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Quasi-distributed optical fiber sensing for the coupled vibration analysis of high-speed train-bridge coupled system under earthquakes

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SENSORS AND ACTUATORS A-PHYSICAL 2024年 374卷

作者： Xiang, Ping Xie, Xiaonan Zhang, Xuebing Wu, Han Chen, Zhizhan Wang, Li Liu, Xiaochun Yang, Delei Wang, Huaping Cent South Univ Sch Civil Engn Changsha 410075 Hunan Peoples R China Xiangtan Univ Coll Civil Engn Xiangtan 411105 Hunan Peoples R China Univ Huanghuai Dept Bldg Engn 6 Kaiyuan Rd Zhumadian Henan Peoples R China Lanzhou Univ Sch Civil Engn & Mech Lanzhou Peoples R China City Univ Hong Kong Depsrtment Civil & Architectural Engn Hong Kong Peoples R China

Due to the extensive construction of high-speed rail lines passing through seismically active areas, the possibility of a sudden earthquake occurring during train operation is very high. Additionally, the earthquake will intensify the dynamic response of trains and bridges, causing serious bridge damage. In this work, the dynamic response behavior of the bridge structures in the coupled train-bridge system under the earthquake is investigated based on the 4-table shaking table system. Shaking table experiments are also conducted on a high-speed railroad model of simple-supported girder bridge at a scale of 1/10 with the simulated layers of China Railway Track System type II (CRTS II) ballastless track slabs. The strain responses of various components, including rails, track plates, base plates, and beams, were measured on the bridge using quasi-distributed fiber optic gratings, both with and without seismic actions. Additionally, the seismic isolation characteristics of the fasteners and the CA mortar layer were investigated. The dynamic performance of the coupled train-bridge system under earthquakes was studied in both the time and frequency domains.

关键词： Train-bridge system Earthquake Dynamics performances Frequency Quasi-distributed fiber Bragg grating

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Fracture mechanics and crack propagation of nanoscale silicon carbide via molecular dynamics simulation

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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 2024年第12期130卷 1-13页

作者： Han, Xu Li, Rui Xue, Lianghao Wang, Shizhao Wuhan Univ Inst Technol Sci Wuhan 430072 Peoples R China Wuhan Univ Sch Power & Mech Engn Wuhan 430072 Peoples R China Univ Sci & Technol China Dept Modern Mech Hefei 230000 Peoples R China

The fracture toughness, mechanical properties, and crack propagation behaviour of defective single-layer silicon carbide (SiC) nanosheets were investigated through a molecular dynamics (MD) study. Various types of defects were modelled to examine their mechanical properties and toughness under different temperatures. The results indicated that the mechanical properties of both defect-free and defective SiC diminished with increasing temperature and defect size. At room temperature, the failure stress of SiC decreased by approximately 47.22, 48.73, and 52.34 GPa for crack lengths of 25 & Aring;, and circular and square notches with diameters of 25 & Aring;, respectively. Similar trends were observed in Young's modulus and failure strain. Additionally, higher stress concentrations at the corners suggested that samples with square defects had the weakest properties. As the crack size increased, the stress intensity factor of SiC also increased. Defects propagated in the direction perpendicular to the stress loading, and larger defect sizes mitigated the adverse effect of temperature on failure stress. This research is significant in analysing the mechanical behaviour of SiC, a key wide-bandgap semiconductor structure with substantial potential applications in advanced power devices.

关键词： Fracture toughness Crack propagation Mechanical properties Molecular dynamics

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Control of Variable Speed Pumped Storage Unit Based on Power Electronic Transformer Under Unbalance of Power Grid Voltage 27

Control of Variable Speed Pumped Storage Unit Based on Power...

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27th International Conference on Electrical Machines and Systems, ICEMS 2024

作者： Huang, Pei Peng, Xiang Dian, Renjun School of Information Science and Engineering Wuhan University of Science and Technology Wuhan China Wuhan University of Science and Technology Engineering Research Center for Metallurgical Automation and Measurement Technology Ministry of Education Wuhan China

ISBN: (纸本)9784886864406

To enhance the power density and improve the grid-connection capability of the variable-speed pumped storage unit, this paper proposes a topology for full-power variable-speed pumped storage based on power electronic transformer. This topology does not require a power frequency transformer and can isolate the double frequency fluctuation of the high-voltage DC bus voltage in the event of asymmetric faults in the grid, so as not to affect the control of the motor side and improve the unit's ability to adapt to the power grid. © 2024 The Institute of Electrical Engineers of Japan.

