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Evaluation on elevated-temperature stability of modified 718-type alloys with varied phase configurations

International Journal of Minerals,Metallurgy and Materials 2020年第8期27卷 1123-1132页

作者： Zhan Qiao Chong Li Hong-jun Zhang Hong-yan Liang Yong-chang Liu Yong Zhang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science&EngineeringTianjin UniversityTianjin 300354China Key Laboratory of the Ministry of Education for Modern Metallurgy Technology North China University of Science and TechnologyTangshan 063210China Science and Technology on Advanced High Temperature Structural Materials Laboratory AEEC Beijing Institute of Aeronautical MaterialsBeijing 100095China

Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical ***,the inferior stability of theγ″phase limits the application of Inconel 718,which coarsens rapidly at temperatures greater than 650°*** improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical *** the aforementioned objective,this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti *** increasing Al/Ti ratio,three particle configurations were formed:γ′/γ″composite,isolatedγ′,andγ′/γ″/γ′composite *** results of aging tests demonstrate that the isolatedγ′and theγ′/γ″/γ′composite structure exhibited better thermal stability at temperature as high as 800°*** isolatedγ′exhibited a reduced coarsening rate compared with theγ′/γ″/γ′composite particles because the isolatedγ′phase was rich in Al,Ti,and ***,theγ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number ofγ″*** obtained results provide necessary data for the compositional optimization of novel 718-type alloys.

关键词： Inconel 718 structure thermal stability interface

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Conjugated Bond-Based Peridynamic Model of Laminated Composite Materials with Arbitrary Poisson's Ratio and Shear Modulus

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SSRN 2023年

作者： Liu, Shuo Che, Lu Fang, Guodong Liang, Jun Institute of Advanced Structure Technology Beijing Institute of Technology Beijing100081 China School of Civil Aviation Northwestern Polytechnical University Xi’an710072 China Yangtze River Delta Research Institute of NPU Taicang215400 China Science and Technology on Advanced Composites in Special Environments Key Laboratory Harbin Institute of Technology Harbin150001 China

The bond-based peridynamic (BB-PD) theory is inadequate in describing the four independent engineering material constants of composite lamina, which results in fixed values its Poisson’s ratios and shear moduli. This study presents a novel lamina conjugated BB-PD model encompasses not only the fiber bond and matrix bond, but also the transverse bond and conjugated bond pair. By defining these four basic PD bonds, the improved conjugated BB-PD model can overcome the restriction of material properties. The determination of the four basic PD micro-modulus parameters is achieved through the utilization of the equivalent relationship of strain energy density. In addition, the lamina conjugated BB-PD model is extended to deal with composite laminates with different stacking sequences. The present study validates the accuracy and applicability of the conjugated BB-PD model for composite materials by conducting simulations of the elastic deformation and progressive damage behavior of unidirectional laminae and laminates. Moreover, the proposed model provides an elucidation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading. © 2023, The Authors. All rights reserved.

关键词： Elastic moduli

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DC Overvoltage Analysis of GFM-controlled Wind Farm Connected via MMC-HVDC System Caused by Receiving-end AC Faults

DC Overvoltage Analysis of GFM-controlled Wind Farm Connecte...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Siying Chen Min Cheng Yingbiao Li Jiawei Yu Yihua Zhu Mingkang Wu Jiabing Hu Jianan Yan State Key Laboratory of Advanced Electromagnetic Technology and School of Electrical and Electronic Engineering Huazhong University of Science and Technology China Yunnan Power Grid China CSG Key Laboratory for Power System Simulation (Electric Power Research Institute China Southern Power Grid) State Key Laboratory of HVDC (Electric Power Research Institute China Southern Power Grid) National Energy Power Grid Technology R&D Centre Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System China

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

DC overvoltage occurs when short circuit fault exists at the receiving-end and is harmful to the safety of the system where wind farms are connected to the grid through high-voltage direct current (HVDC) transmission based on the modular multilevel converter (MMC). To address this issue, this paper first analyzed the mechanism of the DC overvoltage and innovatively proposed a strategy in which grid-forming-controlled wind farms are integrated into the AC grid through MMC-HVDC, whose sending-end applies grid-following control and constant DC voltage control. However, secondary DC overvoltage appears during the fault recovery stage and is mainly caused by the saturation of the PI controller of constant active power control. simulations are carried out on a test with MATLAB/Simulink, and results verify the efficacy of the proposed methods in suppressing DC overvoltage that appeared during receiving-end faults and their recovery stage.

