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Biaxial tensile behavior of Ti-6Al-4V under proportional loading

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Chinese Journal of Aeronautics 2023年第5期36卷 344-362页

作者： Lin QI Yazhou GUO Kanghua JIN Huaipu KANG Yulong LI School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Applications Northwestern Polytechnical UniversityXi’an 710072China School of Civil Aviation Northwestern Polytechnical UniversitySuzhou 215699China npu yangzi river delta research institute Suzhou 215400China

The biaxial tensile behavior of isotropic Ti-6Al-4 V is characterized in this paper.A novel cruciform specimen was designed and optimized to achieve uniform stress and strain distribution within the gauge *** tensile tests were conducted at three different loading ratios by the biaxial testing *** Digital Image Correlation(DIC)technique was applied to determine strain distribution,and a high-speed camera was employed to record the fracture *** Inverse Analysis(IA)approach with a combined experimental and numerical method was proposed to determine the true stresses at the gauge section of the specimen during biaxial tensile *** results indicate that the initial yield locus can be described by the Cazacu criterion accurately,whereas the Mises criterion can predict better the strengthening behavior of Ti-6Al-4 V in the first quadrant in the principal stress space.

关键词： Biaxial tensile testing Inverse analysis Strengthening behavior Ti-6Al-4V Yield locus

Effects of surface topography and specimen thickness on high-speed raindrop impact damage of CFRP laminates

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Chinese Journal of Aeronautics 2023年第6期36卷 186-200页

作者： Naidan HOU Renxi ZHAO Xuan WANG Zhongbin TANG Hao CUI Yulong LI School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Joint International research Laboratory of Impact Dynamics and Engineering Application Xi'an 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Application Xi'an 710072China School of Civil Aviation Northwestern Polytechnical UniversitySuzhou 215400China npu yangzi river delta research institute Suzhou 215400China

Raindrop impact erosion has been observed since early days of aviation,and can be catastrophic for exposed materials during supersonic flight.A single impact waterjet apparatus is established for mimicking drop impacts at the velocities between 350 m/s and 620 m/*** Fiber Reinforced Polymer(CFRP)laminates with three different surface morphologies and specimen thicknesses are tested here.A central region with no visible damage has been noticed,surrounded by a"failure ring"with common damage patterns including resin removal,matrix cracking,fiber breakage and mass fiber *** features are presented in the"failure ring"whose whole scope extends larger along the longitudinal direction than the transverse direction of the top *** mechanism of the resin removal is related to fiber-matrix debonding,and its onset and propagation can be facilitated by initial surface asperities with the shear action of the lateral *** cases of multiple impact,good surface quality can slow down the evolution of resin removal and fiber exposure on the CFRP surface,reducing the erosion speed and delaying the occurrence of structural damages in the subsequent *** wave dominates the occurrence of matrix cracking on the CFRP surface,and subsequently,results in material loss and peeling of the top-layer because of lateral *** the increase of the specimen thickness,both the interlaminar and intralaminar failures decrease as the impact damage mechanism changes from plate bending stress to the reflection of stress waves.

关键词： Carbon fiber reinforced plastics Failure analysis Impact testing Lateral jetting Surface roughness Waterjet

HYDRAULICS OF COMPOUND CHANNEL WITH VEGETATED FLOODPLAINS

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Journal of Hydrodynamics 2002年第1期14卷 23-28页

作者： Huang Ben-sheng, Lai Guan-wen, Qiu Jing, Lin Shu-zhong (Guangdong research institute of Water Conservancy & Hydro-Power, Guangzhou 510610, China res. inst. of Water Conservancy Guangzhou 510610 China

Experimental researches were conducted on flood carrying capacity of compound open channels with wide and narrow floodplains as well as hydrodynamic behavior of overbank flow across vegetated floodplains. results show that hydrodynamic behavior of compound channels with narrow floodplains is different from that of the wide floodplains. In such compound channels with narrow vegetated floodplains as in the Pearl river delta nework, it has been found that vegetated domains become really impenetra ble when the length of vegetated domain is larger than Lm, the length of f low in floodplain coming into the main channel, and that the influence of vegeta ted floodplains upon flood stages of a channel is not very significant.

