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Impact Wear And Damage Behaviors Of T2 Copper Under Controlled Cumulative Impact Energy

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SSRN 2024年

作者： Liu, Shaopeng Li, Xiaobo Hu, Qiang Zhuang, Hui Shen, Mingxue State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Nanchang330013 China School of Materials Science and Engineering East China Jiaotong University Nanchang330013 China Institute of Applied Physics Jiangxi Academy of Sciences Nanchang330095 China

A self-made impact wear tester was employed to evaluate the dynamic response and damage behavior of T2 copper. The results found that the work-hardening effect caused by repeated impact will enhance its impact resistance, resulting in a continuous rise in peak impact force. In contrast, the change in energy dissipation shows an almost opposite trend. The impact damage mechanism of T2 copper can be segmented into two stages, with a critical cumulative impact energy of 1.18×104 mJ. When the cumulative impact energies below 1.18×104 mJ, the absorbed kinetic energies are expended on plastic deformation, resulting in deformation texture and parallel slip traces. Subsequent severe plastic deformation promotes the proliferation and slip of dislocations, triggering the activation of multi-slip systems and the emergence of uneven folds, commonly called the "orange peel phenomenon". As the cumulative impact energy grows, the primary impact damage mechanism shifts from plastic deformation to fatigue wear, oxidation, and plastic deformation. Furthermore, severe plastic deformation facilitates alterations in deformation texture, where the Cube {001} and P {011} components at the edge of the wear crater gradually shift into Coper {112} component, α*-fiber with //RD connects the {112} component. At the center of the wear crater, the deformation texture evolves from Cube {001}, Brass {011} components to P {110}, Brass {110} components. © 2024, The Authors. All rights reserved.

关键词： Copper

GPR-AI Master: GPR Data Analysis Utilizing Deep Learning and ECS for Backfill Grouting Detection in Shield Tunnels

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GPR-AI Master: GPR Data Analysis Utilizing Deep Learning and...

Progress in Electromagnetic Research Symposium (PIERS)

作者： Kang Li Xiongyao Xie Biao Zhou Changfu Huang Zhuqing Zhang Honglin Lin Li Zeng Department of Geotechnical Engineering College of Civil Engineering Tongji University Shanghai China State Key Laboratory of Disaster Reduction Civil Engineering Tongji University Shanghai China China Railway 15th Bureau Group Co. Ltd. Shanghai China Xiamen Rail Transit Group Co. Ltd. Xiamen China

ISBN: (数字)9798350375909

ISBN: (纸本)9798350375916

The quality of backfill grouting behind the shield tunnel is crucial for the structural support of the tunnel lining and tunnel excavation alignment. The actual grouting condition cannot be visually observed directly in the tunnel construction due to the presence of segmental linings. Ground-penetrating radar (GPR), due to its portability and excellent penetration of tunnel linings, is a promising method for non-destructive assessment of grouting quality. However, traditional GPR data processing suffers from subjectivity and lack of quantifiability. Therefore, utilizing artificial intelligence techniques for GPR data analysis holds significant importance. Based on experimental model data, we have developed a deep learning model using residual networks ResNet-18, enabling rapid and quantitative processing for GPR grouting thickness detection. The model’s performance on the test dataset demonstrates that the deep learning model based on experimental data exhibits favorable results in the identification of grouting thickness. To address the portability of data analysis, we propose a model deployment method based on Elastic Cloud Servers. Users can access this system through an interactive interface, allowing them to directly upload GPR data and obtain visual results. The visual results include GPR raw data, grouting thickness distribution, and grouting thickness assessment. This application not only ensures the objectivity of GPR data analysis but also overcomes the closed nature of traditional data processing and transmission. Finally, we have explored and envisioned the applications of automated GPR data collection and intelligent data analysis, which hold significant reference value for the safety and automation of shield tunnel construction projects.

