Table of Content

25 November 2025, Volume 36 Issue 11

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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

2025, 36(11):  2477-2485.  DOI: 10.3969/j.issn.1004-132X.2025.11.001

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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.

Inversion Method-based Equivalent Modeling of Stators in Permanent Magnet Motors

Zhaoyi LU, Hongzi FEI, Hu YU, Guihou ZHOU, Depeng ZENG, Wanyou LI

2025, 36(11):  2486-2491.  DOI: 10.3969/j.issn.1004-132X.2025.11.002

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The stator core and winding configurations in permanent magnet motors were complex. When performing finite element simulations of vibration and noise， failure to apply equivalent treatment would compromise the accuracy of the simulation calculations. This paper employed an inversion method， commencing with modal testing of stator components to extract the 2nd~4th order cylindrical mode under both pre- and post-winding assembly conditions. Leveraging experimental data， a high-fidelity simulation model of the stator core was developed to derive the equivalent mechanics parameters. With the validated stator core simulation model， two winding modeling approached equivalent mass method and equivalent model method were implemented. Simulation-to-test comparisons revealed significant discrepancies in the equivalent mass method. Finally， elastic modulus and Poisson's ratio for the winding equivalent model were inversely identified via modal test data. The equivalent model demonstrats less than 5% error in modal simulations.

Research on Output Characterization of Hydro-penumatic Suspensions Considering Gas Dissolution and Temperature

Xiumei LIU, Yunlong LUO, Beibei LI, Shen LIU, Qihang LIU, Yongtao LI, Qiao ZHAO

2025, 36(11):  2492-2500.  DOI: 10.3969/j.issn.1004-132X.2025.11.003

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Considering the influences of gas dissolution and temperature variation in the suspensions during the vehicle working， a specific type of hydro-pneumatic suspension was taken as the research object. By incorporating Henryp's law， a revised mathematical model of the suspension's output characteristics was proposed， and the performances was analyzed under different excitation signals. A testing platform was constructed for evaluating the output characteristics of the hydro-pneumatic suspensions. The output characteristics were tested under different steps and sinusoidal signal excitations， in order to investigate the dynamic and static dissolution characteristics of the gas， as well as the output force characteristics variation curves with temperature and gas dissolution. The results indicate that gas dissolution is solely related to gas pressure， with a positive correlation between the them， which is independent with the excitation frequency and amplitude. A higher gas working pressure may result in bigger solubility and faster dissolution rate. Furthermore， higher gas dissolution causes a reduction in the gas pressure of the hydro-pneumatic suspensions， thereby decreasing the output force. Conversely， an increase in oil temperature will result in an increasing of the gas pressure， leading to an increase in output force， accompanied by minor gas precipitation phenomena. Considering factors such as temperature and gas solubility， the normalized root mean square error between the theoretical and testing results of the output force characteristics of the hydro-pneumatic suspensions is as 0.76%.

Research on Load Spectrum Editing Based on Optimal Pseudo Wigner-Ville Distribution Method

Lingyun YAO, Zhishun YANG, Li LI, Yongjie LIN

2025, 36(11):  2501-2508.  DOI: 10.3969/j.issn.1004-132X.2025.11.004

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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.

Nonlinear Dynamics of Continuously Tunable Planetary Gear Metamaterial

Shuai MO, Xuan HUANG, Wenbin LIU, Wei ZHANG

2025, 36(11):  2509-2516.  DOI: 10.3969/j.issn.1004-132X.2025.11.005

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A continuous steady-state metamaterial with tunable mechanics was designed based on planetary gears. The excellent tunable mechanics properties of metamaterials were studied， which showed the designed metamaterials had a wide range of programmable stiffness and a significantly tunning band gap. The configuration relationship between tunability and structural parameters was analyzed. Then， a rigid-flexible coupling nonlinear dynamics model of planetary gear metamaterials was established and the dynamics characteristics of planetary gear metamaterials were explored by numerical simulation in the processes of dynamic tunning. Moreover， the influences of the system dynamic parameters on the bifurcation characteristics and stability were explored under coupling excitations， and the distribution characteristics of the system vibration response with the coupling parameter plane were disclosed. Finally， an improved non-iterative cell mapping method was used to analyze the dependence of the vibration response of the system on the initial conditions. The results show that the planetary gear metamaterials have a wide range of stiffness tunability and significantly variable band gap interval. Under the influences of internal and external excitations， the system exhibits various dynamics characteristics. The dynamics characteristics of flexible construction are mainly affected by structural parameters， and the dynamics characteristics of rigid construction are affected by multiple sets of coupling parameters and initial conditions.

New Parallel Compound Movable Tooth Transmission Principle and Its Meshing Characteristics

Hengyi LEI, Xuesong DU, Zilong JIANG, Caichao ZHU

2025, 36(11):  2517-2524.  DOI: 10.3969/j.issn.1004-132X.2025.11.006

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The transmission ratio of single-stage movable tooth transmissions was relatively low，while the series-connected movable tooth transmission structure was lack of compactness and inability to achieve power splitting transmission.Therefore， a novel parallel compound movable tooth transmission device was proposed， which comprised of a primary planetary gear transmission and a planar steel ball movable tooth transmission. The operating principles and structures of this device were introduced， along with the tooth number calculation method. The profile equations of the double-circular-arc tooth profiles were derived， and the analysis of the meshing characteristics was conducted. The results show that this innovative transmission device features a compact structure， enabling a high transmission ratio. By adjusting the number of teeth， the device achieves both forward and reverse output rotation， power splitting transmission， and “concave-convex” tooth contact. It exhibits high load-bearing capacity and is suitable for applications requiring large transmission ratios and high power density.

