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Establishment of Dynamic Model for Axle Box Bearing of High-Speed trains Under Variable Speed Conditions

Chinese Journal of mechanical engineering 2022年第4期35卷 340-351页

作者： Yongqiang Liu Baosen Wang Bin Zhang Shaopu Yang School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Trafc and Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Engineering and Computing University of South CarolinaColumbiaSouth Carolina 29208USA State Key Laboratory of Mechanical Behavior and System Safety of Trafc Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

In this study,a dynamic model for the bearing rotor system of a high-speed train under variable speed conditions is *** contrast to previous studies,the contact stress is simplifed in the proposed model and the compensation balance excitation caused by the rotor mass eccentricity *** angle iteration method is used to overcome the challenge posed by the inability to determine the roller space position during bearing *** simulation results show that the model accurately describes the dynamics of bearings under varying speed profles that contain acceleration,deceleration,and speed oscillation *** order ratio spectrum of the bearing vibration signal indicates that both the single and multiple frequencies in the simulation results are consistent with the theoretical *** on bearings with outer and inner ring faults under various operating conditions are performed to verify the developed model.

关键词： Variable speed conditions High-speed train Bearing model Angle iteration Order ratio spectrum

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Low-light Traffic Objects Detection for Automated Vehicles 6

Low-light Traffic Objects Detection for Automated Vehicles

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

作者： Wang, Xuewei Wang, Dongmei Li, Siyuan Li, Shaohua Zeng, Pengtian Liang, Xiao Shijiazhuang Tiedao University State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang China

ISBN: (数字)9781665453745

ISBN: (纸本)9781665453745

The low-light condition brings huge challenges to the traffic object detection, limiting its application in complex scenarios such as the round-the-clock traffic monitoring and automatic driving. To address this issue, an accurate traffic object detection method in low-light conditions is proposed. First, the dark channel prior knowledge is utilized to restore the scene radiance via the transmission map and the estimation of the atmospheric light. Meanwhile, the grayscale is adjusted by adaptive gamma transformation to further improve the brightness of the image and reduce the impact of low-light conditions. Second, a LL4PH-Net framework equipped with preset anchors and detection branches is developed to detect low-light traffic objects. The performance of the algorithm is tested on the public BDD100K dataset. Experimental results show that compared with the SOTA methods, the proposed LL4PH-Net acquires the best detection mAP, the most lightweight model and a good time efficiency. It can effectively detect traffic objects even under low-light conditions. © 2022 IEEE.

关键词： Image enhancement

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Effect of Relative Phase of Loose Tie Rods on Nonlinear Dynamic behavior of Rod-Fastening Rotor-Bearing-Seal system

SSRN

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SSRN 2024年

作者： Wu, Xianglin Gu, Xiaohui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

The circumferential rod-fastening rotor is composed of multiple disks fastened together by preload provided by tie rods evenly distributed along the circumference of rotor. After the rotor has been running for a period of time, some tie rods will loosen and fail to provide preload due to thermal load, centrifugal load, etc. Which causes the preload that was originally evenly distributed in the circumferential direction to become uneven. Uneven preload introduces anisotropy of contact interface stiffness between rotor disks and generalized bending moments, which have important effects on nonlinear dynamic characteristics of rotor-bearing-seal system. Further, it is common for multiple tie rods to become loose at the same time in practical engineering, the relative position of loose tie rods in the circumferential direction will also have an important impact on rotor dynamics. The relevant research has not been done yet. In this paper, a contact model of the rough machined surface is firstly established by combining the statistical contact theory and fractal contact theory, and then the contact stiffness model between disks is established based on the contact model. Finally, the dynamic model of the circumferential rod-fastening rotor-bearing-seal system is established and solved. The effect of relative phase of loose tie rods on the nonlinear dynamic characteristics of rod-fastening rotor-bearing-sealing system is studied. It can be concluded that relative phase of the loose tie rod has an important influence on the frequency, bifurcation, and periodic motion of the rotor system. At lower speed, the anisotropy of contact stiffness caused by loose rods has little effect on the rotor trajectory, while the generalized bending moment has a greater influence on dynamics of the system. At higher speed, the anisotropy of contact stiffness has a great influence on the axis rail of the rod-fastening rotor. © 2024, The Authors. All rights reserved.

