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Nanosecond Laser Machining of Spiral Grooves of Dry Gas Seal Rotational Ring Surfaces Wenqian LI, Zhanqiang LIU, Jinfu ZHAO, Bing WANG, Yukui CAI China Mechanical Engineering    2025, 36 (10): 2207-2214.   DOI: 10.3969/j.issn.1004-132X.2025.10.006 Abstract （719）   HTML （156）    PDF（pc） （3972KB）（1086）       Knowledge map    Save An experimental study on the nanosecond laser processing of the spiral groove on the dry gas seal rotational ring surfaces made of GH4169 was carried out. Orthogonal tests and one-factor methods were utilized to reveal the effects of laser power， scanning speed， filling spacing and repetition frequency on the spiral groove depth and bottom roughness Ra， and to determine the appropriate combination of laser processing parameters. The results show that the greatest influence on the depth of the spiral grooves on the surfaces of GH4169 alloy is the laser power， followed by the repetition frequency and the scanning speed， and the greatest influence on the roughness of the groove bottoms is the scanning speed， followed by the repetition frequency and the scanning spacing. With the laser power of 18 W， scanning speed of 40 mm/s， fill spacing of 0.005 mm， and repetition frequency of 50 kHz， the spiral grooves on the machined rotational ring surfaces is able to meet the machining requirements of groove depth of 7 μm， and groove bottom roughness of Ra≤0.8 μm. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Molecular Dynamics Simulation of Microscopic Crack Initiation and Extension Mechanism in 8Cr4Mo4V Bearing Steels Tianyu MA, Gu GONG, Hongrui CAO, Jianghai SHI, Xunkai WEI, Lijun ZHANG China Mechanical Engineering    2025, 36 (10): 2179-2189.   DOI: 10.3969/j.issn.1004-132X.2025.10.003 Abstract （773）   HTML （123）    PDF（pc） （7456KB）（935）       Knowledge map    Save To investigate the influences of cementite on the mechanics properties of the matrix and the initiation and propagation of microcracks in 8Cr4Mo4V bearing steels， molecular dynamics models were used to systematically analyze the effects of cementite's geometric parameters （such as shape， size， and position） on crack initiation and extension mechanism. And combined with cohesive force theory， the characteristics of interface crack propagation were studied. The results indicate that cementite significantly enhances the mechanics properties of the bcc-Fe matrix， with smaller cementite particles providing a more pronounced strengthening effectiveness. While the shape and position of cementite exert a relatively minor impact on overall mechanics performance， sharper inclusions accelerate crack propagation， and the position of inclusions determines the crack propagation path. Furthermore， interfaces between the bcc-Fe matrix and cementite， as well as twin boundaries with larger misorientation angles， exhibit increased resistance to crack initiation and propagation. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Tribological Properties of Polyelectrolyte-Modified PEEK Composite Materials GAO Chuanbao, ZHANG Xinyue, CEN Jiajia, CHEN Qin, FENG Haiyan, CHEN Kai, ZHANG Dekun China Mechanical Engineering    2026, 37 (1): 14-21.   DOI: 10.3969/j.issn.1004-132X.2026.01.002 Abstract （408）   HTML （130）    PDF（pc） （2572KB）（826）       Knowledge map    Save To enhance the tribological properties of PEEK， a “modify-then-form” approach was proposed. Hydrophilic SPMK was grafted onto the PEEK powder surface via UV-induced polymerization， then the PEEK-SPMK composites were prepared by hot-pressing. The friction and wear behaviors of modified PEEK under various operating conditions were analyzed， revealing the influence mechanism and lubrication mechanism of polyelectrolyte SPMK powder modification on the tribological behavior of PEEK composites.Results indicate that SPMK powder modification significantly enhances PEEK surface wettability. The friction coefficient（0.028） and wear rate（5.6×10{}^{-\mathrm{7}} mm³/（N·m）） of PEEK-SPMK in physiological saline are markedly reduced compared to pure PEEK. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Method for Accelerated Tribological Property Evolution Experiments of Conformal Contact Surfaces in Mixed Lubrication Regime ZHANG Ziyang, GONG Yajing, WANG Yuechang China Mechanical Engineering    2026, 37 (1): 22-29.   DOI: 10.3969/j.issn.1004-132X.2026.01.003 Abstract （292）   HTML （101）    PDF（pc） （2108KB）（811）       Knowledge map    Save An acceleration experimental design method for hybrid-lubrication conformal-contact surface tribological evolution was proposed. The method was based on the concept of “viscosity-reduction acceleration”， where the asperity contact states were preserved while the evolution of tribological behavior was accelerated by increasing the interaction frequency between surface asperities. The approach was validated by Plint TE-92 friction and wear tester.The results show that at the non-accelerated condition （sliding speed is as 0.2 m/s， temperature is as 25 °C， duration is as 20 min） and the corresponding accelerated condition （sliding speed is as 0.4 m/s， temperature is as 47 °C， duration is as 10 min） share the highly consistent values of friction coefficient， and 3D surface parameters Sq and Ssk. It indicates that the wear effect of 10-minute in test with accelerated parameters is equivalent to that of 20-minute in test with non-accelerated parameters. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Influences of Rotational Speed and Flow Rate on Pressure Pulsations of a Rim-driven Axial Flow Pump Mengjie CHEN, Zhuo ZHANG, Wu OUYANG, Chenxing SHENG, Bao LIU, Wei LIU China Mechanical Engineering    2025, 36 (10): 2198-2206.   DOI: 10.3969/j.issn.1004-132X.2025.10.005 Abstract （469）   HTML （85）    PDF（pc） （5874KB）（806）       Knowledge map    Save A novel RDP generated pressure pulsations during operations， which might negatively impact pump performance and system stability. The numerical simulation was employed to analyze the external characteristics and internal flow patterns of RDP under different rotational speeds and flow conditions. Utilizing POD， the main energy modes were extracted through spatiotemporal feature decomposition to investigate the influences of rotational speed and flow rate on the pressure pulsation at the trailing edges of the impeller blades， revealing the relationship between nonlinear dynamics and fluid-structure interaction phenomena. The results show that each rotational speed corresponds to a distinct optimal operating point， with the optimal point shifting towards lower flow rates as the rotational speed decreases. Moreover， the pressure pulsations are predominantly governed by nonlinear dynamics behavior， with nonlinear interaction effects between the impeller blades and guide vanes becoming more pronounced at lower rotational speeds and higher flow rates. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Aerodynamic Optimization of Radial Turbines Based on Surrogate Model of Pre-screened Strategies and DFFD Parameterization Tianqi WANG, Jiang CHEN, Hang XIANG, Xiaofei SONG China Mechanical Engineering    2025, 36 (10): 2171-2178.   