Research on Lubrication Characteristics of Textured Piston-cylinder Pairs of Axial Piston Pumps under Low-pressure Stroke

Gang LUO, Tao HE, Chuanli WANG, Kaiping ZHAO, Hao ZHANG

2025, 36(11):  2525-2536.  DOI: 10.3969/j.issn.1004-132X.2025.11.007

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The lubrication states of piston-cylinder pairs were the key to determining the service life of axial piston pumps. Therefore， a textured piston-cylinder pair was proposed to reduce the failure risk of oil film under low-pressure stroke. A textured lubrication model for piston-cylinder pairs was established based on a dynamic node mesh to address the variable support length of piston. Besides， the pressure equation was discretized by using a finite difference method， the pressure and thickness distribution of oil films were obtained by a double-layer cycle of film pressure and eccentricity. The influences of working parameters and texture parameters on lubrication characteristics were analyzed. The results show that the greater the texture radius and texture area ratio， the better the antifriction effectiveness， and the order of the effect in reducing friction（from high to low） is： texture area ratio， texture radius， texture depth. Both increasing the texture radius and decreasing the texture depth may enhance the bearing capacity of oil film， and a texture area ratio of 30% has higher adaptability. Combined with loading test， the maximum reduction in friction coefficient of textured specimen compared to that of non-textured specimen is as 29.8%. The results may provide some references for frictional design of axial piston pumps.

Research on Tribological Properties of Hardened Bearing Steel Surfaces by Electric Pulse Assisted Hard Turning

Fujian SUN, Qianfang ZHU, Zhiqiang LIANG, Yanjun LU, Jinlong CHEN, Yubin XIAO, Hao HUANG, Jianping YUAN

2025, 36(11):  2537-2543.  DOI: 10.3969/j.issn.1004-132X.2025.11.008

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The poor hard turning performance of hardened bearing steels significantly reduced the surface integrity of the workpieces， resulting in poor friction and wear performance of hardened bearing steels. Based on the superiority of electric pulse assisted cutting technology， the surface integrity and surface wear resistance of hardened bearing steels were studied. The results show that the surface integrity of the workpieces is improved significantly， the friction coefficient is reduced by 20%， the width and depth of the wear scar are reduced by 48.7% and 93.33% respectively， and the friction and wear performance of the hardened bearing steels is significantly improved.

Study on Dynamics Characteristics of Porous Matrix Hydrodynamic and Hydrostatic Mechanical Seals

Liyun HAN, Xueping LI, Xiangkai MENG, Yangyang LIANG, Lihao ZHANG, Xudong PENG

2025, 36(11):  2544-2553.  DOI: 10.3969/j.issn.1004-132X.2025.11.009

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A porous hydrodynamic and hydrostatic mechanical seal was proposed by combining the porous material and L grooves（PL-MS）. A dynamic mathematical model of the seal was developed based on the perturbation method， by considering the mass transfer between the fluids in porous matrix and the lubrication films between seal rings， as well as the film cavitation. The perturbed equations were solved with the finite element method and the dynamic coefficients of the porous hydrodynamic and hydrostatic mechanical seal were numerically analyzed. The results show that the PL-MS generates greater film stiffness coefficients K_zz，K_αα，K_ββ than those of the ordinary porous mechanical seals and partial distributed porous mechanical seals due to the synergism of the hydrostatic effect of porous matrix and hydrodynamic effect of L grooves. It is a good way to increase the film stiffness coefficients K_zz，K_αα，K_ββ by increasing the porous permeability and optimizing the L groove geometrical parameters at the sacrifice of the stiffness coefficients K_αβ，K_βα and damp coefficients d_zz，d_αα，d_ββ .

Dynamics Response of Super-harmonic Resonance of a Pre-deformed Jeffcott Cracked Rotor

Bo ZHANG, Mingxia CHENG, Yunfan SHI, Li CHEN

2025, 36(11):  2554-2562.  DOI: 10.3969/j.issn.1004-132X.2025.11.010

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Based on the theories of rotor dynamics and nonlinear dynamics， the dynamics response of 2/3 super-harmonic resonance of the system was studied for the rigidly supported horizontal Jeffcott cracked rotors under the condition of 1∶1 internal resonance. Considering the gravity-induced pre-deformation effect and crack respiration behavior， a system dynamical equation with quadratic nonlinearity introduced by pre-deformation and cubic nonlinearity was established. The multi-scale method was used to derive the evolution equation of the system， and the influences of the changes of system parameters on the dynamics behaviors of the system were discussed in detail， and it is shown that with the increasing of crack depths and lateral damping coefficients， the frequency response curves of the system exhibit “frequency island” phenomenon. It is clarified that the square nonlinearity exhibits a softening effect on the system， while the cubic nonlinearity exhibits a hardening effect. Numerical integration of the system's dynamics equation was conducted using the Runge-Kutta method to observe the jumping phenomenon， and the approximate solutions obtained through the multi-scale method were validated. The findings provide theoretical guidance for the nonlinear dynamics analysis of crack faults in Jeffcott rotor systems.