关键词： compund chennel vegetated floodplains flood carrying capacity velocity distributions the Pearl river delta

Effect of Barium-Precursors on Reaction Kinetics in Y-Ba-Cu-O System

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Journal of Rare Earths 2001年第4期19卷 241-245页

作者：王龙妹 Central Iron and Steel res. inst. Beijing 100081 China

The reactions of stoichiometric Y2O3, CuO, and different Ba salts or oxides (BaCO3, Ba(NO3)(2), BaO2, BaCuO2) for forming various compounds in the Y-Ba-Cu-O system (i.e., YBa2Cu3O7-delta, BaCuO2, Y2BaCuO5 and Y2Cu2O5) were systematically investigated by thermal analysis and X-ray diffractometry. The relevant activation energies were calculated from thermogravimetric data. It is found that the reaction pathway significantly depends on the thermal stability of the Ba precursors. Binary BaO-CuO phases form at low temperature (650 similar to 700 degreesC) when in presence of easy- to -decompose Ba precursors, and then slowly transform to ternary compounds. On the contrary, when Ba ions are released at temperature higher than 900 degreesC, ternary phases form directly from the components.

关键词： rare earths Y-Ba-Cu-O precursors sequencing kinetics

Effect of Hydrogen on Cryogenic Mechanical Properties of Cr-Ni-Mn-N Austenitic Steels

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Journal of Materials Science & Technology 1999年第1期15卷 67-70页

作者： Ma, Luming Liang, Guojun Tan, Jun Rong, Lijian Li, Yiyi Chinese Acad Sci Inst Met Res Shenyang 110015 Peoples R China

The method of high-pressure hydrogen charging was used to investigate the internal hydrogen effects on cryogenic mechanical properties of two Cr-Ni-Mn-N austenitic steels, 22-13-5 and 21-6-9. Specimens saturated with hydrogen up to 65 multiplied by 10** minus **6-68 multiplied by 10** minus **6 were tested in air at temperatures ranging from 77 to 293 K. Hydrogen causes the increases in cryogenic strength, both yield strength and ultimate tensile strength. Hydrogen decreases cryogenic ductility, and the maximum hydrogen embrittlement tendency was found at a certain low temperature. Cr-Ni-Mn-N austenitic steels show the feature: delta //L greater than phi //L at low temperatures, here, delta //L and phi //L are the hydrogen induced loss rates of elongation and reduction of area, respectively. Hydrogen has less effect on cryogenic Charpy impact toughness and notched tensile strength, however, hydrogen decreases cryogenic fracture toughness of the steels. At temperature below M//d, the fracture toughness is obviously decreased due to the formation of strain-induced marten-sites, whether hydrogen is charged or not. (Edited author abstract) 7 Refs.

关键词： Steel

Electrochemically modified piezoelectric crystal biosensor for detection of Staphylococcus aureus

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Chinese Journal of Chemistry 1996年第3期14卷 222-227页

作者： Si, SH Chen, JH He, FJ Nie, LH Yao, SZ HUNAN UNIV NEW MAT RES INSTCHANGSHA 410082HUNANPEOPLES R CHINA

Electropolymerized o-phenylenediamine firm is used as a functional coating for the immobilization of anti-S. aureus antibody on the surface of a gold-plated piezoelectric crystal, and this piezoelectric immunosensor is applied to detect S. aureus. The frequency shift (delta F = F-20s - F-380s, Hz) between the frequency at the 20th second (after the addition of sample, F-20s) and that at 380 seconds later (F-380s) was introduced to construct a calibration graph, and shortening of assay time was achieved. The S. aureus concentrations in the range of 10(5)-10(9) cells/mL can be detected by this system.

关键词： piezoelectric biosensor detection of S-aureus electrochemical modification

Structural and Magnetic Properties of Mechanically Alloyed Nd_(15)Fe_(70)T_(15)N_δ(T=V,Mo) Magnets

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Journal of Materials Science & Technology 1995年第1期11卷 1-4页

作者： Xinguo ZHAO Zhidong ZHANG Wei LIU Qun WAN and Xaokai SUN(institute of Metal research, Chinese Academy f Sciences, Shenyang, 110015, China) CHINESE ACAD SCI INST MET RESSHENYANG 110015PEOPLES R CHINA