关键词： Deep learning Training Visualization Analytical models Data analysis Data models Software

Damage Behaviour of rail Flash-Butt Welding Joints Under Controlled Impact Kinetic Energy

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SSRN 2024年

作者： Shen, Mingxue Mei, Lang Gong, Fengjun Li, Chunhong Li, Qiuping State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Nanchang330013 China School of Materials Science and Engineering East China Jiaotong University Nanchang330013 China Jiangxi Ruichang Railway Construction Co. Ltd. Nanchang330199 China

rail welded joints are a critical component of seamless railway tracks, and they are essential for maintaining the continuity and smoothness of the tracks. However, they also represent weak points in the entire track, which makes these areas susceptible to frequent damage and rail breaks. This study employs an impact wear testing platform with controlled energy to compare and analyse the impact wear characteristics of three different locations (i.e., weld zone, heat-affected zone and base material) on the U75VG flash-butt welding joint. Results indicate significant differences in material properties, such as hardness and microstructure, within different zones of the flash welded rail joints, which leads to varying impact damage behaviours. The heat-affected zones, which are located on both sides of the weld zone, exhibit the weakest ability to resist impact deformation. Thus, these areas are the most vulnerable in the entire welded rail joint and are prone to damages, such as squat. In general, damage in different zones of the welded joint gradually evolves from plastic deformation and local pitting into fatigue wear with delamination as the main failure mechanism, while the surface of the heat-affected zone tends to develop an oxide debris layer. The distinct damages observed in different zones of the welded joint pose challenges to the problem of track irregularities. This study offers a theoretical framework for predicting the evolution of damage in welded joints. © 2024, The Authors. All rights reserved.

关键词： Heat affected zone

Structural Characterization of Residual Soil and the Effect of Drying and Wetting Cycles on Its Strength 1

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6th GeoChina International Conference on Civil and Transportation Infrastructures: From engineering to Smart and Green Life Cycle Solutions, GeoChina 2021

作者： Bai, Wei Kong, Lingwei Xu, Liming Zhang, Xianwei Sun, Zhiliang An, Ran Yue, Xiu State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Hubei Wuhan China Xiamen Rail Transit Group Limited Corporation Fujian Xiamen China University of Chinese Academy of Sciences Beijing China

ISBN: (数字)9783030803162

ISBN: (纸本)9783030803155

A series of indoor tests was performed to obtain the physical and mechanical properties and structural characterization of granite residual soil. Experimental results indicated that clot and flocculation are the primary forms of microstructure, and the residual appearance of the parent rock’s crystal pattern is reserved. Structural strength is provided by strong cementation and residual chemical bond force. The clay mineral is mostly kaolin, which exhibits a laminated structure. The grain particle of granite residual soil presents the mixed features of sand and clay. The coefficient of compressibility is mostly distributed with in the range of 0.30–0.35 MPa−1, which is for medium compressible soil. Granite residual soil demonstrates good mechanical performance even under saturation condition. However, strength variability is notable. Drying and wetting cycles reduce the strength of granite residual soil, and strength decreases by approximately 30% after two drying and wetting cycles. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Granite

Microstructures and Properties of Tinbzr / Titazr Medium-Entropy Alloy by Stepwise Laser Cladding on Pure Ti Substrate

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SSRN 2023年

作者： Liu, Jiabin Lv, Hao Gao, Mingyu Liu, Xinying Dong, Weiping Fang, Youtong State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou310058 China College of Engineering Zhejiang Normal University Jinhua321004 China Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province Zhejiang Normal University Jinhua321004 China College of Electrical Engineering Zhejiang University Hangzhou310058 China

