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NONLINEAR ANALySIS OF DyNAMIC STABILITy FOR LAMINATED CIRCULAR CyLINDRICAL THICK SHELLS WITH ENDS ELASTICALLy SUPPORTED AGAINST ROTATION

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Acta Mechanica Solida Sinica 1994年第1期7卷 15-28页

作者： y.K.CHEUNG y.M.fu Department of Civil and Structural Engineering University of Hong Kong Hong Kong Department of Engineering Mechanics Hunan University ChangshaP.R.China

Based on Timoshenko-Mindlin kinematic hypotheses and Hamilton's principle,a dynamic non-linear theory for general laminated circular cylindrical shells with transverse shear deformation is developed.A multi-mode solution for periodic in- plane loads is formulated for the non-linear dynamic stability of an anti-symmetric angle-ply cylinder with its ends elastically restrained against *** resulted equations in terms of time function are solved by the incremental harmonic balance method.

关键词： Hamilton's principle dynamic stability

Effects of Rare Earth Elements on the Characteristics of Low Temperature Plasma Nitrocarburized Martensitic Stainless Steel

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Journal of Materials Science & Technology 2012年第11期28卷 1046-1052页

作者： R.L.Lju y.J.Qiao M.F.yan y.D.fu College of Materials Science and Chemical Engineering Harbin Engineering UniversityHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Low temperature plasma nitrocarburizing of 17-4PH martensitic stainless steel was conducted at 430 ℃ with and without rare earth （RE） addition. The microstructure, kinetics, microhardness, wear behavior as well as corrosion resistance of the modified layer were studied by optical microscopy, X-ray diffraction, Vickers microhardness tester, pin-on-disc tribometer and potentiodynamic polarization tests. The results show that the thickness of plasma RE nitrocarburized layer is much thicker than that formed by nitrocarburizing without RE addition. The incorporation of RE does not change the kind of the phases and the nitrocarburized layer consists mainly of nitrogen and carbon expanded martensite （aN）, γ-Fe4N and a-Fe with a trace of CrN phases. The surface microhardness of plasma nitrocarburized layer can be increased by 100 HV after RE addition. Wear resistance of the specimen can be apparently improved by low temperature plasma nitrocarburizing with and without RE addition and without sacrificing its corrosion resistance. Wear reduction effect of low temperature plasma nitrocarburizing with RE addition is better than that of the conventional one.

关键词： Stainless steel Low temperature Plasma nitrocarburizing Rare earth (RE) Wear and friction

Cracking evolution behaviors of lightweight materials based on in situ synchrotron X-ray tomography： A review

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Frontiers of Mechanical Engineering 2018年第4期13卷 461-481页

作者： y. Luo S. C. Wu y. N. Hu y. N. fu State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China Shanghai Synchrotron Radiation Facility Shanghai 201204 China

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomo- graphy can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional （3D） X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects （porosity, void, inclusion, precipitate, etc.） or artificial defects （notch, scratch, pit, etc.） strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.

关键词： fatigue crack initiation and growth fatigue damage mechanism damage tolerance defect characterization laser welded aluminum alloys

Nitrogen Contents on Tribological Properties of Magnetron Sputtered SICN Coatings

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材料热处理学报 2004年第05B期25卷 854-857页

作者： TIETUNSUN y.Q.fu J.WEI H.J.DU Departmentofphysics ShanghaiJiaotongUniversityShanghaiChina／／SchoolofMechanicalandProductionEngineeringNanyangTechnologicalUniversitySingapore639798 SchoolofMechanicalandProductionEngineering NanyangTechnologicalUniversitySingapore639798／／SingaporeInstituteofManufacturingTechnologySingapore71NanyangDriveSingapore638075 SingaporeInstituteofManufacturingTechnology -Singapore71NanyangDrivesingapore638075

Silicon carbonitride (SiCN) coatings were deposited on silicon and tungsten carbide substrates by co-sputtering silicon and carbon in argon and nitrogen mixture atmosphere using magnetron-sputtering system. The effect of the N2 concentration, RF substrate bias voltage and target current on film deposition rate, roughness, adhesion, mechanical and tribological properties of coatings were investigated. The deposition rate was found to increase with the increasing nitrogen concentration. X-ray photoelectron spectroscopy analysis showed that high nitrogen concentration in the nitrogen-argon gas mixture enhanced the incorporation of C and N but reduced the incorporation of Si. SiCN coatings have good tribological properties at a N2 concentration of approximately 60%.

关键词： SiCN涂层磁控管溅射含氮量硬度磨损

Stability of aneurysm solutions in a fluid-filled elastic membrane tube

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Acta Mechanica Sinica 2012年第4期28卷 1209-1218页

作者： A. T. Irichev y.-B. fu Steklov Mathematical Institute Gubkina Str. 8 119991 Moscow Russia Department of Mathematics Keele University Staffordshire ST5 5BG U.K.

When a hyperelastic membrane tube is inflated by an internal pressure, a localized bulge will form when the pressure reaches a critical value. As inflation continues the bulge will grow until it reaches a maximum size after which it will then propagate in both directions to form a hat-like profile. The stability of such bulging solutions has recently been studied by neglecting the inertia of the inflating fluid and it was shown that such bulging solutions are unstable under pressure control. In this paper we extend this recent study by assuming that the inflation is by an inviscid fluid whose inertia we take into account in the stability analysis. This reflects more closely the situation of aneurysm forma- tion in human arteries which motivates the current series of studies. It is shown that fluid inertia would significantly reduce the growth rate of the unstable mode and thus it has a strong stabilizing effect.

