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Chinese Physics B 2019年第1期28卷 171-177页

作者： Y M Lu C Li x H Chen S Han P J Cao F Jia Y x Zeng x k liu W Y xu W J liu D L Zhu College of Materials Science and Engineering Shenzhen Key Laboratory of Special Functional MaterialsShenzhen Engineering Laboratory for Advanced Technology of CeramicsGuangdong Research Center for Interfacial Engineering of Functional MaterialsShenzhen UniversityShenzhen 518060China

Gallium oxide(Ga_2O_3) thin films were deposited on a-Al2O3(1120) substrates by pulsed laser deposition(PLD) with different oxygen pressures at 650?C. By reducing the oxygen pressure, mixed-phase Ga_2O_3 films with α and β phases can be obtained, and on the basis of this, mixed-phase Ga_2O_3 thin film solar-blind photodetectors(SBPDs) were *** the responsivities of the mixed-phase Ga_2O_3 SBPDs and the single β-Ga_2O_3 SBPDs at a bias voltage of 25 V,it is found that the former has a maximum responsivity of approximately 12 A/W, which is approximately two orders of magnitude larger than that of the latter. This result shows that the mixed-phase structure of Ga_2O_3 thin films can be used to prepare high-responsivity SBPDs. Moreover, the cause of this phenomenon was investigated, which will provide a feasible way to improve the responsivity of Ga_2O_3 thin film SBPDs.

关键词： Ga2O3 mixed-phase solar-blind photodetector pulsed laser deposition

Aeroelasticity Analysis of High-aspect-ratio Composite Wing

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Aeroelasticity Analysis of High-aspect-ratio Composite Wing

Computer Aided Simulation on Precision Cold Forging of Universal Joint Cross

International Conference on Industrial Technology and Management Science(ITMS 2015)

作者： k.x.liu W.Zhou x.R.Wang xi’an High Technology Institute

The pneumatic elastic model establishing and analysis of the high-aspect-ratio composite wing is an important task for the long-endurance aircraft’s design. The pneumatic elastic analysis theory and fluidstructure interaction（FSI） analysis method are applied in this paper to establish the structured finite element model for the high-aspect-ratio composite wing. Based on the analysis of initialized static model, the software Mp CCI is used to analyze the model with the bidirectional FSI theory, and discuss the pneumatic elasticity characteristics of the wing model in the coupling state. And the relative structure and flow field parameters are supported.

关键词： high aspect ratio composite fluid structure interaction pneumatic elasticity

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Journal of Shanghai Jiaotong university(Science) 2000年第1期5卷 270-273页

作者： H. liu, G.N liu, k J Huo ,T liu, x H Zhang, k liu, k Tao, Y. J. liu 1. Mechanical Engineering School, xi’an Jiaotong University, xi’an, 710049, China 2.Strength Centre, Zhengzhou Research Institute of Mechanical Engineering, Zhengzhou 450052, China 3.Fo

The 3D FEM numerical simulation on multi-action precision cold forging technology of universal joint cross and differential spider is done in this article using DEFORM Software, a commercial computer aided engineering software specializing in forming and heat treatment simulation technology, and suitable for cold, warm and hot forging process. The material flow properties, the dynamic variation of stress and strain in the process of deformation and the load-stroke curve have also been achieved. A good consistency is exhibited between simulation results and practical data. Based on the DEFORM simulation results, the optimized procedure has been found for forging a universal joint cross. What should be emphasized here is that a better understanding of practical forging characters and the environmental factors can greatly improve the simulation accuracy thus make the simulation results more reliable.

关键词： Forging simulation Universal joint cross DEFORM software

Harmonic balance-based approach for optimal time delay to control unstable periodic orbits of chaotic systems

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Acta Mechanica Sinica 2020年第4期36卷 918-925页

作者： Y.M.Chen Q.x.liu J.k.liu Department of Mechanics Sun Yat-sen UniversityGuangzhou 510275China

As a classical technique for chaos suppression,the time-delayed feedback controlling strategy has been widely developed by stabilizing unstable periodic orbits(UPOs)embedded in chaotic systems.A critical issue for achieving high controlling precision is to search for an appropriate time *** paper proposes a simple yet effective approach,based on incremental harmonic balance method,to determine the optimal time delay in the delayed feedback *** time delay is adjusted within the iterative scheme provided by the proposed method,and finally converges to the period of the target *** long as the optimal time delay is fixed,moreover,the attained solution makes it quite convenient to analyze its stability according to the Floquet theory,which further provides the effective interval of the feedback gain.

