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Dynamic analysis of asymmetric piecewise linear systems

Applied Mathematics and Mechanics(English Edition) 2025年第4期46卷 633-646页

作者： Ruiliang ZHANG Yongjun SHEN Xiaotong YANG School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang050043China School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China

Piecewise linear systems are prevalent in engineering practice,and can be categorized into symmetric and asymmetric piecewise linear *** that symmetry is a special case of asymmetry,it is essential to investigate the broader model,namely the asymmetric piecewise linear *** traditional averaging method is frequently used for studying nonlinear systems,particularly symmetric piecewise linear systems,with the harmonic response of the oscillator serving as a key prerequisite for calculating steady-state ***,asymmetric systems inherently exhibit nonharmonic,asymmetric responses,rendering the traditional averaging method *** overcome this limitation,this paper introduces an improved averaging method tailored for an oscillator characterized by asymmetric gaps and *** the traditional method,which assumes a purely harmonic response,the improved averaging method redefines the system response as a superposition of a direct current(DC)term and a first harmonic ***,the DC term can be regarded as the offset induced by model ***,the DC term is treated as a slow variable function of time,with its time derivative assumed to be zero when calculating the steady-state solution,akin to the amplitude and phase in the traditional averaging *** validation demonstrates that the responses computed in both time and frequency domains with the improved averaging method exhibit greater accuracy compared with those derived from the traditional *** these improved results,the study also examines the parameter effect,stability,and bifurcation phenomena within the amplitude-frequency responses.

关键词： nonlinear vibration piecewise linear system asymmetry averaging method offset

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Study on the Mechanism of Polygonal Wear in Wheels Based on Wheel-Rail Contact Normal Force

Study on the Mechanism of Polygonal Wear in Wheels Based on ...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Zhou, Zichao Liu, Yongqiang Guo, Tao Wang, Tiecheng Huo, Wenbiao State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China CRRC TANGSHAN CO. LTD. Tangshan063000 China

ISBN: (纸本)9789819639687

To address the issue of high-order polygonal wear in high-speed trains operating at 300 km/h, this paper investigates the influence of bogie modal vibration on the initiation and progression of such wear phenomena. The model simulation incorporates the modal vibrations of both the frame and the wheelset, while also accounting for non-Hertzian contact and track irregularity within a long-term iterative wear model, thereby enhancing its alignment with real-world operational conditions. The main conclusions are: The vibration frequency of the wheel-rail contact normal force, influenced by running speed and sleeper spacing, plays a key role in the initiation of polygonal wear. The fourth-order bending resonance of the wheelset is the primary cause of the 20th-order polygon wear and its rapid development. Suspension parameters have a significant impact on the wear index, and proper adjustment of these parameters can effectively slow the progression of polygonal wear. The findings of this paper hold theoretical value and practical significance in understanding the formation and progression mechanisms of polygonal wear, as well as in developing effective measures for its mitigation. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Railroads

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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 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 Hefei China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang 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

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Research on the power generation efficiency of bladeless wind turbines under different degrees of freedom based on bidirectional fluid-solid coupling

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Zhendong yu Chongji/Journal of Vibration and Shock 2025年第12期44卷 150-161页

作者： Wei, Hongwei Liu, Kan Wei, Keqin Jia, Yaya Liu, Qingkuan School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China

A simplified model of the bladeless wind turbine was established and the formula for its power generation efficiency was derived. Numerical simulations were conducted using computational fluid dynamics software Fluent and user-defined functions (UDF), studying the vortex-induced vibration characteristics and power generation efficiency of single and dual degree-of-freedom bladeless wind turbines under different reduced wind speeds. The study shows that the difference in the degrees of freedom of the wind turbine significantly affects its vibration response, aerodynamic characteristics and power generation efficiency. The vibration amplitude initially increases and then decreases as the reduced wind speed increases, remaining stable in certain wind speed ranges. The vibration trajectory of the dual degree-of-freedom wind turbine at reduced wind speeds primarily forms a figure-eight pattern, exhibiting multi-frequency vibrations when the wind speed approaches the natural frequency, with the trajectory becoming chaotic. The power generation efficiency follows a trend of increasing first and then decreasing with the changing reduced wind speed, with the efficiency of the dual degree-of-freedom wind turbine being higher than that of the single degree-of-freedom wind turbine. At a reduced wind speed of Ur = 2. 4, the maximum power generation efficiency of the single degree-of-freedom wind turbine is 25. 19%;at Ur = 3.4, the maximum power generation efficiency of the dual degree-of-freedom wind turbine is 57. 14%. Power generation efficiency is influenced by the combined effects of incoming wind speed, vibration velocity, and lift-drag coefficients. With changes in degrees of freedom and reduced wind speeds, the wake vortex shedding patterns of the wind turbine also vary. The vortex shedding patterns of the three-dimensional bladeless wind turbine at different heights in the span direction are similar to those of the two-dimensional wind turbine, but due to smaller vortice

