检索结果-南通市图书馆

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2.1. Department of Civil engineering,shanghai {2.,shanghai 2.0072.china 2. School of Transportation engineering,Tongji {2.,shanghai 2.0092.china Department of Civil engineering Shanghai University Shanghai China School of Transportation engineering Tongji University Shanghai China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Optical and acoustic phonon modes confined in gallium phosphide nanoparticles

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第6期29卷 561-566页

作者： ZHANG Zhaochun and ZHANG Neng School of Material science and engineering,{2. university,{2. 2.0072.china School of Material science and engineering Shanghai University Shanghai China

The main aim of this paper is to discuss the confinement effects on the optical and acoustic phonon vibrational modes in gallium phosphide（GaP） nanoparticles（cylindric grain）.The Raman scattering from the GaP nanoparticles was *** was found that the red-shifts of the longitudinal optical（LO） mode and transverse optical（TO） mode were 15 cm？1 and 13.8 cm？1,*** is generally accepted that the red-shifts of the optical phonon modes are due to the presence of smaller nanosized particles（～1.2.nm） acting as the nanoclustered building blocks of the GaP *** the low frequency Raman spectrum,a set of Stokes lines with almost the same spacing was clearly *** scattering feature originates from the discrete phonon density of states of the nanoclustered building *** to Lamb＇s vibrational theory,the Raman shift wavenumbers of the spheroidal mode and torsional mode of the lowest energy surface modes for the nanoclustered building blocks were *** agreement can be achieved between the calculated results and the observed scattering *** results indicate that the corresponding Raman peaks are due to scattering from the localized acoustic phonons in the nanoclustered building blocks in the GaP nanoparticles.

关键词： spectroscopy phonon mode Raman scattering gallium phosphide nanoparticles confinement effects

An interpolating boundary element-free method (IBEFM) for elasticity problems

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 758-766页

作者： REN HongPing 1 , CHENG YuMin 2.& ZHANG Wu 1 1 School of Computer engineering and science,{2. university,{2. 2.0072. china 2.2. Institute of Applied Mathematics and Mechanics,{2. university,{2. 2.0072. china School of Computer engineering and science Shanghai University Shanghai China shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China

The paper begins by discussing the interpolating moving least-squares (IMLS) method. Then the formulae of the IMLS method obtained by Lancaster are revised. On the basis of the boundary element-free method (BEFM), combining the boundary integral equation method with the IMLS method improved in this paper, the interpolating boundary element-free method (IBEFM) for two-dimensional elasticity problems is presented, and the corresponding formulae of the IBEFM for two-dimensional elasticity problems are obtained. In the IMLS method in this paper, the shape function satisfies the property of Kronecker δ function, and then in the IBEFM the boundary conditions can be applied directly and easily. The IBEFM is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution to the nodal variables. Thus it gives a greater computational precision. Numerical examples are presented to demonstrate the method.

关键词： moving least-squares (MLS) approximation interpolating moving least-squares (IMLS) method boundary integral equation meshless method boundary element-free method (BEFM) interpolating boundary element-free method (IBEFM) elasticity problem

Impact chaos control and stress release——A key for development of ultra fine vibration milling

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2002年第5期12卷 18-23页

作者： WANG Shulin(Department of Power engineering, university of{2. for science and Technology,{2. 2.0093, china) shanghai Univ Sci & Technol Dept Power Engn Shanghai 200093 Peoples R China

Through our previous experimental and analytical studies, it has been discovered that the key for the development of vibration milling is the impact chaos control and stress release. The necessities for the chaos control and stress release are: (i) to strictly e-liminate the sub-harmonics; (ii) to control the super-harmonics to a lower level and (iii) to load the system compressively with relatively higher period, in order that the vibration energy can be absorbed by the particles effectively and sufficiently. A new vibration model for ultra fine milling is proposed, which has wide applications in preparing ultra fine particles.

关键词： vibration mills ultra fine milling impact chaos control stress release.

Influence of Mo on the microstructure and mechanical properties of TiC-based cermets

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2010年第4期29卷 346-350页

作者： WANG Xingqing,HE Xiaoxiang,and GUO Hailiang School of Materials science and engineering,{2. university,{2. 2.0072.china School of Materials science and engineering Shanghai University Shanghai China

The microstructures and mechanics properties of TiC-based cermets composed of TiC, WC, Ni, Co, Mo, and Cr3C2.were investigated. The results show that Mo has a great effect on the sintering densification, microstructures, and mechanical properties. The microstructures and distribution of Mo and Ti in the TiC-based cermets were analyzed. It was indicated that a new phase with Ti, Mo, W, and C was formed on the rim of （Ti,W）C grains by means of an addition of Mo into the TiC-based cermets. The new phase with a surrounding structure was of great aid to improve the wettability of the liquid phase on the solid phase surface of TiC, decrease the porosity and refine the grains of the hard phase, which gave rise to the increase in strength and hardness. The properties of the TiC-based cermets could be further improved to some extent by adding WC, Cr2.3, and Co.

