最新刊期
- 摘要：ObjectiveUnder low-speed and heavy-load conditions, the frequency band division of vibration signals of rolling bearings in agricultural machinery equipment is easily disturbed by low-frequency background energy, which reduces the accuracy and stability of fault diagnosis. To solve this problem, an improved empirical wavelet transform (SEW-EWT) algorithm with collaborative optimization of spectral smoothing and low-frequency energy enhancement was proposed.MethodsFirstly, the amplitude spectrum was obtained by Fourier transform of the original signal. Gaussian kernel convolution smoothing was adopted to suppress high-frequency random spikes. The frequency band boundaries were initially determined based on local extrema of the smoothed spectrum, and an energy proportion threshold was introduced to eliminate low-energy pseudo-segments, so as to improve the stability of frequency band division. Secondly, on the premise of maintaining the energy conservation of the filter bank, a low-frequency weighted enhancement function was constructed. Higher weights were assigned to the low-frequency interval to strengthen the modal energy proportion of weak impact features and realize adaptive purification of key components. Then, Hilbert transform was performed on the selected effective modes and envelope spectrum features were extracted to provide input for fault state discrimination. Finally, the diagnostic performance of the algorithm was verified based on a rolling bearing test dataset containing 4 operating states.ResultsThe results show that the precision, recall and F1-score of SEW-EWT reach 97.2%, 97.8% and 97.5% respectively, which are about 3.8% higher than those of traditional EWT. The mean square error is stable at about 0.03, which is about 30% lower than that of the baseline method. The average recognition accuracy reaches 97.75%, and the standard deviation drops to 0.58%, which is about 66.3% lower than that of EWT. Compared with mainstream diagnostic methods, the overall accuracy is 3.25 to 8.0 percentage points higher, with balanced recognition performance for various faults. This algorithm can improve the identifiability of bearing fault features and diagnostic consistency under low-speed conditions, and provides reference for condition monitoring of rolling bearings in agricultural machinery equipment.关键词：Agricultural machinery equipment;Rolling bearings;Empirical wavelet transform;Low-speed vibration signals;Feature extraction;Fault diagnosis （编辑：李凯阳）7|3|0更新时间：2026-10-16
- 摘要：ObjectiveTo reveal the coupled vibration mechanism of a precision cycloidal reducer under the combined effects of error excitations and motor input, and to provide a theoretical basis for error control and coordinated optimization of electromechanical parameters.MethodsFirstly, a standard three-crank double-cycloid precision cycloidal reducer was investigated. Based on the small-vibration coordinate method and Lagrange equations, an 11-degree-of-freedom planar bending-torsional coupled dynamic model incorporating the input shaft, crankshafts, cycloidal gears, and output carrier was established. The incremental relation among servo-motor voltage, current, and electromagnetic torque were further introduced to formulate an electromechanical coupled dynamic model. Then, time-varying meshing of the input-stage gear pair, two-dimensional elastic support of the eccentric bearings, and unilateral contact of the cycloid-pin tooth pairs were considered to investigate the effects of error excitations, load fluctuations, and motor parameters on the dynamic responses.ResultsTorsional vibration at the input side is converted into planar vibration of the cycloidal gears through the crankshafts and eccentric bearings and is subsequently transmitted to the output carrier through eccentric-support reaction forces, forming a coupled transmission path of input torsion-cycloidal-gear planar motion-output torsion. The input-stage gear error mainly affects the torsional responses of the input shaft and crankshafts, and its influence gradually attenuates toward the output side, whereas the cycloid-pin tooth error directly changes the multi-tooth contact state and instantaneous load distribution and therefore has a greater influence on the output dynamic transmission error. Compared with the baseline condition, increases in the input-stage gear error, cycloid-pin tooth error, and load fluctuation increase the peak-to-peak output dynamic transmission error by 12.37%, 30.55%, and 7.96%, respectively. Input-shaft speed fluctuations and current disturbances form a bidirectional electromechanical coupling through back electromotive force and electromagnetic torque. Increasing mechanical damping effectively suppresses input-side vibration, whereas reducing winding inductance intensifies current ripple.关键词：Precision cycloidal reducer;Bending-torsional coupling;Electromechanical coupling;Small-vibration coordinate method;Dynamic modeling1|0|0更新时间：2026-10-16