关键词： Energy dissipation

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A study on the discrete element simulation of heterogeneous asphalt under freeze–thaw cycles

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Discover Civil engineering 2025年第1期2卷 1-19页

作者： Xu, Shuo Yan, Zhanyou Zhang, Yijunjie Zhao, Li Chang, Ruiqing School of Civil Engineering Shijiazhuang Tiedao University Hebei China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei China School of English Studies Tianjin Foreign Studies University Tianjin China School of Traffic and Transportation Shijiazhuang Tiedao University Hebei China

To investigate the meso-mechanical behavior of heterogeneous asphalt mixtures more effectively, a discrete element method (DEM) model was developed and used to simulate uniaxial compression tests. The Weibull distribution function was introduced into the model to characterize the heterogeneity of asphalt particle contact strength, and a nonlinear damage equation derived from linear damage theory was utilized to simulate the initial damage evolution process of the asphalt mixture. The results show that: (1) After 5, 10, and 15 freeze–thaw cycles, the peak stress of the asphalt mixture decreased by 12.2%, 18.7%, and 24.9%, respectively, while the peak strain increased by 1.92%, 6.14%, and 16.1%, consistent with experimental results. (2) Both simulation and experimental damage variable evolution diagrams exhibit an ‘S’ shape, and the Weibull function effectively expresses the heterogeneous characteristics of the asphalt mixture. (3) The shape parameter m characterizes the peak stress and brittleness of the material, while the scale parameter a characterizes its deformation capacity.

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The Influence of Parameter Optimization of Rubber Nodes in High-Speed Train Turning Arms on Suppressing Hunting Motion

The Influence of Parameter Optimization of Rubber Nodes in H...

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International Conference on Artificial Intelligence and Autonomous Transportation, AIAT 2024

作者： Guo, Tao Li, Ya Liu, Yongqiang Zhan Tianyou College Dalian Jiaotong University Dalian116028 China CRRC Tangshan Co. Ltd. Tangshan063000 China Shijiazhuang Enric Gas Equipment Co. Ltd. Shijiazhuang051000 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China

ISBN: (纸本)9789819639724

To solve the problems of frequent occurrence of lateral instability and abnormal wear of the tread surface during the service of high-speed trains, the stiffness characteristics and its parameters optimization of the rotating arm rubber node were analyzed in this paper. A high-speed train dynamic model was established using the dynamic analysis software Universal Mechanism with a type of 350 km/h high-speed train in China as the research object. Based on the mechanism of primary and secondary vehicle instability, the phenomena of abnormal hunting of the vehicle body and abnormal vibration of the bogie was reproduced through simulation, and the vehicle response and hunting characteristics were analyzed. The Poynting Thomson model, which can represent the stiffness frequency variation characteristic of rotating arm rubber node, was optimized by the genetic optimization algorithm. The research results indicate that the optimized arm node has a significant inhibitory effect on the instability of primary and secondary hunting movements. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Railroad transportation

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Effects of Day-Night Temperature Fluctuations on Top-Down Cracking Development in Road structures

SSRN

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SSRN 2025年

作者： Li, Ting Qiao, Haoyu Xu, Peng Yang, Guangqing Faculty of Engineering University of Porto Porto4200 465 Portugal State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

Top-down cracking has become a significant issue in road structures. Temperature is a key factor in the occurrence of top-down cracking. However, there is a lack of research on how day-night temperature fluctuations impact the propagation of top-down cracking in road structures, leading to an incomplete understanding of its development. This study employs the extended finite element method, which is an innovative approach for crack analysis, to create a simulation model of road structure with top-down cracking, integrating thermal boundary theory. The model's accuracy is confirmed through comparison with previous studies. The research then examines the temperature distribution and various influential factors, including ambient temperature, material properties, and cracking characteristics, using the stress intensity factor as the main indicator. Grey relational analysis is used to further investigate the effects of different parameters on the stress intensity factor. Additionally, the study explores the propagation path of top-down cracking in road structure under cyclic temperature loading. The findings provide new insights into the thermally-induced mechanisms behind top-down cracking development in road structures. © 2025, The Authors. All rights reserved.

