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Dynamic analysis of axle box bearings on the high-speed train caused by wheel-rail excitation

Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 441-460页

作者： Qiaoying MA Shaopu YANG Yongqiang LIU Baosen WANG Zechao LIU State Key Laboratory of Mechanical behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

To explore the impact of wheel-rail excitation on the dynamic performance of axle box bearings,a dynamic model of the high-speed train including axle box bearings is ***,the dynamic response characteristics of the axle box bearing are *** investigation focuses on the acceleration characteristics of bearing vibration under excitation of track irregularities and wheel *** addition,experiments on both normal and faulty bearings are conducted separately,and the correctness of the model and some conclusions are *** to the research,track irregularity is unfavorable for bearing fault detection based on resonance *** the same speed conditions,the acceleration peak of bearing is inversely proportional to the length of the wheel flat and directly proportional to its *** paper will contribute to a deeper understanding of the dynamic performance of axle box bearings.

关键词： high-speed train track irregularity wheel flat dynamic simulation

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

arXiv

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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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A Cyclic Constitutive Model Based on Crystal Plasticity for Body-Centered Cubic Cyclic Softening Metals

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Acta Mechanica Solida Sinica 2024年第1期37卷 33-42页

作者： Xuehong Ren Wenjie Zhao Shaopu Yang Guilin Wen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China School of Mechanical Engineering Tianjin Sino-German University of Applied SciencesTianjin 300350China State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Under the framework of the small deformation crystal plasticity theory,a crystal plastic cyclic constitutive model for body-centered cubic(BCC)cyclic softening polycrystalline metals is *** constitutive model introduces the isotropic softening rule that includes two different mechanisms:namely softening under monotonic deformation and softening under cyclic deformation on each slip ***,a modified Armstrong-Frederick nonlinear kinematic hardening rule is *** appropriate explicit scale transition rule is selected to extend the single crystal constitutive model to the polycrystalline constitutive *** the model is used to predict the uniaxial and multiaxial ratcheting deformation of BCC axle steel EA4T to verify the rationality of the proposed *** simulation results indicate that the newly established crystal plasticity model can not only describe the cyclic softening characteristics of BCC axle steel EA4T well,but also reasonably describe the evolution laws of uniaxial ratcheting and nonproportional multiaxial ratcheting ***,the established crystal plastic cyclic constitutive model can reasonably predict the ratcheting behavior of BCC single crystal as well.

关键词： Crystal plasticity Constitutive model Softening Ratcheting

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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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Dimension reduction graph-based sparse subspace clustering for intelligent fault identification of rolling element bearings

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International Journal of mechanical system Dynamics 2021年第2期1卷 207-219页

作者： Le Zhao Shaopu Yang Yongqiang Liu State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuangHebeiChina School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuangHebeiChina

Sparse subspace clustering(SSC)is a spectral clustering *** high-dimensional data are often dispersed over the union of many low-dimensional subspaces,their representation in a suitable dictionary is ***,SSC is an effective technology for diagnosing mechanical system *** main purpose is to create a representation model that can reveal the real subspace structure of high-dimensional data,construct a similarity matrix by using the sparse representation coefficients of high-dimensional data,and then cluster the obtained representation coefficients and similarity matrix in ***,the design of SSC algorithm is based on global expression in which each data point is represented by all possible cluster data *** leads to nonzero terms in nondiagonal blocks of similar matrices,which reduces the recognition performance of *** improve the clustering ability of SSC for rolling bearing and the robustness of the algorithm in the presence of a large number of background noise,a simultaneous dimensionality reduction subspace clustering technology is provided in this *** the feature extraction of envelope signal,the dimension of the feature matrix is reduced by singular value decomposition,and the Euclidean distance between samples is replaced by correlation distance.A dimension reduction graph-based SSC technology is *** and bearing data of Western Reserve University show that the proposed algorithm can improve the accuracy and compactness of clustering.

关键词： correlation distance dimension reduction sparse subspace clustering

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Love Waves in a Piezoelectric Semiconductor Thin Film on an Elastic Dielectric Half-Space

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固体力学学报（英文版） 2023年第1期36卷 45-54页

作者： Ru Tian Guoquan Nie Jinxi Liu Ernian Pan Yuesheng Wang State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China 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 State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Engineering and Institute of Pioneer Semiconductor Innovation National Yang Ming Chiao Tung UniversityTaiwanChina Department of Mechanics Beijing Jiaotong UniversityBeijing 100044China

In this paper,Love waves propagating in a piezoelectric semiconductor(PSC)layered structure are investigated,where a PSC thin film is perfectly bonded on an elastic dielectric *** dispersion equations are derived *** influence of semiconducting properties on the propagation characteristics is examined in *** results show that the semiconducting effect reduces the propagation speed,and that the Love waves can propagate with a speed slightly higher than the shear wave speed of the elastic dielectric *** wave speed and attenuation significantly depend on the steady-state carrier density and the thickness of the PSC thin *** is also found that when the horizontal biasing electric field is larger than the critical value(corresponding to the zero attenuation),the wave amplitude is *** findings are useful for the analysis and design of various surface wave devices made of PSC.

关键词： Love wave Piezoelectric semiconductor Layered structure Dispersion Attenuation

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Speed following control of truck based on driver intention recognition 4

Speed following control of truck based on driver intention r...