- 摘要：ObjectiveTo address the issues of uneven initial population distribution, susceptibility to local optima, and insufficient directionality in local exploration within traditional artificial lemming algorithm (ALA) for mobile robot path planning, a multi-strategy improved artificial lemming algorithm (IALA) was proposed in this paper.MethodsFirstly, Latin hypercube sampling was employed to initialize the population, enhancing the quality of global exploration starting points. Secondly, an anti-predation strategy was introduced during the exploration phase. Embedded after the algorithm's long-distance migration and burrowing behaviors, it forces individuals to deviate from current local optima, expanding the search scope. Finally, a raccoon tree-climbing strategy was proposed for the exploitation phase. This strategy combines the linear advancement update method from the raccoon optimization algorithm with Lévy flight, enhancing the algorithm's directional advancement capability and convergence robustness in the mid-to-late stages. To validate the proposed algorithm's effectiveness, experiments were conducted using six standard test functions and two sets of grid maps.ResultsTest results demonstrate that IALA achieves superior optimization accuracy and stability compared to the comparison algorithms. In path planning tests on 20×20 and 40×40 grid maps, its optimal path lengths were reduced by 1.17 and 3.82 units, respectively, compared to the standard lemming optimization algorithm. Additionally, IALA exhibited smaller standard deviations and smoother paths, validating its stability and reliability.关键词：Artificial lemmings optimization algorithm;Path planning;Latin hypercube sampling;Anti-predation strategy;Raccoon tree-climbing strategy3|4|0更新时间：2026-10-13
- 摘要：ObjectiveTo address numerous discrete tooth number combinations, unclear planet number arrangement and stage ratio allocation patterns, and the lack of rapid criteria for preferred topology family identification in early configuration design of high power wind turbine gearboxes, a physics based surrogate evaluation method was proposed for discrete feasible domain analysis of three stage NGW planetary gear trains.MethodsA physical surrogate model composed of the summed volumes of the sun gear, planet gears and ring gear rim was established based on contact strength-dominated scale estimation. The system surrogate volume and the outer diameter of the first-stage ring gear were adopted as surrogate indices to characterize the overall scale and radial envelope of candidate schemes. Under the constraints of concentricity, assembly, adjacency and transmission ratio error, full-domain enumeration was performed for tooth number combinations and planet number combinations. The effects of the planet number and staged transmission ratios on the surrogate indices were analyzed, and the stability of the obtained laws was verified by parameter perturbation and rechecking via detailed parametric optimization sorting.ResultsThe 12.5 MW case yielded 101 534 schemes and 57 topology families. Low surrogate volume schemes were mainly concentrated in regions with a large first stage planet number, relatively low first stage transmission ratio, and relatively high final stage transmission ratio. The planet number non increasing rule covered all schemes in the top 0.1% of surrogate volume and reduced candidate schemes by 45.04% while retaining 98.43% of the top 0.5% schemes. The Spearman rank correlation coefficient between average topology family surrogate volume and average mass after detailed parameter optimization was 0.956, indicating that the model supports early configuration pattern identification and preferred topology family screening.关键词：Wind turbine gearbox;NGW planetary gear train;Discrete feasible domain;Surrogate model;Configuration pattern7|0|0更新时间：2026-10-09
- 摘要：ObjectiveThis study aims to investigate the regulatory mechanism of surface micro-textures on the frictional characteristics of gear tooth surfaces, targeting the energy loss and wear caused by tooth surface friction in gear transmissions. The goal is to explore effective methods for reducing the friction coefficient and improving lubrication conditions on tooth surfaces, thereby providing theoretical support for enhancing surface performance.MethodsA numerical simulation model based on mixed lubrication theory was established. By analyzing the influence of surface textures on oil film pressure distribution, oil film thickness distribution, and friction coefficient under different operating conditions, and comparing the results with those of smooth surfaces, the impact of surface textures on the frictional performance of tooth surfaces was investigated.ResultsSimulation results show that surface textures can effectively improve lubrication and reduce the friction coefficient. Among the studied parameters, textures with a diameter around 100 μm and an area ratio of approximately 20% demonstrated the best friction-reducing effects.关键词：Gear transmission;Mixed lubrication;Surface texturing;Micro-dimple;Lubrication characteristics10|0|0更新时间：2026-09-15