关键词： Bending moments

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Multi-Objective Parallel Human-machine Steering Coordination Control Strategy of Intelligent Vehicles Path Tracking Based on Deep Reinforcement Learning

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Chinese Journal of mechanical engineering (English Edition) 2025年第1期38卷 1-19页

作者： Wang, Hongbo Feng, Lizhao Li, Shaohua Chen, Wuwei Zhou, Juntao School of Automotive and Transportation Engineering Hefei University of Technology Hefei230009 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

In the parallel steering coordination control strategy for path tracking, it is difficult to match the current driver steering model using the fixed parameters with the actual driver, and the designed steering coordination control strategy under a single objective and simple conditions is difficult to adapt to the multi-dimensional state variables’ input. In this paper, we propose a deep reinforcement learning algorithm-based multi-objective parallel human-machine steering coordination strategy for path tracking considering driver misoperation and external disturbance. Firstly, the driver steering mathematical model is constructed based on the driver preview characteristics and steering delay response, and the driver characteristic parameters are fitted after collecting the actual driver driving data. Secondly, considering that the vehicle is susceptible to the influence of external disturbances during the driving process, the Tube MPC (Tube Model Predictive Control) based path tracking steering controller is designed based on the vehicle system dynamics error model. After verifying that the driver steering model meets the driver steering operation characteristics, DQN (Deep Q-network), DDPG (Deep Deterministic Policy Gradient) and TD3 (Twin Delayed Deep Deterministic Policy Gradient) deep reinforcement learning algorithms are utilized to design a multi-objective parallel steering coordination strategy which satisfies the multi-dimensional state variables’ input of the vehicle. Finally, the tracking accuracy, lateral safety, human-machine conflict and driver steering load evaluation index are designed in different driver operation states and different road environments, and the performance of the parallel steering coordination control strategies with different deep reinforcement learning algorithms and fuzzy algorithms are compared by simulations and hardware in the loop experiments. The results show that the parallel steering collaborative strategy based on a deep

关键词： Deep reinforcement learning

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Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

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Frontiers of Structural and Civil engineering 2022年第2期16卷 239-249页

作者： Pengfei LI Jinquan ZHANG Shengqi MEI Zhenhua DONG Yan MAO Bridge and Tunnel Technology Research Center Research Institute of HighwayMinistry of TransportBeijing100088China National Engineering Laboratory of Bridge Structure Safety Technology Research Institute of HighwayMinistry of TransportBeijing100088China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China School of Civil Engineering Shijiazhuang Tiedao UniversityShijiazhuang050043China

Damping is known to have a considerable influence on the dynamic behavior of *** fixed damping ratios recommended in design codes do not necessarily represent the complicated damping characteristics of bridge *** study investigated the application of stress-dependent damping associated with vehicle-bridge coupling vibration and based on that investigation proposed the stress-dependent damping *** results of the investigation show that the stress-dependent damping ratio is significantly different from the constant damping ratio(5%)defined in the standard *** vehicles travel at speeds of 30,60,and 90,the damping ratios of the bridge model are 3.656%,3.658%,and 3.671%,*** peak accelerations using the regular damping ratio are 18.9%,21.3%,and 14.5%of the stress-dependent damping ratio,*** the vehicle load on the bridge is doubled,the peak acceleration of the mid-span node increases by 5.4 times,and the stress-related damping ratio increases by 2.1%.A corrugated steel-web bridge is being used as a case study,and the vibration response of the bridge is compared with the measured *** acceleration response of the bridge which was calculated using the stress-dependent damping ratio is significantly closer to the measured acceleration response than that using the regular damping ratio.

关键词： vehicle-bridge vibration system dynamic analysis stress-dependent damping energy dissipation

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Development and stability analysis of a high-speed train bearing system under variable speed conditions

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International Journal of mechanical system Dynamics 2022年第4期2卷 352-362页

作者： Baosen Wang Yongqiang Liu Bin Zhang Shaopu Yang School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuangChina School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuangChina Department of Electrical Engineering University of South CarolinaColumbiaUSA State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuangChina

During a high-speed train operation,the train speed changes frequently,resulting in motion change as a function of time.A dynamic model of a double‐row tapered roller bearing system of a high-speed train under variable speed conditions is *** model takes into consideration the structural characteristics of one outer ring and two inner rings of the train *** angle iteration method is used to determine the rotation angle of the roller within any time period,solving the difficult problem of determining the location of the *** outer ring and inner ring faults are captured by the model,and the model response is obtained under variable speed *** are carried out under two fault conditions to validate the model *** simulation results are found to be in good agreement with the results of the formula,and the errors between the simulation results and the experimental results when the bearing has outer and inner ring faults are found to be,respectively,5.97% and 2.59%,which demonstrates the effectiveness of the *** influence of outer ring and inner ring faults on system stability is analyzed quantitatively using the Lempel–Ziv *** results show that for low train acceleration,the inner ring fault has a more significant effect on the system stability,while for high acceleration,the outer ring fault has a more significant ***,when the train acceleration changes,the outer ring has a greater *** practice,train acceleration is usually small and does not frequently change in one operation ***,the inner ring fault of the bearing deserves more attention.

