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SSRN 2023年

作者： Fu, Xuanran Song, Xiaolin Zeng, Ying Peng, Jinfang State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China Key Laboratory of Advanced Technologies of Materials Ministry of Education School of Material Science and Engineering Southwest Jiaotong University Chengdu610031 China

Rare-earth magnesium alloys (Mg-RE) are gaining growing prominence across multiple industries due to the enhanced mechanical properties and improved formability they offer compared to conventional magnesium alloys. β′ phase of Mg-RE alloys exhibits exciting behavior in strengthening and enhancing corrosion resistance;however, mechanical behaviors of some β′ phases themselves remain unknown. Therefore, our objective is to identify the mechanical and thermomechanical properties of β′ phases. Herein, a theoretical study to investigate the structural, electronic, elastic and anisotropic properties of β′–Mg7RE phase from first-principle calculations is described. We also predicted the melting temperature and Debye temperature of these intermetallics. The calculated results confirm that all the β′–Mg7RE phases are thermodynamically and mechanically stable. Additionally, the calculated value of bulk modulus for all β′–Mg7RE phase is similar, with a value of approximately 38 GPa. The degree of anisotropy in the bulk modulus of the β′–Mg7RE phase is relatively lower compared to the shear and Young's moduli. Among the β′ phase, β′–Mg7Lu exhibits the most severe anisotropy. Furthermore, the highest degree of Young's and shear moduli anisotropy for all β′ phases are observed in the (001) plane. The value of the electron localization function between Mg and RE atoms ranges from 0.48 to 0.56. In more detail, the density of states (DOS) indicates that hybridization is generated by strong interaction between the Mg–p states and RE–d states below the Fermi level. Indeed, the results will provide insights into the factors that influence the mechanical properties of the β′ phase, contributing to a better understanding of its performance and potential applications. © 2023, The Authors. All rights reserved.

关键词： Elastic moduli

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Experimental Study on Multiaxial Ratchetting-Fatigue Interaction of Sus301l Stainless Steel Tubular Welded Joint

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SSRN 2024年

作者： Luo, Huiliang Qu, Kaicheng Yu, Chao Kan, Qianhua Kang, Guozheng Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace Engineering Southwest Jiaotong University Sichuan Chengdu610031 China Institute of Applied Mechanics State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Sichuan Chengdu610031 China

The multiaxial low-cycle fatigue tests of the SUS301L stainless steel tubular welded joints are conducted to investigate their multiaxial ratchetting and ratchetting-fatigue interaction. The strain distribution of welded joint and its whole-life evolution are acquired by using the digital image correlation (DIC) method. The experimental results demonstrate that heterogeneous multiaxial ratchetting is observed in the different regions of welded joint if the multiaxial fatigue loadings are asymmetrical (with a non-zero axial mean stress) and depends remarkably on the different loading paths and loading levels. Analogous to the uniaxial one, the highest ratchetting strain occurs in the fusion zone (FZ) of welded joint and the increase of ratchetting strain rate in the later stage of multiaxial fatigue tests is attributed to the fatigue damage;meanwhile, the multiaxial ratchetting strain produced under the asymmetrical fatigue loading condition apparently shortens the fatigue life of welded joint, compared with that under the symmetrical loading condition (with a zero axial mean stress). The fatigue life of welded joint is also dependent on the applied loading levels and loading paths. This study provides a solid data support to establish a fatigue life-prediction model to assess the multiaxial fatigue life of welded joint with considering ratchetting. © 2024, The Authors. All rights reserved.

关键词： Welds

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3d Rolling Contact Finite Element Analysis of High-Speed railway Turnout Considering Ratchetting Effect

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SSRN 2024年

作者： Wu, Yihang Zhao, Jizhong Miao, Hongchen Zhang, Xu Wen, Zefeng Xu, Jiangmang Wang, Ping Kan, Qianhua Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace Engineering Southwest Jiaotong University Chengdu611756 China State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China MOE Key Laboratory of High-speed Railway Engineering School of Civil Engineering Southwest Jiaotong University Sichuan Chengdu610031 China

The present work introduces a three-dimensional finite element model for the wheel-turnout-sleeper system, incorporating a cyclic constitutive model that accurately captures the nonlinear hardening behavior of rail steel under cyclic loadings. Through dynamic analysis, the transient rolling contact status of the wheel-turnout, stress and strain responses of the turnout, and wheel-rail forces are investigated under varying crossing speeds and number of cycles. It is found that during the wheelset crossing, the contact stress remains relatively stable on the stock rail, and multi-point contact occurs at the wing rail and long point rail, and the contact stress on the surface of the long point rail is more significant. With an increase in crossing speed in the same cycle, there is a gradual rise in contact stress on the long point rail face. At the same crossing speed, with the increase of number of cycles, the contact position between the wheelset and the long point rail gradually moves back, and the top width of the contact position gradually expands. Additionally, a progressive accumulation of ratcheting strain is observed on the rail, and the ratcheting strain on the long point rail significantly exceeds that on the stock rail. The research findings are helpful for analyzing the failure mechanism in rolling contact fatigue of turnouts. © 2024, The Authors. All rights reserved.

