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VISCO-PLASTIC CONSTITUTIVE MODEL FOR UNIAXIAL AND MULTIAXIAL RATCHETING AT ELEVATED TEMPERATURES

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 431-436页

作者： G.z.Kang q.gao J.z.ang Dept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 ChinaDept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 ChinaDept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

Based on the experimental results of the ratcheting for SS304 stainless steel, a new visco-plastic cyclic constitutive model was established to describe the uniaxial and multiaxial ratcheting of the material at room and elevated temperatures within the framework of unified visco-plasticity. In the model, the temperature dependence of the ratcheting was emphasiz.d, and the dynamic strain aging occurred in the temperature range of 4 00-600℃ for the material was taken into account particularly. Finally, the prediction capability of the developed model was checked by comparing to the corresponding experimental results.

关键词： constitutive model ratcheting elevated temperature multiaxial loading

Crack Initiation Mechanism of z.CN20.09M Duplex Stainless Steel during Corrosion Fatigue in Water and Air at 290 °C

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Journal of Materials Science & Technology 2015年第11期31卷 1144-1150页

作者： H.C.Wu B.Yang Y.z.Shi q.gao Y.q.Wang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Collaborative Innovation Center of Universal Iron & Steel Technology School of Materials Science and Engineering Anhui University of Technology

The crack initiation mechanism of a z.CN20.09M duplex stainless steel （DSS） during corrosion fatigue （CF） in water and air at 290 ℃ was investigated by using a CF cracking machine and a scanning electron microscopy （SEM）. The cracks were initiated successively at the persistent stip bands （PSBs）, phase boundaries （PBs） and pitting corrosion points （PCPs） of the specimens when they were tested in water at 290 ℃, while in airat 290 ℃ the cracks were only initiated at the PSBs and PBs. And the cracks were found mainly to initiate at the PSBs and PBs when the specimens were tested in water and air at 290 ℃, respectively. The results also reveal that the cracks were likely to be initiated at the first 20% of fatigue life of the specimens tested in water at 290 ℃. However, the cracks were not found until 50% of fatigue life when tested in air at 290 ℃. Moreover, the crack numbers of the specimens tested in water at 290 ℃ were much more than those tested in air at 290 ℃.

关键词： Duplex stainless steel Corrosion fatigue Crack initiation High temperature water

An application of interacting shear flows theory: exact solution for unsteady oblique stagnation point flow

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Acta Mechanica Sinica 2006年第5期22卷 397-402页

作者： Guibo Li Minguo Dai z. gao College of Physical and Environmental Oceanography Ocean University of China Qingdao 266003 China LHD Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

An analytical solution of the governing equations of the interacting shear flows for unsteady oblique stagnation point flow is obtained. It has the same form as that of the exact solution obtained from the complete NS... 详细信息

关键词： Navier-Stokes equations Interacting shear flows Unsteady oblique stagnation point flow Exact solution

Reducing force transmissibility in multiple degrees of freedom structures through anti-symmetric nonlinear viscous damping

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Acta Mechanica Sinica 2012年第5期28卷 1436-1448页

作者： z.-K.Peng z.-q.Lang G.Meng S.A.Billings State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Department of Automatic Control and Systems Engineering University of Sheffield

In the present study, the Volterra series theory is adopted to theoretically investigate the force transmissibility of multiple degrees of freedom （MDOF） structures, in which an isolator with nonlinear anti-symmetric viscous damping is assembled. The results reveal that the anti-symmetric nonlinear viscous damping can significantly reduce the force trans- missibility over all resonance regions for MDOF structures with little effect on the transmissibility over non-resonant and isolation regions. The results indicate that the vibration isolators with an anti-symmetric damping characteristic have great potential to solve the dilemma occurring in the design of linear viscously damped vibration isolators where an increase of the damping level reduces the force transmissibility over resonant frequencies but increases the transmissibility over non-resonant frequency regions. This work is an extension of a previous study in which MDOF structures installed on the mount through an isolator with cubic nonlinear damping are considered. The theoretical analysis results are also verified by simulation studies.

关键词： Nonlinear viscous damping Force transmissibility - Vibration isolation Volterra series

Continuous edge chromatic numbers of abelian group actions

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Science China Mathematics 2025年

作者： Su gao Ruijun Wang Tianhao Wang School of Mathematical Sciences and Laboratory of Pure Mathematics and Combinatorics Nankai University

We prove that for any generating set S of z.n, the continuous edge chromatic number χ′c（G） of the Schreier graph of the Bernoulli shift action G = F(S, 2z.n) is χ′（G） + 1 = |S| + 1. In particular, for the stan...

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A PROBABILISTIC ASSESSMENT OF TEMPERATURE EFFECTSON THE LOW CYCLE FATIGUE BEHAVIOUR OF 1Cr_(18)Ni_9Ti STEEL WELD METAL

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Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 477-484页

作者： q.gao Y.X.z.ao L.X.Cai

Based on the test results obtained from the single-step test and the incremental-step test at room temperature and 240℃, a probabilistic assessment of temperature effects on the cyclic stress-strum response and the fatigue life of 1Cr18Ni9Ti steel weld metal is performed. In orber to assess the temperature effect on cyclic stress amplitude where there is a scatter of the material cyclic constitution, a probabilistic assessment approach on the basis of probabilistic modified Ramberg-Osgood relations is *** investigation shows that the cyclic stress amplitude and the scatter of cyclic stress amplitude data are decreased at 240℃. Similarly, from the consideration of the fatigue life scatter a probabilistic assessment of temperature effect on the fatigue life is suggested on the basis of probabilistic Langer S-N relations. The investigation shows that the crack initiation life is increased and the scatter of crack initiation life data is decreased at 240℃.

