequency-domain feature information of authentic bearing vibration signals concurrently. Experimental results show that the bearing vibration signals generated by WLT-ACGAN model exhibit consistent time-domain and frequency-domain features with those of the actual bearing vibration signals. Furthermore, the fault diagnostic model constructed with the balanced dataset augmented by the generated signals exhibits a high degree of accuracy when the data are imbalanced. Reference | Related Articles | Metrics | Comments（0）

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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, SHAN Chenwei１, ２, XIA Ziwen1, 2 China Mechanical Engineering    2025, 36 (04): 636-645.   DOI: 10.3969/j.issn.1004-132X.2025.04.001 Abstract （1655）      PDF（pc） （25364KB）（145）       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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Cross-domain Fault Diagnosis of Bearings Based on Joint Subdomain Contrast Alignment YANG Kang1, CHEN Xuejun1, 2, ZHANG Lei3, LIU Feng3 China Mechanical Engineering    2025, 36 (05): 1065-1073.   DOI: 10.3969/j.issn.1004-132X.2025.05.018 Abstract （1592）      PDF（pc） （5744KB）（29）       Knowledge map    Save The fault data of bearings exhibited significant distribution discrepancies under varying operating conditions， relatively low diagnostic accuracy was resulted in practical fault detection models. Additionally， most existing research on cross-domain bearing fault diagnosis primarily emphasized inter-domain alignment and intra-class comparison， while neglecting the influences of interactions between subdomains. Therefore， a cross-domain fault diagnosis method of bearings was proposed based on joint subdomain contrast alignment. In order to highlight the fault features， the bearing vibration signals were transformed into time-frequency graph by short-time Fourier transform， and the fault features were obtained by inputting them into the feature extraction module. Domain adaptation methods achieved cross-domain recognition by transferring knowledge learned from the source domain to the target domain. During the domain adaptation processes， a joint subdomain contrast alignment strategy was used to bring samples from the same subdomain closer together while separating samples from different subdomains， which aligned the subdomain distributions of the same class samples among the source and target domains， thereby enhancing the models generalization ability in the target domain. Resnet34 was used as the feature extraction network on the model architecture， and the maximum mean difference was used at the output of the network to align the global distribution of the source domain and the target domain. Compared with the classical domain adaptation methods， the experimental results on the bearing fault data set of Case Western Reserve University shows that the cross-domain fault diagnosis method of bearings based on joint subdomain contrast alignment has better feature transfer ability.  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 （1542）      PDF（pc） （7015KB）（110）       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 （1495）      PDF（pc） （8056KB）（52）       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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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 （1484）      PDF（pc） （5837KB）（81）       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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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 （1328）      PDF（pc） （11269KB）（135）       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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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 （1263）      PDF（pc） （7105KB）（44）       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 （1138）      PDF（pc） （9510KB）（93）       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 （1096）      PDF（pc） （8675KB）（108）       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 （996）      PDF（pc） （9035KB）（42）       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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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 （974）      PDF（pc） （5531KB）（39）       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 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 （972）      PDF（pc） （4422KB）（474）       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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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 （789）      PDF（pc） （12617KB）（143）       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 （694）      PDF（pc） （4789KB）（108）       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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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 （505）      PDF（pc） （5871KB）（136）       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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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 （488）      PDF（pc） （6279KB）（223）       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 （449）      PDF（pc） （8473KB）（194）       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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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 （440）      PDF（pc） （15004KB）（168）       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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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 （436）      PDF（pc） （6974KB）（118）       