最新刊期
卷 49 ， 期 3 ， 2025
- 摘要：ObjectiveThe finite element model under symmetric (friction disc)-antisymmetric (steel disc) was established to investigate the thermoelastic instability (TEI) and perturbation field distribution of multi-layer material friction pairs, which was based on the Galerkin method.MethodsThe radial distribution of critical speed and perturbation growth rate variation were obtained through coordinate transformation and Matlab numerical model analysis. A transient perturbation field calculation model for sliding surfaces was proposed based on the perturbation method and finite element model, and the distribution of temperature and pressure perturbation field on the sliding surface was obtained.ResultsThe results indicate that the wave number corresponding to the minimum critical speed is the main characteristic wave number at which the perturbation growth rate increases the fastest. Thermoelastic instability first occurs at the outer diameter of the friction pair, and then gradually expands towards the inner diameter as the angular speed increases. The temperature and pressure perturbation fields are periodically distributed along the circumference of the friction pair, but the amplitude of perturbation at the outer diameter side is higher than that at the inner diameter side due to the difference in radial distribution of the linear speed. The amplitude of perturbation will rapidly increase with the relative sliding time due to the exponential growth effect when the relative sliding speed exceeds the critical speed. The results provide a basis for further research on the formation mechanism of hot spots and the distribution of temperature and pressure fields.关键词：Friction pair of the clutch;Thermoelastic instability;Critical speed;Perturbation field38|1|0更新时间：2025-03-20
- 摘要：ObjectiveThe development of new energy vehicles has put higher requirements on the micro-morphology of the tooth surface. However, the stability of gear transmission can be affected by the existence of tooth profile error. To accurately study the effect of tooth profile error on the meshing performance of involute gears, and thus provide the guidance for the development of high-precision gears in new energy vehicles, compared with the three-section measurement of tooth surface, which is the current method, a construction method of tooth surface, using the multi-section form, based on the dot matrix of measured tooth surface, was proposed to make the constructed tooth surface more approximate to the actual one.MethodsFinite element simulation was used to analyze the variation of tooth contact stress in the meshing cycle and transmission error under different loads between the constructed gear with tooth profile error using the multi-section method and the one using the three-section method.ResultsThe results show that compared with the gear with tooth profile error, constructed by the three-section method, variation of the maximum contact stress of the one with the multi-section method is obvious in the whole meshing cycle and the change of contact area and allocation way of load brought by tooth profile error is precisely demonstrated. Meanwhile, with the increment of the load torque, the growth of the transmission error amplitude of gear with tooth profile gear, constructed by the multi-section method is higher, which reflects the state of actual tooth surface better. The solid foundation for further research on the rapid and efficient construction of gear model, which is fitted to the actual one, is laid.关键词：Involute gear;Multi-section;NURBS surface;Tooth shape error;Tooth contact;Transmission error20|3|0更新时间：2025-03-20
- 摘要：ObjectiveTo meet the requirements of high power density and compactness, the planetary gear is designed as a thin-walled structure, which reduces the stiffness of the planetary gear and makes it easy to deform, thereby affecting the bearing capacity and service life of the bearing. In response to this problem, the deformation and contact performance of the planetary gear needle roller bearing assembly were analyzed and studied based on the principle of virtual work in elastic mechanics and the design method of rolling bearings.MethodsA mechanical analysis model of thin-walled planetary gear train with axial-rotation coupling was established by virtual work principle and rolling bearing design method, and verified by finite element simulation. The deflection curve of planetary ring, bearing load distribution, contact stress and other performance parameters were obtained by numerical calculation, and then the influence of driving torque and axial-rotation coupling on bearing capacity and life was analyzed.ResultsThe results show that the flexural deformation of the flexible planetary ring has obvious influence on the load distribution of the bearing, and the coupling effect of planetary ring and needle roller should be considered in the calculation of the performance of the actual planetary gear train needle roller bearing. The best way to consider the convex shape of the needle roller is logarithmic. Bearing load and contact stress increase with the increase of revolution speed and driving torque, and the position angle 55°-305° is the bearing area of needle roller. Bearing fatigue life decreases with the increase of revolution speed and driving torque.关键词：Needle roller bearing;Contact property;Fatigue life;Deflection deformation16|0|0更新时间：2025-03-20
