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Effect of Brazing Temperature on Microstructure And Shear Strength of Tial/Ti3al Joint Vacuum Brazed with Tih2-24ni Powder Filler

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SSRN 2024年

作者： Li, Li Wu, Bingzhong Zhang, Haowen Shen, Yuzun Zhang, Wentao Jiang, Yuqiang Li, Xiaoqiang School of Materials Science & Engineering East China Jiaotong University Nanchang330013 China State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Nanchang330013 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510640 China

TiH2-24Ni (at.%) powder filler was innovatively designed and prepared by mechanical milling to vacuum braze TiAl-based and Ti3Al-based alloys at brazing temperatures of 1060 ~ 1120 ℃ for 10 min. The interfacial microstructure and formation mechanism of TiAl/Ti3Al brazed joints as well as the relationships among brazing temperature, microstructure and joint strength were systematically investigated. Results show that the TiAl/Ti3Al brazed joints are mainly composed of four interfacial reaction layers: TiAl alloy/γ-TiAl + α2-Ti3Al (layer Ⅰ)/α2-Ti3Al (layer Ⅱ)/α2-Ti3Al + α-Ti + δ-Ti2Ni (layer Ⅲ)/α2-Ti3Al + B2 (layer Ⅳ)/Ti3Al alloy. The hard δ-Ti2Ni gradually decreases and refines while the distribution of the low-hardness α-Ti is obviously homogenized with brazing temperature, but those in the joint brazed at 1120 ℃ are reversed. The shear strength of the TiAl/Ti3Al brazed joint first increases and then decreases with brazing temperature, and the maximum shear strength of 335 MPa is obtained at 1100 ℃. The cracks tend to initiate and propagate along the hard blocky δ-Ti2Ni in layer Ⅲ while the fracture surfaces show typical quasi-cleavage fracture characteristics. © 2024, The Authors. All rights reserved.

关键词： Shear strength

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

It is of importance to determine the complex band structure of damped periodic structures for the evaluation of their wave attenuation performance. In view of this, the current paper proposes a new analysis approach based on the energy method and the virtual spring model for determining the complex band structure. 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 previously existed nonlinear eigenvalue solution problem is transformed into a linear eigenvalue solution problem by decoupling the wave numbers of the stiffness matrix and reduce order. The calculation procedure of the proposed approach is demonstrated by a case study of a periodically discrete-supported Euler beam, and then extended to deal with two-dimensional periodic structures. The accuracy of the proposed approach is verified by comparison the results with those 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 attenuation 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

Single-Frame Temporal Phase-Shifting Shearography for Real-Time Nondestructive Testing

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SSRN 2023年

作者： Wu, Rong Lu, Yang Liu, Yande School of Mechatronics and Vehicle Engineering East China Jiaotong University Nanchang330013 China Key Laboratory of Conveyance Equipment East China Jiaotong University Ministry of Education Nanchang330013 China State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure East China Jiaotong University Ministry of Education Nanchang330013 China

Shearography, which is an effective nondestructive testing tool, can detect internal defects of composites materials. Temporal phase-shifting shearography has a simple setup and high accuracy. It is suitable for quasi-static detection because it requires the acquisition of a sequence of speckle patterns before and after specimen deformation. To achieve dynamic shearographic NDT, this study adopted high-frequency synchronous driving mode of high-frame-rate (HFR) camera and piezoelectric transducer phase shifter to generate and acquire phase-shifted patterns. Subsequently, a single frame TPS shearography requiring one phase-shifted pattern in the deformed state was proposed. Finally, using parallel computing technology and efficient approximations of arctangent function, a real-time four-step TPS shearographic NDT technique with high-quality phase imaging was developed. The experimental results demonstrate the effectiveness and robustness of the proposed method. The results show that the proposed method could reach a rate of approximately 24 fps at the spatial resolution of megapixels for defect detecting. © 2023, The Authors. All rights reserved.

关键词： Nondestructive examination

Evaluation of BDS and GPS RAIM availability based on data collected in June 2020

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Geodesy and Geodynamics 2021年第3期12卷 181-189页

作者： Xiaping Ma Kegen Yu Ershen Wang Xiaoxing He Tieding Lu Qinzhen Li School of Geomatics Xi'an University of Science and TechnologyXi'an710054China Shanghai Key Laboratory of Space Navigation and Positioning Techniques Shanghai200030China School of Environmental Science and Spatial Informatics China University of Mining and TechnologyXuzhou221116China School of Electronic and Information Engineering Shenyang Aerospace UniversityShenyang110136China State Key Laboratory of Rail Transit Engineering Informatization(FSDI) FSDIXi'an710043China School of Civil Engineering and Architecture East China Jiaotong UniversityNanchang330013China Faculty of Geomatics East China University of TechnologyNanchangJiangxi330013China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu611756China

