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Contact behavior of Worn Bearings with Elastoplastic Functionally Graded Coating Based on Mixed Elastohydrodynamic Lubrication

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Acta Mechanica Solida Sinica 2021年第1期34卷 124-136页

作者： Xue-Qian Fang Yao Ning Shao-Pu Yang Hai-Hua Wang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang050043China Hebei Key Laboratory for Mechanics of Smart Materials and Structures Shijiazhuang050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang050043China

The dynamic contact behavior of worn bearings with elastoplastic functionally graded coating is studied,and the interacting effect between worn band and functionally graded surface is *** surface deformation and roughness are included in the film *** mixed elastohydrodynamic lubrication combined with point contact model is introduced to analyze the oil pressure in the contact *** using the Fourier transform method and Papkovich-Neuber potential function,the displacements and stress fields in the elastoplastic functionally graded coating are *** second-order central difference method is used to solve the Reynolds *** is found that the repeated surface interaction can result in the sharp increase in pressure in bearings,and the oil pressure increases with increasing graded *** entrainment of oil in the inlet and outlet zones becomes more evident if a large graded index is selected.

关键词： Wear bearings Contact behavior Elastoplastic functionally graded surface Mixed elastohydrodynamic lubrication.Central difference method

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Study on vibration reduction of two-scale system coupled with dynamic vibration absorber

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1335-1352页

作者： Honglin WAN Xianghong LI Yongjun SHEN Department of Mathematics and Physics Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The dynamic vibration absorber with inerter and grounded stiffness(IGDVA)is used to control a two-scale system subject to a weak periodic *** vibration suppression effect is *** amplitude of the main system coupled with absorber is significantly reduced,and the high frequency vibration completely ***,through the slow-fast analysis and stability theory,it is found that the stability of the autonomous system exerts a notable regulating effect on the vibration response of the non-autonomous *** adding the dynamic vibrator absorber,the center in the autonomous system changes to an asymptotically stable focus,consequently suppressing the vibration in the non-autonomous *** research reveals that the parameters of the absorber affect the real parts of the eigenvalues of the autonomous system,thereby regulating the stability of the *** from a qualitative standpoint to a quantitative approach,a comparison of the solutions before and after the introduction of the dynamic absorber reveals that,when the grounded stiffness ratio and the mass ratio of the dynamic absorber are not equal,the high-frequency part in the analytical solution *** a result,this leads to a reduction in the amplitude of the trajectory,achieving a vibration reduction effect.

关键词： two-scale system dynamic vibration absorber vibration control inerter

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Cluster oscillation and bifurcation of fractional-order Duffing system with two time scales

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Acta Mechanica Sinica 2020年第4期36卷 926-932页

作者： Yanli Wang Xianghong Li Yongjun Shen Department of Mathematics and Physics Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China Department of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The dynamical behavior on fractional-order Duffing system with two time scales is investigated,and the point-cycle coupling type cluster oscillation is firstly observed *** taking the fractional order as bifurcation parameter,the dynamics of the autonomous Duffing system will become more complex than the corresponding integer-order one,and some typical phenomenon exist only in the fractional-order *** attractors exist in various parameter space,and Hopf bifurcation only happens while fractional order is bigger than 1 under certain parameter ***,the bifurcation behavior of the autonomous system may regulate dynamical phenomenon of the periodic excited *** results into the point-cycle coupling type cluster oscillation when the fractional order is bigger than *** related generation mechanism based on slow-fast analysis method is that the slow variation of periodic excitation makes the system periodically visit different attractors and critical points of different bifurcations of the autonomous system.

关键词： Fractional-order Duffing system Cluster oscillation Slow-fast analysis method Bifurcation

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Research on brake failure control of heavy commercial vehicles based on turning conditions 4

Research on brake failure control of heavy commercial vehicl...

