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SSRN 2024年

作者： Bo, Wang Qing, Wu Shuihui, Luo Spiryagin, Maksym Kaikai, Lyu Weihua, Ma State Key Laboratory of Rail Transit Vehicle system Southwest Jiaotong University Chengdu China Centre for Railway Engineering Central Queensland University Rockhampton Australia Locomotive & Car Research Institute China Academy of Railway Sciences Beijing China

To analyze the plastic flow of wheels and its impact on rolling contact fatigue (RCF), this article proposes a multibody dynamics approach that is simple to model and fast to compute, based on the mechanics of wheel-rail contact and Tresca yield criterion. This method is used to study the plastic flow of the wheels and is validated by comparing it with plastic flow analysis based on the shakedown theory. The study shows that the dynamics indicators of maximum shear stress, adhesion saturation and stress ratio effectively reflect the plastic deformation of the wheel. Additionally, increasing wheel speed and curve radius, and decreasing wheel-rail friction coefficient, can effectively reduce the area and magnitude of plastic deformation in the wheel. Ignoring the impact of temperature effects on RCF, it is found that the more severe the plastic flow, the greater the likelihood of RCF. That is, alleviating the plastic flow of the wheel can reduce RCF damage in wheels. This approach to managing the health of wheels provides a comprehensive understanding of the interplay between operational parameters and the mechanical behavior of wheel materials, guiding maintenance strategies and operational decisions to enhance safety and extend the lifespan of railway components. © 2024, The Authors. All rights reserved.

关键词： Plastic flow

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A Splitting Diffusion Model for Synchronous Grouting during Shield Tunnelling in Fault Fracture Zone

A Splitting Diffusion Model for Synchronous Grouting during ...

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2024 International Conference on Construction and Real Estate Management: ESG Development in the Construction Industry, ICCREM 2024

作者： Zeng, Yi Zhang, Yanlong Wang, Beiling Xu, Yan Yelv, Gendi Xiong, Wang Lu, Andian Gao, Yue He, Zhenyuan Fu, Yanbin Liao, Longhui Shanghai Tunnel Engineering & Rail Transit Design and Research Institute Shanghai China Guangdong Provincial Key Laboratory of Tunnel Safety and Emergency Support Technology & Equipment Guangzhou China Guangdong Hualu Transport Technology Co. Ltd. Guangzhou China State Key Laboratory of Intelligent Geotechnics and Tunnelling College of Civil and Transportation Engineering Shenzhen Univ. Guangdong Shenzhen China Shenzhen Traffic Engineering Quality Supervision Station Guangdong Shenzhen China Sinohydro Bureau 14 Co. Ltd. Guangdong Shenzhen China Guangdong GDH Pearl River Delta Water Supply Co. Ltd. Guangdong Guangzhou China College of Civil and Transportation Engineering Shenzhen Univ. Guangdong Shenzhen China

ISBN: (数字)9780784485910

ISBN: (纸本)9780784485910

The whole process of splitting diffusion and the response of surrounding rock for synchronous grouting in fault fracture zone is studied in this paper. Based on the Griffith strength criterion, the initial splitting pressure is obtained. Combined with the law of grout diffusion along the radial as semi-elliptical plane, a theoretical model that is suitable for grouting splitting diffusion in fault fracture zone is presented, and analytical solutions of spatial distribution, including grout flow velocity, flow volume, splitting diffusion depth, and splitting channel width, are highlighted. The test results show that it is easy to split at the waists of both sides of the tunnel in fault fracture zone, which confirms that the diffusion model based on Griffith strength criterion is applicable to explain mechanical behaviors of grouting splitting. The parameter analysis shows that the lateral earth pressure coefficient and elastic modulus of rock are the major factors affecting the grouting splitting depth. © ASCE.

关键词： Mortar

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Research on Comprehensive Compensation Strategy for Long-distance Cable Traction Power System

Research on Comprehensive Compensation Strategy for Long-dis...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Dongiie Li Minwu Chen Jiadong Han Yinatao Chen Yinyu Chen Diwen Xiao School of Elcetrical Engineering Southwest Jiaotong University Chengdu China State Key Lab of Rail Transit Engineering Informatization Xian China NR Electric Co. Ltd. Southwest Jiaotong University Nanjing China

ISBN: (纸本)9781665409858

The construction of electrified railway faces power quality problems dominated by reactive power and negative sequence due to the complex terrain and weak power grid structure in highland areas. To solve the problems, this paper discusses the technical scheme of Long-distance Cable traction power supply system (LCTPS) and its control strategy. Firstly, a Long-distance cable power supply model is constructed and a reactive power compensation scheme applicable to this system is designed. Then, a reactive power negative sequence compensation scheme is designed based on the theory of cophase power supply. Furthermore, a comprehensive compensation control strategy was established based on IEEE standards. Finally, a simulation model is established to analyze the correctness of the compensation scheme and verify the effectiveness of the compensation strategy.