- 摘要：ObjectiveTo address the issues that the acquisition of gear single-flank composite deviation relies on professional testing equipment and the mapping relation between individual geometric deviations and composite deviations is insufficiently analyzed, a method for reconstructing and analyzing gear single-flank composite deviation based on individual tooth-flank elemental deviations was proposed to achieve the mapping from tooth surface geometric errors to single-flank composite deviations.MethodsFirstly, a unified error field for full-tooth error information was constructed based on tooth profile deviation and pitch deviation data. A local contact competition model was established with the gear meshing contact ratio and normal clearance as constraints. Secondly, the envelope response of the dominant contact tooth surface was extracted to reconstruct the single-flank composite deviation curve. Thirdly,the least squares sine fitting method was used to perform parametric analysis on the reconstruction results to analyze the main error components and frequency domain characteristics of the single-flank composite deviation. Finally, the test verification was carried out using the Klingelnberg P26 gear measurement center and the Intra M21137 single-flank gear rolling tester.ResultsTest results show that the peak-to-peak values of the single-flank composite deviations of the left and right tooth surfaces reconstructed using the proposed method are 6.8 μm and 7.1 μm, respectively, with deviations from the single-flank gear rolling test results both less than 0.1 μm. The reconstructed curves and test curves exhibit good consistency in overall trend, periodicity, and local fluctuation characteristics. This demonstrates that the proposed method can reconstruct the single-flank composite deviation from individual tooth surface deviations, establishing a mapping relation between tooth surface geometric errors and single-flank composite deviations, providing a reference for gear accuracy evaluation, error tracing, and transmission error analysis.关键词：Gear single-flank composite deviation;Individual deviation;Local contact competition;Single-flank gear rolling test;Tooth profile deviation （编辑：贾文倩）8|0|0更新时间：2026-09-12
- 摘要：ObjectiveChallenges including filtering distortion, outlier interference and non-stationary component resolution exist in gear tooth surface waviness extraction, and conventional approaches fail to achieve both geometric fidelity and high spectral resolution. A robust method for waviness extraction and spectral characterization along gear feature lines was proposed.MethodsFirstly, normal deviation signals were constructed along gear feature lines and detrending processing was completed, so as to realize one-dimensional dimensionality reduction of three-dimensional tooth surface errors and provide a unified geometric benchmark for waviness separation. Secondly, a robust Gaussian regression filtering model was established, and M-estimation and biweight iterative mechanism were introduced to suppress boundary distortion and spike interference and ensure the geometric fidelity of main waviness morphology. Then, adaptive multi-scale decomposition of the filtered signals was performed using CEEMDAN-HHT, and a space-frequency-energy characterization framework was constructed to analyze the multi-scale features of non-stationary waviness components. Finally, comparative tests were conducted based on simulation and measured data to quantitatively verify the filtering performance and characterization accuracy of the method.ResultsThe results show that compared with the standard Gaussian filter, the robust Gaussian regression filter improves the outlier suppression capability from 1.13 dB to 5.0 dB and reduces the boundary error by about 80%. Compared with FFT, CEEMDAN-HHT reduces the reconstruction root mean square error from 0.70 μm to 0.63 μm. The adaptability of the method under complex interference is verified by measured data, and local transient waviness defects and global dominant undulations can be clearly identified, which provides reference for quantitative evaluation and cause tracing of gear tooth surface waviness.关键词：Gear waviness;Feature line;Robust gaussian regression filter;CEEMDAN;Hilbert spectrum （编辑：李凯阳）13|1|0更新时间：2026-08-26