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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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 （410）      PDF（pc） （12715KB）（112）       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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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 （399）      PDF（pc） （2504KB）（158）       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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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 （395）      PDF（pc） （4522KB）（125）       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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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 （387）      PDF（pc） （5720KB）（59）       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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Study on Absolute Linear Time-grid Displacement Sensors with  Multi-frequency Magnetic Field Coupling YANG Jisen1, 2, 3, YUAN Junsong1, 3, XIU Fu1, 3, LIU Jiacheng1, 3, ZHANG Xiaolong1, 3 China Mechanical Engineering    2025, 36 (05): 889-897.   DOI: 10.3969/j.issn.1004-132X.2025.05.001 Abstract （387）      PDF（pc） （8864KB）（143）       Knowledge map    Save Aiming at the problems of mutual crosstalk among magnetic fields affecting the measurement accuracy of the sensors and reducing the signal-to-noise ratio when the excitation frequency of two code channels of a dual-row planar magnetic field sensor was the same， a multi-frequency magnetic field coupled absolute linear time-grid displacement sensor design scheme was proposed， which achieved the solution to the problems of eliminating the crosstalk of the magnetic fields among the code channels while solving the absolute displacement. The sensor was divided into fixed scale and dynamic scale， both using double-layer alternating structure， fixed scale using two columns of incremental code channel combination， divided into fine and coarse machines， the pairs of poles of two rows of excitation coils were two integers of the reciprocal relation， the absolute displacement measurement was realized by using the pairs of poles within the displacement difference. Precision machine measurement channel and rough machine measurement channel were input  different frequencies of the excitation current signals at the same time，  the precision machine was input the 1 MHz high-frequency current signals， the high-frequency excitation current signals might effectively enhance the inductive signals， improve the signal-to-noise ratio of the electrical processing system. Through the method of outlier frequency reduction， the sensor resolution was improved， which effectively solved the problems that it were difficult to reconcile the signal-to-noise ratio enhancement of the signals by increasing the frequency of the excitation signals and the high resolution of the sensors. Theoretical validation and error analysis of the sensors were carried out through electromagnetic simulation analysis. Finally， the experimental platform was built to carry out prototype experiments， and the experimental results show that the absolute sensor structure with multi-frequency magnetic field coupling effectively eliminates the magnetic field crosstalk between the fine and coarse machines， and the signal-to-noise ratio of the sensors is improved， with measurement errors are less than ±17.34 μm in the measurement range of 140 mm.  Reference | Related Articles | Metrics | Comments（0）

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Hybrid Optimization for Housing Structure Stiffener and Support Location LI Jian1, DING Xiaohong1, ZHANG Yijie2, XIONG Min1, WANG Han1, ZHANG Heng1 China Mechanical Engineering    2025, 36 (01): 69-77.   DOI: 10.3969/j.issn.1004-132X.2025.01.007 Abstract （382）      PDF（pc） （9519KB）（71）       Knowledge map    Save The internal stiffener layout and support location of housing structure played an important role in improving of structural performance and lightweight. A design method for hybrid distribution optimization of stiffener and support locations of housing structures was proposed. Independent support elements and stiffener base structures were introduced to establish a mathematical model for the hybrid optimization of stiffener distribution and support location of the housing structure. The optimal design for stiffener distribution of the housing structure was performed by an adaptive growth method. The support location was optimized based on the bi-directional evolutionary structural optimization method. The results show that the support locations and distribution of stiffeners obtained from the hybrid optimization have better mechanics properties than the optimized results of the housing structure with known support locations. 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 （379）      PDF（pc） （4565KB）（90）       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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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 （376）      PDF（pc） （5557KB）（115）       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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Tool Wear Prediction Method Based on ISABO-IBiLSTM Model ZENG Hao, CAO Huajun, DONG Jianxiong China Mechanical Engineering    2024, 35 (11): 1995-2006.   