Sliding Mode Control for Pneumatic Swing Angle Servo Systems Based on Disturbance Observation and Friction Compensation

Qiong WEI, Linyong BAI, Zichao CHEN, Daode ZHANG, Yi LI

2025, 36(11):  2563-2573.  DOI: 10.3969/j.issn.1004-132X.2025.11.011

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External uncertain disturbances and friction were important factors affecting the control performance of pneumatic swing angle servo systems（causing local fluctuations and creep phenomena）. A sliding mode control strategy was proposed based on disturbance observation and friction compensation， an improved extended state observer was designed to observe external uncertain disturbances by introducing a hyperbolic tangent function and angular velocity error term to enhance the disturbance rejection ability of systems. Since the observer might not effectively observe the static-dynamic high-order jump of system friction， which leaded to ineffective improvement of the creep phenomenon， therefore the friction torques were identified to make up for the insufficient observation. Finally， aiming at the insufficient robustness and difficulty in tuning control parameters of the systems， a nonsingular fast sliding mode controller was designed. The controller outputs were smoothed by using the super-twisting algorithm with integral characteristics to improve the inherent chattering problems in sliding mode control， and the disturbance observation values and friction torque identification values were feedback compensated. Simulation and experimental results show that compared with four control strategies， the proposed control method effectively enhances the disturbance rejection ability of the systems and improves the trajectory tracking performance of the pneumatic swing angle servo systems.

Dynamic Perception and Experimental Study of Tactile Texture Based on Ultrasonic Resonance Squeeze Film Effect

Zhibo CHEN, Guoping LI, Sitong XIANG, Yanding WEI

2025, 36(11):  2574-2582.  DOI: 10.3969/j.issn.1004-132X.2025.11.012

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Using the mechanism that modulating sliding friction at the contact interfaces might perceive changing tactile texture features， an ultrasonic resonance tactile dynamic perception device was proposed based on the squeeze film effect. The theoretical model of the friction-reducing mechanism of the squeeze film effect was constructed under the high squeeze factor of the squeeze film， and the mapping relationship between the friction-regulating performance and the actual material texture was established through the friction factor calibration experiments. The results show that the device may achieve the dynamic regulation of surface friction factor is as 0.295~0.807 under the excitation of 36.314 kHz resonance signals and the voltage amplitude is as 0~200 V. A LSTM neural network was used to construct a temporal force signal and tactile texture prediction model to objectively evaluate the tactile texture reproduction performance of the device， and the average error of the model prediction results is as 3.33%， which verifies the device has a good reproduction effectiveness of tactile texture.

Research on Stochastic Nonlinear Optimal Control of Maglev Trains

Weiwei LIU, Kuo LI, Hongji WANG, Xi YU

2025, 36(11):  2583-2592.  DOI: 10.3969/j.issn.1004-132X.2025.11.013

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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.

Design and Experimental Study of Stiffness Self-tuning Wideband Dynamic Vibration Absorbers

Zhi WANG, Shanfu LI, Jing TIAN, Mengkang YUE

2025, 36(11):  2593-2600.  DOI: 10.3969/j.issn.1004-132X.2025.11.014

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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.

Design Methodologies for High-precision Sensing Mechanisms Based on Pressure Amplification​

Lejun HE, Yi XI, Wen LIU, Xiang YAN, Mingjie XIN, Chaoyang WANG

2025, 36(11):  2601-2608.  DOI: 10.3969/j.issn.1004-132X.2025.11.015

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Aiming at the issues of delayed response in gas self-closing valves under gas leakage conditions， a high-precision sensing mechanism was designed based on the pressure amplification effect to improve the accuracy of abnormal flow cutoff. In the general parameterization （GP） stage， a pressure amplification sensing mechanism was explored， and a corresponding pressure amplification unit structure was designed. The spool dynamics model and a zonal pressure drop mathematical model were established， revealing the core mechanism by which minute flow changes trigger an exponential pressure drop surge and the key influences of spring stiffness on response characteristics. In the inverse parameterization / specific parameterization （IP/SP）stage， key parameter optimization was carried out based on the proposed GIS-P derivation method： through IP combined with FLUENT flow field simulation data， key empirical parameters in the pressure drop mathematical model were calibrated； then， via SP focusing on the target cutoff flow rate， the optimal spring stiffness was determined based on the analysis of the spool force-displacement characteristics. The research confirms that the proposed pressure amplification unit and the GIS-P optimization method may provide an effective theoretical basis and key parameter design guidance for the development of high-precision gas self-closing valves.

An Identification Method of PIGEs for Rotary Axes of Five-axis Machine Tools

Xiang LI, Huanlao LIU, Yulin WANG, Xin DAI

2025, 36(11):  2609-2617.  DOI: 10.3969/j.issn.1004-132X.2025.11.016

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In order to quickly identify PIGEs of rotary axis of five-axis machine tools， and improve the accuracy in identifying geometric errors of rotary axis， a simple identification method was proposed for PIGEs of rotary axis using three installation modes of DBB. The mathematical model of bar length changes included installation errors and PIGEs of rotary axis was established based on homogeneous coordinate transformation under three installation modes of DBB. The effects of PIGEs on the paths of DBB were analyzed by simulation under three installation modes， and the results show that eight PIGEs may be identified by controlling uniaxial motion under three installation modes. In the identification experiments， the influences of identification accuracy were eliminated by measuring the installation errors of DBB， and the identification of eight PIGEs of rotary axis was realized. Finally， eight PIGEs of rotary axis were compensated， and the experimental results show that the maximum absolute value of the compensated errors is reduced from 103.9 μm to 0.46 μm， which verifies the effectiveness and accuracy of the proposed identification method.