DOI: 10.3969/j.issn.1004-132X.2025.10.002 Abstract （567）   HTML （97）    PDF（pc） （3107KB）（744）       Knowledge map    Save There were some problems such as difficult geometric control， many control variables and low optimization efficiency in aerodynamic optimization of three-dimensional complex blade surfaces of radial turbines. To solve these problems， multi-degree-of-freedom parameterization of radial turbine runner and blade multidimensional geometry were implemented based on DFFD method. Then an differential evolution algorithm assisted by surrogate models of pre-screened strategies（Pre-SADE） was introduced. Finally， a data-driven three-dimensional aerodynamic optimization platform for centripetal turbines was constructed by combining python and batch script of process automation. The platform was used to carry out the joint optimization design of flow channel-static/rotating blades for the radial turbines. The results show that after optimization， the adiabatic efficiency and mass-flow of the design point of the centripetal turbines are increased by 1.66% and 1.7% respectively， which effectively reduces the shock intensity in the guide vane channel and the shock loss on the suction surfaces of the guide vane， and the efficiency characteristics of the design rotational speed are improved in all working conditions. Finally， the method and platform may ensure the aerodynamic optimization efficiency， and effectively reduce the optimization variables and sample real evaluation times， significantly improve the optimization efficiency， and meet the rapid and elaborate optimization design requirements of radial turbines. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Development and Applications of Metal Laser Additive Manufacturing Technology for High-end Equipment Kai YANG, Lei WANG, Yongkai TANG, Moubin LIU, Ziao GUO China Mechanical Engineering    2025, 36 (09): 2068-2080.   DOI: 10.3969/j.issn.1004-132X.2025.09.019 Abstract （601）   HTML （62）    PDF（pc） （3960KB）（706）       Knowledge map    Save A comprehensive review of the innovative applications and development of laser additive manufacturing technology in high-end equipment manufacturing was provided. Firstly， the basic principles and advantages were introduced， including the ability to achieve integrated manufacturing of complex structures， optimized design of materials and structures， and improvement of component performance. Further， the innovative opportunities brought by laser additive manufacturing technology to high-end equipment manufacturing in aspects were discussed such as new material development， new process innovations， new structures design， and new functions integration. The challenges faced in the applications of laser additive manufacturing technology in high-end equipment manufacturing were analyzed， such as technical difficulties in material system development and new material applications， manufacturing equipment development， online monitoring and quality control technology during the manufacturing processes， and improvement of post-processing technologies. Finally， the future development trends of laser additive manufacturing technology for high-end equipment were outlooked. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Tribological Properties and Mechanism of Nanostructured Carbon Films under Coupling Effect of Temperature and Electric Field YU Zhimin, CHEN Lei, FAN Xue China Mechanical Engineering    2026, 37 (1): 30-39.   DOI: 10.3969/j.issn.1004-132X.2026.01.004 Abstract （295）   HTML （50）    PDF（pc） （7563KB）（646）       Knowledge map    Save The nanostructured carbon films including amorphous carbon films and graphene nanocrystalline carbon films were prepared on SiO2 substrates. A self-designed reciprocating tribometer capable for applying coupled multi-physical fields was employed to investigate the tribological properties of the different nanostructured carbon films under the coupling effect of temperature and electric field. At room temperature， the electric field was the dominant factor for affecting the friction coefficient of nanostructured carbon films. When the temperature of tribopair was 200 ℃， temperature became the main influencing factor. Under the coupling effects of temperature and electric field， the structured evolution to graphitic-like structure leads the reduction of friction coefficient of amorphous carbon film. While the nanostructure of graphene nanocrystalline carbon film is stable， but the aggravated wear results in significant fluctuations of friction coefficient. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research Progresses of Current Carrying Tribological Behavior of Materials under Influences of Service Environment SHEN Mingxue, CHEN Siyang, WU Haihong, XIAO Li, Wang Nenghui, JI Dehui China Mechanical Engineering    2026, 37 (1): 2-13.   DOI: 10.3969/j.issn.1004-132X.2026.01.001 Abstract （447）   HTML （43）    PDF（pc） （29450KB）（620）       Knowledge map    Save The research progresses on current-carrying tribological behavior of materials under service environmental influences were reviewed herein. It was summarized that the tribological performance and the dynamic evolution of electrical arcs under various environmental conditions such as humidity， temperature， atmosphere， crosswind， and air pressure. The mechanism of current-carrying wear under different service environments was clarified， along with the roles of third‑body media （e.g.， water， ice， oxide films） induced by the environments in wear damage and arc erosion of the friction pairs. The intrinsic relationship between external environmental factors and material damage in current-carrying friction pairs was revealed to advance the development of current-carrying friction theory. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Experimental and Molecular Dynamics Simulation for Mechanics Properties of 45 Steel Treated by Plasma Zhaobo PENG, Jinxing KONG, Dongxing DU, Hankun LUO, Hen YUE China Mechanical Engineering    2025, 36 (10): 2190-2197.   DOI: 10.3969/j.issn.1004-132X.2025.10.004 Abstract （676）   HTML （48）    PDF（pc） （2599KB）（599）       Knowledge map    Save To investigate the influences of plasma treatment on the mechanics properties of 45 steel， the changes of mechanics properties of 45 steel before and after treatment were studied by combining experiments and molecular dynamics simulation. The test results show that the hardness and tensile mechanics properties of 45 steel are obviously decreased after plasma treatment. Under the treatment durations of 1， 5 and 10 min， the nano-hardnessis decreased by 12%， 21% and 28% respectively， and the longer the treatment time， the better the modification effect， and the duration of the modification effect is more than 20 h. When the thickness of tensile specimens is as 0.1， 0.15 and 0.2 mm， the tensile strength decreases by 3.3%， 4.5% and 5.3%， and the elongation after fracture decreases by 39.69%， 42.17% and 42.49%， respectively. The molecular dynamics simulation results show that the number and strength of Fe-Fe bonds in 45 steel are reduced after plasma modification， resulting in the reduction of yield strength and surface hardness of the materials， which is basically consistent with the experimental results. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Flow Field Characteristics of Mesoscopic Impinging Jets under Influences of Wall Micro-defects Rui HONG, Jianjun HU, Yang XIAO, Yaolan JIN, Jing YAO, Xiangdong KONG China Mechanical Engineering    2025, 36 (10): 2215-2223.   