- 摘要：ObjectiveAs the core component of a wind turbine pitch system, pitch bearings must endure complex fatigue loads generated by blades throughout their entire life cycle. Cracking at the plugging hole is one of the most common failure modes. To address this issue, the stress components driving the failure were analyzed, the potential reasons for the actual service life being shorter than the design simulation results were pointed out, and an on-site rectification scheme was proposed for engineering application practices.MethodsFirstly, the macroscopic morphology of the crack fracture at the plugging hole was analyzed to preliminarily identify the damage type. Secondly, a global finite element model (FEM) of the entire pitch system and a sub-model of the plugging hole were established and solved. The stress state and fatigue life at the plugging hole were evaluated, and the direction of the driving stress causing the crack was identified. Thirdly, considering the actual manufacturing process and fracture observation, the influence of surface scratches on the bearing life was discussed. Finally, an on-site rectification scheme involving the installation of a flange at the plugging hole was proposed, and its feasibility was analyzed using the FEM.ResultsThe results demonstrate that the circumferential stress along the intersection line between the plugging hole and the pin hole acts as the driving factor for the fatigue life of the plugging hole. During the bearing manufacturing process, surface defects such as scratches significantly reduce the bearing life. The rectification scheme using an additional flange not only substantially extends the bearing life but also features low cost and easy implementation. This study provides a methodological reference for ring fatigue assessment during the pitch bearing design phase, offers process control recommendations for practical production, and presents a feasible solution for risk mitigation in operational wind turbines.关键词：Wind turbine;Pitch bearing;Plugging hole;Fatigue fracture;Finite element analysis （编辑：李立）5|1|0更新时间：2026-08-26
- 摘要：ObjectiveA shipborne 6-degree-of-freedom (DOF) parallel platform can compensate for the 6-DOF motions generated by vessels, thereby improving the reliability and safety of offshore operations and extending the operational time window. Such platforms possess advantages including a large workspace, high load-carrying capacity, and low susceptibility to singularities within the workspace. For shipborne application scenarios, a multi-scale comprehensive study was conducted with the F-norm condition number, natural frequency, and stiffness index selected as optimization objectives.MethodsFirstly, the required workspace of the 6-DOF parallel platform was analyzed based on the motion response of ships at sea, and this workspace was used as a constraint for the dimensional synthesis of the mechanism. Secondly, considering the practical requirements of high response speed, high frequency response, and high precision for shipborne 6-DOF parallel platforms, the F-norm condition number, natural frequency, and stiffness were adopted as multi-objective optimization performance indices to analyze the influence of mechanism parameters on these indices. Thirdly, the non-dominated sorting genetic algorithm Ⅱ (NSGA-II) was employed for multi-objective optimization, and the optimal mechanism parameters for the shipborne 6-DOF parallel platform were selected from the obtained Pareto-optimal set. Finally, simulation verification was carried out.ResultsThe simulation results demonstrate that, under the same control gain, the optimized parameters of the 6-DOF parallel platform achieve superior compensation performance. The residual motion amplitudes along the X, Y, and Z directions and around the X, Y, and Z axes are reduced by 44.6%, 66.7%, 65.6%, 70.5%, 26.3%, and 40.1%, respectively.关键词：Wave compensation;Ship-mounted Stewart platform;Multi-objective dimensional synthesis4|0|0更新时间：2026-08-26
- 摘要：ObjectiveAiming at the core pain point of low bearing fault diagnosis accuracy caused by poor diagnosis performance and weak model generalization under smallsample and classimbalanced conditions during bearing feature extraction, a bearing fault diagnosis method based on an adaptive crossattention mechanism was proposed.MethodsFirstly, to address the blindness in selecting the mode number N of variational mode decomposition (VMD), the approximate range of N was determined by the centralfrequency criterion, and a simplified model was adopted to screen out the optimal N within this range. Secondly, VMD and short-time Fourier transform were employed to decompose vibration signals. Convolutional neural network (CNN) was used to extract timefrequency features. A signal processing method with coordinated optimization of adaptive cross-attention (ACA) and Transformer encoder was proposed to construct the CNN-Transformer-ACA diagnosis model. Finally, the reliability of the model was verified using a selfbuilt dataset and the public Case Western Reserve University dataset.ResultsThe results show that after adding strong noise with a signaltonoise ratio of -2 dB and a standard deviation of 2.58 to the datasets and performing unbalance correction, the fault diagnosis accuracy still reaches 97.32% on the Case Western Reserve University dataset and 98.18% on the selfbuilt dataset. The research results provide a feasible scheme for improving bearing safety and faultdetection capability.