Structural and magnetic properties of Nd15Fe70T15Nδ(T=V, Mo) alloys, made by mechanical alloying (MA) followed by heat-treatment and nitriding, have been investigated *** of annealing temperature on the structure and magnetic properties of the materials were studied by means of X-ray diffraction, AC susceptibility and high field magnetization measurements. Under pure argon atmosphere, the optimum temperatures for the heat treatment are found to be 75 and 850℃ for Nd15Fe7015Nδ and Nd15Fe70Mo15Nδ respectively. Correspondingly, the following magnetic properties are achieved : (1) Nd15Fe70V15Nδ:Br=0.63 T,,HC=8.01kA/cm (10.1 kOe), (BH )max=50.3 kJ/m3 (6 32 MGOe), (2) Nd15Fe70Mo15Nδ :Br=0.42 T. iHc=5.6 kA/cm (7.4 kOe), (BH )max=26.6 kJ/m3 (3.34 MGOe)

关键词： Fe T=V,Mo T Magnets Structural and Magnetic Properties of Mechanically Alloyed Nd

Microstructure and Properties of Spray Deposited 2024-20Si-5Fe Alloy

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Journal of Materials Science & Technology 1998年第5期14卷 402-406页

作者： Yuan, Xiaoguang Ren, Luquan Cui, Chengsong Xu, Daming Li, Qingchun Jilin Univ Technol Engn Bion Res Inst Changchun 130025 Peoples R China Harbin inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

A rapidly solidified Al-Si-Fe-Cu-Mg alloy was prepared by spray deposition. The microstructure of the alloy includes silicon phase and delta -(Al,Fe,Si), Al//8Si//6Mg//3Fe, FeAl//2 and small FeSi//2 phases. The reasons of the formation of silicon and delta -(Al,Fe,Si) phase were analyzed. The tensile properties at the room temperature to 350 degree C were investigated, and the strengthening mechanism was suggested. The wear resistance and cutability of the alloy were measured as well. (Edited author abstract) 11 Refs.

关键词： Aluminum alloys

Accelerating the Screening of Modified MA2Z4 Catalysts for Hydrogen Evolution Reaction by Deep Learning-Based Local Geometric Analysis

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 290-302页

作者： Zheng, Jingnan Wang, Shibin Deng, Shengwei Yao, Zihao Hu, Junhua Wang, Jianguo Zhejiang Univ Technol Inst Ind Catalysis Coll Chem Engn State Key Lab Breeding Base Green Chem Synth Techn Hangzhou 310032 Peoples R China Zhengzhou Univ Sch Mat Sci & Engn Zhengzhou 450001 Peoples R China Zhengzhou Univ State Ctr Int Cooperat Designer Low Carbon & Envir Sch Mat Sci & Engn Zhengzhou 450001 Peoples R China

Machine learning (ML) integrated with density functional theory (DFT) calculations have recently been used to accelerate the design and discovery of single-atom catalysts (SACs) by establishing deep structure-activity relationships. The traditional ML models are always difficult to identify the structural differences among the single-atom systems with different modification methods, leading to the limitation of the potential application range. Aiming to the structural properties of several typical two-dimensional MA(2)Z(4)-based single-atom systems (bare MA(2)Z(4) and metal single-atom doped/supported MA(2)Z(4)), an improved crystal graph convolutional neural network (CGCNN) classification model was employed, instead of the traditional machine learning regression model, to address the challenge of incompatibility in the studied systems. The CGCNN model was optimized using crystal graph representation in which the geometric configuration was divided into active layer, surface layer, and bulk layer (ASB-GCNN). Through ML and DFT calculations, five potential single-atom hydrogen evolution reaction (HER) catalysts were screened from chemical space of 600 MA(2)Z(4)-based materials, especially V-1/HfSn2N4(S) with high stability and activity (delta G(H*) is 0.06 eV). Further projected density of states (pDOS) analysis in combination with the wave function analysis of the SAC-H bond revealed that the SAC-dz(2) orbital coincided with the H-s orbital around the energy level of -2.50 eV, and orbital analysis confirmed the formation of sigma bonds. This study provides an efficient multistep screening design framework of metal single-atom catalyst for HER systems with similar two-dimensional supports but different geometric configurations.

关键词： graph convolutional neural network hydrogen evolution reaction modified MA(2)Z(4) substrate single atom catalyst MONOLAYER MACHINE