DOI: 10.3969/j.issn.1004-132X.2024.11.011 Abstract （373）      PDF（pc） （8106KB）（79）       Knowledge map    Save Aiming at the existing tool wear prediction methods which caused the problems of poor prediction accuracy due to lack optimization algorithms and inadequate network structure. A tool wear prediction model with the combination of improved SABO(ISABO) and improved BiLSTM(IBiLSTM) network(ISABO-IBiLSTM model) was proposed. Firstly, the acceleration vibration signal and force signal data were preprocessed by truncation method, Hampel filtering method, and improved complete ensemble empirical mode decomposition with adaptive noise(ICEEMDAN)-improved wavelet thresholding noise reduction method. Then, the time-domain, frequency-domain, and time-frequency-domain features of the preprocessed signal data were extracted, and the features are screened by Spearman and maximum mutual information correlation coefficient to construct the inputs of the model. Finally, the ISABO algorithm was used to perform parameter optimization of the IBiLSTM network, and based on the obtained optimized parameters, the network was trained to achieve wear prediction. The experimental data analysis results show that the proposed ISABO-IBiLSTM model has a prediction accuracy of 98.49% to 98.83% for tool wear, which is significantly improved compared to BiLSTM, IBiLSTM, and improved convolutional neural networks(ICNN)-BiLSTM models. Reference | Related Articles | Metrics | Comments（0）

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Optimization Decision of CFRP Processing Parameters Considering Cutting Energy Consumption and Surface Quality YAN Wei1, 3, WANG Xinyi2, 3, ZHANG Hua3, ZHU Shuo2, 3, JIANG Zhigang2, 3 China Mechanical Engineering    2024, 35 (10): 1834-1844.   DOI: 10.3969/j.issn.1004-132X.2024.10.013 Abstract （368）      PDF（pc） （4698KB）（73）       Knowledge map    Save The factors affecting secondary processing energy consumption and quality of CFRP were more complex than those of traditional materials, which made the existing empirical formulas difficult to apply. Taking the cutting force analysis of CFRP secondary machining as the starting point, the optimization decision problems of CFRP processing parameters were studied by considering energy consumption and quality. Firstly, the effects of fiber angle on CFRP processing form were analyzed, and the cutting force models were derived. Secondly, a multi-objective optimization model was established with three cutting elements and fiber direction angle as variables and cutting energy consumption and surface roughness as objectives. A multi-mutation driven particle swarm optimization(DM-PSO) and AHP integrated processing parameter optimization decision-making method was proposed. Finally, the feasibility and superiority of the above models and methods were verified by the milling experimental design. Reference | Related Articles | Metrics | Comments（0）

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Effects of Instantaneous Currents and Subsequent Aging Processes on Mechanics Properties and Microstructure of 7075 Aluminum Alloys CUI Xiaohui1, 2, YU Zhuoxing1, XIAO Ang3, YAN Ziqin4, YANG Guang1, WANG Hanpeng1, LI Rui1 China Mechanical Engineering    2024, 35 (12): 2139-2148.   DOI: 10.3969/j.issn.1004-132X.2024.12.006 Abstract （365）      PDF（pc） （31804KB）（53）       Knowledge map    Save  The ultrafast solution with pulsed instantaneous currents and subsequent aging strengthening of aluminum alloys were proposed and the mechanics properties and microstructure evolution of aluminum alloys were analyzed by means of macro and micro experiments. The results show that the yield strength of 7075 aluminum alloys decreases gradually with the increase of discharge voltages, but the elongation of 7075 aluminum alloys shows a trend of “small increase-decrease-large increase”. When the peak pulse currents exceed 86 kA(corresponding to a discharge voltage of more than 9 kV), the mechanics tensile curve of the material appears the Portevine Le Chatelier(PLC) effects. When the peak pulse currents exceed 96 kA(corresponding discharge voltage exceeds 10 kV), the elongation of the samples increases by more than 508.09%. It is found that the dislocation density in the materials decreases at 10 kV voltage, η′ phase dissolves back into the aluminum matrix and forms susaturated solid solution, which significantly improves the plasticity of the materials. The results show that ultrafast(<1 ms) solution of 7075 aluminum alloys may be achieved by pulsed instantaneous currents. The strength of 7075 aluminum alloys reaches the peak after 21 hrs of artificial aging, and the hardness after peak aging reaches 98.69% of that of conventional solution quenching. 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 （364）      PDF（pc） （9450KB）（136）       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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Construction of Assembly Information Model Based on Assembly Feature Automatic Extraction for STEP Models JIA Kang1, 2, TANG Jing1, 2, REN Dongxu1, 2, WANG Hao1, 2, ZHAO Qiangqiang1, 2, HONG Jun1, 2 China Mechanical Engineering    2025, 36 (01): 123-132.   DOI: 10.3969/j.issn.1004-132X.2025.01.013 Abstract （357）      PDF（pc） （8528KB）（80）       Knowledge map    Save Assembly information modeling was the foundation of digital assembly and intelligent assembly. However, the manual interactive modeling was inefficient and prone to errors in assembly feature recognition and assembly feature fitting, which was difficult to meet the precise modeling needs of complex mechanical systems. Based on the assembly process information implied by a 3D assembly model, this paper used STEP model files as inputs to study the algorithms for automatic extraction of assembly features and recognition of fitting relationships focused on geometric information. Furthermore, an information reasoning algorithm was proposed for constructing an integrated assembly information model from the perspectives of assembly accuracy modeling and assembly sequence planning. Finally, the effectiveness of the proposed algorithms was demonstrated through the construction of assembly instance information models based on the developed system. 