DOI: 10.3969/j.issn.1004-132X.2025.10.007 Abstract （351）   HTML （91）    PDF（pc） （4590KB）（594）       Knowledge map    Save In order to study the effects of micro-defects caused by erosion wear and cavitation on flow field law and fluid energy conversion characteristics after long-term service of the nozzle-receiver pilot stage of the jet pipe servo valves. Micro-PIV technology was used to directly test the flow structure and vortex distribution in the square cavity when the original mesoscopic close-range jet impacted the micro-defect target plate. The influences of micro-defect size， shape， and location on vortex morphology and the evolution were investigated， and the underlying mechanism governing the splitting and merging phenomena of vortex cores within a square cavity were elucidated. The results show that the existence of wall micro-defects directly affects the energy transfer and dissipation of the wall jets， leading to a significantly different vortex structure and energy distribution in the jet gap and square cavity than that when there are no defects. As the size of the micro-concave increases， the circular-like vortex pairs in the square cavity on both sides show a tendency to gradually split and move away from the bottom wall. While as the size of micro-convex increases， the cocoon-like vortex pairs in the square cavity on both sides show an evolutionary law of gradually normalization and moving closer to that of the bottom wall. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Instantaneous Covalent Bonding Modification of Diamond Surfaces with Graphene Bo YAN, Ni CHEN, Ning HE, Jiafeng SHE, Xianzi CHEN China Mechanical Engineering    2025, 36 (10): 2472-2475.   DOI: 10.3969/j.issn.1004-132X.2025.10.037 Abstract （527）   HTML （41）    PDF（pc） （2296KB）（508）       Knowledge map    Save The paper focused on the high-performance requirements for diamond engineering surfaces in high-tech fields such as aerospace， micro-electro-mechanical systems， biomedicine， and nuclear energy. It addressed key challenges including the susceptibility of diamond to graphitization and amorphization under high loads and contact with ferrous metals， as well as the poor frictional behavior of conventional diamond surfaces. A novel concept of “in-situ instantaneous transformation” of diamond surfaces into graphene was proposed， along with the development of a laser induced-flywheel mechanical cleavage method. This method successfully stabilized a unique diamond-nano-graphite-graphene covalent structure in ambient conditions. Experimental results demonstrate that this new structure synergizes the excellent properties of diamond， graphite， and graphene. It offers a novel approach to resolving engineering bottlenecks associated with diamond applications and holds promise for opening up new avenues for the use of diamond， diamond coatings， graphene， and all-carbon devices in mechanical， electronic， aerospace， and other fields. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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China Mechanical Engineering    2026, 37 (1): 1-1.   Abstract （207）   HTML （54）    PDF（pc） （276KB）（445）       Knowledge map    Save Reference | Related Articles | Metrics | Comments（0）

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Failure Probability Analysis of Temperature Field in Wet Friction Components Based on Macro-Micro Frictional Contact Model WU Jianpeng, DING Ao, MA Biao, LI Heyan, WANG Liyong, YANG Chengbing China Mechanical Engineering    2026, 37 (1): 40-50.   DOI: 10.3969/j.issn.1004-132X.2026.01.005 Abstract （285）   HTML （47）    PDF（pc） （29170KB）（430）       Knowledge map    Save Aiming at accurately quantifying the failure probability of temperature fields for wet friction components， a macro-micro friction contact model， with the interaction of thermal-mechanical coupling simulation and single asperity contact model， was established to acquire temperature， and a statistical model for temperature field failure probability was constructed. The method utilized kernel density estimation to establish the probability density function of failure parameters and emploied Monte Carlo simulation for probability calculation. Experimental results show high agreement between simulation data and test data. The established statistical model may effectively and accurately calculate the failure probability of wet friction components. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Intelligent Decision-making for Assembly Processes of Micro-device Products Lingling SHI, Yimin DU, Lili GUO, Zhijing ZHANG, Xin JIN, Jiadi LI China Mechanical Engineering    2025, 36 (10): 2159-2170.   DOI: 10.3969/j.issn.1004-132X.2025.10.001 Abstract （568）   HTML （54）    PDF（pc） （27673KB）（343）       Knowledge map    Save To solve the problems that the assembly process planning of micro-device products relies on manual experience heavily， a knowledge-driven fine-grained micro-device assembly process planning method was proposed. And a micro-device assembly process decision software integrating product and system knowledge was developed. This planning method took the resource constraints of the assembly systems into account， and planned the assembly processes of micro-devices from process， steps， and process parameters. Based on interval-type hesitant fuzzy entropy， a mixed attribute matching weight parameter determination method ensured the effectiveness of the process decision algorithm. The developed decision system realized rapid decision-making of the assembly processes of micro-device products. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research on Stochastic Nonlinear Optimal Control of Maglev Trains Weiwei LIU, Kuo LI, Hongji WANG, Xi YU China Mechanical Engineering    2025, 36 (11): 2583-2592.   DOI: 10.3969/j.issn.1004-132X.2025.11.013 Abstract （465）   HTML （1）    PDF（pc） （1506KB）（273）       Knowledge map    Save To improve the stability of the maglev systems， the stochastic differential equations for the controlled maglev systems were established based on Hamilton's theory， where the nonlinear characteristics of the aerodynamic lift and levitation forces were taken into account. The dynamic planning equations for an optimal control strategy were developed with the objectives of maximizing the reliability， extending the longest average first-passage time， and minimizing the maximum Lyapunov exponent. The results show that the conditional reliability of the maglev systems may be improved and the average first-passage time prolonged by considering the joint action of PD control and optimal control. Moreover， the maximum Lyapunov exponent is always negative， satisfying the conditions for the trivial solution of the maglev systems to be asymptotically stable with a probability of 1. After optimal control， the joint probability density of the systems undergoes a change in behavior， which improves the system's stability. When the intensity of Gaussian white noise is low， the optimal control strategy for maximum reliability has better performance indicators. However， the strategy for minimum the maximum Lyapunov exponent only exhibits good performance within a certain range. The study of the optimal control problem of the maglev trains provides a theoretical basis for improving the train's stability and prolonging the time until the first-passage failure occurs. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Overview and Prospects of Data-driven Low-carbon Design and Manufacturing of Electromechanical Products WANG Liming, XIAO Xingyuan, LI Fangyi, WANG Xiaoguang, LI Jianfeng, NIE Yanyan, LIU Weitong, LI Liuyuan, WANG Yitong, WANG Boyun, CUI Yuqi China Mechanical Engineering    2026, 37 (4): 764-779.   