关键词： Power grids

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Effect of phase structure on the photoluminescence properties of Er³⁺-doped CaWO4 mineral materials

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JOURNAL OF MATERIALS CHEMISTRY C 2024年第32期12卷 12363-12371页

作者： Zhang, Yixiao Meng, Guichen Guan, Pengfei Wang, Haotian Zhu, Xiaolong Yang, Jian Hou, Jingshan Zheng, Ming China Univ Min & Technol Sch Mat Sci & Phys Xuzhou 221116 Peoples R China Shanghai Inst Technol Sch Mat Sci & Engn Shanghai 201418 Peoples R China East China Normal Univ Key Lab Polar Mat & Devices Minist Educ Shanghai 200241 Peoples R China

The incorporation of rare earth elements into the mineral materials of natural phosphors is beneficial for effectively regulating the photoluminescence (PL) properties of minerals and improving the utilization rate of mineral materials. Er3+-doped CaWO4 ceramics are prepared by applying a high-temperature solid-state reaction method, and the average grain size of the doped ceramics is greatly reduced. The PL properties of the ceramics are closely related to their crystal phase structure and symmetry. When the doping concentration is 0.2 mol%, the phase structure and microstructure of the ceramics are significantly changed and lattice symmetry is minimal;therefore, the PL intensity reaches the maximum value with a relative change of 225.8% in the PL intensity. When the temperature increases to 180 degrees C, all the ceramics have good fluorescence thermal stability. The CIE color coordinate of CaWO4:0.2%Er3+ ceramic is found to fall in the green region of the visible spectrum and has the longest fluorescence lifetime of up to 52.3 mu s. This study shows that the excellent PL properties of CaWO4:0.2%Er3+ ceramics lay a foundation for the research on mineral fluorescent ceramics in the fields of optical temperature measurement, LEDs, optical imaging and display, thus expanding the application of scheelite ceramics in the optical field.

关键词： Photoluminescence

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Ordered sulfonated polystyrene particle chains organized through AC electroosmosis as reinforcing phases in Polyacrylamide hydrogels

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2024年 662卷 1063-1074页

作者： Zhang, Yajun Yan, Chao Li, Jiaojiao Li, Xiangmeng Wang, Yu Liu, Xinlei Zhu, Xijing North Univ China Sch Mech Engn Taiyuan 030051 Peoples R China North Univ China Shanxi Prov Key Lab Adv Mfg Technol Taiyuan 030051 Peoples R China Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian 710054 Peoples R China

Polyacrylamide (PAM) hydrogels have garnered significant attention due to their unique swelling properties, biocompatibility, and stability, resulting in them being promising candidates for various applications, ranging from drug delivery to tissue engineering. However, traditional PAM hydrogels suffer from low strength and poor toughness, which limits their widespread use. In this study, based on the theory of filler -reinforced composites, we introduced ordered sulfonated polystyrene (SPS) particles into PAM hydrogels using electric field -assisted techniques. The effects of the geometric dimensions and filling concentration of SPS particles on thermal stability, swelling/deswelling behavior, and mechanical properties of composite hydrogels were investigated. When filled with ordered 100 nm SPS particles at a concentration of 2.0 g & sdot;L -1 , the resulting SPS/PAM composite exhibited improved water retention capacity, as well as a fracture elongation of 316 % and a tensile strength of 23 kPa. These findings in the paper provide valuable insights into the understanding of PAM hydrogels and open up new avenues for the development of advanced hydrogel-based systems with enhanced performance and functionality.

关键词： Tissue engineering

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Study on the effect of Ar-He shielding gas on the weld formation, microstructure and mechanical properties of 5083 aluminum alloy weld

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JOURNAL OF MATERIALS RESEARCH AND technology-JMR&T 2024年 28卷 683-694页

作者： Chen, Haoxin Tianli, Zhang Zhu, Zhiming Xu, Lianyong Lin, Sanbao Yang, Shanglei Kou, Sindo Shanghai Univ Engn Sci Sch Mat Sci & Engn Shanghai 201620 Peoples R China Tsinghua Univ Dept Mech Engn Beijing 100084 Peoples R China Tianjin Univ Sch Mat Sci & Engn Tianjin 300072 Peoples R China Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China Univ Wisconsin Dept Mat Sci & Engn Madison WI 53706 USA

In this paper, the ER5356 aluminum alloy wire was used for cold metal transfer (CMT) welding of the 5083-H111 base metal with 20 mm thickness. The effects of four shielding gases, which were 100%Ar, 75%Ar+25%He, 50% Ar+50%He and 100%He on the weld formation, microstructure and mechanical properties were investigated using optical microscope, scanning electron microscope (SEM), x-ray diffraction (XRD) and mechanical testing. The results showed that with the increase of He in the shielding gas, the weld penetration and width increased, and the porosity in the weld zone decreased significantly;the microstructure changed from coarse dendrites to fine equiaxed crystals, and the microstructure was gradually refined;the tensile strength of deposited metal increased from 220 MPa to 270 MPa, with an increase of 22.7%, the tensile fracture was quintessential ductile fracture, and the hardness increased from 64.2 HV to 68.4 HV. The addition of He in the shielding gas can effectively inhibit the generation of pores and promote the beta-Al3Mg2 phase in the weld microstructure, thus improving the mechanical properties of the deposited metal.