In this work, two varieties of near-equiatomic TiNbZr and TiTaZr medium-entropy alloy claddings are fabricated on pure Ti by in-situ alloying of element powders during stepwise laser cladding. Their stratified component distribution, microstructural characteristics and phase constitutions are analyzed by multiple characterization techniques, with their hardness and wear resistance tested. The results show that irregular-shaped grains correspond to a single body-centered-cubic solid-solution phase in both medium-entropy alloy claddings are realized on the hexagonal closed-packed pure Ti substrates. Further characterizations reveal that the subgrain structures in the TiNbZr cladding are cellular grains, while the ones in the TiTaZr cladding are more developed and denser dendrite arms, which leads to increased residual stress. The hardness of TiNbZr and TiTaZr claddings are 450 ± 30 HV0.2 and 513 ± 27 HV0.2, respectively, 2.6 times and 3 times that of the pure Ti substrate (170 ± 11 HV0.2). Also, the consequent wear rates decrease from 2.08×10-4 mm3·N-1·m-1 (Ti substrate) to 0.49×10-4 mm3·N-1·m-1 (TiNbZr) and 0.32×10-4 mm3·N-1·m-1 (TiTaZr). Such high hardness and enhanced wear resistance are attributed to the solid-solution strengthening of the body-centered-cubic phase and the residual stress in the claddings. The realization of hard MEA layers by stepwise laser cladding offers a flexible and effective way for protecting pure Ti. © 2023, The Authors. All rights reserved.

关键词： Titanium alloys

key technologies and applications of intelligent dispatching command for high-speed railway in China

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railway Sciences 2023年第3期2卷 336-346页

作者： Shuxin Ding Tao Zhang Kai Sheng Yuanyuan Chen Zhiming Yuan Signal and Communication Research Institute China Academy of Railway Sciences Corporation LimitedBeijingChina Traffic Management Laboratory for High-Speed Railway National Engineering Research Center of System Technology for High-Speed Railway and Urban Rail TransitBeijingChina State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of SciencesBeijingChina

Purpose–The intelligent Central Traffic Control(CTC)system plays a vital role in establishing an intelligent high-speed railway(HSR)*** the core of HSR transportation command,the intelligent CTC system is a new HSR dispatching command system that integrates the widely used CTC in China with the practical service requirements of intelligent *** paper aims to propose key technologies and applications for intelligent dispatching command in HSR in ***/methodology/approach–This paper first briefly introduces the functions and configuration of the intelligent CTC *** new servers,terminals and interfaces are introduced,which are plan adjustment server/terminal,interface for automatic train operation(ATO),interface for Dynamic Monitoring System of Train Control Equipment(DMS),interface for Power Supervisory Control and Data Acquisition(PSCADA),interface for Disaster Monitoring,***–The key technologies applied in the intelligent CTC system include automatic adjustment of train operation plans,safety control of train routes and commands,traffic information data platform,integrated simulation of traffic dispatching and ATO *** technologies have been applied in the Beijing-Zhangjiakou HSR,which commenced operations at the end of *** these key intelligent functions has improved the train dispatching command capacity,ensured the safe operation of intelligent HSR,reduced the labor intensity of dispatching operators and enhanced the intelligence level of China’s dispatching ***/value–This paper provides further challenges and research directions for the intelligent dispatching command of *** achieve the objectives,new measures need to be conducted,including the development of advanced technologies for intelligent dispatching command,coping with new requirements with the development of China’s railway signaling system,the integration of traffic dispatching and train control and the application of

关键词： High-speed railway Intelligent dispatching command Intelligent centralized traffic control key technologies and application

Study on the Dual-Motion Fretting Wear Characteristics of Zr-4 Alloy Tube Under Different Radial Alternating Load and Temperature

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SSRN 2024年

作者： Ding, Siyuan Peng, Jinfang He, Zhiyi Xiao, Dingjun Li, Bo Liu, Jianhua Zhu, Minhao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China Key Laboratory of the Ministry of Education School of Material Science and Engineering Southwest Jiaotong University Chengdu610031 China Southwest Jiaotong University China School of Environment and Resource Southwest University of Science and Technology Sichuan Mianyang621010 China Key Laboratory of Materials in Dynamic Extremes Southwest Jiaotong University Chengdu610031 China

Based on the self-developed multi-mode fretting wear tester , the paper conducted dual-motion fretting wear tests on Zr-4 alloy tubes in the fuel rod section of pressurized water reactors in the nuclear industry at different temperatures (room temperature, 300 °C) and different radial alternating loads under the condition of 90° phase difference. The experimental results show that when the phase difference is 90°, different radial loads and temperatures have a significant effect on the dual-motion fretting wear characteristics of Zr-4 alloy tubes. The alternating radial load of dual-motion fretting wear test will cause the contact area of the specimen to have different fretting operation areas. © 2024, The Authors. All rights reserved.