关键词： rails

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Power Loss Analysis of Axle Bearings of High-Speed Train Excited by Track Irregularity and Wheel Flat

Power Loss Analysis of Axle Bearings of High-Speed Train Exc...

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TEPEN International Workshop on Fault Diagnostics and Prognostics, TEPEN-IWFDP 2024

作者： Luo, Yaping Zhang, Weihua Song, Dongli Zhang, Fan Gu, Fengshou Bevan, Adam Gong, Jue State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China School of Design Southwest Jiaotong University Chengdu610031 China Centre for Efficiency and Performance Engineering University of Huddersfield HuddersfieldHD1 3DH United Kingdom Institute of Railway Research University of Huddersfield HuddersfieldHD1 3DH United Kingdom Pittsburgh Institute Sichuan University Chengdu610065 China

ISBN: (纸本)9783031734069

When trains run at high speeds, the friction power losses within axle bearings are severe under the wheel-rail impacts, especially existing track irregularity and wheel flat. In such situation, the mechanical behavior of axle bearings is seriously affected, which may even induces bearing structural damage, threatens train safety. To analyse and simulate the power loss of axle bearings excited by track irregularity and wheel flat, a numerical model of power loss in axle bearing is posed, with coupled vehicle-track dynamics system. The power loss model synergistically incorporates the dynamic interactions among the bogie system, track system, vehicle-rail relationship, and axle bearings. Further, it also takes into account the impacts of inlet shear heating and kinematic replenishment/ starvation within the axle bearing on power loss. Results indicate that the power loss within the axle bearing is intensified due to track irregularity. Bearing power losses increase as vehicle speed and wheel flat length increase. Additionally, the power loss of the outside row in axle bearing is higher than that of the bearing inside row. The model offers useful mechanism theories for both the structural design and condition monitoring of axle bearings in high-speed trains. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Axles

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Wind tunnel tests on aerodynamic characteristics of vehicles on same-storey highway and rail bridge under crosswind

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Journal of Central South University 2022年第8期29卷 2513-2531页

作者： ZOU Yun-feng XUE Fan-rong HE Xu-hui HAN Yan LIU Qing-kuan School of Civil Engineering Central South UniversityChangsha 410075China Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure Changsha 410075China School of Civil Engineering and Architecture Changsha University of Science&TechnologyChangsha 410004China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced *** study focuses on a container truck and CRH2 high-speed train as research *** tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of *** results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of *** summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same *** best shielding effect on lateral forces of trucks occurs when the train is located downstream of ***,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.

关键词： same-storey highway and rail bridge container truck CRH2 high-speed train aerodynamic characteristics wind tunnel test crosswind

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Buried pipeline-soil interaction caused by shield tunnelling based on a simple continuum model 2

Buried pipeline-soil interaction caused by shield tunnelling...

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2nd International Conference on Internet of Things and Smart City, IoTSC 2022

作者： Ma, Bin Xu, Chaochang Ke, Wenhai Yuan, Hui Wei, Yuangang Zhu, BiTang China Railway Second Bureau Group Co. Ltd. Chengdu610000 China School of Civil Engineering and Architecture East China Jiaotong University Nanchang330013 China State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure Nanchang330013 China

ISBN: (纸本)9781510654990

Two problems exist in the theoretical research on pipeline-soil interaction caused by tunnelling. First, it is difficult for the existing mathematical models to maintain both simplicity and accuracy;second, most studies focus on the vertical pipeline-soil interaction and ignore the horizontal pipeline deformation. Based on a continuum medium model, the pipeline-soil interaction caused by shield tunnelling was simulated to determine both the vertical and horizontal soil displacement fields. The governing equations for both the pipeline deformation function and attenuation function were constructed based on the variation principle. These two functions are coupled and then decoupled by an iterative process. The model has the following advantages: 1. The model has a simple solution form that is convenient for application. 2. The model includes the influence of soil continuity and produces results with a good precision. 3. The proposed model is able to calculate the analytical expression of the soil spring factor and soil shear stiffness factor, making it possible to quantitatively analyze the pipeline-soil interaction. Through comparison with monitoring data, the proposed method was verified. Ultimately, the parametric study shows that large horizontal pipeline deformation may be caused by shield tunnelling, and the influence of soil continuity on pipeline-soil interaction is remarkable. © 2022 SPIE

关键词： Pipelines

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Automatic Detection and Localization of Surface Defects in High-Speed railway Ballastless Track Based on Cascaded Group Attention and Optoelectronic Encoder

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SSRN 2024年

作者： Ye, Wenlong Ren, Juanjuan Liang, Jie Liu, Wengao Yi, Haonan Zhang, Allen A. Lu, Chunfang School of Civil Engineering Southwest Jiaotong University Chengdu610031 China State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China MOE Key Laboratory of High-Speed Railway Engineering Southwest Jiaotong University Chengdu610031 China China Railway Society Beijing100844 China

To accurately detect the surface defects of ballastless tracks, a method named YOLO-Track for intelligent identification and location of surface defects on ballastless tracks is proposed in this paper. Besides, an intelligent detection vehicle for ballastless track surface defects is developed. The method enhances the feature extraction of surface defects in shallow and deep networks by using cascaded group attention, which saves computational cost, and realizes the mileage location of surface defects by using photoelectric encoding. The comprehensive experiments demonstrate that the YOLO-Track model achieves a precision of 99.1% and a mAP@0.5 of 97.7%. These values are 1.95% and 3.06% higher, respectively, than those achieved by the YOLOv7 model. The YOLO-Track model has 23.05M parameters and 39.4 GFLOPS, which are 29.98% and 61.86% lower, respectively, than those of the YOLOv7 model. In the field, the method accurately identifies the fastener status and locates the actual mileage position of the fastener. © 2024, The Authors. All rights reserved.