Design and Tests of Piezoelectric Pump with Flexible Valvular Valves in Conical Channels

Tianxiang YAN, Jiaxuan ZHANG, Muchun LAN, Hucheng CHEN, Haiyan JIANG

2025, 36(11):  2618-2624.  DOI: 10.3969/j.issn.1004-132X.2025.11.017

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To improve the infusion performance of piezoelectric pump with flexible valvular valves， a piezoelectric pump with flexible valvular valves in conical channels was designed combined with unequal flow resistance characteristics of conical channels. The water delivery performance results show that， when the driving peak-to-peak voltage is 300 V， the maximum water delivery flowrate is as 104.6 g/min， and the pressure difference is as 1.53 kPa of piezoelectric pump with flexible valvular valves in conical channels， which are much better than those of piezoelectric pump with flexible valvular valves in straight channels. The blood transport tests results of piezoelectric pump with flexible valvular valves in conical channels show that when the driving peak-to-peak voltage is 300 V， the maximum blood transport flowrate is as 86.4 g/min， the pressure difference is as 1.45 kPa， and the damage to erythrocytes and platelets is small during blood transport.

Temperature Field Analysis of Main Bearings in Wind Turbines Based on Thermal Network Method

Yunfeng LI, Jincheng LI, Zhidan ZHONG

2025, 36(11):  2624-2632.  DOI: 10.3969/j.issn.1004-132X.2025.11.018

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Based on thermal network method，a bearing temperature field analysis method was established to address the heating and temperature rise problems of the main bearings in wind turbine with a three-row cylindrical roller structure. By slicing the rollers of the bearings， a force balance equation system of the bearings was established by using deformation coordination conditions， the roller slice loads were obtained by solving the equation systems. The sliding motions between the roller slices and the raceway surfaces were also analyzed. Then， based on the load actions and relative sliding motions between the bearing parts， the heat generation powers of the friction heat source at the contact positions of the rollers， raceways， retainers and sealing rings were obtained. Finally， according to the friction heating positions and specific internal structures of the bearings， the thermal network method was used to set up the internal network nodes of the bearings， and the thermal network balance equation system of the bearings was established. For a specific the main bearing in a 2.0 MW wind turbine， the effects of lubrication viscosity， axial clearance， roller number and rotational speed on bearing temperature were solved and analyzed.

Study on Flow Characteristics of Variable Displacement Opposed Piston Pumps

Wei YANG, Chen JIA, Chao HE, Wenxin FAN, Zhiqiang FAN, Zhenglu LI

2025, 36(11):  2633-2640.  DOI: 10.3969/j.issn.1004-132X.2025.11.019

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To address the high power loss in fixed-displacement pumps used in construction machinery， a variable-displacement opposed-piston pump was designed. The pump's AMESim simulation model was developed through equivalent modeling methodology. The model validity was experimentally verified through comprehensive bench testing. Experimental validation reveals a maximum 9.30% deviation between simulated and measured average flow rates， within acceptable limits when accounting for leakage and valve backflow effects. Using this validated simulation model， the flow characteristics of the variable displacement opposed piston pumps was investigated under varying rotational speeds， phase differences， and their coupled effects. The simulation results show that the pump flow and pressure increase with increasing speed and decrease with increasing phase difference. When the phase difference increases from 0° to 150° at rated speed， the average flow rate decreases by 74.00%， the maximum instantaneous pressure droppes by 88.87%. These results demonstrate that the pumps have a wide range of flow， pressure adjustment. The pumps enable continuous output flow regulation through coordinated speed and phase difference adjustment， establishing a theoretical foundation for variable displacement pump control strategies.

Axial Contact Position Testing Method of Conductive Slip Rings Based on Visual Inspection Technology and Profilometric Design

Zhiyuan QIAN, Nianhuan LI, Junye LI, Jun LI, Chao HAN, Haihong WU

2025, 36(11):  2641-2651.  DOI: 10.3969/j.issn.1004-132X.2025.11.020

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To address the challenges of measuring the contact position and distance of elastic alloy wires in conductive slip rings， an axial contact position testing method was proposed based on visual detection. By designing an equivalent profiling slip ring and an axial position testing device， visual detection was applied to extract the angle， installation distance， and axial contact position of the elastic alloy wires. In the tests， the slip ring diameter and the installation distance of the brush plate were used as boundary conditions to investigate their influences on the axial contact position. The testing results show that the diameter and the installation distance significantly affect the variation laws of the axial contact position distance and the opening angle. Compared with the traditional methods， the proposed method achieves a testing error of 0.03 mm and a repeatability error of 0.0065 mm， accurately extracting contact position data. It effectively reveals the action mechanism of contact state changes， realizes high-precision measurement and optimization of the contact characteristics of conductive slip rings， and provides a reliable measurement means for high-precision equipment.

A Smooth Motion Path Planning Method for Six-axis Robots Considering Redundancy

Haiping LIANG, Yaoan LU, Weijia LIAN, Chengyong WANG

2025, 36(11):  2652-2657.  DOI: 10.3969/j.issn.1004-132X.2025.11.021

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The existing redundancy optimization methods might fail to fully exploit the robot's redundancy when six-axis industrial robots performing five-axis machining tasks， limiting the smoothness of the planned motion path. An efficient algorithm was proposed for collision-free and smooth joint motion planning of six-axis robots. The method fully utilized the robot's redundancy by varying the redundancy variable at each cutter location data to generate all possible candidate robot postures. To enhance computational efficiency， a two-step search strategy was introduced combining rough and fine searches with a greedy approach， and the robot postures were selected from feasible postures with greedy strategy. The proposed method does not require segmenting the machining path and may optimize the robot's posture along the entire machining path simultaneously. The effectiveness of the proposed algorithm was validated by simulation calculations on joint motion paths of six-axis industrial robots conducting five-axis milling surface machining tasks.