关键词： Pressurized water reactors

Leakage Mechanisms and Countermeasures of an Operated Underwater Shield Tunnel Based on Detailed Field Inspections: A Case Study

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SSRN 2023年

作者： Gong, Chenjie Cheng, Mingjin Ge, Yangyang Song, Jianrong Zhou, Zhong School of Civil Engineering Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure Central South University HN Changsha410075 China School of Civil Engineering Central South University HN Changsha410075 China State Key Laboratory of Special Functional Waterproof Materials Beijing Oriental Yuhong Waterproof Technology Co. Ltd Beijing101309 China

Aiming to alleviate problems in the urban living environment, an increasing number of shield tunnels have been built in rivers or underwater areas. Most of these tunnels will experience leakage after long-term operation, which will potentially impact the safety of the tunnel and induce dangerous accidents, resulting in loss of personnel and property. This paper reported the leakage of a double‒line ultralarge‒diameter underwater shield tunnel across the Yangtze River during the service stage. After a detailed geological survey and field inspections of the whole tunnel, the leakage characteristics and patterns of the prototype tunnel were summarized using long-term monitoring data. An in-depth distribution of leak-related defects was demonstrated through sketches and field photographs. The factors that may affect the leakage of the prototype tunnel (i.e., groundwater table, longitudinal settlement, and soil conditions), were interpreted based on field measurements. The triggering mechanisms of two typical leakage accidents during tunnel operation were systematically analyzed. Subsequently, the leakage mechanisms of the prototype tunnel were categorized into three patterns: joint leakage, bolt hole leakage and concrete crack leakage. In view of the leakage-associated damage to the prototype tunnel, four countermeasures against leakage treatment were proposed: backfill grouting, joint grouting, installing a sealing cover on the bolt hole, and adding a caulking gasket as a second line of defense. The proposed mitigation measures are validated through laboratory tests and field applications. This unique case of tunnel prototype engineering can provide a reference for water leakage prevention and control in the design, construction, and operation stages of similar underwater shield tunnel projects. © 2023, The Authors. All rights reserved.

关键词： Grouting

Novel Energy-Based Analysis Approach for Determining Elastic Wave Complex Band of Damped Periodic Structures Using Virtual Springs

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SSRN 2023年

作者： Guo, Wenjie Hong, Xian Yang, Jian Luo, Wenjun Yan, Jianwei Deng, Jie State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Nanchang330013 China Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Ningbo China Ningbo315100 China Key Laboratory of Ocean Acoustic and Sensing School of Marine Science and Technology Northwestern Polytechnical University Xi’an710072 China

The determination of the complex band of damped periodic structures is of importance for the evaluation of their wave attenuation performance. To this end, a new analysis approach based on the energy method and the virtual spring model is proposed for determining the complex band of structures. Its essence is to use a virtual spring to simulate periodic boundary conditions, such that the wave numbers will only appear in the stiffness matrix of the virtual spring. Subsequently, the previous nonlinear eigenvalue solution problem is transformed into a linear eigenvalue solution problem by decoupling and degrading the wave numbers of the stiffness matrix. The calculation procedure of the proposed approach is demonstrated by taking a periodically discrete-supported Euler beam in the case study, and then it is extended to deal with two-dimensional periodic structures. The accuracy of the proposed approach is verified by comparison to the results in existing studies. The effects of the material frequency variation and damping on the propagation and attenuation of vibration waves are investigated. The results reveal that the material frequency variation effect and damping have a significant effect on the wave decay range and rate. The proposed method has excellent applicability and promising application potential in calculating the complex band structures analysis of coupled periodic structures. © 2023, The Authors. All rights reserved.

关键词： Periodic structures