关键词： high-speed train bearing model variable speed conditions stability analysis Lempel-Ziv complexity

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Optimal Energy-Efficient Operation of a Metro train on a Long and Steep Downhill Segment

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CSEE Journal of Power and Energy systems 2023年第6期9卷 2356-2365页

作者： Deqiang He Hanqing Jian Yanjun Chen Jian Miao Zhixiao Luo Chonghui Ren Lang Zhang the department of State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi Key Laboratory of Manufacturing System&Advanced Manufacturing TechnologySchool of Mechanical EngineeringGuangxi UniversityNanning 530004China the department of Guangxi Police College Nanning 530028China. the department of Nanning Rail Transit Co. Ltd.Nanning 530029China

Because the standard four-stage operation and con-trol strategy cannot fully utilize the gravitational potential energy of a train operating on a long and steep downhill segment,this paper further improves the method for train operation and control *** improved operation includes three stages of acceleration,coasting-speed limit cruising,and *** the speed limit,time limit,and distance limit as the constraints,the coasting condition switching point,braking condition switching point,traction coefficient,and braking force coefficient are used as the decision ***,an improved train traction energy consumption model is constructed,and an improved differential evolution algorithm is designed to solve this *** improved method is used to simulate two long and steep downhill segments of the Nanning *** results show that the improved method can meet the requirements of speed limit,time limit,and distance *** with the standard four-stage operation,the improved train operation and control strategy can reduce train energy consumption by more than 40%on the two long and steep downhill segments;compared with other similar algorithms,the improved algorithm is more suitable for solving the model.

关键词： Energy-efficient operation improved differential evolution algorithm long and steep downhill segment metro train

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Design and Wave Propagation Characterization of Starchiral Metamaterials

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Acta Mechanica Solida Sinica 2022年第2期35卷 215-227页

作者： Yajun Xin Han Wang Cong Wang Jinxin Yao Qian Ding Haoqiang Gao Shuliang Cheng Yongtao Sun Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province Yanshan UniversityQinhuangdao 060000China Hebei Province Low-Carbon and Clean Building Heating Technology Innovation Center Yanshan UniversityQinhuangdao 060000China Department of Mechanics and Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin UniversityTianjin 300072China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Metamaterials with simple artificial topological properties made from industrially produced single-phase materials have extraordinary innovation and *** this paper,we investigated wave propagation characteristics of a hexastarchiral lattice metamaterial with periodic assemblies and used the finite element(FE)method to study the band gap ***,in order to understand the mechanism of band gaps,we discussed the mode shapes of unit cells and found that the bending of the ligament and the overall rotation have a high correlation with the generation of omnidirectional band *** relationships bet ween geometric parameters and band gap properties have also been systematically studied,which demonstrated that the band gaps of the proposed metamaterial could be reasonably predicted through the evolution of geometric ***,the transmission characteristics of finite sandwich panel structures composed of periodic unit cells were calculated to verify the correctness of the band gap simulation results,which proved that the proposed artificial metastructure has potential application value in vibration and noise reduction projects.

关键词： Hexastarchiral lattice metamaterials Band gap properties Finite element method Rotational resonance

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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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Periodic-phase-diagram similarity method for weak signal detection

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International Journal of mechanical system Dynamics 2021年第2期1卷 248-255页

作者： Ruilan Tian Yangkun Zhang Shaopu Yang Kai Yuan Qiang Xue Quanrong Ren State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuangChina Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuangChina

The periodic-phase-diagram similarity method is proposed to identify the frequency of weak harmonic *** key technology is to find a set of optimal coefficients for Duffing system,which leads to the periodic motion under the influence of weak signal and strong *** the phase diagram similarity,the influences of strong noise on the similarity of periodic phase diagram are *** principle of highest similarity of periodic phase diagram with the same frequency is detected by discussing the persistence of similarity of periodic motion phase diagram under the strong noise and the periodic-phase-diagram similarity method is *** weak signals of early fault and strong noise are input into Duffing system to obtain the identified *** stochastic subharmonic Melnikov method is extended to obtain the conditions of the optimal coefficients for the identified *** on the results,the constructed frequency conversion harmonic weak signals are considered to form a datum periodic *** the change of frequency in the datum periodic system,the phase diagram similarity of the two constructed systems can be *** on the periodic-phase-diagram similarity method,the frequency of weak harmonic signals can be identified by the principle of highest similarity of periodic phase diagram with the same *** results of numerical simulation and the early fault diagnosis results of actual bearings verify the feasibility of the periodic-phase-diagram similarity *** accuracy of the detection effect is 97%,and the minimum signal-to-noise ratio is−80.71 dB.

关键词： periodic system signal-to-noise ratio stochastic subharmonic Melnikov method strong noise weak signal

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