关键词： Industrial electronics Reactive power Analytical models Power cables Simulation Power quality IEEE Standards

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DiagLLM: multimodal reasoning with large language model for explainable bearing fault diagnosis

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Science China(Information Sciences) 2025年第6期 41-55页

作者： Jie WANG Tianrui LI Yan YANG Shiqian CHEN Wanming ZHAI School of Computing and Artificial Intelligence Southwest Jiaotong University Engineering Research Center of Sustainable Urban Intelligent Transportation Ministry of Education State Key Laboratory of Rail Transit Vehicle System

Accurate and reliable bearing fault diagnosis is critical for ensuring the safe operation of mechanical *** data-driven methods encounter challenges in training advanced deep learning models, primarily due to the scarcity of fault data and inconsistencies in data distributions. Additionally, these methods often suffer from limited interpretability and reliability, as they lack constraint-guided learning based on the physical mechanisms underlying bearing failures, which hampers their utility in machine condition monitoring. Recent advancements in large language models(LLMs) demonstrate their potential to address these challenges. To this end, we aim to enhance the generalization and interpretability of bearing fault diagnosis by leveraging the capabilities of multimodal LLMs. Specifically, a novel framework called DiagLLM is designed to achieve this goal. DiagLLM leverages the powerful reasoning capabilities of large language models and incorporates contextual information from both envelope spectrum images and expert knowledge to accurately diagnose bearing faults. To effectively tune DiagLLM, diagnostic visual instruction-following data are constructed to link fault feature descriptions with signal characteristics, and the entire model is fine-tuned using a parameter-efficient training pipeline. Extensive experiments are conducted on two publicly available bearing fault diagnosis datasets, and the results show that DiagLLM outperforms leading baselines, particularly in scenarios with limited data and cross-data generalization.

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Corrosion and Corrosion-Fatigue Properties of Composite Ceramic Coated Aluminum Alloy Formed by Combining Surface Nanocrystallization Pre-Treatment, Micro-Arc Oxidation, and Sealing Post-Treatment

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SSRN 2024年

作者： Su, Kaixin Zhang, Jiwang Wu, Shengchuan Guan, Jinfa Li, Hang Ji, Dongdong Xie, Honglan State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China School of Electrical Engineering Southwest Jiaotong University Chengdu611756 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai201204 China

This study investigates the corrosion and corrosion-fatigue (pre-corrosion fatigue and synergistic-corrosion fatigue) properties of composite ceramic coated 6082-T6 aluminum alloy, formed by combining shot peening surface nanocrystallization pre-treatment, micro-arc oxidation (MAO) ceramic coating, and acrylic resin sealing post-treatment. Results reveal that the pre-treatment results in larger internal defects connecting the ceramic coating's outer surface, leading to inferior corrosion resistance compared to plain ceramic coatings. In contrast, the post-treatment effectively reduces coating porosity, thereby enhancing corrosion resistance. Additionally, owing to the presence of compressive residual stress and grain-refined layers within the substrate beneath the ceramic coating, composite ceramic coated specimens subjected to the pre-treatment exhibit superior corrosion-fatigue properties compared to plain ceramic coated specimens. However, the post-treatment enhances the corrosion-fatigue property of ceramic coated specimens by significantly improving their corrosion resistance. © 2024, The Authors. All rights reserved.