Optimization and Experiments of Flow-guiding Structure of Cathode in Electrochemical Machining of Internal Splines

Yang LI, Hongyu WEI

2025, 36(11):  2658-2664.  DOI: 10.3969/j.issn.1004-132X.2025.11.022

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Due to the complex profile and space limitations of involute internal splines， the uniformity of the flow field was difficult to control， which in turn made it difficult to improve the processing accuracy during electrochemical machining. The electrolyte flow mode， flow channel structure and processing mode were analyzed， a cathode flow guide structure was designed， and flow field analyses were conducted based on simulation platform. The results show that the inlet and outlet flow guide structure may eliminate flow field defects such as vortices， significantly increase the electrolyte flow rate in processing areas， and meet the requirements of electrochemical machining of involute internal splines. Processing experiments were carried out using the inlet and outlet flow guide structure. The machining processes are stable， the workpiece surface is bright and clean without marks， the roughness value Ra is as 0.8 μm， and the internal spline accuracy reaches level 5， verifying the rationality of the flow guide structure.

Development of External Balances and Support Devices Based on Sonic Boom Measurement Test

Wei JIA, Renhui TIAN, Jing LIU, Duowei WANG, Wenhua LIU

2025, 36(11):  2665-2669.  DOI: 10.3969/j.issn.1004-132X.2025.11.023

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To study the sonic boom characteristics of aircraft in a supersonic flow field， a set of specialized external balance and support device was developed to meet the measurement requirements of aerodynamic loads. By adopting multi-component coupling series connection， setting a new type of hybrid Wheatstone measuring bridge， and conducting finite element method analyses and optimizations， two critical issues were resolved： the mismatch between force and moment loads caused by severe model center deviation from balance element centers in traditional external balances， and the interconnection and reliability issues stemming from inherent clearance and coupling effects in multi-linkage systems. The aerodynamic force component may be precisely measured by Wheatstone bridge's measuring mechanism during sonic boom measurement wind tunnel tests. The results show that the measurement results of the external balance are stable and reliable， and may effectively capture the changes in aerodynamic force， providing key data support for the measurement of sonic boom characteristics.

Design， Mechanical Characteristics Analysis， and Testing of a Flexible Wedge-Block Mechanism for Aircraft Hatch Connection

Hongji YANG, Jie CHEN, Zhuoran LI, Yunhao ZHAO, Jing ZHAO

2025, 36(11):  2670-2677.  DOI: 10.3969/j.issn.1004-132X.2025.11.024

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Aiming at the shortcomings of the traditional connection methods for aircraft access panels， such as low maintenance efficiency and poor reusability， a wedge mechanism which is composed of a flexible wedge block and a wedge groove was designed. The engagement and disengagement of the wedge-block mechanism were achieved by preload force generated from the cooperation between the hinge rotation of flexible wedge block and the wedge groove， and the threaded holes of different diameters on the flexible wedge block and the wedge groove. The pseudo-rigid body method and integral method were adopted to establish the deformation model and mechanical model， and the mechanical characteristics of key design parameters were analyzed. Simulation and physical tests show that the wedge mechanism has the ability to resist loosening and disengagement under medium and low-frequency working conditions.

Kinematic Modeling of a Novel Rigid⁃Flexible Hybrid Continuum Robots

Jiaxiang DONG, Quanquan LIU, Xiping HU, Xuezhi ZHAO

2025, 36(11):  2678-2684.  DOI: 10.3969/j.issn.1004-132X.2025.11.025

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A study of the kinemetic modeling was carried out for a novel rigid-flexible hybrid continuum robot driven by tension-torsion synergistic actuation. A kinetostatic model was developed based on the piecewise constant curvature（PCC） framework， which comprehensively considered various loads. To solve the highly nonlinear inverse kinematics， a BP neural network model optimized by the Newton-Raphson based optimizer（NRBO）， denoted as NRBO-BP model， was constructed. Experimental results show that the average bending angle errors at the end of the single/dual-segment flexible robots are as 4.2° and 7.1°， respectively. The maximum position error in trajectory tracking based on NRBO-BP model is as 2.5 mm， which verifies the accuracy and effectiveness of the proposed methods.

Fast Prediction of Microstructure Performance Based on 3D Convolutional Neural Network

Qianhao LONG, Ying ZHOU, Liang GAO, Hao LI

2025, 36(11):  2685-2693.  DOI: 10.3969/j.issn.1004-132X.2025.11.026

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The significant scale difference between microstructure and macro structure， and the coupling of complex micro-geometric configuration and substrate properties which make the analysis of macro-equivalent performance of microstructure is very difficult. Therefore， a prediction model of microstructure homogenization elastic tensor was proposed based on three-dimensional convolutional neural network. A parametric modeling of microstructure was completed by level set method， and the equivalent elastic tensor of microstructure was calculated by numerical homogenization. A data representation method coupling geometric configuration and substrate properties was proposed to match the mixed inputs and equivalent elastic tensor labels， and the matched data samples were used as the dataset for neural network training. Finally， model performance was analyzed from partial errors of the predicted results and the calculation efficiency. The proposed model may significantly improve the performance analysis efficiency of the microstructure within the allowable error range.