关键词： Location

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Crystallographic anisotropy-dependent wear behavior of nickel-based single crystal superalloys across scales

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Wear 2025年 571卷

作者： Tuo, Xiaohui Liu, Yangqin Wei, Xin Xiao, Chen Chen, Xiang Shi, Wei Chen, Lei Qian, Linmao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle System School of Mechanical Engineering Southwest Jiaotong University Chengdu610031 China Research Institute of Frontier Science Southwest Jiaotong University Chengdu610031 China AECC Sichuan Gas Turbine Establishment Chengdu610500 China

As a material extensively utilized in aerospace applications, the mechanical properties of nickel-based single crystal (NBSC) superalloys are susceptible to anisotropic characteristics. These anisotropic features significantly impact surface wear in multi-axis stress environments, highlighting the importance of wear management for extending the lifespan of components. In this paper, the effect of anisotropy on the wear resistance of different crystal planes of NBSC superalloys at macroscale and room temperature was investigated. The results showed that the wear depths of (100), (110), and (111) crystal planes exhibit periodicities of 90°, 180° and 60°, respectively. It was confirmed that while these anisotropic effects persist at high temperatures, they are diminished due to the formation of a protective glaze layer. Nanoscale tests further revealed that the anisotropic influence on surface wear depended on the angle between the slip system and the sliding direction. The smaller the angle, the more prone the material is to wear. These findings are not only beneficial for enhancing the cross-scale analysis techniques, but also for optimizing the selection of grain orientations to maximize the lifetime of NBSC superalloys. © 2025 Elsevier B.V.

关键词： Single crystals

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Research on LC Ratio of Metro Traction Drive System Applied in Oscillation Analysis

Research on LC Ratio of Metro Traction Drive System Applied ...

引用

International Joint Conference on Energy, Electrical and Power engineering, CoEEPE 2021

作者： Gu, Jing Kang, Jinsong Guo, Wanlu College of Electronic and Information Engineering Tongji University Shanghai China Institute of Rail Transit Tongji University Shanghai China The State Key Laboratory of Heavy Duty AC Drive Electric Locomotive Systems Integration Zhuzhou China CRRC Zhuzhou Electric Locomotive Co Ltd Zhuzhou China

ISBN: (纸本)9789811919213

Metro is a kind of green transportation with low energy consumption and large capacity, which has the characteristics of high speed, high efficiency and low pollution. In the metro traction drive system, due to the negative impedance introduced by the traction motor and the limited selection of filter parameters, it is likely to cause continuous oscillation of the DC bus voltage and current, resulting in system instability. In order to provide a theoretical basis for the suppression of oscillation, the stability analysis of the simplified second-order system is carried out by the Routh criterion in this paper. In addition, the small signal equivalent model of the system considering the motor control module is established and the Nyquist stability criterion is used to analyze the system stability. The simulation results show that the stability analysis method based on simplified second-order system is more intuitive, and the accuracy is not reduced when the errors of the two methods and the actual simulation results are 2.6% and 5.9% respectively. It has a good significance for the parameter selection of filter link in the traction drive system. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： System stability

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Origin and Customization of Bandgap in Chiral Phononic Crystals

arXiv

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arXiv 2024年

作者： Ding, Wei Zhang, Rui Chen, Tianning Qu, Shuai Yu, Dewen Dong, Liwei Zhu, Jian Yang, Yaowen Assouar, Badreddine School of Mechanical Engineering State Key Laboratory of Strength & Vibration of Mechanical Structures Xi’an Jiaotong University Shaanxi Xi’an710049 China School of Civil and Environmental Engineering Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore Train and Track Research Institute State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China Institute of Rail Transit Tongji University Shanghai201804 China Université de Lorraine CNRS Institut Jean Lamour NancyF-54000 France

The wave equation governing the wave propagation in chiral phononic crystals, established through force equilibrium law, conceals the underlying physical information. This has led to a controversy over the bandgap mechanism. In this letter, we theoretically unveil the reason of this controversy, and put forward an alternative approach from wave behavior to formulate the wave equation, offering a new pathway to articulate the bandgap physics directly. We identify the obstacles in coupled acoustic and optic branches to widen and lower the bandgap, and introduce an approach based on spherical hinges to decrease the barriers, for customizing the bandgap frequency and width. Finally, we validate our proposal through numerical simulation and experimental demonstration. © 2024, CC BY.

关键词： Energy gap

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