The satellite pseudo-range fault detection with the Receiver Autonomous Integrity Monitoring(RAIM)method is affected by several satellite observations and the geometric distribution of *** poor geometry distribution of satellites will conceal the positioning errorcaused by the satellite pseudo-range fault,resulting in unreliable detection ***,the availability evaluation must be made before RAIM to ensure that the fault detection performance will not be *** June 23,2020,China successfully launched the 30 th(last)navigation satellite of BeiDou’s third-generation navigation satellite system(BDS-3),which is also the 55 th BeiDou navigation *** all the available satellites of BDS-1,BDS-2 and BDS-3,the positioning performance of BDS can be greatly *** order to evaluate the RAIM availability of BeiDou Navigation Satellite System(BDS)and Global Positioning System(GPS)in China,this paper first deduces the mathematical models and their characteristics of the three RAIM availability evaluation ***,the study area(N10°-70°,E60°-150°)is divided into 4536 grid points at intervals of 1°×1°in latitude and longitude,and the elevations of these grid points are taken from the global terrain data *** Horizontal Protection Level(HPL)values of these grid points are calculated during 8-15 June 2020 using BDS and GPS ephemeris *** RAIM availability differences between the two systems are compared and *** analysis shows the Horizontal Protection Level method(HPLM)based on single-satellite pseudo-range fault is the most practical and *** the 8-day observation period,the HPL values of BDS are significantly smaller than those of GPS in terms of geographic location and observation time,and the variation of HPL time series of BDS is also smaller than that of GPS,which indicates that the RAIM availability of GPS in China is not as good as that of *** importantly,in the four flight stages of the

关键词： BDS GPS RAIM availability Horizontal protection level Evaluation

Vibration Characteristics of Rolling Bearing Cage Under Speed Variation Conditions

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SSRN 2023年

作者： Tu, Wenbing Liu, Chenlu Liang, Jie Liu, Yuqing Chen, Zaigang School of Mechatronics and Vehicle Engineering East China Jiaotong University Nanchang330013 China Key Laboratory of Conveyance and Equipment of Ministry of Education East China Jiaotong University Nanchang330013 China College of Mechanical Engineering Southwest Jiaotong University Chengdu610031 China State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China

Speed variation conditions deteriorate the force state of the rolling bearing internal components and aggravate the cage vibration, which can affect the service life and reliability of rolling bearings. This work introduced the rubbing effect and hydrodynamic contact between the cage and the guiding ring, taking into account the effect of the slip between the rolling elements and the cage. The dynamic analysis model of the cylindrical roller bearing was established, and the vibration characteristics of the cage were discussed under the start-stop conditions and different fluctuations of rotation rate. Results showed that the vibration of the cage mainly occurred at the middle and late stages of the acceleration process, and the impact mainly occurred at the middle stage of the deceleration process under the start-stop conditions. The fluctuations of rotation rates of the inner ring affected the dynamic stability of the cage and aggravated the impact and vibration of the cage. Rectangular fluctuation of rotation rate causes the most severe vibration and impact of the cage, followed by simple harmonic wave and triangular fluctuation. The findings offer theoretical guidance for enhancing the performance of bearings and ensuring their safe and reliable operation. © 2023, The Authors. All rights reserved.

关键词： Roller bearings

Analysis of Bearing Vibration Measuring Points Based on Locally Linear Embedding Algorithm

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Science Technology and engineering 2025年第6期25卷 2356-2363页

作者： Luo, Ya Ge, Ke-Ke Yuan, Xiao-Wen Wang, Hao Huang, Yi-Bin Tu, Wen-Bing State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiao Tong University Nanchang330013 China School of Mechatronic and Vehicle Engineering East China Jiao Tong University Nanchang330013 China

In order to solve the problem of difficulty in determining the optimal measurement points for bearing signal acquisition. Taking the NU306 bearing-housing system as the research object, the bearing housing to carry out multi-measurement points vibration test experiment. The local linear embedding algorithm was used to linearly reduce the multi-dimensional space data of the bearings to obtain the sensitivity matrix of the measurement point. The optimal position of the measuring point under varying load and rotation speed was studied when the inner or outer ring are defective. The results show that for bearings with outer ring failures, the optimal measurement point is the one closest to the location of the failure when the load or rotational speed increases. For bearings with inner ring failures, the optimal measurement point is the one at lower loads far from the center of the housing when the load or rotational speed increases. The results can provide an effective reference for the selection of measurement points under different operating conditions. © 2025 Beijing Kexue Jishu yu Gongcheng Zazhishe. All rights reserved.