关键词： Shielding gas Aluminum alloy Weld formation Microstructure Mechanical properties

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Phase formation and elemental transport in the vacuum diffusion bonding between CoCrFe 0.2 NiMn and CoCrFe 16 NiMn multicomponent alloys

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VACUUM 2024年 226卷

作者： Li, Fangjie Zhu, Zongxin Hu, Han Yang, Dongye Liu, Min Shen, Qin Zheng, Jun Xiong, Changhong Zhang, Yan Shanghai Univ Engn Sci Sch Mat Sci & Engn 333 Longteng Rd Shanghai 201602 Peoples R China Shanghai Inst Technol Sch Mat Sci & Engn 100 Haiquan Rd Shanghai 201418 Peoples R China Shanghai Univ Engn Sci Sch Mech & Automot Engn 333 Longteng Rd Shanghai 201602 Peoples R China Anhui Univ Technol Key Lab Green Fabricat & Surface Technol Adv Met M Minist Educ Maanshan 243002 Peoples R China

To efficiently explore the influence of Fe content on the phase stability of the multicomponent CoCrFexNiMn (hereafter abbreviated as Fex) alloys. A diffusion layer with continuous, concentration gradient of Fe element is created based on diffusion couple technique. The microstructure and element distribution of the diffusion bonded layer between Fe0.2 and Fe alloys are analyzed. A new layer of FCC and HCP solid solution phases generates in the diffusion zone, which is consistent with the prediction of parametric approach and phase diagram calculation. As diffusion proceeds, the FCC phase is transformed from the BCC phase with the decreasing of Fe content and the HCP phase might be the transitional phase during this transition. The newly formed FCC and HCP phases are shown specific orientation relationships with the BCC phase. Elemental analysis indicated that the diffusion rate of the alloy components in the FCC phase is Cr > Mn > Co > Ni. The large concentration gradient in the diffuse interface and grain boundaries diffusion of BCC phase promoted the Fe diffusion, causing the BCC phase to transform into FCC phase.

关键词： High entropy alloy Diffusion bonding Phase transformation Microstructure

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Improved mechanical and corrosion properties of plasma torch melt surface nitrogen assisted M2 steels

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JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL 2025年第5期32卷 1226-1244页

作者： Zhang, Hai-nan Yu, Jian-bo Yang, Zhi-gang Jiang, Jin-tao Dong, Ying Zhang, Xiao-xin Wang, Jiang Ren, Zhong-ming Shanghai Univ Sch Mat Sci & Engn State Key Lab Adv Special Steel Shanghai 200444 Peoples R China Shijiazhuang Tiedao Univ Engn Res Ctr Matamat & Microdevices Sch Mat Sci & Engn Shijiazhuang 050043 Hebei Peoples R China

A novel plasma torch nitriding technology was applied for the first time to improve the surface properties of M2 high-speed steel by adjusting different experimental parameters. The nitrogen content, precipitate, microstructure, mechanical property, and corrosion resistance of the nitrided layer were comprehensively analyzed using an ONH analyzer, scanning electron microscope (SEM), micro-area X-ray diffractometer, transmission electron microscope (TEM), Vickers microhardness tester, high-temperature wear tester, 3D profilometer, tensile testing machine, and electrochemical workstation. The research results show that the novel plasma torch nitriding technology can achieve synergistic strengthening of nitrogen, carbon, and alloying element solid solution, precipitation strengthening, and martensitic structure on the surface of M2 high-speed steel. The nitrogen content on the specimen surface increased up to 0.17%, while the size and area of carbides were reduced by 89% and 86%, respectively, indicating a transformation towards fine nitrogen-rich precipitates. Compared to the original M2 steel, the nitrided specimens exhibited significant improvements in overall performance. The hardness increased from 228 HV0.2 to a maximum of 795 HV0.2, the wear coefficient decreased from a maximum of 0.8 to 0.49, the tensile strength increased from 753 MPa to a maximum of 934 MPa, and the corrosion current density decreased from 1.2 x 10(-5) to a minimum of 1.9 x 10(-6)A/cm(2).