DOI: 10.3969/j.issn.1004-132X.2026.04.001 Abstract （1627）   HTML （22）    PDF（pc） （3560KB）（232）       Knowledge map    Save Carbon footprint data served as the core basis for quantifying the full life-cycle carbon emissions of electromechanical products and driving the low-carbon transformation of the manufacturing industries. Focusing on the whole processes of carbon footprint data from acquisition to application， the relevant research approaches were systematically reviewed. The acquisition technologies for multi-source heterogeneous carbon footprint data and the data quality evaluation system were organized， addressing the question of "how data comes". Focusing on “how to use”， applications of data-driven technologies in low-carbon design and manufacturing were elaborated， including data-based carbon footprint correlation modeling， intelligent prediction， generation of low-carbon design solutions， and multi-objective decision-making methods， as well as data-driven manufacturing energy consumption prediction， low-carbon process planning， and intelligent workshop scheduling strategies. Finally， challenges and future directions for data integrity and system integration in low-carbon manufacturing were discussed， offering theoretical references for the green and low-carbon development of electromechanical products. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A Full-position Welding Pool Identification and Deviation Measurement Method Based on DeepLab-EMCAD XIONG Yecheng, LIU Haisheng, WANG Zhongren, SHI Tielin, XIA Hai, YANG Hongbo China Mechanical Engineering    2025, 36 (12): 2993-3001.   DOI: 10.3969/j.issn.1004-132X.2025.12.023 Abstract （506）   HTML （4）    PDF（pc） （5775KB）（221）       Knowledge map    Save A method for full-position welding pool identification and deviation measurement was proposed based on DeepLab-EMCAD. A lightweight MobileNetV3 network was adopted as the backbone of the model encoder， and the atrous spatial pyramid pooling（ASPP） module was optimized to reduce the model parameters and improve the segmentation efficiency. The EMCAD multi-attention mechanism was integrated into the decoder to enhance the segmentation accuracy of the welding pools. A deviation calculation method was proposed to quantitatively describe the deviation based on the segmentation results of the welding pools. Experimental results show that compared with the baseline model， the proposed model improves the average intersection over union and average pixel accuracy in welding pool segmentations by 5.72% and 5.5% respectively， and the inference time is reduced by 29.69 ms， with the number of parameters decreasing by 4.854×107. Compared with classic segmentation networks， the proposed model has the best performance in handling the edges of the welding pools. The deviation detection errors are controlled within 0.1 mm. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A Novel Deformable Serial Pipeline Inspection Robots：Design， Modeling and Experimentation Yixin ZHANG, Yinan MIAO, Zhiheng YI, Wenjing WAN, Xingjian WANG, Song ZENG, Shaoping WANG China Mechanical Engineering    2025, 36 (09): 2140-2149.   DOI: 10.3969/j.issn.1004-132X.2025.09.026 Abstract （812）   HTML （14）    PDF（pc） （4346KB）（217）       Knowledge map    Save In response to the urgent demands for daily maintenance and inspection of oil and gas pipelines， a novel modular pipeline inspection robot named RoboChain-Ⅰ， featuring adaptive deformation capabilities， was proposed herein. Unlike most wheel-based pipeline robots， the robot adopted a cell-inspired modular biomimetic design with more flexible joint redundant rotational degrees of freedom（DOF）， allowing the robot to actively deform in response to pipelines with varying shapes and diameters. Each module was equipped with dual-wheel independent drive， and a pair of pitch and yaw actuation mechanisms were installed at the front and rear. The modules were connected by passive elastic damping support structures or controllable electromagnetic adhesion-separation rigid structures， which improved the robot's ability to navigate complex pipelines and adapt to various environments. The forces acting on the robots during their motions inside the pipeline were modeled， and kinematics simulations were conducted using Adams. The selection of design parameters for the model was validated accordingly. A comprehensive series of experiments were conducted to evaluate RoboChain-Ⅰ's performance， including terrestrial locomotion， straight pipe traversal， elbow pipe navigation， diameter-varying pipeline adaptation， and active mother-child separation. Experimental results validate the robot's effectiveness and reliability in performing inspection tasks within complex three-dimensional pipeline networks with diameters ranging from 175~440 mm， demonstrating maximum velocities of 0.87 m/s on flat surfaces and 0.4 m/s within pipelines. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Flow Field Disturbance and Stable Operation Characteristics of Marine Steam Turbines under Extreme Variable Conditions Yuang SHI, Lei ZHANG, Luotao XIE, Luhan YIN China Mechanical Engineering    2025, 36 (10): 2258-2265.   DOI: 10.3969/j.issn.1004-132X.2025.10.012 Abstract （420）   HTML （1）    PDF（pc） （2843KB）（216）       Knowledge map    Save To identify the mechanism of flow field disturbance in marine steam turbines under extreme variable conditions and ensure their safe and stable operations， a full-size three-dimensional through-flow and structural model of the high power density steam turbines was established. By introducing high-precision multi-layer grid division technology， combined with the Euler multiphase flow model and turbulence model， a numerical calculation method was proposed for internal steady-state and transient flow fields of steam turbines under a wide range of variable conditions. The analysis of flow field disturbance characteristics under variable conditions of the steam turbines was carried out， revealing the internal flow characteristics of the steam turbines under extremely low flow conditions， and the threshold values of instability flow and the stable operation power flow of the whole machine were determined. A unidirectional flow-solid coupling calculation method and process for the last stage of the steam turbines were proposed based on the high-precision flow field distribution basic data. The static and dynamic stress variation laws of key parts of the last stage blades were calculated， the flow-induced vibration excitation source of the last stage blades was identified， and the instability characteristics were analyzed. The vibration characteristics of the blades were evaluated， providing technical reference for the safe and stable operations of the steam turbines. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A Probabilistic Fatigue Life Prediction Method for Wind Turbine Towers Based on a Physics-informed Neural Network XIE Bingbing, ZHAO Feng, GUO Xinxing, QIAO Li, CHENG Sichuang, LIU Xiaohui, ZHANG Tongzhou, HU Weifei China Mechanical Engineering    2026, 37 (5): 1017-1025.   