Research on Optimization of Uniformity of Robot Spraying Coatings for Changing Positions on Convex and Concave Characteristic Surfaces

Yao DAI, Yong ZENG, Xueya ZHAO, Junhao WAN, Jintong GU, Xinyi ZHU

2025, 36(11):  2694-2703.  DOI: 10.3969/j.issn.1004-132X.2025.11.027

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Aiming at the problems of optimizing coating uniformity in surface spraying involving convex and concave features， a novel spraying trajectory optimization method was proposed based on incorporated posture changes during the spraying processes. The effects of geometric parameters associated with convex and concave surfaces on coating uniformity during both vertical and variable posture spraying were studied， suitable bulge heights and depression depth ranges for the vertical spraying technique were identified. Subsequently， for convex and concave features that were incompatible with vertical spraying， a continuous variable inclination angle spraying trajectory optimization method utilizing arc transitions was introduced. Finally， a continuously variable inclination angle coating thickness model and an optimization target model were developed to enhance coating uniformity on surfaces with convex and concave features. Simulation and experimental results demonstrate that， compared to the vertical spraying method， the applications of the proposed technique to surfaces with convex and concave features result in a 41.06% reduction in the standard deviation of film thickness and a 15.23% increase in the proportion of areas meeting the required film thickness accuracy.

Robotic Grinding Path Generation Method Guided by CAD for Automobile Wheel Hubs

Quanyin YANG, Yuning ZHANG, Tong XIAO, Jinlong LIANG, Jintao WANG, Jinting XU

2025, 36(11):  2704-2709.  DOI: 10.3969/j.issn.1004-132X.2025.11.028

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An adaptive generation method of robotic grinding paths guided by CAD drawings was proposed to remove burrs on wheel hub hole side edges smoothly， addressing inconsistent raw materials， missing 3D models， and only 2D CAD drawings. First， theoretical grinding paths were quickly extracted based on point correspondences between CAD main and sectional views， and actual 2D hole contours were acquired using a 2D industrial camera. A registration model between the theoretical paths and actual contours was established， and a neighborhood-based weighted averaging method was used to restore depth information of the actual contours， generating adaptive grinding paths. Then， B-spline curve fitting was applied to smooth path points， and a spherical quadrilateral interpolation model was used to optimize tool orientations， ensuring continuous and smooth grinding in high-curvature or challenging regions. Experimental results show that the generated paths are continuous， smooth， and tool orientations remain stable. Compared with theoretical paths， path accuracy is improved by over 90%， and the average production cycle is as 88 s， meeting industrial requirements.

High-precision Industrial Robot Teaching Method Based on 6D Light Pens

Jihuang LIANG, Weifeng WANG, Haibin WU

2025, 36(11):  2710-2719.  DOI: 10.3969/j.issn.1004-132X.2025.11.029

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Aiming at the problems of poor precision， sensitivity to light and restricted teaching range in current industrial robot vision teaching methods， a high-precision industrial robot teaching method was proposed based on a 6D light pen. The light pen was equipped with three infrared-emitting marker balls， and infrared binocular camera mounted on the robot's end-effector captured the marker balls to obtain their 3D position coordinates and 3D pose information. Two measures were implemented to enhance the vision teaching precision of the 6D light pens. Firstly， a hand-eye calibration method was proposed based on infrared light-emitting marker balls， which significantly improved the transformation precision from the camera coordinate system to the robot tool coordinate system. Secondly， an adaptive camera tracking method was proposed， allowing the robot to automatically track the position of the light pen through the camera mounted on the end-effector， ensuring that the marker balls remain centered in the camera's field of view， thus effectively improving the teaching precision. Finally， the captured teaching trajectory was transformed into the robot base coordinate system to achieve trajectory programming and tracking. Experimental results show that the maximum single-point error of the light pens is as 0.63 mm， the maximum pose error is as 2.1432°， and the maximum trajectory error is as 0.73 mm. The proposed teaching method may achieve high-precision and high-efficiency teaching for robots.

In-situ Monitoring Method of Milling Cutter Wear Based on Spatial Attention Mechanism U-Net

Song ZHANG, Chaoyong ZHANG, Chuanjun ZHU, Saixiyalatu BAO

2025, 36(11):  2720-2727.  DOI: 10.3969/j.issn.1004-132X.2025.11.030

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To address the issues of high workload and low accuracy in existing machine vision-based off-line tool wear measurement， an in-situ monitoring method for milling tool wear in machining centers was proposed based on a spatial attention mechanism U-Net. Firstly， an automatic tool wear monitoring experimental platform was established. Through PMC programming， the platform employed NC codes to control spindle orientation and rotation angles， enabling automatic positioning of the wear areas on the lateral cutting edges of the milling cutters. Secondly， communication with the machine tool through the Focas protocol and C# scripts， automatic in-situ imaging of the milling cutter's bottom edge and each lateral edge were realized. Next， label files were created by using LabelMe software， the spatial attention mechanism U-Net semantic segmentation method was employed to accurately identify the wear areas， and the quantifiable tool wear values were obtained by combining the morphological method. Finally， the proposed model was compared with semantic segmentation models such as Deeplabv3+， full convolutional networks（FCN）， Lraspp， SegNet， and PspNet to verify the effectiveness and accuracy of the proposed method.