关键词： TiC-based cermets Mo effect sintering densification microstructure mechanical properties

A complex variable meshless method for fracture problems

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 46-59页

作者： CHENG Yumin1 & LI Jiuhong2.1. shanghai Institute of Applied Mathematics and Mechanics, shanghai {2., shanghai 2.0072. china 2. Department of Building engineering, Xi’an {2. of Technology, Xi’an 710048, china shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China Department of Building engineering Xi’an University of Technology Xi’an China

Based on the moving least-square (MLS) approximation, the complex variable moving least-square approximation (CVMLS) is discussed in this paper. The complex variable moving least-square approximation cannot form ill-conditioned equations, and has greater precision and computational efficiency. Using the analytical solution near the tip of a crack, the trial functions in the complex variable moving least-square approxi- mation are extended, and the corresponding approximation function is obtained. And from the minimum potential energy principle, a complex variable meshless method for fracture problems is presented, and the formulae of the complex variable meshless method are obtained. The complex variable meshless method in this paper has greater precision and computational efficiency than the conventional meshless method. Some examples are given.

关键词： moving least-square approximation, complex variable moving least-square approximation, meshless method, complex variable meshless method, fracture.

A Resistivity Gradient Piezoelectric FGM Actuator

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2000年第4期16卷 383-386页

作者： S. U.Adikary and Zhongyan MENG (School of Materials science and engineering,{2. university,{2. 2.1800, china) Dengren JIN (School of Materials science and engineering,{2. Jiaotong university,{2. 2.0030, china) School of Materials science and engineering Shanghai University Shanghai 201800 China School of Materials science and engineering Shanghai Jiaotong University Shanghai 200030 China

A resistivity gradient actuator based on lead zirconate titanate ceramics was successfully developed and the bending deflections up to 140 μm were obtained. The actuator material was a matrix of PZT ceramic into which smooth gradient of piezoelectric activity was introduced. The application of an electric field then causes the actuator to bend due to differential strains induced by the piezoelectric effect. The resistivity gradient of the actuator was achieved by doping PZT with suitable donor and acceptor dopants. PZT powder was modified and synthesized by using two stage powder fabrication method. The actuator was fabricated by uniaxial pressing followedby isostatic pressing with two layers of different resistivities.

关键词： PZT FGM

Sorption of a triazol derivative by soils: importance of surface acidity

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2003年第3期15卷 383-387页

作者： WU De-yi (School of Environmental science and engineering,{2. Jiaotong university,{2. 2.02.0, china.) School of Environmental science and engineering Shanghai Jiaotong University 上海 200240

The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2.(1H-1,2.4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H_2._2.treated soils was investigated. The sorption isotherm for each untreated and treated soil was non-linear, and was best fitted to Freundlich sorption equation. Soils containing high amount of clay content or organic matter or both sorbed much higher amounts of the chemical than soils that had low contents of these soil constituents. H_2._2.treated soils showed considerable sorptive affinity for S3307D. It was concluded that both organic matter and mineral fraction in natural soils contributed to the sorption of the basic compound. Sorption by the H_2._2.treated soils increased as suspension pH decreased, but all suspension pHs exceeded the pKa of the compound by more than two units. This implies that organic base protonation can occur on surfaces of soil components, and surface acidity (exchangeable acidity ) is important in sorption process of the organic base rather than suspension pH.

关键词： sorption organic base soil surface acidity

Phase transition in the Zr_(60)Al_(15)Ni_(2.) bulk metallic glass subjected to rolling at room temperature

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2006年第6期49卷 655-662页

作者： YAN Zhijie1, 2. LI Jinfu1, ZHOU Yaohe1 & WU Yanqing3 1. State Key Laboratory of Metal Matrix Composites, School of Materials science and engineering,{2. Jiao Tong university,{2. 2.0030, china 2. School of Materials science and engineering, Taiyuan university of science and Technology, Taiyuan 03002., china 3. School of Environmental science and engineering,{2. Jiao Tong university,{2. 2.0030, china State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China School of Materials science and engineering Taiyuan University of Science and Technology Taiyuan China School of Environmental science and engineering Shanghai Jiao Tong University Shanghai China

The microstructure evolution of the Zr60Al15Ni2. metallic glass during rolling at room temperature is investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC); high-resolution transmission electron microscopy (HREM). The results show that the values of full width at half maximum (FWHM) of the XRD patterns; exothermic enthalpy ΔH of DSC plots do not monotonically change with the variation of deformation degrees . As is not large than 2.%, the values of FWHM; ΔH are lower than that of the as-cast state. When reaches 30%, the values of FWHM; ΔH become larger than that of the as-cast state, while their values begin to decrease again as reaches about 85%. These results indicate that the reversible transitions between ordered; disordered atomic configurations occur during rolling, which is further verified by the HREM images. The reversible phase transition can be explained by the competition between the diffusion controlled reordering; shear-induced disordering during rolling.

关键词： metallic glasses, plastic deformation, phase transformations, shear bands.