DOI: 10.3969/j.issn.1004-132X.2026.05.001 Abstract （357）   HTML （31）    PDF（pc） （2177KB）（197）       Knowledge map    Save To address the limitations that the traditional fatigue design for wind turbine towers using deterministic S-N curves might not accurately quantify fatigue life dispersion， a probabilistic fatigue life prediction method was proposed based on physics-informed neural networks. By embedding the physical prior knowledge such as fatigue life dispersion， monotonicity and nonlinearity into the neural networks， a probabilistic prediction model capable of accurately quantifying uncertainty was constructed. Compared with traditional methods， the proposed method reduces the normalized root mean square error（NRMSE） by up to 31.58%. A 16 MW wind turbine simulation model was established in accordance with IEC standards， and tower load data were obtained by using Bladed software. Combined with wind-speed distribution， rain flow counting and the Miner rule， the probabilistic fatigue life prediction of the towers was achieved. The results show that the proposed method effectively characterizes the probabilistic features of fatigue damages， and the tower lifetime varies significantly with reliability requirements （shortening from 83.3 years at 50% probability to 18.2 years at 99.9% probability）， which provides a reliable basis for probabilistic fatigue design and safety assessment of wind turbine towers. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Prediction and Conditioning of Surface Integrity for Cutting Difficult-to-machine Metallic Materials LIU Zhanqiang, ZHAO Yongyao, WANG Bing, ZHAO Jinfu, LIU Annan, YAO Longxu China Mechanical Engineering    2026, 37 (3): 509-527.   DOI: 10.3969/j.issn.1004-132X.2026.03.001 Abstract （492）   HTML （23）    PDF（pc） （3737KB）（184）       Knowledge map    Save Machined surface integrity， a composite reflection of the geometric， physical， chemical， and mechanical properties of the machined surface layers， is dictated by the thermo-mechanics loads and material removal modes inherent to the cutting processes. This integrity directly governed the in-service performance and lifespan of engineered components. A thorough investigation into how conditioning strategies influenced surface integrity was therefore fundamental to realize high-integrity surfaces， and was critically important for optimizing the machining of difficult-to-cut metallic materials. This review began by categorizing the metrics of machined surface integrity for these materials based on three aspects： geometric features， microstructural evolution， and surface-layer mechanical properties， while also summarizing the approaches for developing predictive models. Subsequently， it elucidated research advancements in machined surface integrity conditioning strategies of difficult-to-cut metallic materials， critically comparing the distinct influence mechanisms of tool and process optimization， multi-energy field assisted machining， and workpiece pre-treatment on machined surface integrity. Finally， this paper explored the prediction accuracy of current models and the general applicability of conditioning strategies， offering an outlook on future research priorities. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A Process Knowledge Generalization Based on Standardized Expression of Process Data Qiao ZHENG, Ruiqiang LYU, Bencheng CUI, Rui ZUO China Mechanical Engineering    2025, 36 (11): 2728-2737.   DOI: 10.3969/j.issn.1004-132X.2025.11.031 Abstract （380）   HTML （1）    PDF（pc） （4783KB）（175）       Knowledge map    Save In the aviation field， the reuse rate of process design knowledge for parts with long cycles and complex processes was low， and there was a lack of effective knowledge recommendation and inheritance. The current methods for process knowledge generalization mainly focused on using fuzzy knowledge and reasoning algorithms to overcome the dependence of process methods on the environment. These methods did not significantly help in addressing the incompleteness and inconsistency of formalized expressions. This paper was based on the standardized expression of process data， the knowledge graph construction and heuristic search for process recommendations were carried out， resulting in a higher knowledge reuse rate， which provided a way of thinking for the high-reusability， high-efficiency， and knowledge-driven process planning of parts with long cycles and complex processes. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Multi-objective Trajectory Planning of Manipulators Based on Improved SSA Jianlin LIU, Haisong HUANG, Qingsong FAN, Chi MA, Langlang ZHANG China Mechanical Engineering    2025, 36 (09): 2047-2056.   DOI: 10.3969/j.issn.1004-132X.2025.09.017 Abstract （1874）   HTML （8）    PDF（pc） （5244KB）（172）       Knowledge map    Save To optimize the three objectives of efficiency， energy consumption and impacts at the same time， a multi-objective trajectory planning model was proposed based on an improved SSA. Firstly， the artificial potential field method （APF） was used for path planning to obtain the shortest and collision-free path of the manipulator grasping the materials， and the key motion sequence was extracted to establish a multi-objective function. Then， aiming at the problems of multi-objective salp swarm algorithm （MSSA）， such as poor diversity of initial population， easy to fall into local optimum and slow convergence in solution set space， an improved algorithm namely logistic-sine multi-objective salp swarm algorithm（LMSSA）was proposed. The algorithm combined logistic-sine chaotic mapping， pinhole imaging learning strategy and golden sine development strategy to optimize the control nodes of the seventh-order B-spline curve and complete the multi-objective motion trajectory planning of the robotic arms. Finally， the trajectory planning model was applied to the actual grasping tasks of the manipulator UR16e by building MATLAB-CoppeliaSim-UR16e experimental platform. Experimental results show that based on LMSSA， the manipulator motion planning method realizes the accurate， efficient and energy-saving motion trajectory planning of the manipulator， and is successfully applied to the actual operation scenes. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Efficient Aerodynamic Optimization Method for Turbine Blades Based on Multi-degree-of-freedom Parameterized Dimensionality Reduction HUANG Pengfei, CHEN Jiang, CHENG Jinxin, LI Bin, XIANG Hang China Mechanical Engineering    2026, 37 (2): 255-263.   DOI: 10.3969/j.issn.1004-132X.2026.02.001 Abstract （381）   HTML （27）    PDF（pc） （14472KB）（170）       Knowledge map    Save In view of the high design dimension and difficulty in constructing surrogate models in the aerodynamic optimization of three-dimensional turbine blades， a multi-degree-of-freedom parameterized dimensionality reduction method was proposed to construct an efficient optimization framework， that integrated DFFD and PCA， and combined the pre-screened surrogate model assisted differential evolution （Pre-SADE） algorithm. Taking a small gas turbine as the object， a snapshot set was generated through experimental design， and the 36-dimensional DFFD design space was mapped to the 10-dimensional basis modal coefficient space. A concise and effective surrogate model was established in the dimensionality reduction space and rapid optimization was completed. The results show that the proposed method significantly reduces the shock wave intensity and aerodynamic loss while improving the design point flow （+0.46%） and isentropic efficiency （+3.191%）， and the optimization time is reduced by 24.58%. The study verifies the intuitiveness， effectiveness and optimization efficiency improvement advantages of this dimensionality reduction method in high-dimensional design problems， providing a more efficient and low-cost solution for blade aerodynamic optimization. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Thermal Image Input-based ResNet Method for Thermal Error Modeling of Machine Tool Spindles Mingfan LI, Long YANG, Sheng LI, Huan GUO, Guoqiang FU China Mechanical Engineering    2025, 36 (09): 2057-2067.   DOI: 10.3969/j.issn.1004-132X.2025.09.018 Abstract （1660）   HTML （1）    PDF（pc） （5627KB）（167）       Knowledge map    Save To achieve a high-precision and highly generalizable thermal error model of machine tools， a thermal image input-based ResNet method was proposed for thermal error modeling of CNC machine tool spindles. A thermal image dataset labelled was constructed with thermal error rounding， and a ResNet-based classification model was trained for thermal error prediction using thermal images as inputs. Considering the regression characteristics of the machine tool thermal error time series， a regression output layer was constructed by integrating the probabilities of different classification labels from the classification output layer in a weighted manner， enabling thermal error regression prediction without retraining. The deep features of thermal images and the classification performance of the ResNet model were visualized， confirming the effectiveness of ResNet in feature extraction and strong classification ability. Finally， the ResNet model was compared with GoogLeNet and VGGNet models under different operating conditions， demonstrating the high accuracy and generalization of the ResNet-based thermal error classification and regression models. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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A Method for Detecting Surface Defects on Wind Turbine Blades Based on Improved YOLOv5s Jun WANG, Guibing GAO China Mechanical Engineering    2025, 36 (09): 2108-2116.   DOI: 10.3969/j.issn.1004-132X.2025.09.023 Abstract （571）   HTML （0）    PDF（pc） （4285KB）（167）       Knowledge map    Save In order to improve the intelligent， efficient， and convenient development of wind turbine blade health monitoring technology， a wind turbine blade surface defect detection method was proposed based on improved YOLOv5s algorithm according to target recognition technology. Firstly， the original backbone network of YOLOv5s was replaced with an AFPN to enhance the network's learning ability. Secondly， the CBAM was embedded into the backbone extraction network， which enhanced the model's ability to extract surface defect features of leaves. Then， the minimum point distance intersection over union（MPDIoU） loss function was used to replace the CIoU loss function， improving the precision of bounding box localization. Finally， an improved detection method was used to detect defects in the blades of a certain wind turbine unit. The detection results show that the improved algorithm improves precision， recall and mean average precision（mAP） by 4.1%， 2.9% and 4.8%， respectively， reaching as 91.9%， 89.3% and 93.5%， which has significant precision advantages and better model stability. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research on Load Spectrum Editing Based on Optimal Pseudo Wigner-Ville Distribution Method Lingyun YAO, Zhishun YANG, Li LI, Yongjie LIN China Mechanical Engineering    2025, 36 (11): 2501-2508.   DOI: 10.3969/j.issn.1004-132X.2025.11.004 Abstract （380）   HTML （1）    PDF（pc） （2654KB）（164）       Knowledge map    Save To improve the quality of load spectrum editing， this paper utilized the PWVD method to edit the load spectrums. According to the principle of the minimum clustering metric parameter， the optimal PWVD matrix for the load spectrum was determined， and the instantaneous energy distributions of the load spectrums were calculated， which was used to delete small damage loads and generate a compressed load spectrum. The results show that the edited load spectrum based on the optimal PWVD method is consistent with the original load spectrum calculation results in terms of statistical parameters， power spectral density， rain flow count and fatigue simulation. The compressions of the load spectrum（Y⁃direction） edited by PWVD， Wigner-Ville distribution（WVD）， S transform and short time Fourier transform are as 28.21%， 15.02%， 19.15% and 15.79%， respectively. The predicted life of the edited load spectrum is the same as that of the original load. Therefore， the method of utilizing the optimal PWVD to edit the load spectrum has the potential for applications in accelerating the fatigue durability analysis of vehicle components. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Forward Kinematics and Singularity of Kinematically Decoupled Stewart-type Parallel Mechanisms Ningning HUANG, Jingjing YOU, Pengda YE, Huiping SHEN, Chenggang LI, Hongtao WU China Mechanical Engineering    2025, 36 (09): 1951-1960.   DOI: 10.3969/j.issn.1004-132X.2025.09.006 Abstract （436）   HTML （3）    PDF（pc） （3200KB）（163）       Knowledge map    Save The forward kinematics equation of the six-degree-of-freedom parallel mechanisms was nonlinear and strongly coupled， and generally did not have a symbolic positive solution， which was not conducive to the real-time feedback control of the robots. Thus， a “7-4” Stewart-type parallel mechanism was designed with weak coupling in structures but decoupled in motions. The forward kinematics equation and link length coordination equation were solved analytically， and the singularity research was carried out. Firstly， based on the “2-1” kinematic links， a six-degree-of-freedom “7-4” Stewart-type parallel mechanism was synthesized， and the structural coupling characteristics of the mechanisms were analyzed based on the azimuth feature set theory. Secondly， based on 13 compatible equations and the theory of tetrahedral geometry， an analytical algorithm for solving the forward kinematics equation was proposed. At the same time， it was proved that the number of real solutions under general configuration was 8（they were symmetrical about the same plane ）. Then， according to the geometric constraint relationship between the moving ball hinges， the link length coordination equation was constructed. It is found that the equation also has a symbolic solution. The Jacobian matrix of the mechanisms was derived， and various singular types were analyzed. Finally， the internal relationship between the forward kinematics and singularity of the parallel mechanisms was analyzed. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Experimental Study of Characteristics of Gas Pressure Reducing Valves under Different Working Conditions Bin QIN, Jiaxu HAO, Jingwen LIN, Quan ZHANG China Mechanical Engineering    2025, 36 (11): 2477-2485.   DOI: 10.3969/j.issn.1004-132X.2025.11.001 Abstract （453）   HTML （11）    PDF（pc） （1718KB）（163）       Knowledge map    Save Pressure reducing valves were often used in gas pipeline systems to control the downstream pressure. At present， the pressure reduction range of conventional small pressure reducing valves was small， and it was difficult to meet the pressure reduction demands under ultra-high pressure. A small pressure reducing valve with adjustable output pressure under ultra-high pressure was proposed， with an input pressure of 19~60 MPa and an output pressure of 7~13 MPa. By establishing a test platform and setting different upstream pressure and downstream resistance of the pressure reducing valves， the stability of the performance of the pressure reducing valves and the characteristic change were studied under four types of working conditions. Through experimental validation， the pressure reducing valve may maintain stable downstream pressure in ultra-high pressure usage scenarios. The response time of the valves after the pipeline connection is between 0.5 and 6.0 seconds， with pressure fluctuations within 10 seconds after response being between 0.12% and 4.49%. The results indicate that the trend of pressure changes after the reducing valves are related to the upstream pressure： when the upstream pressure decreases， the output pressure first declines and then rises， while when the upstream pressure is stable， the output pressure tends to decrease. The results may guide the applications of the pressure reducing valves in hydraulic systems. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Design and Experimental Study of Stiffness Self-tuning Wideband Dynamic Vibration Absorbers Zhi WANG, Shanfu LI, Jing TIAN, Mengkang YUE China Mechanical Engineering    2025, 36 (11): 2593-2600.   DOI: 10.3969/j.issn.1004-132X.2025.11.014 Abstract （419）   HTML （2）    PDF（pc） （4520KB）（156）       Knowledge map    Save To address the issues of traditional dynamic absorbers losing resonance and exhibiting a significant decline in vibration reduction performance when the external excitation frequency shifted， a novel wideband dynamic vibration absorber was designed that altered the stiffness to change the natural frequency， and to broaden the vibration absorption bandwidth. The vibration absorption and frequency adjustment mechanism of the absorbers were theoretically analyzed， followed by PID parameter optimization by using an ISSA， finally， an ISSA-PID controller was employed to adjust the structural parameters of the absorbers， achieving adaptive wideband vibration absorption. Simulation results indicate that the ISSA optimization requires fewer iterations and demonstrates greater optimization capability compared to the sparrow search algorithm（SSA） optimization. The control scheme optimized by ISSA reduces the overshoot by 44.8% compared to that of the pre-optimization condition and reduces by 33.3% compared to that of the SSA-optimized scheme. In addition， the settling time of the control scheme optimized by ISSA is reduced by 16.2% compared to that of the SSA-optimized scheme. The testing results indicate that the wideband dynamic vibration absorber has a wide vibration absorption bandwidth and significant vibration reduction effectiveness， demonstrating substantial engineering application value. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Ultrasonic Assisted Cutting Simulation and Validation Experimental Research Based on River Ice Mesostructure Guojun DONG, Ruida LAI, Yong DAI, Zhiqing GUO, Mengwei WU China Mechanical Engineering    2025, 36 (10): 2405-2412.   DOI: 10.3969/j.issn.1004-132X.2025.10.030 Abstract （396）   HTML （0）    PDF（pc） （4829KB）（154）       Knowledge map    Save Taking the Songhua River ices as the research objects， starting with the study of the mesostructure of river ices and combined with ultrasonic assisted cutting validation experiments， the effectiveness of ultrasonic-assisted ice cutting and the feasibility of improving production efficiency were analyzed. The simulation results indicate that ultrasonic assisted cutting may reduce the cutting force by approximately 38% when applied to the complex crystalline structure of natural river ices. Validation experiments demonstrates that this method enhances the feed rate and maintains the cutting quality of the ices， effectively preventing edge collapse and crack formation. In comparison to traditional cutting techniques， there is a significant improvement in both production quality and efficiency for river ices， thereby confirming the feasibility of employing ultrasonic assisted cutting for large-scale preparation of standard ice blocks. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Rotor Unbalance Recognition Based on Multidimensional Complex Feature Fusion and CNN-GRU Jianjian WANG, Yuhe LIAO, Lei YANG, Jiutao XUE China Mechanical Engineering    2025, 36 (09): 1905-1915.   DOI: 10.3969/j.issn.1004-132X.2025.09.001 Abstract （771）   HTML （11）    PDF（pc） （3434KB）（153）       Knowledge map    Save The existing unbalance identification algorithm without trial weight adopted an optimization algorithm framework and approximated the optimal solution through numerous iterative operations. However， such strategies typically faced the limitations of slow convergence speed and the tendency to fall into local extrema. Therefore， neural networks were used to directly learn and analyze the complex mapping relationship between unbalance vibration response and unbalance， thus realizing high-precision unbalance identification. A sufficient unbalance vibration dataset with labels was constructed by simulating the rotor dynamics model. A feature fusion mechanism was designed to address the multi-dimensional complex-valued characteristics of unbalanced data. At the core algorithm level， a CNN-GRU hybrid model was constructed. In this model， CNN was responsible for extracting local spatial features from vibration data， while GRU captured temporal dependencies within the vibration data. By integrating information from both spatial and temporal domains， the model’s generalization ability and recognition accuracy were significantly enhanced. The unbalance recognition results of test set data and experimental bench demonstrate that this method may accurately predict the unbalance of the rotors， providing a rapid and accurate guide for dynamic balancing in the field without trial weights. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research on Differential Steering Mechanism Based on Tire Cornering Biaofei SHI, Xiaoming YE, Haoyu LYU, Feng LAI China Mechanical Engineering    2025, 36 (10): 2224-2231.   DOI: 10.3969/j.issn.1004-132X.2025.10.008 Abstract （1754）   HTML （55）    PDF（pc） （1816KB）（151）       Knowledge map    Save Differential steering based on tire cornering suited low-speed， large steering radius scenarios of distributed drive electric vehicles（DDEV） without steering mechanisms. In order to study the mechanism of differential steering based on tire cornering， a 7-degree-of-freedom DDEV dynamic model with no steering mechanism and PAC2002 tire model were established. Then， the formation mechanism of differential steering was analyzed and a systematic analysis method from the input of differential longitudinal force to the output of vehicle steering radius of differential steering was proposed by considering the tire force longitudinal-lateral-coupling characteristics. Leveraging the proposed systematic analysis method， the stability of differential steering and the influences of differential longitudinal force， vehicle parameters and tire characteristics on steering radius were studied. Finally， a Carsim/Simulink joint simulation platform was established to simulate differential steering under different influencing factors. The results show that within the range of tire cornering， the larger the differential longitudinal force， the larger the ratio of track width to wheelbase， and the smaller the tire lateral stiffness， the smaller the steering radius. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Prediction of Fatigue Property of SLM Metal Parts Based on Multi-scale Simulations Jinyu ZHOU, Yifei CHEN China Mechanical Engineering    2025, 36 (09): 2087-2096.   