引用

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

作者： Wang, Guiyang Li, Shaohua Wang, Hesen State Key Laboratory of Mechanical Behavior in Traffic Engineering Structure and System Safety Dept. Name of Organization Shijiazhuang050043 China

ISBN: (纸本)9781728184968

Autonomous emergency braking (AEB) system enables vehicles to avoid collisions or mitigate the damage. Due to large braking distance, a safety distance model on the basis of the vehicles driving state and the process of vehicle braking is established. The driver's reaction time and early warning vehicle speed following controller are established, and the predictive AEB algorithm based on the driver's operation intention is established. Finally, TruckSim-Matlab/Simulink co-simulation for the AEB control strategy is conducted. The simulation result shows that the proposed control strategy can hierarchically warn and automatically brake, which is effective. © 2020 IEEE.

关键词： MATLAB

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Influence of vehicle-road coupled vibration on tire adhesion based on nonlinear foundation

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Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 607-624页

作者： Junning ZHANG Shaopu YANG Shaohua LI Yongjie LU Hu DING School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang 050043China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

The influence of pavement vibration on tire adhesion is of great significance to the structure design of vehicle and *** adhesion between tire and road is the key to studying vehicle dynamics,and the precise description of tire adhesion affects the accuracy of dynamic vehicle ***,in most models,only road roughness is considered,and the pavement vibration caused by vehicle-road interaction is *** this paper,a vehicle is simplified as a spring-mass-damper oscillator,and the vehicle-pavement system is modeled as a vehicle moving along an Euler-Bernoulli beam with finite length on a nonlinear *** road roughness is considered as a sine wave,and the shear stress is ignored on the *** to the contact form between tire and road,the LuGre tire model is established to calculate the tire adhesion *** Galerkin method is used to simplify the partial differential equations of beam vibration into finite ordinary differential equations.A product-to-sum formula and a Dirac delt function are used to deal with the nonlinear term caused by the nonlinear foundation,which realizes the fast and accurate calculation of super-high dimensional nonlinear ordinary differential *** addition,the dynamic responses between the coupled system and the traditional uncoupled system are compared with each *** obtained results provide an important theoretical basis for research on the influence of vehicle-road coupled vibration on tire adhesion.

关键词： vehicle system dynamics vehicle-road coupled vibration LuGre tire model Galerkin method

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The Scheme to Determine the Convergence Term of the Galerkin Method for Dynamic Analysis of Sandwich Plates on Nonlinear Foundations

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Acta Mechanica Solida Sinica 2021年第1期34卷 1-11页

作者： Hong-Yan Chen Hu Ding Shao-Hua Li Li-Qun Chen Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematicsand MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversitygShanghai 200444China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversitxyShiyiazhuang 050043China

The vibration of a plate resting on elastic foundations under a moving load is of great significance in the design of many engineering fields,such as the vehicle-pavement system and the aircraft-runway *** or runways are always laminated *** Galerkin truncation method is widely used in the research of *** number of truncation terms directly affects the convergence and accuracy of the response ***,the selection of the number of truncation terms has not been clearly stated.A nonlinear viscoelastic foundation model under a moving load is *** on the natural frequency of linear undisturbed derivative systems,the truncation terms are used to determine the convergence of vibration *** criterion for the convergence of the Galerkin truncation term is *** scheme is related to the natural frequency with high efficiency and *** the dynamic response of the sandwich beam under a moving load,the feasibility of the scheme is *** effects of different system parameters on the scheme and the truncation convergence of dynamic response are *** research in this paper can be used as a reference for the study of the vibration of elastic foundation ***,the model established and the truncation analysis method proposed are helpful for studying the vibration of vehicle-pavement system and related systems.

关键词： ndwich plate Galerkin method Convergence Nonlinear foundation

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Modeling,analysis,and simulation of X-shape quasi-zero-stiffness-roller vibration isolators

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 1027-1044页

作者： Xiaoye MAO Mengmeng YIN Hu DING Xiaofeng GENG Yongjun SHEN Liqun CHEN Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Existing quasi-zero stiffness(QZS)isolators are *** terms of their advantages,a novel X-shape QZS isolator combined with the cam-roller-spring mechanism(CRSM)is *** from the existing X-shape isolators,oblique springs are used to enhance the negative stiffness of the ***,the CRSM is used to eliminate the gravity of the loading mass,while the X-shape structure leaves its static *** existing QZS isolators are demonstrated and classified according to their nonlinearity mechanisms and classical *** is shown that the oblique spring can realize negative stiffness based on the simplest *** X-shape has a strong capacity of loading mass,while the CRSM can achieve a designed restoring force at any *** proposed isolator combines all these advantages *** on the harmonic balance method(HBM)and the simulation,the displacement transmissibilities of the proposed isolator,the X-shape isolators just with oblique springs,and the X-shape isolators in the traditional form are *** results show that the proposed isolator has the lowest beginning isolation frequency and the smallest maximum displacement ***,it still has some disadvantages similar to the existing QZS *** means that its parameters should be designed carefully so as to avoid becoming a bistable system,in which there are two potential wells in the potential energy curve and thus the isolation performance will be worsened.

关键词： quasi-zero stiffness(QZS) cam-roller X-shape isolator nonlinear isolation

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