关键词：Rolling bearing;Adaptive variational mode decomposition;Small sample and unbalance processing;Adaptive cross-attention;Bearing fault diagnosis （编辑：刘星泽）27|1|0更新时间：2026-08-20
- 摘要：ObjectiveSince existing research on brake discs has primarily focused on single materials and has rarely considered both wear feedback and fatigue life validation simultaneously, the coupled thermal-mechanical-wear behavior and differences in fatigue life between cast iron brake discs and carbon-ceramic brake discs were investigated under identical braking conditions.MethodsThree-dimensional finite element models of two types of brake discs were developed using Abaqus. The patterns of temperature, stress, and wear changes during the braking process were analyzed using contact friction heat generation, thermal stress response, and the Archard wear model. Based on these results, the fatigue life of the two brake discs was predicted using the Manson-Coffin strain-life method and the stress-life method, respectively, and the model results were validated through bench tests.ResultsSimulation results show that carbon-ceramic brake discs reach higher peak temperatures than cast iron brake discs during braking, but they exhibit lower thermal stress levels and wear depth, and their fatigue life is significantly longer than that of cast iron brake discs. Bench test results further validates that the thermal-mechanical-wear coupling model can accurately reflect the temperature, stress, and wear trends, as well as the fatigue life, of brake discs during the braking process. This study provides a basis for the subsequent optimization of brake disc design and material selection.关键词：Cast iron brake disc;Carbon-ceramic brake disc;Finite element model;Temperature;Stress;Wear;Fatigue life prediction （编辑：贾文倩）15|3|0更新时间：2026-08-19
- 摘要：ObjectiveThe tiltrotor main reducer continuously transmits high-power loads during nacelle attitude conversion, and its vibration response is jointly affected by gear meshing excitation, structural flexibility, and additional inertial effects induced by attitude variation. To reveal the modulation mechanism of tilt attitude on the vibration characteristics of the reducer, a rigid-flexible coupling dynamic model considering variable-attitude effects was established for a tiltrotor reducer.MethodsFirstly, the time-varying mesh stiffnesses of the input-stage spiral bevel gear pair and the terminal planetary helical gear pair were calculated, respectively. Secondly, dynamic models of the gears and transmission shafts were developed, and the finite element model of the housing was reduced using the Craig-Bampton method. Finally, the full-system dynamic equations incorporating additional inertial terms were formulated. Based on the proposed model, the vibration responses under continuous tilt transition, typical tilt attitudes, and different tilt directions were investigated.ResultsThe results show that the tilt attitude significantly alters the spatial distribution of vibration energy in the system. The middle section of the transmission chain, the second-stage transmission region, and the output shaft region are relatively sensitive to attitude variation. The inter-stage vibration transmission is enhanced at the 45° transition attitude, whereas harmonic components and modulation sidebands are evidently amplified at the 90° hovering attitude. In addition, the system response exhibits asymmetry under different tilt directions, and the overall vibration level during the 95°-to-0° tilt transition is higher than that during the reverse process. The results can provide a basis for variable-attitude vibration control and structural optimization design of tiltrotor main reducers.关键词：Tiltrotor reducer;Rigid-flexible coupling;Variable attitude;Gear dynamic;Vibration response19|3|0更新时间：2026-08-18