关键词： Shot peening

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Analytical Solution of Transient Forces in a Null-Flux Superconducting Electrodynamic Suspension Train Based on Harmonic Approximation

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IEEE Transactions on Energy Conversion 2025年

作者： Gong, Tianyong Ma, Guangtong Liu, Kang Luo, Jun Queval, Loic Southwest Jiaotong University School of Electrical Engineering Sichuan Chengdu610031 China GeePsCNRS Laboratory China Southwest Jiaotong University State Key Laboratory of Rail Transit Vehicle System Sichuan Chengdu610031 China University of Paris-Saclay GeePs-CNRS Laboratory CentraleSupélec Gif-sur-Yvette91192 France

Electrodynamic suspension (EDS) technology has broad application prospects in high-speed rail transit systems. Accurate and efficient electromagnetic force calculations are essential for system design and optimization. This paper derives analytical expressions for transient forces in a null-flux superconducting EDS train based on the harmonic approximation of mutual inductance. Neumann's formula, combined with a cross-sectional discretization technique, is employed to accurately compute the dynamic mutual inductance between the onboard superconducting magnets and the ground suspension coils. Induced current in the coils is derived from dynamic circuit theory, and the transient forces on the magnets are obtained via the virtual displacement method. An equivalent impedance is introduced to account for electromagnetic coupling among the suspension coils. This model is validated against experimental data, with relative errors of less than 3%. A comparative analysis with both finite element and widely used analytical models demonstrates that our model yields force calculation error below 2.4%, while reducing computation time by 43% compared to the most popular analytical model. The influence of mutual inductance harmonics on transient forces is analyzed. The results indicate that over 98% of the average suspension force is determined by the fundamental mutual inductance, while the force harmonics are even multiples of the magnet-to-coil length ratio, originating from the 3rd, 5th, and 11th harmonics of the mutual inductance. This study establishes a theoretical foundation and offers methodological guidance for optimizing the electromagnetic performance of EDS trains. © 1986-2012 IEEE.

关键词： Light rail transit

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Small excitation self-powered sensing energy harvester for rail traffic condition monitoring 5

Small excitation self-powered sensing energy harvester for r...

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5th International Conference on Mechanical, Electric, and Industrial engineering, MEIE 2022

作者： Qin, Yuanjing Liu, Mengzhou Fu, Hailing School of Integrated Circuits Tsinghua University Beijing100084 China State Key Laboratory of Rail Transit Control & Safety Beijing Jiaotong University Beijing100044 China Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University LeicestershireLE11 3TU United Kingdom

A small excitation bistable vibration energy harvester for railway transportation is developed for self-powered condition monitoring utilizing low-frequency vibration of key train components. Analyze operational vibration data collected from trains to determine design requirements. A free sliding magnet is placed in a tube with a top fixed magnet and two limit springs, using gravity, magnetism, and spring force to provide two stable positions for the movable magnet. This structure can enter the bistable operating region under small excitation amplitude and has a wide operating bandwidth. Build and test prototypes using conditions similar to real train operating conditions. A wide operating bandwidth (7 Hz-46 Hz) is obtained due to the bistability. Peak output power is 3.17mW measured into a 900 ω resistive load at 30 Hz and 1.4g. © Published under licence by IOP Publishing Ltd.

关键词： Condition monitoring

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Suppressing localized-rail bending modal vibration by designing high-frequency vibration-absorbing fasteners

Research Square

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Research Square 2024年

作者： Tao, Zhecheng Li, Dadi Wei, Lai Ma, Chaozhi Qu, Sheng Huang, Caihong Gao, Hao Zhu, Bin Dai, Huanyun Ye, Yunguang State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou China China Academy of Railway Sciences Corporation Limited Beijing100081 China

Since the view that the localized rail 3rd-order bending mode (B3 mode) can cause high-order polygonization (mainly 18~23) of high-speed train wheels was put forward in 2017, many scholars have attempted to link a connection between the localized rail bending modes and wheel polygonization phenomenon and polygonal wheel passing frequency (PWP frequency). Since most of the reported studies did not consider the multi-component assembly characteristics of the fastener system, the phenomenon of localized rail bending modes could not be accurately reproduced by many theoretical models, which hindered scholars from exploring the solution to the polygonal wheel problem. To advance the research on this scientific issue, this paper first establishes a flexible track model considering the structural and parametric characteristics of fasteners, verifies the model by using vehicle tracking test data, and then investigates the influence of fastener parameter matching on the localized rail bending modes, and obtains the following conclusions: (1) There is nearly 1:1 mapping relationship between the localized rail bending modal frequency and PWP frequency, which supports that the localized rail bending mode is one of the causes of wheel polygonization;(2) The iron plate of the fastener system plays a role of dynamic vibration absorber (DVA) in the vehicle-rail coupled system, and the quality of the iron plate and the stiffness of the upper/lower rubber pads significantly influence the localized rail bending modal frequency. Finally, this paper proposes a design principle of a high-frequency vibration-absorbing fastener, which provides a feasible solution to mitigate the localized rail bending modal vibration and high-order wheel polygonization. Meanwhile, it points out that this measure may induce other high-frequency vibration problems, e.g., aggravating modal vibration above 800 Hz. Further, this paper proposes a concept of differentiated arrangement of fasteners, suggesting tha