DOI: 10.3969/j.issn.1004-132X.2025.09.021 Abstract （419）   HTML （1）    PDF（pc） （3453KB）（145）       Knowledge map    Save A multi-scale ternary numerical model of “process-microstructure-properties” was proposed to investigate the relationships of the processing parameters of metal SLM， the microstructure of the formed parts and the fatigue properties. In detail， to analyze the evolution processes of temperature field， velocity field， and pore defects under different processing parameters， the meso dynamics process of the molten pool was studied with consideration of multiple physical field coupling phenomena such as recoil force. Using the temperature field data， the microstructure distribution of the representative volume element（RVE） was obtained based on cellular automaton model， and the effects of processing parameters on grain sizes and defect characteristics were investigated. Finally， the hazard levels of defects were evaluated under different processing parameters by stress intensity factors， and the macro fatigue strength of corresponding RVE was predicted. The results show that the proposed multi-scale model may effectively predict the fatigue properties of SLM metal parts under different processing parameters. This work provides a reference for optimizing SLM processing parameters. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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China Mechanical Engineering    2025, 36 (12): 3065-.   Abstract （130）      PDF（pc） （669KB）（145）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Full-cycle Fatigue Life Prediction of Rolling Bearings Based on Paris Modeling Huiming YANG, Xia YANG, Yuqi HUANG China Mechanical Engineering    2025, 36 (09): 2003-2010.   DOI: 10.3969/j.issn.1004-132X.2025.09.012 Abstract （730）   HTML （8）    PDF（pc） （2078KB）（141）       Knowledge map    Save In order to predict the fatigue life of rolling bearings， a modified critical plane was established according to the bearing crack extension mode， which transformed the cracks from two-dimensional extension to three-dimensional extension. Combining the Smith-Watson-Topper-fatigue indicator parameter（SWT-FIP） method with S-N curve， based on the modified critical plane method and the modified Paris model， the equivalent elliptical crack area difference was used as fatigue crack extension characterization quantity， and the equivalent crack length was calculated to establish a full-cycle fatigue life prediction model of the rolling bearings covering crack initiation life， crack extension life and fatigue spalling life. The full-cycle fatigue life prediction model was validated with 2 types of accelerated life test datasets of bearings， and compared with L-P model and original Paris model. Results show that the full-cycle fatigue life prediction model of rolling bearings may predict the fatigue life of bearings more accurate than that of original Paris model and L-P model. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Filtering Characteristics of WJGL Pulsation Attenuator Based on Electro-Hydraulic Analogy Principles Chaozhong MENG, Fan YANG, Jiaxin YU, Yuqiang WANG China Mechanical Engineering    2025, 36 (09): 1961-1967.   DOI: 10.3969/j.issn.1004-132X.2025.09.007 Abstract （480）   HTML （1）    PDF（pc） （2019KB）（139）       Knowledge map    Save In WJGL， the instability in water jet from low-frequency pressure pulsations （0~500 Hz） in fluid supply systems needed urgent resolution. A water pressure pulsation attenuator was designed using flexible liners for coupling vibrations and Herschel-Quincke tubes （HQ tubes） for phase cancellation， achieving dual filtering. A transfer matrix model was established based on one-dimensional analytical approach and electro-hydraulic analogy principle， and the feasibility was experimentally verified through prototype testing. The influence mechanism of key parameters， such as HQ tube structures， insert tube lengths， and liner elastic modulus on low-frequency pulsation attenuation were quantitative analyzed in simulations. The results show that the damping performance of polyurethane liners improves as their elastic modulus decreases， while the loss angle negatively affects transmission loss. Under certain conditions， changing the insert tube lengths has minimal impact on transmission loss（TL）， but increasing the HQ tube lengths and reducing the diameter enhances attenuation. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Design and Optimization of Human-machine Compatibility of Knee-ankle Exoskeletons Xinyao TANG, Rong YIN, Xupeng WANG, Jiayin YANG, Xiaoyi LIU, Yuyang HAO China Mechanical Engineering    2025, 36 (10): 2369-2378.   DOI: 10.3969/j.issn.1004-132X.2025.10.026 Abstract （583）   HTML （7）    PDF（pc） （3723KB）（135）       Knowledge map    Save To address the challenges of poor compatibility in current exoskeletons and human legs， a knee-ankle exoskeleton was designed based on human-machine compatibility. The spatiotemporal data of lower limb joint movements were collected through a motion capture system. A four-bar mechanism with a J-shaped motion trajectory that might adapt to the instantaneous center of human knee joint movement was designed based on the physiological characteristics of knee joint rolling and sliding motions. A linkage mechanism optimization design method for simulating knee joint motions was proposed. The optimized four-bar mechanism was validated through numerical simulation to fit human motion well. The development of an power-assisted exoskeleton control system was achieved by combining angle sensors， and the effectiveness of the power-assisted exoskeleton performance was verified through gait and electromyography experiments. The experimental results show that the peak change in knee joint angle after wearing is less than 5%， the knee joint torque decreases， and the activity of muscles such as the lateral thigh muscle， gastrocnemius muscle， and biceps longus muscle decreases. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Study on Crack Propagation of Freight Train Wheel Treads under Ramp Emergency Braking Conditions ZHAO Jie, LU Chun, HE Jiahuan, MA Tinghai, YE Zhang China Mechanical Engineering    2025, 36 (12): 2811-2819.   DOI: 10.3969/j.issn.1004-132X.2025.12.001 Abstract （600）   HTML （9）    PDF（pc） （3749KB）（134）       Knowledge map    Save The fatigue crack propagation of freight train wheel treads under ramp emergency braking conditions was studied based on the extended finite element method， taking into account the frictional heat generation， conduction heat dissipation， and the variation of material parameters with temperature. By analyzing the temperature fields and stress fields during the rolling contact processes under ramp emergency braking conditions， the results indicate that the existence of tread cracks affects the wheel-rail contact stress distribution， the high contact stress regions are divided into two sub-regions by the tread cracks， and stress concentration occurs at the crack front， and the tread crack propagation behavior is closely related to the relative positions of cracks and contact regions. During the braking processes， the circumferential compressive stress generated by high temperature will inhibit the tread crack growth， but the residual tensile stress after cooling will promote the tread crack propagation. During the stages of tread temperature rising， the tread crack propagation mode is a mixed Ⅱ-Ⅲ multiaxial propagation mode， dominated by mode Ⅱ propagation. During the stages of cooling， the tread crack propagation mode is mixed Ⅰ-Ⅱ-Ⅲ multiaxial propagation mode， dominated by mode Ⅰ and mode Ⅱ. Table and Figures | Reference | Related Articles | Metrics | Comments（0）