- 摘要：ObjectiveCompared with conventional parallel mechanisms, kinematic redundant parallel mechanisms offer advantages such as a larger orientation workspace and the ability to avoid singular configurations. However, their degree of mobility (L) is greater than the number of degrees of freedom (n) of the end effector, which results in an excessive number of rigid bodies and makes dynamic modeling more difficult. Therefore, a dynamic modeling method based on the principle of virtual work was proposed for the 3-[P(RR-RRR)SR] kinematic redundant parallel mechanism, further simplifying the modeling process.MethodsFirstly, generalized variables were selected in the high-dimensional generalized space corresponding to the degree of mobility (L) of the mechanism. The kinematic transfer relations between the velocity and acceleration of each component within the mechanism and the system output velocity and acceleration were derived, and the Jacobian matrices of each component and the generalized variable were solved. Then, the dynamic model of the parallel mechanism was established using the principle of virtual work. Finally, the model was simulated by tracking the quintic polynomial trajectory of the end effector and compared with the calculation results of Adams software.ResultsThe analysis results indicate that the maximum relative error between the theoretical and simulated values of the driving force/torque at each joint is only 1.58%. This demonstrates the accuracy and reliability of the model, and also suggests that this method can provide reference for in-depth analysis of the dynamic characteristics of the mechanism and research on control strategies.关键词：Kinematic redundancy;Parallel mechanism;Dynamic modeling;Principle of virtual work;Jacobian matrix16|0|0更新时间：2025-03-20
- 摘要：ObjectiveOil lubricated rolling bearings can easily form elasto-hydrodynamic lubrication（EHL） between the rolling element and the raceway. The EHL oil film plays an important role in the stiffness and damping of rolling bearings, and the study and calculation of the stiffness and damping of rolling bearings must consider the role and influence of EHL oil film.MethodsApplying the fitting formula for stiffness and damping of point contact EHL friction pairs, the influence of load and speed on deep groove balls bearing stiffness and damping was investigated, and the theoretical calculation results were compared and analyzed with relevant test results.ResultsThe results show that the radial stiffness and damping of rolling bearings increase with the increase of load when the rotational speed is constant, and decrease exponentially with the increase of rotational speed when the load is constant. The variation trend of stiffness and damping of rolling bearings with load and speed is completely consistent with the test results, proving the correctness of the theoretical calculation results. The results also indicate that the fitting formula for stiffness and damping of point contact EHL friction pairs is correct, providing convenience for calculating the dynamic characteristics of rolling bearings under EHL conditions.关键词：EHL;Deep groove ball bearing;Stiffness;Damping12|0|0更新时间：2025-03-20
- 摘要：ObjectiveAs an important strengthening process for gears, the quenching heat treatment will generate relatively high residual stress, which will further affect the meshing stiffness and dynamic performance of gears. Based on the analysis of the distribution law of quenching residual stress, the quantitative impact of residual stress on the meshing dynamic characteristics of gears was revealed.MethodsA gear quenching simulation model was established based on the direct thermo-mechanical coupling method to solve the quenching residual stress. Combined with the single node method, this residual stress was regarded as the prestress to solve the time-varying meshing stiffness of the helical gear pair. Based on this, the lumped parameter method was used to establish a 10-degree-of-freedom dynamic model of the helical gear pair. The Runge-Kutta method was used for numerical solution, and the time domain diagram and frequency domain diagram of the dynamic load during the vibration response of the helical gear pair were obtained.ResultsCompared with the situation without considering the residual stress, the bending deformation of a single tooth becomes larger in the four-tooth meshing area and smaller in the five-tooth meshing area. The contact deformation does not change much, and the time domain peak values of meshing stiffness and dynamic load become larger, the dynamic load frequency domain amplitude spectral density at the meshing frequency increases.关键词：Helical gear;Residual stress;Time-varying meshing stiffness;Dynamic load11|0|0更新时间：2025-03-20
Theory·Research