A Process Knowledge Generalization Based on Standardized Expression of Process Data

Qiao ZHENG, Ruiqiang LYU, Bencheng CUI, Rui ZUO

2025, 36(11):  2728-2737.  DOI: 10.3969/j.issn.1004-132X.2025.11.031

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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.

Automatic Tooth Alignment Method Based on Mesh Features

Mengjie HU, Yuhang FANG, Xujia QIN, Zhengqiang WU

2025, 36(11):  2738-2746.  DOI: 10.3969/j.issn.1004-132X.2025.11.032

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Aiming at the problems of strong data dependence and low occlusion accuracy of point cloud-based deep learning automatic tooth alignment method， a deep learning automatic tooth alignment method was proposed based on mesh features. The design model included shape encoder， global feature encoder， feature decoder and mapper， and tooth occlusion generation network. The shape encoder extracted the tooth shape features from the triangular mesh data on the surfaces of the tooth model， the global feature encoder extracted the global features of the tooth set from the simplified tooth point clouds， and the feature decoder and mapper fused and reduced the dimension of the global features and local features of the tooth to generate the final tooth arrangement results， reducing the data dependence. The tooth occlusion network generated the upper and lower occlusal surfaces based on the spatial position of the jaw and the characteristics of the teeth， which improved the accuracy of the upper and lower occlusal surfaces. In order to further improve the performance of the model， the similarity loss function was introduced into the loss function， which helped to prevent overfitting and improve the quality of automatic tooth alignment. The experimental results show that compared with four existing methods， the proposed method reduces the ADD index， and significantly improves the accuracy of deep learning automatic tooth alignment.

Staged Measurement Model and Method for Geometric Shape of Super Large Ring Forging Processes Based on Multi-source Information Fusion

Xiaokai WANG, Gefei ZHENG, Kangwen HUANG, Ziqiang LIU, Xinghui HAN, Lin HUA

2025, 36(11):  2747-2756.  DOI: 10.3969/j.issn.1004-132X.2025.11.033

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To enhance the geometric shape measurement accuracy in super-large ring rolling processes， a staged measurement method was proposed based on multi-source information fusion. This method utilized real-time data from three laser displacement sensors， combining with the characteristics of the rolling feed and rounding-sizing stage， to accurately measure the ring's diameter growth velocity， center offset， and roundness error in distinct phases. Theoretical models for the ring's diameter growth velocity and outer contour roundness errors were established， the formation mechanism of the diameter growth velocity and roundness error of ring were analyzed. By constructing a finite element simulation model of ϕ10 m super large ring rolling in ABAQUS software， the proposed multi-source fusion method was comparatively analyzed against industrial camera imaging and single-point laser measurement， which verified superior accuracy of the proposed method and the influences of the mandrel feed speed on the ring's geometric state were explored. Finally， the effectiveness of the proposed method was confirmed by scaled-down rolling experiments， with the outer contour fitting accuracy reaching as 91.7% in the final rolling stages.

Hot Deformation Behavior and Processing Maps of Ti₂AlNb-based Alloys

Tong ZHOU, Jun CHENG, Kelu WANG, Shiqiang LU, Xin LI, Jie LIU

2025, 36(11):  2757-2765.  DOI: 10.3969/j.issn.1004-132X.2025.11.034

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The hot deformation behavior of Ti₂AlNb-based alloys in the temperature range of 650~850 ℃ and strain rate range of 0.001~1 s^-1 was investigated by isothermal constant strain rate compression tests， and the three-dimensional processing maps were constructed based on dynamic material modelling. The flow stress curves of Ti₂AlNb-based alloys were analyzed and the SVM constitutive model was established， then the 3D processing maps were theoretically analyzed， and finally the accuracy of the constructed 3D processing maps was verified with the microstructures. The results show that the flow stress of Ti₂AlNb-based alloys increases with the decreasing of deformation temperature and the increasing of strain rate. The SVM model may accurately predict the flow behavior of Ti₂AlNb-based alloys under different deformation processing parameter conditions， with a correlation factor of 0.999 and an average relative error of 0.67%. The 3D processing maps show that the regions with high values of power dissipation efficiency η are concentrated in the region of low strain rate. The better hot deformation processing parameters for Ti₂AlNb-based alloys under different strains are as 675~725 ℃， 0.001~0.003 s^-1， and the optimal hot deformation processing parameters are as 700 ℃， 0.001 s^-1.

Experimental Study of Propulsion Characteristics of Marine Methanol⁃Diesel Dual⁃fuel Engines

Enzhe SONG, Zongwei GUO, Tian YANG, Lili LU, Chong YAO, Qiangzhi XIN, Baofu JIA

2025, 36(11):  2766-2773.  DOI: 10.3969/j.issn.1004-132X.2025.11.035

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In order to investigate the characteristics of marine methanol powers and provide calibration data for modeling simulation studies， a marine methanol-diesel dual fuel engine was subjected to propulsion characteristics tests. The economy， combustion performance and emission performance of the engines were compared under pure diesel mode and dual fuel mode. The results show that the addition of methanol has a small effect on the equivalent fuel consumption of the engines， but it may reduce the unit power cost by 18.22% at most under the same operating conditions； the addition of methanol leads to the shortening of the combustion duration and the reduction of the average effective pressure at each operating point； the CO and HC emissions of the engines under the dual-fuel mode are higher than those of under the diesel mode， and the NO _x emissions under dual-fuel mode are slightly higher than those of the diesel mode only at high loads.