关键词： Aneurysms Localized bulging Stability Bi- furcation

Electromagnetoelastic behaviors of functionally graded piezoelectric solid cylinder and sphere

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Acta Mechanica Sinica 2007年第1期23卷 55-63页

作者： H. L. Dai y.M. fu J.H. yang Department of Engineering Mechanics Hunan University Changsha 410082 China

Analytical studies on electromagnetoelastic behaviors are presented for the functionally graded piezoelectric material （FGPM） solid cylinder and sphere placed in a uniform magnetic field and subjected to the external pressure and electric loading. When the mechanical, electric and magnetic properties of the material obey an identical power law in the radial direction, the exact displacements, stresses, electric potentials and perturbations of magnetic field vector in the FGPM solid cylinder and sphere are obtained by using the infinitesimal theory of electromagnetoelasticity. Numerical examples also show the significant influence of material inhomogeneity. It is interesting to note that selecting a specific value of inhomogeneity parameter β can optimize the electromagnetoelastic responses, which will be of particular importance in modern engineering designs.

关键词： functionally graded piezoelectric material (FGPM) Electromagnetoelastic Solid cylinder Solid sphere Perturbation of magnetic field vector

STUDy ON NANOMETER ZINC PARTICLES FABRICATED By GAS EVAPORATION METHOD

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Acta Metallurgica Sinica(English Letters) 2003年第3期16卷 161-168页

作者： A.A.A.Saleh X.J.Zhai y.C.Zhai y.fu A.L.Zhang School of Materials and Metallurgy Northeastern UniversityShenyang110004ChinaSchool of Materials and MetallurgyNortheastern UniversityShenyang110004ChinaSchool of Materials and MetallurgyNortheastern UniversityShenyang110004ChinaSchool of Materials and MetallurgyNortheastern UniversityShenyang110004ChinaSchool of Materials and MetallurgyNortheastern UniversityShenyang110004China

Nanometer Zn particles with mean diameters 12-100nm made by evaporating its powders in argon gas were studied mainly by X-ray diffraction and electron microscopy. They are collected at various distances and those factors influencing the mean particle size were studied. The optimal synthetic conditions were obtained, i.e., evaporation temperature is 1200℃; argon flow rate is 0.4m3/h; amount of powder charged is 3g; distance from evaporation source is 10cm. It was found that the size of particles was governed by argon flow rate, evaporation temperature, amount of metal charged and distance from the source. The size increases remarkably with distance in the space where no metal vapor exists. This implies that the crystallites grow by coalescence. Electron micrographs and diffraction patterns are reproduced to show the size, shape and state of oxidations. Nanoparticles with definite crystal habits were sometimes observed among those with irregular ones.

关键词： gas evaporation method nanometer Zn XRD TEM

An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage

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Chinese Physics B 2012年第8期21卷 360-364页

作者：谢刚 Edward Xu Niloufar Hashemi 张波 Fred y.fu Wai Tung Ng The Edward S.Rogers Sr.Electrical and Computer Engineering Department University of Toronto State key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Crosslight Software Inc.Burnaby BCCanada

A reduced surface electric field in an AlGaN/GaN high electron mobility transistor （HEMT） is investigated by employing a localized Mg-doped layer under the two-dimensional electron gas （2-DEG） channel as an electric field shaping layer. The electric field strength around the gate edge is effectively relieved and the surface electric field is distributed evenly as compared with those of HEMTs with conventional source-connected field plate and double field plate structures with the same device physical dimensions. Compared with the HEMTs with conventional sourceconnected field plates and double field plates, the HEMT with a Mg-doped layer also shows that the breakdown location shifts from the surface of the gate edge to the bulk Mg-doped layer edge. By optimizing both the length of Mg-doped layer, Lm, and the doping concentration, a 5.5 times and 3 times the reduction in the peak electric field near the drain side gate edge is observed as compared with those of the HEMTs with source-connected field plate structure and double field plate structure, respectively. In a device with VGS = -5 V, Lm 1.5 m, a peak Mg doping concentration of 8×10^17 cm-3 and a drift region length of 10 m, the breakdown voltage is observed to increase from 560 V in a conventional device without field plate structure to over 900 V without any area overhead penalty.

关键词： AlGaN/GaN HEMT reduced surface electric field Mg-doped layer breakdown voltage

Optimal operation of water distribution networks under local pipe failures

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Journal of Central South University of Technology 2007年第3期14卷 436-441页

作者：田一梅 G.y.fu 迟海燕刘烨 School of Environmental Science and Engineering Tianjin University Department of Civil Engineering Faculty of Applied Science University of British Columbia Vancouver BC V6T 1Z4 Canada

The optimal operation of water distribution networks under local pipe failures, such as water main breaks, was proposed. Based on a hydraulic analysis and a simulation of water distribution networks, a macroscopic model for a network under a local pipe failure was established by the statistical regression. After the operation objectives under a local pipe failure were determined, the optimal operation model was developed and solved by the genetic algorithm. The program was developed and examined by a city distribution network. The optimal operation alternative shows that the electricity cost is saved approximately 11%, the income of the water corporation is increased approximately 5%, and the pressure in the water distribution network is distributed evenly to ensure the network safe operation. Therefore, the proposed method for optimal operation under local pipe failure is feasible and cost-effective.

关键词： water distribution network local pipe failure macroscopic model optimal operation