- 摘要：ObjectiveIn response to the problem of the large distance between the two cranks of the composite crank connecting rod machine and to avoid the transient vibration and the phase error caused by the chain transmission, an innovative combination crank connecting rod mechanism with the transient high-precision sinusoidal output characteristics was proposed.MethodsThe transient characteristics of chain transmission on the output of the mechanism were analyzed and calculated, resulting in a maximum fluctuation torque of ±5%. A coaxial reverse transmission mechanism was designed to coaxially arrange two cranks, achieving smooth and precise transmission. Using Ansys software to analyze the torsion angle of the bevel gear shaft, taking into account the transmission backlash of the bevel gear, the error between the output law of this mechanism and the standard sine curve was analyzed.ResultsThe results indicate that the absolute speed error caused by the torsional deformation of the bevel gear shaft and the backlash of the bevel gear transmission is relatively small. Thus, the mechanism has transient high-precision characteristics, and can meet the low-cost testing requirements for products such as wave energy power generation devices and automotive suspension vibrations.关键词：Precise sine law output;Combined crank connecting rod mechanism;Coaxial reverse transmission mechanism;Suspension vibration test;Wave energy power generation test5|0|0更新时间：2025-03-20
- 摘要：ObjectiveMore attention is paid to the quality of life and health under the great work pressure, and the health care effect of traditional Chinese medicine (TCM) massage to relieve the fatigue and promote the metabolism is more and more obvious. Flapping is an important technique in TCM massage. A flexible flapping device was proposed.MethodsThe reciprocating swing was realized with the help of a crank-rocker mechanism, and a flexible rotary joint was added at its end to complete the flapping action through the inertia. A posture-adjusting mechanism was designed to realize the flapping angle required by users. The dynamic model of flapping mechanism was established, and the dynamic parameters of outbound and return trips were analyzed to verify the feasibility of the flapping action. Then the measurement system of flapping was built to test the effect of the flapping speed on the flapping force.ResultsThe research has certain guiding significance for the design of TCM massage robots.关键词：Traditional Chinese medicine massage;Flexible rotation;Dynamics;Flapping force7|1|0更新时间：2025-03-20
- 摘要：ObjectiveAiming at the difference of load sharing and dynamic characteristics between high-contact-ratio spur gears and conventional spur gears, a method for calculating the dynamic tooth root strain was proposed considering the dynamic characteristics of the gear system.MethodsA dynamic model of the gear system was established with the lumped-mass method, and the dynamic meshing force was calculated by using the Newmark-β method to solve the system dynamics equations. The dynamic analysis model of gear structure was established by the finite element method, the load sharing between gear teeth was determined with the loaded tooth contact analysis method, and the time history of tooth root strain was calculated by the transient analysis method. The dynamic tooth root strain of the high-contact-ratio spur gear under different input speeds and torques was solved by using the proposed method, and the calculated results were compared with the conventional spur gear.ResultsThe results indicate that the load sharing rate of the single tooth pair of high-contact-ratio spur gear is between 0.2 and 0.6, and the tooth root strain of high-contact-ratio spur gear increases and then decreases twice respectively. The peak value of tooth root strain of high-contact-ratio spur gear increases with the increase of input speed and torque, and the peak value of the tooth root strain of high-contact-ratio spur gear is obviously lower than that of conventional spur gears under different working conditions. The dynamic tooth root strain of high-contact-ratio spur gear obtained by the method was compared with the test results. The relative error between the peak value of the tooth root strain and the measured results is less than 10%, which verifies the validity of the calculation method.关键词：High-contact-ratio spur gear;Dynamic meshing force;Load sharing between gear teeth;Finite element method;Dynamic tooth root strain11|4|0更新时间：2025-03-20