关键词： PI control simulation Power control Wind farms Robustness Wind turbines Safety

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Film cooling effectiveness in the presence of internal hole random roughness: A comprehensive analysis

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International Communications in Heat and Mass Transfer 2025年 165卷

作者： Wang, Xinyu Ye, Lin Li, Wei Zheng, Tianyi Liang, Xiyuan Liu, Cunliang School of Power and Energy Northwestern Polytechnical University Shaanxi Xi'an710129 China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University Shaanxi Xi'an710049 China Science and Technology on Altitude Simulation Laboratory Sichuan Mianyang621000 China Hunan Aviation Powerplant Research Institute Aero Engine Corporation of China Hunan Zhuzhou412002 China

Film cooling, with its excellent cooling performance, is widely applied in the active thermal protection design of aerospace propulsion systems. However, during manufacturing and service, film holes are affected by drilling processes and particle deposition, leading to significant deviations between the actual cooling structures and the original design. These deviations primarily manifest as hole blockage and increased surface roughness, which may cause cooling degradation. Therefore, it is essential to investigate the film cooling performance under structural damage and the jet-mainstream mixing mechanisms of damaged holes. This study focuses on internal roughness as a form of structural damage by investigating three levels of hole roughness—Ra = 3.1 μm (Film hole I), Ra = 35.9 μm (Film hole II), and Ra = 64.9 μm (Film hole III). The selected roughness levels and blowing ratios correspond to the practical range encountered in turbine cooling. The film cooling effectiveness distribution is measured using pressure-sensitive paint technology, and numerical simulations are conducted to analyze the flow field and support the experimental results. The results indicate that cooling degradation caused by internal roughness is mainly reflected in the reduction of high cooling effectiveness areas and the deterioration of cooling performance near the film hole exit. However, increased roughness also leads to an expansion of the film coverage in the spanwise, enhancing cooling performance downstream. Flow field analysis reveals that internal roughness increases the inhomogeneity of coolant velocity distribution inside the hole, strengthening the counter-rotating vortex pair and causing jet lift-off, which reduces the high cooling effectiveness area. Additionally, roughness-induced disturbances enhance turbulence intensity, promoting jet-mainstream mixing and increasing the overall film coverage. © 2025

关键词： Solar sails

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Controllable preparation and microwave absorption properties of shape anisotropic Fe_(3)O_(4) nanobelts

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Journal of Materiomics 2021年第5期7卷 957-966页

作者： Jialiang Pan Rujing Zhang Jun Ling Min Wang Zechen Li Zhen Zhen Limin He Hongwei Zhu State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China The First Scientific Research Institute of Wuxi Wuxi214035JiangsuChina Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material AECC Beijing Institute of Aeronautical MaterialsBeijing100095China

To substantially prevent electromagnetic threatens,microwave absorbing materials(MAMs)are required to eliminate surplus electromagnetic *** a typical MAM,Fe_(3)O_(4) particles with complex permittivity and permeability have been widely applied due to the coexistence of magnetic loss and dielectric ***,the necessary high mass fraction significantly limited its applications,thus Fe_(3)O_(4) nanostructures have been extensively investigated to overcome this *** this work,uniform Fe_(3)O_(4) nanobelts were prepared by electrospinning and two-step thermal *** controlling the composition and viscosity of the electrospinning precursor solution,Fe_(3)O_(4) nanobelts with tunable lateral sizes(200 nme1 mm)were *** samples with low content(only 16.7 wt%)Fe_(3)O_(4) exhibited wide maximum effective absorbing bandwidths(EAB)over 3 GHz,and Fe_(3)O_(4) nanobelts with smaller lateral sizes showed a maximum EAB of 4.93 ***,Fe_(3)O_(4) nanobelts with smaller lateral sizes presented superior reflection loss properties,the lowest reflection loss reached-53.93 dB at 10.10 GHz,while the maximum EAB was up to 2.98 *** excellent microwave reflection loss of Fe_(3)O_(4) nanobelts was contributed to the enhanced synergistic effect of magnetic loss,dielectric loss,and impedance matching,originated from the hierarchically cross-linked networks and shape *** study could broaden the practical applications of magnetic absorbers,and provided an approach for the development of shape anisotropic magnetic materials.