Vehicle Lateral Control Strategy Integrating Road Curvature Feedforward

Xinyou LIN, Zhongwei JIN, Yunliang TANG

2025, 36(11):  2774-2782.  DOI: 10.3969/j.issn.1004-132X.2025.11.036

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Aiming at the problems of low tracking accuracy of autonomous vehicles in the road with large curvature curves， the influences of road curvature on the lateral control strategy were focused， the lateral control strategy was improved and optimized based on the traditional model predictive control（MPC） algorithm from three aspects of vehicle model modeling， yaw stability and time domain optimization， respectively. The road curvature was integrated into the vehicle model， and an error dynamics model with curvature feedforward was established. And then， a lateral control strategy was designed based on curvature feedforward MPC algorithm. Then， a lateral stability constraint consisting of lateral vehicle speed and steady-state lateral angular velocity was added to the strategy to enhance the lateral stability of the vehicles under high curvature conditions. A MAP map was established based on genetic algorithm to optimize the prediction and control time domains of the strategy， taking into account the relationships among vehicle speed， road curvature and time domain. Simulation analysis was conducted， and the results show that the improved lateral control strategy may effectively improve the path tracking precision and lateral stability of the vehicles. Finally， the effectivenesses of the curvature feedforward MPC strategy were verified through real vehicle road tests.

Multi-threaded Semi-global Stereo Matching Method for Internal Inspection of Workpieces

Hongchen WU, Xiaorong CHEN, Baiyang LI

2025, 36(11):  2783-2791.  DOI: 10.3969/j.issn.1004-132X.2025.11.037

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To address the problems that traditional detection methods were difficult to conduct three-dimensional quantitative analysis inside workpieces， a binocular vision detection method was proposed based on multi-threaded semi-global stereo matching（M-SGSM）. Firstly， the Zhang's calibration method was used to obtain the parameters of the binocular endoscope， and image distortion correction and epipolar rectification were performed. Secondly， a multi-threaded regional overlap segmentation strategy was designed to optimize the stereo matching algorithm， improve the efficiency of disparity map calculation， and generate a 3D color point cloud. Finally， a self-calibration area measurement method combined with Euclidean distance calculation was proposed to realize three-dimensional quantitative analysis. Experimental results show that the optimized stereo matching algorithm improves computational efficiency by approximately 30%， the generated 3D point cloud has a clear structure， the Euclidean distance measurement error is less than 3%， and the area measurement error is less than 1.5%. This method provides an efficient and high-precision solution for three-dimensional internal detection of workpieces.

Rigid-flexible Coupling Identification of MDOF Excitation for Door Limiter and Shaking Optimization of Window Frame during Closing

Chengzhan LI, Pengcheng GUO, Congchang XU, Luoxing LI, Yongfu XIAO, Shuxia JIANG

2025, 36(11):  2792-2800.  DOI: 10.3969/j.issn.1004-132X.2025.11.038

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Aiming at the problems that traditional NVH analysis struggled to accurately extract and predict the dynamic excitation and response of vehicle doors during rotation， a new method was proposed and applied to vibration transfer function analysis based on rigid-flexible coupling for identifying MDOF excitation. Taking the abnormal shaking of the window frame during door closing in a specific vehicle model as the research objective， a whole vehicle rigid-flexible coupling model was established by using multibody dynamics method. The MDOF acceleration dynamic excitation at the limiter installation points was extracted for transfer function analysis. The comparison between simulation and testing results shows that consistent peak values of vibration acceleration are detected at 12 Hz， which verifies the accuracy of the rigid-flexible coupling model. Then， the key factors affecting window frame shaking during door closing were analyzed via simulation， identifying the limiter structure as the core optimization target. An optimization scheme was proposed， and vibration transfer function analysis under the extracted dynamic excitation shows that the optimized limiter structure may significantly reduce the window frame shaking level during door closing.

Strain Extremum Characterization Method for Oil and Gas Pipelines under Oblique Reverse Faults

Xiangchong GAO, Peijun LIU, Huanguo CHEN, Chengcheng PENG, Shujia SONG, Zijun LIN

2025, 36(11):  2801-2809.  DOI: 10.3969/j.issn.1004-132X.2025.11.039

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Long-distance pipelines were more susceptible to significant deformation under the influences of oblique reverse faults， and their strain extremums were difficult to accurately characterize， making it challenging to reflect the actual deformation states of the pipelines. To address this issue， a strain extremum characterization method for pipelines was proposed based on strain sensor monitoring to enhance the accuracy and early warning capability of buried long-distance pipeline strain monitoring. A pipe-soil coupling finite element model was established to analyze the deformation behavior of pipelines under oblique reverse faults， and the accuracy of the model was validated. Then， a high-precision tensile and compressive strain extremum characterization model was constructed using Stacking ensemble learning. Finally， a pipeline strain dataset was established， the strain data from the 3， 9 and 12 o' clock positions along the pipelines within 20 times the pipe diameter on both sides the fault was utilized to train the model. This model accurately fits the strain characteristics of the pipelines under multidimensional nonlinear conditions， effectively capturing stress concentration and deformation patterns induced by oblique reverse faults. The results show that the proposed strain extremum characterization method may precisely reflect the maximum tensile and compressive strains of pipelines under oblique reverse faults， providing significant engineering value for pipeline deformation monitoring and early warning systems.