- 摘要：ObjectiveTooth flank fracture is a contact fatigue failure mode of high-cycle/ultra-high-cycle fatigue damage where cracks initiate due to material damage at deep locations inside the tooth. It is proposed to establish a calculation method for the risk threshold of tooth flank fracture in the gear tooth interior based on the multiaxial stress evaluation approach.MethodsBased on contact theory, gear meshing geometry theory and the fundamental theories of elasticity, a parsing model for the equivalent contact internal-field multiaxial stress of gear pairs was established, and a coupled mathematical model for gradient-bearing contact fatigue risk prediction of gears was formulated. The micro-element discretization numerical method was adopted to solve contact problems involving singular integrals of contact stress components for the elastic half-plane. In addition, research on the risk threshold of tooth flack fracture in the gear tooth interior was conducted based on the multiaxial stress evaluation method.ResultsThe results indicate that under the multiaxial stress field, the risk threshold is the highest in the zone between the hardened layer and the core inside the gear tooth, where cracks are prone to initiate and the tooth flank fracture failure is prone to occur. The risk threshold obtained by the proposed model is relatively close to that derived from ISO 6336-4 technical specifications. Moreover, the fracture position of the test gear is basically consistent with the risk area calculated by the proposed model. These findings demonstrate that the proposed model can serve as a reference for the preliminary design of gears resistant to tooth surface fracture, and can be used as a tooth flank fracture risk assessment method supplementary to existing technical specifications. The established tooth flank fracture risk prediction model based on multiaxial stress fatigue provides a reference for the design and manufacturing of the gear transmission engineering equipment.关键词：Cylindrical gear;Tooth flank fracture;Multi-axial fatigue;Parsing model;Stress distribution （编辑：刘星泽）110|155|0更新时间：2026-08-04
- 摘要：ObjectiveTo address the unclear key factors affecting loads of the rack‑and‑pinion climbing‑type ship‑lift chamber driving mechanism, based on the collected historical operational data including ship‑chamber operation frequency, water depth inside the chamber, driving mechanisms and synchronizing shaft systems, variation rules of rack‑and‑pinion loads under different operating conditions of the ship‑lift were investigated.MethodsA mechanical analysis and numerical calculation model for the ship‑chamber driving system was established based on data‑fitting results. Through statistical analysis, the influencing mechanisms of varying water‑depth conditions, operating modes and unbalanced loads among driving units on pinion loads were systematically revealed, and targeted countermeasures were formulated.ResultsThe results show that the rack-and-pinion load during the uniform upward and downward movement of the ship chamber is mainly affected by the misladen water depth and the system frictional resistance. During the acceleration and deceleration stages, the inertial loads induced by the self-weight of the ship chamber and the rotating components in the system produce prominent peak values of the rack-and-pinion loads. There are significant deviations in the rack-and-pinion loads among drive units, which are basically unaffected by the operation process, operating conditions and overall load conditions of the ship lift, presenting a random distribution characteristic. Optimized control over pinion loads can be achieved through precise regulation of chamber water depth.关键词：Ship lift;Ship chamber driving mechanism;Rack-and-pinion;Operating load;Misladen water depth;Eccentric load of drive units （编辑：贾文倩）54|34|0更新时间：2026-07-17
- 摘要：ObjectiveIn view of the current lack of systematic force analysis of center-input multi-crank transmission mechanisms, taking the hybrid small-tooth-difference star wheel reducer as the research object, the force analysis of its second-stage transmission was focused, the visualization and simulation verification of bearing forces were realized to provide a reference for subsequent structural design and engineering application.MethodsForce equilibrium equations were established for the involute star wheel, crank shaft, planetary carrier, and the overall small-tooth-difference mechanism. Expressions for the interaction forces among components were derived, and the consistency of the subsystem derivation was verified through the global force analysis. Based on the vector synthesis principle, a visualization module for bearing forces was implemented, showing the force magnitude and fluctuation pattern of each bearing during the input shaft rotation cycle. A 3D solid model was built using RecurDyn for dynamic simulation.ResultsThe simulation results show that the force amplitudes and fluctuation trends of each bearing are highly consistent with the theoretical calculations, verifying the feasibility of the proposed calculation method.关键词：Hybrid small-tooth-difference star wheel reducer;Force analysis;Bearing force;Visualization;RecurDyn simulation （编辑：贾文倩）33|57|0更新时间：2026-07-17