- 摘要：ObjectiveFemoral veni puncture is widely used in clinical scenarios such as critical emergency treatment, emergency dialysis, drug rehydration, etc. However, the success rate of femoral veni puncture often depends on the experience of doctors. Thus, an ultrasound-guided robot system for femoral vein puncture was developed.MethodsFirstly, a 2-DOF end puncture actuator of the puncture robot was designed for angle adjustment of the swing arm and femoral vein puncture feeding.Then, based on the 7-DOF serial robot arm, an ultrasound-guided femoral vein puncture robot system was built to ensure the space of ultrasound scanning and puncture. Finally, the positioning accuracy of the end puncture actuator and the robot was verified.ResultsThe test results show that the absolute positioning accuracy of the angle of the puncture swing arm of the end puncture actuator is within 0.5°, the absolute positioning accuracy of the puncture feed is within 0.2 mm, and the spatial repeated positioning accuracy of the needle tip of the femoral vein puncture robot based on the 7-DOF robot arm is within 0.2 mm, meeting the requirements of clinical puncture accuracy. The robot system is built to realize semi-automatic puncture through remote operation, which provides important experience for realizing automatic puncture of femoral veins.关键词：Femoral vein puncture;Ultrasonic guidance;Puncture actuator;Medical robot5|0|0更新时间：2025-03-20
- 摘要：ObjectiveTo explore the meshing and dynamic evolution of spur gear pairs under the combined influence of assembly errors and tooth surface friction, a method integrating geometric analysis of spur gear pairs with energy method was employed. The impact of assembly errors and tooth surface friction on spur gear pair meshing was investigated.MethodsA 6-degree-of-freedom bending-torsional coupling vibration model of spur gears was established based on the lumped mass method. Numerical solutions characterizing the meshing behavior and dynamic response of the system were obtained using the Runge-Kutta method.ResultsThe analysis reveals that, the mesh stiffness amplitude of the spur gear pair decreases with the increase of the tooth surface friction coefficient. Additionally, simulation results demonstrate that appropriately adjusting the installation conditions and using reasonable tooth surface friction coefficients of spur gear pairs can improve its transmission accuracy and vibration characteristics. The research findings can provide references for the dynamic analysis of spur gear transmission systems under the influence of systematic errors.关键词：Spur gear;Mesh stiffness;Assembly error;Tooth surface friction;Dynamic response1024|85|0更新时间：2025-03-20
Design· Calculation
- 摘要：ObjectiveHigh-speed dry hobbing is an efficient and cleaner gear manufacturing technology. It is paramount to solve the serious vibration problem raised in the high-speed dry hobbing process under the high-frequent alternating cutting load, which is beneficial for improving productivity and machining accuracy.MethodsTo this end, an orthogonal test was performed to analyze the influence of process parameters on the hobbing vibration characteristics. Furthermore, a comprehensive indicator for evaluating the hobbing vibration was proposed, and the relation between this indicator and the spindle speed and the axial feed rate was developed. Based on this, a process parameter optimization model was constructed and oriented by the optimal vibration indicator and shortest cutting time.ResultsCompared to the original cutting conditions, the optimized cutting parameters enable the reductions of cutting time by 26% and vibration comprehensive indicator by 23%. Moreover, the dimensional accuracy of the machined gears can also be improved. The results can provide an important basis for the optimal selection of process parameters achieving the high-efficiency and high-stability high-speed dry hobbing.关键词：High-speed dry hobbing;Vibration characteristics;Machining efficiency;Parameter optimization7|2|0更新时间：2025-03-20
- 摘要：ObjectiveTo precisely calculate the brake disc braking force of a disc brake system, a brake disc braking force model based on the quasi-static temperature and thermal stress distribution of the brake pad under the influence of heat source was established.MethodsFirst, the energy conversion mechanism during a single braking process was analyzed. Then, based on the quasi-static temperature and thermal stress distribution obtained during the braking process, a stress-braking force model was constructed using numerical methods. Finally, a simulation example was designed to verify the validity of the model.ResultsThe simulation results show that, in the later stages of braking, the temperature-braking force model curve is observed to be slightly higher than the stress-braking force model due to the influence of thermal accumulation effects. The stress-braking force model and the temperature-braking force model exhibit a high degree of consistency in their trends, with a maximum error of 305 N, an average error of 2.371 5 N, and the average relative error of only 0.012 7%. This model not only provides a basis for the numerical analysis of the braking force, but also provides new ideas and methods for the braking force detection.关键词：Disc brake;Thermal coupling;Simulation;Real-time detection5|0|0更新时间：2025-03-20