关键词： Fe_(3)O_(4) Nanobelts Shape anisotropy Microwave absorption Reflection loss

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Research on the Pressure Comfort of Pilot Helmets 32

Research on the Pressure Comfort of Pilot Helmets

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32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021

作者： Wang, Xiujuan Xu, Jing Wang, Juhao Mi, Jiachen Jiang, Yaming Aerospace Life-support Industries LTD Xiangyang441003 China Aviation Key Laboratory of Science and Technology on Life-support Technology Xiangyang441003 China Tiangong University School of Textile Science and Engineering Tianjin 300387 China Intel Engineering Simulation Technology Co. Ltd. Dalian116023 China

ISBN: (纸本)9783932182914

With the advancement of technology, the functions of pilot helmets are constantly being upgraded. The highly integrated helmets with display, positioning, sensing, night vision and camera are the future development trends. Although the multifunctional and highly integrated design enhances the combat maneuverability, the add-on components will result in local tenderness as the weight gain and center of gravity change, which seriously affects the pilot's wearing comfort, especially in high-speed overload conditions. These factors have become potential factors affecting flight safety. At present, experience-based methods are no longer suitable for new product development. Therefore, it is urgent to establish a simulation model on the pressure comfort of "helmet-head", the finite element method is used for simulation calculation. This paper studies different conditions of the center of gravity, and using the standard head shape, ball shape and real head shape as a control, to analyze the center of gravity, the difference of the head shape, and the influence of overload loading on the pressure distribution. By comparing with the actual flight situation, the simulation results are consistent with the actual situation, which proves that the simulation model has good credibility. © 2021 32nd Congress of the International Council of the Aeronautical sciences, ICAS 2021. All rights reserved.

关键词： Flight simulators

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Effect of Dislocation Characteristics on Diamond Radiation Detector Performance by Affecting Dark Current

SSRN

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SSRN 2024年

作者： Mu, Lianxi Yuan, Xiaolu Feng, Zhelin Liu, Linyue Liu, Jinlong Chen, Liangxian Wei, Junjun Ouyang, Xiaoping Li, Chengming Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing100083 China School of Mechanical Engineering University of Science and Technology Beijing Beijing100083 China School of Energy and Power Engineering Xi'an Jiaotong University Xi’an710049 China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear Technology Xi’an710024 China School of Materials Science and Engineering Xiangtan University Xiangtan411105 China

The application of diamond radiation detectors in high-energy physics requires effective control of impurity content in the material. Microwave plasma chemical vapor deposition (MPCVD) technology has made significant progress in the synthesis of high-purity single crystal diamonds. However, when the impurity content is controlled to the ppb level, there are still significant differences in the performance of diamond radiation detectors. In this study, we prepared high-purity single-crystal CVD diamonds using self-made MPCVD equipment. Electron paramagnetic resonance (EPR) testing showed that the content of substituted nitrogen (Ns) impurities in diamonds were 0.77 and 1.04 ppb, respectively. The dislocation densities measured by X-ray rocking curves were 3.3 × 106 cm-2 and 4.7 × 106 cm-2, respectively. After metallization, the charge collection efficiency (CCE) of diamond radiation detectors were 12.61% and 98.27%, respectively. There are significant differences in CCE between diamond detectors. By studying the influence of dislocations and stress distribution in diamonds on dark current, it is believed that after controlling the content of Ns impurities in diamond, the effect of dislocations along the [110] direction on detector performance is greater than that in the [100] direction for diamonds with similar dislocation densities. This may be due to the easy decomposition of dislocations in the [110] direction, leading to unstable diamond growth process and resulting the non-homogeneous epitaxy. © 2024, The Authors. All rights reserved.