引用

4th CAA International Conference on Vehicular Control and Intelligence, CVCI 2020

作者： Lu, Yongjie Wang, Fahui Zhang, Guangfeng State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (纸本)9781728184968

With the rapid rise of the transportation industry, commercial vehicles as an important means of transportation, its safety and stability are paid more and more attention. In order to improve the safety performance of heavy commercial vehicles when braking failure occurs under turning conditions. Based on the vehicle dynamics characteristics, this paper designed the stability control strategy in the case of brake failure in the above conditions, designed a fuzzy PID controller based on yurch angular velocity control, carried out the Trucksim-Simulink joint simulation and hardware in the loop experiment to jointly verify the control effect of the brake. The results show that the influence of vehicle brake failure on vehicle driving stability is reduced, the performance of vehicle brake under long and downhill conditions and turning conditions is improved, and the safety stability of vehicle brake failure in hardware loop is improved, which meets the requirements of national standards for vehicle braking. © 2020 IEEE.

关键词： Commercial vehicles

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A Subdomain Adaptation Based Bearing Fault Diagnosis Method Using Infrared Thermal Images

A Subdomain Adaptation Based Bearing Fault Diagnosis Method ...

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2024 IEEE International Conference on Sensing, Diagnostics, Prognostics, and Control, SDPC 2024

作者： Yao, Jie Gu, Xiaohui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (纸本)9798350388855

A sub-domain transfer learning method based on multi-scale convolutional neural network and infrared thermal images is proposed to improve the diagnostic accuracy of bearing faults. Firstly, infrared thermal images with more characteristic information are used to represent the healthy condition of bearings instead of vibration signals. Then, a multi-scale convolutional neural network model is constructed to enhance the feature extraction ability, and a sub-domain adaptation method is used to deal with the situation when training and testing samples are not consistent of independent identically distribution. The proposed method is verified by two datasets from rotating machinery and railway bearing test bench. The results show its effectiveness and robustness than some popular peer transfer learning strategies and vibration signal based methods. © 2024 IEEE.

关键词： Convolutional neural networks

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Study of Local Trajectory Planning Based on Fuzzy Dubins Risk Field 22

Study of Local Trajectory Planning Based on Fuzzy Dubins Ris...

引用

22nd IEEE International Conference on Industrial Informatics, INDIN 2024

作者： Li, Shaohua Ma, Boyu Yang, Zekun Wang, Xuewei State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (纸本)9798331527471

A reasonable and safe path is crucial for implementing vehicle active obstacle avoidance which can enhance driving safety and consequently reduce traffic accidents. A risk field that reflects road structures and obstacles is established to address the limitations of traditional algorithms. Additionally, a local planning method incorporating a fuzzy Dubins strategy is proposed. By constructing lane risk fields and obstacle potential fields using exponential functions, a fuzzy controller is developed. This controller adjusts the lane-changing timing and distance based on the environmental and obstacle information obtained from the risk fields. The vehicle trajectory planning under obstacle avoidance conditions is then achieved through Dubins curves. Simulation and experimental results indicate that the proposed local trajectory planning method based on the fuzzy Dubins risk field effectively performs active obstacle avoidance operations under various conditions. It adjusts the lane-changing timing and distance according to the relative position between the vehicle and obstacles at different speeds, demonstrating a good adaptability to different conditions. © 2024 IEEE.

关键词： Exponential functions

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Dynamic crushing behavior and energy absorption of hybrid auxetic metamaterial inspired by Islamic motif art

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Applied Mathematics and Mechanics(English Edition) 2023年第3期44卷 345-362页

作者： Ruilan TIAN Huaitong GUAN Xuhao LU Xiaolong ZHANG Huanan HAO Wenjie FENG Guanglei ZHANG Department of Engineering Mechanics Hebei Key Laboratory of Mechanics of Intelligent Materials and StructuresShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption *** this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static *** deformation mode and stress-strain curves are further studied under low,medium,and high crushing *** theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation *** crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing *** FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.

关键词： re-entrant honeycomb auxetic hybrid metamaterial energy-absorption dynamic crushing

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AFS/DYC Control of In-Wheel Motor Drive Electric Vehicle With Adaptive Tire Cornering Stiffness 6

AFS/DYC Control of In-Wheel Motor Drive Electric Vehicle Wit...