- 摘要：ObjectiveThe power sources are important external excitations of the transmission system, so it is necessary to fully explore the influence of different power sources on the dynamic characteristics of the hybrid vehicle power transmission system.MethodsFirstly, the dynamic driving torque of the four-cylinder engine and the permanent magnet synchronous motor was derived and expressed as a function of angular displacement, and the power output model of power source was established. Based on the finite element polycondensation method and the centralized parameter dynamic modeling method, the hybrid dynamic model of the transmission system was established, and the correctness of the modeling method was verified by tests. Finally, the rigid-flexible coupling dynamics model of the power transmission system of hybrid vehicles was established by coupling the power source and the drive system dynamics model, so that the vehicle can operate in pure electric drive mode, engine drive mode and combined drive mode respectively, and the dynamic response characteristics of the system under different drive modes were analyzed. The effects of engine torque fluctuation, motor torque fluctuation and simultaneous operation of engine and motor on the dynamic characteristics of the system were investigated.ResultsThe results show that both engine and motor torque fluctuation will lead to the increase of gear pair meshing torque, bearing force and bearing center trajectory range, as well, the vibration caused by 2 times base frequency of motor and base frequency of four-cylinder engine is the main reason for the increase of the bearing force.关键词：Hybrid vehicle;Power transmission system;Dynamic response characteristic11|2|0更新时间：2025-03-20
- 摘要：ObjectiveAiming at the abnormal noise issue in the parallel mode of a hybrid electric vehicle, its generation mechanism was investigated and optimization solutions were proposed.MethodsFirstly, vibration and noise tests were carried out on the prototype vehicle to identify the type of abnormal noise. Then, a simulation model was established to replicate parallel operating conditions, and its accuracy was verified by comparing simulation results with test data. Finally, a parameter sensitivity analysis was performed to identify the key factors influencing the noise.ResultsThe test and simulation results reveal that the abnormal noise is the gear rattle in the transmission, primarily occurring on the drive motor side. Parameters such as parallel vehicle speed, drive motor torque, and secondary flywheel inertia are found to significantly affect the issue. Validation results demonstrate that increasing the drive motor torque leads to a 66.7% reduction in vibration; elevating the parallel vehicle speed results in a 60% decrease in vibration; and augmenting the rotational inertia of the secondary flywheel yields a 46.7% reduction in vibration. The proposed solutions effectively reduce the gear rattle.关键词：Hybrid electric vehicle;Dedicated hybrid transmission;Parallel mode;Gear rattle;Simulation analysis;Srategy optimization9|3|0更新时间：2025-03-20
Test·Analysis
- 摘要：ObjectiveTo increase the obstacle crossing performance of robots and enhance their terrain adaptability, a “walking jumping dual purpose” robot with a composite jumping mechanism on wheeled robots was designed and studied.MethodsThe bouncing mechanism was designed with a combination of springs and cylinder sliders, where energy was stored in the springs to enable bouncing. Firstly, a rebound mechanism scheme was designed and a virtual simulation prototype was built. Then, in order to study the relation between the sliding rod length and the motion, the relation between the sliding rod of the mechanism and the swing angle of the jumping leg was obtained through the kinematic modeling of the mechanism, and the velocity and acceleration of the mechanism were analyzed. Thirdly, a mechanism dynamics model was established based on the Lagrangian dynamics method, and the influence of the rotation angle and angular acceleration on the torque of each member was obtained. Further analysis through the oblique upward throwing motion model, the relation between the robot’s takeoff angle and its bounce performance was studied.ResultsJumping simulations were conducted on the robot using Adams software to verify the accuracy of the theoretical modeling, as well as the good jumping performance and smoothness of the robot.关键词：Jumping machine;Lagrangian dynamics;Takeoff angle;Bouncing performance;Bouncing stability7|0|0更新时间：2025-03-20
- 摘要：ObjectiveTo address the limited adaptability of traditional pipeline robots in complex working environments, a design proposal for a shape memory alloy (SMA) driven peristaltic metamorphic robot suitable for rigid miniature pipelines was presented.MethodsAn SMA-driven anchoring and telescopic structure was designed. Dynamic simulations and analysis of the robot’s peristaltic movement and turning processes were performed using Adams software, followed by the prototype construction and motion experiments for verification.ResultsThrough the simulations, curves of joint driving torque over time, as well as velocity and displacement curves verify the stability of the robot’s motion. Tests demonstrate that the prototype can move stably in “L”-shaped and three-way junction pipelines with 22 mm diameter. The results prove that the metamorphic robot can achieve the peristaltic movement through the coordination of anchoring and telescopic structures, realize the active turning through metamorphosis, and demonstrate the excellent pipeline traversing capability.关键词：Miniature pipeline;Pipeline robot;Metamorphic mechanism;Adams software53|36|0更新时间：2025-03-20