- 摘要：ObjectiveMeshing clearance affects the transmission accuracy, vibration and noise performance of gear-rack pairs. Aiming at the low accuracy and limited adjustment range of traditional clearance adjustment methods, a novel clearance adjustment mechanism and the method was proposed to realize the precise regulation of meshing clearance for precision transmission working conditions.MethodsFirstly, a clearance adjustment method based on an eccentric ring was proposed, and a radially offset clearance adjustment mechanism with multiple adjusting grooves was designed. Then, a geometric model was established to deduce the nonlinear relationship between structural parameters and meshing clearance. Taking the maximum center distance adjustment range as the objective, particle swarm optimization (PSO) algorithm was adopted to optimize key structural parameters, and prototype machining and tests were carried out for model verification.ResultsThe eccentric ring mechanism can realize segmented adjustment of meshing clearance. Structural parameters have obvious regulation effects on the center distance, and the adjustment process presents discontinuous and nonlinear characteristics. Multiple optimal parameter groups are obtained. The measured experimental data are highly consistent with theoretical results, which verifies the effectiveness of the model and the proposed method. The proposed eccentric ring mechanism can meet the clearance adjustment requirements under multiple working conditions, effectively improving transmission accuracy and reducing vibration and noise. It provides a reference for the structural design and clearance optimization of precision gear-rack pairs.关键词：Gear rack transmission;Gear mesh;Engagement clearance;Eccentric clearance adjustment16|0|0更新时间：2026-07-14
- 摘要：ObjectiveTo address the prominent dynamic excitation and severe structural vibration issues of an NW‑type planetary gearbox under high‑speed and varying load conditions, a multi-objective micro-geometry tooth modification optimization methodology was investigated.MethodsFirstly, a coupled system dynamic model incorporating a flexible housing, bearing stiffness, and non-linear gear meshing features was formulated using finite element sub-structuring techniques. Secondly, based on the extracted operational load profiles, multi-node steady-state contact characteristics and dynamic transmission errors (DTEs) were resolved via tooth contact analysis (TCA) to identify the baseline misalignments. Thirdly, parametric optimization swings utilizing a linear-weighted comprehensive fitness function were executed via a genetic algorithm (GA) to determine the optimized combination of helix crown, helix slope, and profile modification variables across the sun and planetary gears, the search efficiency of which was comparatively verified against the Monte Carlo random sampling strategy. Finally, test verifications were subsequently conducted on a variable-speed order analysis drivetrain platform to record the chassis vibration accelerations before and after micro-geometry implementation.ResultsParameter sweeps indicate that the evolutionary GA scheme exhibits superior convergence stability and searching accuracy over the statistical Monte Carlo routine. Under the dominant 180th meshing order frequency, implementing the GA-optimized modifications trims the DTE of the first-stage gear pair by 51.1% and minimizes the peak contact stress by 12.8%. Dynamic simulations demonstrate that the peak vibration acceleration of the housing drops from 347.26 m/s2 to 137.98 m/s2, yielding a 60.26% reduction. Laboratory order tracking matching the numerical trajectories confirms that the maximum measured vibration acceleration drops from 997.4 m/s2 to 581.4 m/s2, which successfully suppresses tooth flank corner contact and substantiates the outstanding engineering applicability for noise, vibration, and harshness (NVH) mitigation.关键词：Reducer;Gear modification;Vibration;Transmission error （编辑：李立）76|34|0更新时间：2026-06-26