关键词： Plasma torch Nitriding M2 steel Property Precipitate Microstructure

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Experiments and numerical investigation on rock-breaking enhancement mechanism of supercritical CO2 jet drilling

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INTERNATIONAL JOURNAL OF OIL GAS AND COAL technology 2025年第3期37卷 275-300页

作者： Cai, Can Zhou, Shengwen Chen, Hao Li, Bangrun Cao, Wenyang Zeng, Lang Yang, Xianpeng Chen, Kejie Li, Tianzhou Zhang, Liehui Southwest Petr Univ Sch Mechatron Engn Chengdu 610500 Peoples R China Southwest Petr Univ Sch Mech Engn Lab High Pressure Jet Theory & Applicat Technol Chengdu 610500 Peoples R China Southwest Petr Univ State Key Lab Oil & Gas Reservoir Geol & Exploitat Chengdu 610500 Peoples R China

Supercritical CO2 (SC-CO2) jet drilling technology has been proposed to solve the problems of low rock-breaking efficiency and severe thermal wear of PDC cutters in high temperature formation. However, the rock-breaking enhancement mechanisms of SC-CO2 jet on PDC cutter are poorly understood. Therefore, in this paper, SC-CO2 jet-PDC cutter composite rock-breaking experiments and numerical simulation have been employed to study the fundamental factors of SC-CO2 jet enhanced rock-breaking and the influence of different working parameters on composite rock-breaking. The results indicated that the rock debris carrying, and impact effects of SC-CO2 jet are the fundamental causes of cutting force reduction. The main reason for the SC-CO2 jet cooling cutter is the heat absorption of gas expansion and phase transition. The research findings offer a theoretical basis for SC-CO2 jet-PDC cutter composite rock-breaking and could support gas drilling, hot dry rock drilling, and deep oil-gas development.

关键词： supercritical CO2 jet rock-breaking numerical simulation PDC cutter experimental study rock debris carrying one-way fluid-solid coupling cooling effect jet impact

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Multi-Interfacial Heterostructure Design of Carbon Fiber/Silicone Rubber-Oriented Composites for Microwave Absorption and Thermal Management

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advanced FUNCTIONAL MATERIALS 2024年第51期34卷

作者： Liu, Yijie Zhou, Jintang Ning, Zuolong Huang, Hexia Cheng, Zhenyu Duan, Lvtong Wang, Yucheng Tao, Xuewei Liu, Peijiang Ma, Yao Yao, Zhengjun Nanjing Univ Aeronaut & Astronaut Coll Mat & Technol Nanjing 211100 Peoples R China Nanjing Univ Aeronaut & Astronaut Key Lab Mat Preparat & Protect Harsh Environm Nanjing 211100 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Energy & Power Engn Nanjing 210016 Peoples R China Nanjing Inst Technol Jiangsu Key Lab Adv Struct Mat & Applicat Technol Nanjing 211100 Peoples R China Minist Ind & Informat Technol Sci & Technol Reliabil Phys & Applicat Technol Ele Elect Res Inst 5 Guangzhou 511370 Guangdong Peoples R China Army Engn Univ Natl Key Lab Electromagnet Environm Effects & Elec Nanjing 210007 Peoples R China

In order to ensure the operation and longevity of electronic devices, the design of multifunctional composites integrating microwave absorption (MA) and thermal conduction has become the key to solving the problem. However, the superior MA properties and thermal conductivity are usually incompatible in the blend system. In this study, a modified carbon fiber/silicone rubber-oriented structure is designed based on the multiscale design concept of heterostructures with multiple interfaces. The forward deposition-reverse growth mechanism is utilized at the microscopic level to construct multi-interfacial heterogeneous structures on the surface of 1D carbon fibers (CFs). The magneto-electric coupling network of the multi-interfacial heterostructure induces interfacial polarization and enhances MA properties and heat transfer. Subsequently, the structural design of the modified CFs is carried out on a macroscopic scale using the ice template method. The directionally aligned modified CFs/silicone rubber aerogel composites are obtained by backfilling with silicone rubber (SR). The samples achieved an effective absorption bandwidth of 4.41 GHz and a maximum reflection loss of -42.29 dB with ultra-thin thickness (1.3 mm). The thermal conductivity of the sample is improved to 200% compared to pure silicone rubber. The composites with directional alignment have promising applications in lightweight and flexible electronic packaging. The modified carbon fiber/silicone rubber-oriented structure is designed based on the multiscale design concept of heterostructures with multiple interfaces. The sample has achieved an effective absorption bandwidth of 4.41 GHz at 1.3 mm ultra-thin thickness and improved thermal conductivity. The composites with directional alignment have promising applications in lightweight and flexible electronic packaging. image

关键词： directionally aligned aerogel microwave absorption/thermal conductivity composites multifacial heterostructure multifunctions

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