关键词： 1Cr_(18)Ni_9Ti stainless steel weld metal low cycle fatigue temperature effect probabilistic assessment

Analysis of vibration reduction level in an 8/6 switched reluctance machine by active vibration cancellation

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Journal of z.ejiang University-Science C(Computers and Electronics) 2010年第10期11卷 808-816页

作者： Xu LIU z.i-ping PAN z. q. z.U School of Electrical Engineering Zhejiang University Hangzhou 310027 China Department of Electronic and Electrwal Engmeermg University of Sheffield Sheffield S1 3JD UK

This paper proposes an analytical model for predicting the maximum vibration reduction level in a four-phase 8/6 switched reluctance machine(SRM) by employing active vibration cancellation(AVC),one of the most effective and convenient methods for reducing the vibration and acoustic noise produced by *** on the proposed method,the factors that influence the vibration reduction level are analyz.d in *** relationships between vibration and noise reduction levels at resonance frequency and rotor speed are ***,it is shown that a large damping factor will lead to smaller vibration reduction level with AVC while,in contrast,a large resonance frequency will increase the vibration reduction *** finite element analyses and experiments were carried out on a prototype 8/6 SRM to validate the proposed method.

关键词： Active vibration cancellation Analytical model Switched reluctance machine Vibration

EVOLUTION OF THE ELECTROCHEMICAL CHARACTERISTICS DURING PITTING CORROSION OF PURE ALUMINUM IN SODIUM CHLORIDE SOLUTION

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 525-532页

作者： z. z.ang C. Cai F.H. Cao z.N. gao J.q. z.ang C.N. Cao Department of Chemistry Zhejiang University Hangzhou 310027 China Department of Chemistry Ningxia University Yinchuan 750021 China State Key Laboratory for Corrosion and Protection of Metals Institute of Metal Research The Chinese

The corrosion behavior of pure aluminum in neutral 3.0% （mass fraction） sodium chloride （Na-Cl） solution has been studied using electrochemical impedance spectroscopy （EIS） measurement in conjunction with the scanning electron microscopy （SEM） technique. EIS information on the evolution of pitting corrosion over a period of 15 days has been obtained and analyz.d with equivalent circuit technique. The results shown that, during the ensemble constant immersion time, two time constants involved, the high frequency one originated from the protective layer on the corroding surface while the low frequenO, one from the diffusion process or the corrosion reaction and so on. And there existed a period for oxide film to growth and thickening prior to the of the attacking of chloride ions to the substrate. Meanwhile, good relationship between EIS and the material corrosion type/severity has been obtained, which has been interpreted according to the characteristics of corrosion process such as auto acceleration of pitting corrosion and the protection of local anodic reaction to the area around them.

关键词： pure aluminum pitting corrosion electrochemical impedance spectroscopy pit-rnorphology

Multiple Tin Compounds Modified Carbon Fibers to Construct Heterogeneous Interfaces for Corrosion Prevention and Electromagnetic Wave Absorption

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Nano-Micro Letters 2025年第1期17卷 507-527页

作者： z.iqiang Guo Di Lan z.rui Jia z.enguo gao Xuetao Shi Mukun He Hua Guo Guanglei Wu Pengfei Yin College of Science Sichuan Agricultural UniversityYa’an 625014People’s Republic of China School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002People’s Republic of China Institute of Materials for Energy and Environment State Key Laboratory of Bio‑Fibers and Eco‑TextilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071People’s Republic of China Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’anShaanxi 710072People’s Republic of China

Currently,the demand for electromagnetic wave(EMW)absorbing materials with specific functions and capable of withstanding harsh environments is becoming increasingly ***-component interface engineering is considered an effective means to achieve high-efficiency EMW ***,interface modulation engineering has not been fully discussed and has great potential in the field of EMW *** this study,multi-component tin compound fiber composites based on carbon fiber(CF)substrate were prepared by electrospinning,hydrothermal synthesis,and high-temperature thermal *** utiliz.ng the different properties of different substances,rich heterogeneous interfaces are *** effectively promotes charge transfer and enhances interfacial polariz.tion and conduction *** prepared SnS/SnS_(2)/SnO_(2)/CF composites with abundant heterogeneous interfaces have and exhibit excellent EMW absorption properties at a loading of 50 wt%in epoxy *** minimum reflection loss(RL)is−46.74 dB and the maximum effective absorption bandwidth is 5.28 ***,SnS/SnS_(2)/SnO_(2)/CF epoxy composite coatings exhibited long-term corrosion resistance on q235 steel ***,this study provides an effective strategy for the design of high-efficiency EMW absorbing materials in complex and harsh environments.

关键词： Electrostatic spinning Component regulation Heterogeneous interfaces Electromagnetic wave absorption Corrosion protection