引用

6th CAA International Conference on Vehicular Control and Intelligence, CVCI 2022

作者： Li, Shaohua Yang, Zekun Shijiazhuang Tiedao University Behavior and System Safety of Traffic Engineering Structures State Key Laboratory of Mechanical Shijiazhuang China

ISBN: (数字)9781665453745

ISBN: (纸本)9781665453745

A linear tire model with constant conering stiffness does not guarantee the model accuracy, while a traditional nonlinear tire model has to face complicated parameter adjustment problems. In order to improve the adaptive capability of path tracking controller for a in-wheel motor drive electric vehicle (IDEV), the cornering stiffness is regarded as a time-varying parameter when tire sideslip angle increases. For the upper controller, the lateral tire force is estimated online based on square root cubature Kalman filter (SRCKF) to solve the cornering stiffness uncertainty. Then a prediction model of MPC with cornering stiffness modified is proposed to reduce the effect of model mismatch. For the lower controller, an active front steering control (AFS) and direct yaw moment control (DYC) based on integrated MPC is designed to track path and improve handling stability. The proposed control strategy is verified under extreme conditions through CarSim/Simulink simulation. It is shown that the strategy effectively improves the accuracy of path tracking and the stability of vehicle compared with the conventional MPC controller. © 2022 IEEE.

关键词： Tires

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Reinforcement Learning-based Token Pruning in Vision Transformers: A Markov Game Approach

arXiv

引用

arXiv 2025年

作者： Lu, Chenglong Liang, Shen Wang, Xuewei Wang, Wei School of Computer Science Fudan University China LIPADE Université Paris Cité Paris France State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Shijiazhuang Tiedao University Shijiazhuang China

Vision Transformers (ViTs) have computational costs scaling quadratically with the number of tokens, calling for effective token pruning policies. Most existing policies are handcrafted, lacking adaptivity to varying inputs. Moreover, they fail to consider the sequential nature of token pruning across multiple layers. In this work, for the first time (as far as we know), we exploit Reinforcement Learning (RL) to data-adaptively learn a pruning policy. Formulating token pruning as a sequential decision-making problem, we model it as a Markov Game and utilize Multi-Agent Proximal Policy Optimization (MAPPO) where each agent makes an individualized pruning decision for a single token. We also develop reward functions that enable simultaneous collaboration and competition of these agents to balance efficiency and accuracy. On the well-known ImageNet-1k dataset, our method improves the inference speed by up to 44% while incurring only a negligible accuracy drop of 0.4%. The source code is available at https://***/daashuai/rl4evit. © 2025, CC BY.

关键词： Reinforcement learning

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Variable scale-convex-peak method for weak signal detection

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Science China(Technological Sciences) 2021年第2期64卷 331-340页

作者： TIAN RuiLan ZHAO ZhiJie XU Yong State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China Department of Applied Mathematics Northwestern Polytechnical UniversityXi’an 710072China

Avariable scale-convex-peak method is constructed to identify the frequency of weak harmonic signal. The key of this method is to find a set of optimal identification coefficients to make the transition of dynamic behavior topologically persistent. By the stochastic Melnikov method, the lower bound of the chaotic threshold continuous function is obtained in the mean-square *** intermediate value theorem is applied to detect the optimal identification coefficients. For the designated identification system, there is a valuable co-frequency-convex-peak in bifurcation diagram, which indicates the state transition of chaosperiod-chaos. With the change of the weak signal amplitude and external noise intensity in a certain range, the convex peak phenomenon is still maintained, which leads to the identification of frequency. Furthermore, the proposition of the existence of reversible scaling transformation is introduced to detect the frequency of the harmonic signal in engineering. The feasibility of constructing the hardware and software platforms of the variable scale-convex-peak method is verified by the experimental results of circuit design and the results of early fault diagnosis of actual bearings, respectively.

关键词： variable-scale Duffing system stochastic Melnikov method scale transformation circuit experiment fault diagnosis

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