关键词： Road construction

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Analysis of Factors Affecting Vibration Response of Axle Box Bearing of High-Speed Trains

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Journal of Vibration engineering & Technologies 2025年第5期13卷 1-23页

作者： Wang, Min Yang, Shaopu Liu, Yongqiang Chen, Yanhong Zhang, Kai State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China School of Traffic and Transportation Shijiazhuang Tiedao University Shijiazhuang China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang China CRRC TANGSHAN CO. LTD Tangshan China China Water Resources Beifang Investigation Design and Research Co. Ltd. Tianjin China

During the operation of high-speed trains, the vibration characteristics of axle box bearings are influenced by multiple factors. Specifically, this paper investigates the effects of track irregularity excitation, thermal deformation, and lubrication conditions on bearing vibration response under identical working conditions. To achieve this, based on Hertzian contact theory and elastohydrodynamic lubrication principles, a dynamic model of axle box bearing for high-speed train is established. Subsequently, the validity of the proposed model is verified by the experimental data of the single wheelset rolling vibration test bench. Furthermore, the typical fault forms of bearings are simulated, and consequently their effects on bearing vibration characteristics is analyzed. Moreover, the effects of fault size, rotational speed and bearing radial clearance on the system dynamic response are studied by using the eigenvalue of the covariance matrix and root mean square (RMS) value. The results show that track irregularity greatly increases bearing vibration, thermal deformation also causes bearing vibration to intensify. On the other hand, lubrication can effectively reduce bearing vibration. Additionally, the size and location of local bearing faults, along with rotational speed and radial clearance of bearings have great influence on the eigenvalue of the covariance matrix of bearing inner ring and outer ring. Correspondingly, the RMS value of bearing vibration also varies significantly under different speeds.

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Ballast failures restored and detecting methodology for lateral resistance of ballast bed during dynamic stabilization

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engineering Failure Analysis 2025年 176卷

作者： Zhang, Zhihai Xiao, Hong Ma, Chaozhi Tong, Fengzhuang Ding, Dong Li, Jianguo School of Highway Chang'an University Xi'an710064 China School of Civil Engineering Beijing Jiaotong University Beijing100044 China School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou221116 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

Stabilization can effectively restore the bearing capacity and lateral deformation resistance of the failed ballast bed. However, unreasonable operating modes can also affect the lateral stability of the ballast bed and the status of the line. To improve the quality of stabilizing operations and save the construction cost of new railways, the paper established a stabilizing machine-ballasted track model based on the DEM-MFBD algorithm, and carefully analyzed the contact separation, reorganization and migration characteristics of ballast particles during the stabilizing. The microscopic movement mechanism of ballast particles is revealed. Based on the mapping relationship between the PSD of the lateral vibration characteristics of the stabilizing machine and the ballast bed resistance, a new method for detecting the lateral resistance of the ballast is proposed. This detection method realizes the rapid acquisition and data transmission of the ballast bed status, and uses a stabilizing machine as the force source, without the need to add a reaction force device. Therefore, it is more efficient than traditional detection methods. Finally, a multi-point track panel lateral resistance index is proposed, the stabilizing operation effect is evaluated, and the optimal operation mode is given. The results show that the effects of the front and rear stabilizers on the ballast bed should be considered during on-site stabilization, and the operating frequency of the first stabilizer should be appropriately reduced to increase the number of contacts between ballast particles and improve the stability of the ballast bed after the stabilization. The new method for detecting the lateral resistance of the ballast bed can be used to easily obtain the mechanical state of the ballast bed before and after stabilizing operation under different line conditions. More stabilization times does not necessarily mean better results. This study provides effective guidance for improving the perfo

关键词： Subways

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Negative-pressure soft pneumatic actuators enabled by asymmetrically distributed bending units

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Extreme Mechanics Letters 2025年 77卷

作者： Fu, Zeyu Chen, Tianyu Zou, Haoran Zhu, Zhiwei Deng, Zichen Wang, Yifan School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi'an710072 China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore 639798 Singapore State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

Soft pneumatic actuators are highly flexible and can adapt to complex environments, attracting significant attention for their ability to operate in settings where rigid actuators cannot. Most existing soft pneumatic actuators are powered by positive pressure, which has the disadvantage of volume increase during operation and risk of exploding under large pressures. In this study, we designed a new type of soft actuator by inducing asymmetric bending deformation throughout a holey structure under negative pressure. Using finite element analysis and a theoretical model, we studied the effects of various geometric parameters on the structure's bending behavior. We found that the displacement of the circle's center from the central axis is a parameter with the most significant impact on the bending behavior of the structure. By designing circular holes with offset from the central axis, the structure can bend toward the offset direction during subsequent bending deformation. Based on this deformation mechanism, we designed a soft gripper that bends upon actuation and effectively picks up objects. We further designed a bi-directional gripper that bends towards both sides and a circular gripper that contracts towards the center upon evacuation to hold objects. These soft grippers’ grasping capabilities are validated by experimental tests. Finally, by arranging the holes in a wavy pattern within the structure, we created a crawling robot that moves forward through cyclic negative pressure actuation. These findings highlight the potential of leveraging bending behaviors in asymmetrically distributed holey structures for the development of negative-pressure driven soft actuators and robots. © 2025 Elsevier Ltd

关键词： Pneumatic actuators

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