关键词： Chaos control Unstable periodic orbit Delayed feedback Optimal time delay Incremental harmonic balance method

Hard yet tough and self-lubricating(CuNiTiNbCr)C_(x) high-entropy nanocomposite films:Effects of carbon content on structure and properties

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Journal of Materials Science & Technology 2024年第6期173卷 20-30页

作者： Y.T.Li x.M.Chen x.k.Zeng M.liu x.Jiang Y.x.Leng key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China State key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of Mechanical and Electrical Engineering Mianyang Teachers’CollegeMianyang 621000China

The single-phase high-entropy alloy film is difficult to meet severe friction conditions due to its low hardness and high friction ***-composite structure film is composed of at least two separated phases,showing the properties of strength and toughness integration and excellent wear *** design of nanocomposite structures can effectively improve the mechanical properties and tribological properties of high-entropy alloy *** this study,the(CuNiTiNbCr)C_(x) nanocomposite high-entropy films(HEFs)integrated with high hardness,high toughness,and self-lubrication were synthesized by the double-target co-sputtering *** effect of carbon content on microstructure,mechanical properties,and tribological properties of(CuNiTiNbCr)C_(x) films was *** the increase of carbon content in the HEFs,the carbon atoms preferentially react with Ti,Nb,and Cr to form a(TiNbCr)C ceramic-reinforced phase,and then the excess carbon atoms precipitate in the form of amorphous carbon(a-C)lubricating phase in the *** structure of the HEFs changes from an amorphous structure to a nanocomposite structure of amorphous(amorphous CuNiTiNbCr phase+a-C phase)/nanocrystalline(TiN-bCr)C *** the carbon content is about 21.2 at.%,the carbide phase in the film reaches saturation and the hardness and modulus of the films are highest,which are 18 GPa and 228 GPa,*** HEFs with a carbon content of 44.0 at.%show the best toughness and tribological properties with a friction coefficient of 0.16 and a wear rate of 2.4×10^(-6) mm^(3)/(N m),which is mainly attributed to the excellent resistance to fatigue crack growth and the interfacial lubricating layer formed in the friction *** nanocomposite(CuNiTiNbCr)C_(x) HEFs show very promising application prospect in the field of friction protection.

关键词： High-entropy films Nanocomposite Double-target co-sputtering Strengthening-toughening Tribological properties

Accelerating bainite transformation by concurrent pearlite formation in a medium Mn steel:Experiments and modelling

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Journal of Materials Science & Technology 2024年第9期176卷 211-223页

作者： L.k.Huang F.liu M.x.Huang Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina State key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi710072China

Bainite transformation has yet to be utilized and even thoroughly studied in medium Mn ***,we investigate the isothermal bainite transformation in a 10Mn steel at 450°C experimentally and theoretically,focusing on the effect of dislocations introduced by warm *** show that the bainite transformation in the studied medium Mn steel exhibits extremely sluggish kinetics(on a time scale of days),concurrent with the pearlite *** introduced dislocations can significantly accelerate bainite transformation kinetics while also facilitating the pearlite *** is likely the first report on the simultaneous occurrence of these two solid-state reactions in medium Mn *** respect to the roles of dislocations in the acceleration of bainite transformation observed in this work,we propose a new‘carbon depletion mechanism’,in which dislocations-stimulated pearlite formation makes a twofold contribution:facilitating the formation of bainitic ferrite sub-units to further enhance the autocatalytic effect and preventing the carbon enrichment in the remaining *** this basis,a physical model is developed to quantitatively understand the bainite transformation kinetics considering the effect of concurrent pearlite formation,revealing good agreements between model descriptions and experiment *** findings,herein,offer fundamental insights into the bainite transformation in medium Mn steels and uncover a previously unidentified role played by introduced dislocations in influencing the kinetics of bainite formation,which may guide its future application in manipulating microstructure for the development of advanced high-strength steels.