关键词： Dark currents

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Direct Evidence of the Relationship between Piezoelectricity and Catalytic Activity

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SSRN 2025年

作者： Gao, Wenpeng Zheng, Huashan Luo, Huajie Zhang, Haibo Jo, Wook Xie, Bing School of Power and Energy Jiangxi Key Laboratory of Green General Aviation Power Nanchang Hangkong University Nanchang330063 China Functional Materials and Acousto-optic Instruments Institute School of Instrumentation Science and Engineering Harbin Institute of Technology Harbin150080 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Ulsan44919 Korea Republic of Beijing Advanced Innovation Center for Materials Genome Engineering China State Key Laboratory of Material Processing and Die & Mould Technology China School of Materials Science and Engineering

Piezocatalysis is highly valued for its efficient energy conversion and environmental capabilities. However, the fundamental connection between piezoelectricity and piezocatalytic activity remains to be thoroughly investigated. Herein, piezoceramic thin flakes with varying levels of piezoelectricity were examined to quantitatively assess the impact of the piezoelectric coefficient (d33) on the piezocatalytic activation in energy and environment applications. The piezoceramic flake, 220 μm thick, possessing the highest piezoelectricity (d33 = 1100 pC/N), demonstrated the highest H2O2 yield (572 μM h-1) and the fastest degradation rate (k = 0.0725 min-1) of Rhodamine B (RhB), exceeding the best performance of previously reported ceramic blocks. In contrast, the same thickness flake with the lowest piezoelectricity (d33 = 150 pC/N) exhibited the weakest piezocatalytic performance. By analyzing internal carrier characteristics and simulating carrier migration pathways under an electric field, a quantitative relationship between piezoelectricity and piezocatalytic activity was established. The piezoceramic flake with higher piezoelectricity demonstrated a higher effective free carrier concentration, a larger number of transiently migrating carriers, and a shorter migration distance due to a stronger built-in electric field, resulting in enhanced piezocatalytic activity. This work clearly elucidates the relationship between piezoelectricity and piezocatalytic activity. © 2025, The Authors. All rights reserved.

关键词： Piezoelectricity

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Erratum to:Finite element simulation and experimental test of the wear behavior for self-lubricating spherical plain bearings

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Friction 2024年第7期12卷 1620-1620页

作者： Yahong XUE Jigang CHEN Sumin GUO Qingliang MENG Junting LUO School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China Aviation Key Laboratory of Science and Technology on Generic Technology of Self-Lubricating Spherical Plain Bearing Yanshan UniversityQinhuangdao 066004China Education Ministry Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan UniversityQinhuangdao 066004China

Erratum to Friction 10(6):803–841(2022)Yahong Xue,Jigang Chen,Sumin Guo,Qingliang Meng&Junting *** element simulation and experimental test of the wear behavior for self-lubricating spherical plain *** 6(3):297–306(2018).https://***/10.1007/s40544-018-0206-x The authors regret that there was an inadvertent error in Fig.10(c)after checking the *** is important to note that the change does not impact the main conclusion of the *** 10(c)on page 304 was selected as the incorrect picture,and the accurate version of Fig.10(c)is provided as below.

关键词： wear Friction bearings

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A Staged Strategy for MMC Offshore Converter Station Under Asymmetric AC Fault

A Staged Strategy for MMC Offshore Converter Station Under A...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Fangyuan Li Longze Kou Jiapei Zhou Jie Hao State Key Laboratory of Advanced Power Transmission Technology Beijing Key Laboratory of DC Grid Technology & Simulation State Grid Smart Grid Research Institute CO. LTD. Beijing China State Grid Shanxi Electric Power Company electric power Science Research Institute Shanxi China

At present, offshore wind power has become an important development direction for wind power generation. Offshore wind farms often use high-voltage direct current transmission technology with modular multi-level voltage source converters (MMC-HVDC) to transmit electricity to the grid. However, the fault response characteristics of offshore wind farms through the MMC-HVDC transmission system are different from those through AC transmission way. Therefore, it is significant that studying the fault ride through (FRT) technology of offshore wind farms through the MMC-HVDC grid connection system for practical engineering. An electromagnetic transient simulation model for an offshore wind farm composed of a direct drive permanent magnet synchronous generator (D-PMSG) connected to the grid is established through MMC-HVDC transmission technology. The mechanism and suppression strategy of overvoltage generation in the transmission network are provided during the fault clearance and recovery phase of the offshore wind farm HVDC transmission system under AC asymmetric faults. A two-stage improved control strategy for MMC-HVDC offshore converter station in response to asymmetric faults has been proposed, which is beneficial for the joint system to quickly recover from the post fault system voltage and suppress the overvoltage risk during the fault clearing phase. Finally, the proposed strategy is validated based on a domestic ± 500kV project in China, demonstrating its effectiveness.

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