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 （348）      PDF（pc） （10594KB）（109）       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 Test Analysis of Flexible Joint Elastic Components LI Qi, GAO Hong China Mechanical Engineering    2024, 35 (10): 1815-1823,1844.   DOI: 10.3969/j.issn.1004-132X.2024.10.011 Abstract （348）      PDF（pc） （9047KB）（95）       Knowledge map    Save A method for designing elastic components for flexible joints was designed, the design concept and design approach of the cross spring sheet-type elastic components was proposed. Firstly, the structure composition of the flexible joints was planned, the mechanics models of elastic components were established based on beam constraint conditions and constitutive relationships, the specific items of the flexibility matrix and stiffness matrix were determined, and the dynamics modeling of the motion end of the flexible joints was performed simultaneously. Next, instances of the elastic components was designed, and the design was validated through finite element analysis, the modal frequencies and mode displacement of the flexible joints during motion were simulated. Finally, an experimental system was set up to test the designed instances of the elastic components, and the rotational stiffness was calculated. Through cross-validation and analysis of three sets of data samples, the results show good consistency between the theoretical, simulated, and experimental values of the designed elastic components, with a maximum error of 7.59% in the first set, 4.32% in the second set, and 6.70% in the third set. This indicats the feasibility of designed elastic components using beam constraint theory and constitutive relationships. The proposed elastic joint elastic components are versatile and may be applied to articulated robotic arms and to rehabilitation robots and bionic robots, providing a new approach to the design of flexible joints for robots. 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 （341）      PDF（pc） （1871KB）（103）       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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Simulation Analysis and Process Study of Scribing Processes for GaAs Cleavage Processing ZHANG Qingzheng1, JIANG Chen1, GAO Rui2, JIANG Jinxin1 China Mechanical Engineering    2024, 35 (12): 2203-2210.   DOI: 10.3969/j.issn.1004-132X.2024.12.013 Abstract （326）      PDF（pc） （13141KB）（63）       Knowledge map    Save In order to effectively improve the quality of GaAs-based semiconductor laser cavity mirrors, a new type of scribing method was proposed and carried out in simulation analysis and processing experiments. A finite element simulation model of the scribing processes of GaAs materials was established to optimize the existing processing methods and to investigate the distribution of scribing loads and stresses under different processes. A cleavage processing validation experiment was carried out to analyze the morphological characteristics of the cleavage surfaces. It is found that the optimized processing method, which involves scribing from the inside out, can effectively reduce the degree of material surface damages in the scribing processes and reduce the brittle fracture phenomenon. The experimental results were in high consistency with the simulation ones. 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 （324）      PDF（pc） （5325KB）（110）       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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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 （321）      PDF（pc） （7951KB）（186）       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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Study on Formability Enhancements and Springback Reduction Effects of Aluminum Alloys under High Strain Rate XIA Liangliang1, XU Yong2, LI Jie3, XIE Wenlong2, LIU Xuefei3, ZHANG Shihong2 China Mechanical Engineering    2024, 35 (12): 2177-2184.   DOI: 10.3969/j.issn.1004-132X.2024.12.010 Abstract （315）      PDF（pc） （14801KB）（53）       Knowledge map    Save  Aiming at the problems of ruptures due to low formability and dimensional deviations due to large rebound of complex thin-walled components of high-strength and lightweight materials during room temperature forming, 2024 aluminum alloy which was widely used in the aerospace field, was used as the object of the study, and the unidirectional tensile tests were carried out respectively at low and high strain rates to investigate the effects of strain rate on the plasticity of 2024 aluminum alloys. By comparing and analyzing the bending forming of sheet at different angles under traditional stamping, high-speed stamping and impact hydroforming, the study decoupled into the effects of high strain rate and liquid medium on sheet springback. The results suggest that under high strain rate loading, the 2024 aluminum alloys demonstrate a significant enhancement in formability, with a maximum elongation increase of up to 112.92%. Under the impact hydroforming mode, which combined the characteristics of high-strain-rate and liquid medium loading, the 2024 aluminum alloys exhibit a significant reduction in springback, with a maximum reduction in springback angle of up to 110.25%, even leading to a negative springback phenomenon.  Reference | Related Articles | Metrics | Comments（0）