- 摘要：ObjectiveThe fixed damping characteristics of traditional shock absorbers cannot meet the driving requirements of multiple road conditions. A novel mono-tube double-piston damping adjustable shock absorber was designed to solve the defects of insufficient damping force reserve and redundant external control valve structure in existing mono-tube shock absorbers, and to provide reference for the optimal design of off-road vehicle suspension shock absorbers.MethodsFirstly, the mathematical models of damping force in compression and rebound strokes of the shock absorber were derived to provide a basis for quantitative analysis of damping characteristics. Secondly, a three-dimensional fluid model of the internal flow field of the shock absorber was established, and the flow field simulation was completed by using the standard k-ε model to obtain the simulation results of damping characteristics under different working conditions. Then, a special test platform for damping characteristics of the shock absorber was built, and the tests of indicator characteristics and velocity characteristics under different loading speeds and adjustment gears were completed. Finally, the simulation and test data were compared to verify the feasibility of the structural design.ResultsThe results show that the simulation results are in good agreement with the test results, and the maximum relative error is 13.22%. In the compression stroke, the maximum dynamic range of damping force is 2.16 kN, and the peak output reaches 7.05 kN; in the rebound stroke, the maximum dynamic range of damping force is 2.57 kN, and the maximum output is 5.97 kN. The structure can realize wide-range step adjustment of damping force through the double-piston cooperative working mechanism and the built-in 4-gear regulating valve, and effectively improve the multi-working condition adaptability of the shock absorber.关键词：Single-cylinder shock absorber;Adjustable damping shock absorber;Variable damping;Indicator characteristics;Velocity characteristics;Dynamic range （编辑：李凯阳）50|25|0更新时间：2026-06-18
- 摘要：ObjectiveTo satisfy the design requirements for the crowned profile of cylindrical roller bearings, a design method based on multi-circular-arc fitting of the ideal logarithmic curve was proposed.MethodsFirstly, taking the minimum sum of squared deviations between two circular arcs and the ideal logarithmic curve as the optimization objective, the Newton iteration method was adopted to perform unconstrained optimization of structural parameters. Secondly, a transitional tangent arc was arranged between the two arcs. With the minimum sum of squared deviations between the tangent arc and the ideal logarithmic curve set as the objective, penalty functions were introduced according to the constraint that two tangent points fall within the effective length of the roller to convert constrained optimization into unconstrained optimization, and the greedy algorithm was used to optimize parameters of the transitional tangent arc. Finally, fitting verification was carried out on rollers with three different dimensions, and thecontact stress was calculated using finite-length line contact algorithm.ResultsThe results indicate that the fitted curve obtained by the proposed method achieves high approximation to the ideal logarithmic curve with continuous function values at arc intersection points. The contact stress distribution of loaded rollers is close to the ideal condition. Although slight stress jumps occur at intersections due to discontinuous curvature, the maximum contact stress still appears near the roller midsection, which verifies the validity of the presented design method.关键词：Bearing;Roller;Modification curve;Arc fitting;Optimization;Finite line contact;Contact Stress （编辑：刘星泽）60|92|0更新时间：2026-06-08
- 摘要：ObjectiveIn order to study the influence of the rotating pair clearance on the dynamic characteristics of the space deployable mechanism, a space shear-fork deployable manipulator was designed.MethodsA mathematical model of the rotating pair clearance was established, and a dynamic simulation analysis of the space manipulator containing a rotating pair clearance was carried out based on the contact force model of the IMPACT function to analyze the effects of the gap size, the recovery coefficient, the position of the gap and the number of gaps on the dynamic characteristics of its unfolding process.ResultsThe results show that the deployment process remains relatively stable when the joint clearance ranges from 0.02 mm to 0.04 mm and the restitution coefficient of the selected material is between 0.4 and 0.8. The rotational joint clearance exerts a more significant influence on the dynamic characteristics of the executive component at positions farther away from it. The increase in the number of clearances raises the vibration frequency of the manipulator during deployment, which deteriorates the stability of the deployment process. Therefore, the selection of appropriate structural parameters and materials is crucial. The research findings can provide a reference for the research and structural optimization of space deployable manipulators.关键词：Rotating pair clearance;Dynamic simulation;Dynamic characterization;Spatially expandable mechanism52|33|0更新时间：2026-06-08
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-5
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0