关键词： Iron plating

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Experimental study on the effect of brake shoe pressure on wheel wear and fatigue damage behavior during tread braking

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Wear 2025年 571卷

作者： Su, Jiabao Ding, Haohao Wang, Wenjian Huang, Xiaoqing Zhang, Shuyue Lewis, Roger Meli, Enrico Liu, Qiyue Zhou, Zhongrong Tribology Research Institute State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China Mechanical Industry Key Laboratory of Damage Mechanism and Protection Technology for High-speed Friction Pairs Southwest Jiaotong University Chengdu610031 China Baowu Group Masteel Rail Transit Materials Technology Co. Ltd Maanshan243010 China Department of Mechanical Engineering The University of Sheffield Mappin Street Sheffield S1 3JD United Kingdom University of Florence via Santa Marta 3 Tuscany Florence50139 Italy

The widespread adoption of tread braking has made it necessary to study the wear and fatigue damage behavior of wheels under the combined action of brake shoes and rails. This study aims to investigate the influence of brake shoe pressure on wheel damage with an innovative small-scale test rig, the ‘shoe-wheel-rail contact machine’. Two contact modes were designed: shoe-wheel contact and shoe-wheel-rail contact. The results indicated that, with the increase in brake shoe pressure, both the wear loss of the wheel and braking temperature increased significantly. However, compared to the shoe-wheel contact, the wheel wear and fatigue damage were more severe after the shoe-wheel-rail contact, and they were more sensitive to changes in the brake shoe pressure. Notably, under the shoe-wheel-rail contact, wheel fatigue damage was dominated by sub-surface cracks, whereas almost no fatigue cracks were observed under the shoe-wheel contact. Furthermore, when the braking temperature reaches 350 °C, the synergistic effect of the braking temperature and the plastic deformation caused by wheel-rail rolling contact induced the refinement of the microstructure of the wheel material. © 2025 Elsevier B.V.

关键词： Fatigue crack

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Effects of Surface Nanocrystallization Pre-Treatment And Sealing Post-Treatment on Corrosion and Corrosion-Fatigue Properties of Anodic Oxidation And Micro-Arc Oxidation Coated 6082 Aluminum Alloy

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SSRN 2024年

This study investigates the effect of shot peening pre-treatment, sealing post-treatment, and their combined application on the corrosion, pre-corrosion and synergetic-corrosion fatigue properties of anodic oxidation (AO) and micro-arc oxidation (MAO) coated 6082-T6 aluminum alloy. Results reveal that shot peening pre-treatment will lead to penetrating cracks in AO coatings and larger internal defects communicating with the coating outer surface in MAO coatings, resulting in inferior corrosion resistance compared to plain AO and MAO coatings, respectively. Conversely, sealing post-treatment effectively reduces porosity, thereby enhancing corrosion resistance. Pre-corrosion causes a significant decrease in the fatigue property of specimens with MAO coatings subjected to shot peening pre-treatment. However, due to the presence of compressive residual stress and grain-refined layers, MAO coated specimens subjected to shot peening pre-treatment exhibit superior pre-corrosion fatigue properties compared to base material and plain MAO coated specimens. Sealing post-treatment improves the pre-corrosion fatigue property of MAO coated specimens subjected to shot peening pre-treatment by significantly improving its corrosion resistance. The synergetic effect of corrosion media and alternating stresses promotes fatigue crack initiation and propagation, thereby reducing the fatigue life of all kinds of specimens. However, the barrier effect of coatings on corrosion media leads to better synergetic-corrosion fatigue properties of AO and MAO coated specimens compared to base material specimens. Shot peening pre-treatment enhances the synergetic-corrosion fatigue property of AO and MAO coated specimens by inhibiting substrate crack initiation and propagation. However, sealing post-treatment exerts limited influences on synergetic-corrosion fatigue properties of AO and MAO coated specimens. © 2024, The Authors. All rights reserved.

关键词： Anodic oxidation

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