- 摘要：ObjectiveConsidering the impact of modeling errors and external disturbances on the trajectory tracking of pneumatic muscle knee joints, a fuzzy sliding mode control strategy based on a disturbance observer was proposed.MethodsIn this control strategy, the disturbance observer was added to the sliding mode control to estimate and compensate for disturbances, and the fuzzy control was used to adaptively adjust the switching gain
- 摘要：ObjectiveIn the field of industrial manufacturing, the grasping action is the basis for robots to complete complex tasks. Therefore, it is very important to realize accurate perception and grasping of unknown and irregularly shaped objects for robots. A robot grasping experimental platform was built, and a grasping planning method based on multi-angle visual information was proposed.MethodsFirstly, a depth camera was used to collect the point cloud image of the unknown object from multiple views, and it was reconstructed in three dimensions to obtain the position and shape information of the unknown object. Then, the Gaussian process was utilized to fit the hidden surface of the unknown object, and the robot dynamic grasping planning scheme based on the attractor motion was used to realize the customized grasping.ResultsThe proposed grasping planning scheme was verified by the experiments to have the characteristics of fast speed, high precision and strong adaptability, and can meet the requirements of different environments and tasks, which is of great significance for practical application research related to robotics.关键词：Robots;Object grasping;Point cloud reconstruction;Gaussian process9|0|0更新时间：2025-03-20
- 摘要：ObjectiveAiming at the incompatibility between the structure and the control system of the underactuated and fully actuated manipulators, a hybrid drive artificial hand is designed, which has the characteristics of high system integration and flexible structure.MethodsAccording to the dexterity of human hands, the structures of index finger and thumb were optimized to have multi-joint independent drive and adaptive underdrive ability. The driving force of the finger was optimized through the conical screw drive shaft structure. The flat bag structure was used to realize the independent finger swing drive in a narrow space, and the sensor layout was optimized by the thermodynamic diagram mapping relation. Additionally, the multi-mode application of 5 kinds of sensors was studied.ResultsA hand-like prototype with 16 actuators is made, which has the ability of intelligent grasping and surface texture recognition, and the grasping ability is tested under different driving modes, which provides reference for the research of multi-mode control of manipulators.关键词：Structural compatibility;Screw drive;Multi-mode;Texture recognition12|0|0更新时间：2025-03-20
Development·Application
- 摘要：ObjectiveThe depth of the hardened layer of gears is a significant factor influencing on strength and load-carrying capacity of gears. Modern research shows that different failure modes of gears require different effective hardened case depths. The traditional design of the hardened case depth often only considers the relation between the hardened layer and modulus, does not fully consider the influence of gear service environment, performance requirements and failure mode, and does not truly reflect the theoretical connotation of the hardened case depth. [Analysis] Taking the carburized and quenched gear as an example, the domestic and foreign literature and standards on the effective hardened case depth was summarized. The design method of the effective hardened case depth under different failure modes of gears was given, and the recommended value of the best hardened case depth was given.关键词：Hardened case depth;Failure mode;Load-carrying capacity;Carburized and quenched gear9|5|0更新时间：2025-03-20
- 摘要：ObjectiveHigh-altitude wall operations carry inherent risks, and accidents can lead to economic loss and casualties. Wall-climbing robots were utilized as a substitute for human labour presents an effective solution. The stability of the adhesion mechanism in wall-climbing robots significantly impacts their reliability and efficiency, making the study of adhesion technology a crucial aspect of their design. Research on the adhesion mechanisms of wall-climbing robots and their applications lacks a systematic comparative analysis. [Analysis] The adhesion mechanisms and research progress of several standard adhesion methods—magnetic adhesion, negative pressure adhesion, electrostatic adhesion, and biomimetic adhesion were introduced, and their application scenarios were compared. Each adhesion method’s advantages, disadvantages, and future prospects were analyzed. The adhesion methods of commonly used wall-climbing robots were analyzed, summarized, compared, and forecasted, aiming to provide valuable guidance for future research on wall-climbing robots.关键词：Wall-climbing robot;Adsorption mode;Adsorption mechanism;Moving mode10|1|0更新时间：2025-03-20
Review
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