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Enhanced Creep Property of S30432 Steel with Trace Tic/Tib2 Nano-Particles at 600 °C

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SSRN 2023年

作者： Liu, Xingyu Han, Ying Duan, Zhenxin Zu, Guoqing Qiu, Feng Zhu, Weiwei Ran, Xu Key Laboratory of Advanced Structural Materials Ministry of Education Changchun University of Technology Changchun130012 China School of Materials Science and Engineering Changchun University of Technology Changchun130012 China Provincial Key Laboratory of Advanced Materials Processing and Application for Rail Transit Changchun University of Technology Changchun130012 China State Key Laboratory of Automobile Materials Ministry of Education Department of Materials Science and Engineering Jilin University Changchun130025 China

S30432 steel, imbued with trace amounts of TiC/TiB2 nano-particles, was fabricated to assess the influence of these nano-particles on the steel's creep properties under conditions of 600 °C/330 MPa. Our findings elucidate that the inclusion of trace TiC/TiB2 led to a 21% improvement in the creep life of S30432 steel, while diminishing the creep rate from 6.6×10-5 h-1 to 5.7×10-5 h-1. The synergistic precipitation strengthening of the nanoscale Cu-rich phases, needle-like M23C6 phases, and NbN phases was primarily responsible for this exceptional creep resistance. During the long-term creep process, the nanoscale Cu-rich phase was very stable with little change. In the S30432 steel, M23C6 and NbN phases had a non-coherent interface and an orientation relationship of [[EQUATION]]//[[EQUATION]];M23C6 and NbN phases in the S30432 steel incorporating minute TiC/TiB2 nano-particles also had a non-coherent interface but a[[EQUATION]]//[[EQUATION]] orientation relationship. The M23C6 and NbN phases effectively impede the dislocation movement and were shown to increase the creep strength considerably. © 2023, The Authors. All rights reserved.

关键词： Grain boundaries

A Point-Wise Isogeometric Contact Analysis with Interpolatory Nurbs Basis

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SSRN 2024年

作者： Peng, Xuan Zeng, Zheng Wu, Shengchuan Yu, Peng Lian, Haojie Department of Mechanical Engineering Suzhou University of Science and Technology Suzhou215009 China State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong University Chengdu610031 China College of Civil Engineering and Architecture Key Laboratory of Disaster Prevention and Structural Safety Ministry of Education Guangxi Key Laboratory of Disaster Prevention and Structural Safety Scientific Research Center of Engineering Mechanics Guangxi University Nanning530004 China Key Laboratory of In-situ Property-improving Mining Ministry of Education Taiyuan University of Technology Taiyuan030024 China Suzhou Asia-pacific Intelligent Transmission Technology Co. Ltd Suzhou215132 China

The point-to-segment approach is appealing for contact analysis due to its efficiency. In this work, formulations of a point-wise isogeometric contact analysis method for large-deformation bodies are presented. The approach is based on the transformed non-uniform rational basis spline (NURBS) basis, which possesses an interpolation property at the corresponding collocation points at the slave contact boundary. The physical meaning of the contact forces at the collocation points (or control points because of the interpolation property) is clear. The idea is realized under the framework of two-dimensional frictionless contact with penalty regularization. Numerical examples including the contact patch test, Hertzian problem, and iron sliding contact revealed the robustness and accuracy of the proposed method for contact analysis. © 2024, The Authors. All rights reserved.

关键词： Interpolation

Field Experiment Research on the Penetrability of Insoluble Sediment in High-Impurity Salt Mine Caverns

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SSRN 2024年

作者： Li, Yinping Shi, Xilin Chen, Xiangsheng Liu, Zhengyou Lu, Qingfeng Weia, Xinxing State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Hubei Wuhan430071 China State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Jiangxi Nanchang330013 China University of Chinese Academy of Sciences Beijing100049 China Hubei Key Laboratory of Environmental Geotechnology Institute of Rock and Soil Mechanics Chinese Academy of Sciences Hubei Wuhan430071 China Jiangsu Suyan Jingshen Co. Ltd Jiangsu Huaian223200 China

The solution mining salt caverns in impure salt mines include generally two parts: the above clear brine space and the down sediment/brine mixed space. Gas storage by displacing brine in the sediment as well as in the above space is an optimal pathway to overcome barriers of building caverns in high-impurity salt mines and to achieve large-scale underground energy storage. Field experiments of sediment connectivity were carried out in a butted well salt cavern to determine the connectivity of voids within the sediments. Through a combination of sonar and downhole television surveys, as well as drilling exploratory wells, the height and spatial occupancy of the sedimentary deposits, the three-dimensional salt cavern morphology, and the undetectable horizontal section locations due to sediment burying were revealed. Based on this, a test plan for sediment void connectivity was designed, with real-time monitoring of wellhead pressure, temperature, and flow rate using sensors during the experiment. The analysis of field experiment results indicates that over 95% of the target salt cavern space is occupied by sediments, but the sediment voids have good connectivity, with approximately 1 kPa/m pressure loss during brine flow. The sediment permeability ranges from 10-9 m2 to 10-11 m2, and the void ratio can reach up to 40%.Implementing gas storage in sediment voids has many advantages and promising application prospects, 1) 4.5 times capacity expansion compared to conventional salt cavern gas storage;2) Faster gas storage compared to new cavern construction;3) Additional surrounding rock support to reduce salt cavern creep;4) Reduced demand for precise cavern measurements, lowering technical complexity and costs. This research provides field experiments and data support for gas storage in high-impurity salt mine sediment voids, contributing to expanded salt cavern site selection and increased storage capacity. © 2024, The Authors. All rights reserved.

关键词： Sediments