关键词： Medium Mn steels Bainite Thermodynamics kinetics Phase transformation

Phase-field modeling for anisotropic ductile damage of magnesium alloys at finite deformations

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Journal of Magnesium and Alloys 2024年第7期12卷 2967-2984页

作者： C.xie x.k.He x.liu J.H.Ye J.B.Chen Faculty of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211PR China key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province Hunan University of Science and TechnologyXiangtan 411201PR China

The damage anisotropy of an extruded Zk60 Mg alloy is characterized using tensile tests and scanning electronic *** accumulation of anisotropic deformations leads to the great differences of the dimple evolution and strains at fracture along different loading *** introduce the anisotropic deformation information into the damage constitutive relationship,a thermodynamically consistent phase-field model of ductile damage fully coupled with elastoplastic finite deformations is developed in this *** the user-defined constitutive relationship and displacement-temperature coupling element,the finite element simulations are *** results show that:(1)Zk60 Mg alloys presents clear R-value difference in 0°,45°,and 90°tests of intact *** 45°test possesses the greatest R-value(1.50)and the greatest strain at fracture,however,the R-value for 0°is less than 1,indicating the thinning is preferential.(2)The higher ultimate stress leads to a larger average dimension of the dimples,whereas the higher density correlates with a larger elongation ratio at the *** disappearance of the stress-bearing area indicates that the phase-field assumption on stress degradation is completely compatible with the dimple analysis on fractography.(3)The simulation results of the stress-strain relationships and damage paths correlate well with the experimental ductile damage of magnesium alloys at 200◦*** errors are basically attributed to the modeling parameters and finite element iteration *** proposed model presents fine applicability and reliability for the predictions of plastic deformations,ductile damage,and fracture of anisotropic Mg alloys.

关键词： Ductile damage Anisotropy Phase field Constitutive relationship Magnesium

STUDY OF DYNAMIC RECRYSTALLIZATION OF LOW CARBON STEEL IN THIN SLAB CONTINUOUS ROLLING PROCESS

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 265-270页

作者： x.k. Liang x.J. Sun Q.Y. liu H. Dong State key Laboratory of Advanced Steel Processes and Products Central Iron and Steel Research Institute Beijing 100081 China

Combined with the technological characteristics of thin slab continuous rolling process （TSCR）, dynamic recrystallization of an extremely coarse austenite of low carbon steel is studied by Thermecmaster-Z hot simulator. By the analysis of true stress-strain curves and the observation of microstructures at different deformation stages, the critical stress and critical strain are determined under different deformation conditions. The effect of Z parameter on dynamic recrystallization of coarse austenite is studied. The microstructure evolution in real production is also discussed.

关键词： TSCR (thin slab continuous rolling process) coarse austenite dynamic recrystallization

Assessment of semi-empirical mass transfer correlations for pervaporation treatment of wastewater contaminated with chlorinated hydrocarbons

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1911-1916页

作者： liu Sean x. Department of Food Science Rutgers University New Brunswick NJ 08901-8520 USA

Assessment of mass transfer characteristics of pervaporation （PV） treatment of wastewater contaminated with chlorinated hydrocarbons is of great importance for water treatment plant operators conducting initial evaluation, process optimization, and process economics. While a membrane plays a central role in pervaporation processes and separation efficiency, the mass transfer in the liquid layer next to the membrane surface is of equal, if not greater importance. It is one of the few process parameters that can be adjusted in situ to manipulate the outcome of a pervaporation process. In this study, a bench scale pervaporation experiment of removing a common chlorinated hydrocarbon from water was carried out and the results of it were compared to the ones based on well-known semi-empirical correlations. The mass transfer coefficients from the experiments, ranging from 0.8× 10^-5-2.5× 10^-5 m/s under the operating conditions, are higher than those predicted by the correlation. The corresponding separation factors under varying flow velocities are determined to be between 310-950.

关键词： Chlorinated hydrocarbon Mass transfer Pervaporation Wastewater treatment

THERMODYNAMIC ExPLANATION OF LEADING PHASE IN PEARLITE TRANSFORMATION

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Acta Metallurgica Sinica(English Letters) 1997年第2期10卷 145-150页

作者： liu, x.J. Guangdong Industrial Univ Guangzhou China

In this paper a concept of 'leading probability' is presented. The difference in the leading probability between ferrite and cementite depends mainly upon the difference between their driving forces at the beginning of precipitation. The results of theromdynamic calculations showed that the leading probability of cementite increased with the increase of carbon concentration of austenite, and the decrease in transformation temperature was favourable to cementite's being the leading nucleus during pearlite transformation.

关键词： leading phase pearlite transformation decomposition of austenite