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Laboratory Assessment of Lubricants for Wheel/Rail Lubrication

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Journal of Materials Science & Technology 1997年第1期13卷 57-60页

作者： Zhao, XZ Liu, JJ Zhu, BL Wang, CY ZHENGZHOU RES inst mech engn ZHENGZHOU 450052PEOPLES R CHINA

The antiwear properties of two wheel/rail lubricating oils were tested and compared on an Amsler machine. Under same testing conditions, oil A (developed by authors) showed much better wear resistance and higher load-carrying capacity than oil B (imported from abroad). The X-ray diffraction (XRD) analyses of the worn surfaces showed that different extreme pressure (EP) lubricating films were formed on the surfaces when the rollers were lubricated with different oils under boundary lubrication condition. The EP film of oil A was a composite film containing three compounds, FeO, FeSx and FeP, while oil B formed only a simple EP film of FePO4. The composite EP film showed lower shear strength and better antiwear property than the simple EP film, which brought about different wear resistance df the two wheel/rail lubricating oils.

关键词： Lubricating oils

ELASTIC WAVES IN 3-D DISCRETE GRIDS

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Acta mechanica Solida Sinica 1995年第4期8卷 283-293页

作者： Guan, HM Liao, ZP inst engn mech HARBIN 150080PEOPLES R CHINA

Wave motion in finite element models presents some characteristics different from those of wave motion in continuum, which leads to the errors and other special phenomena in finite element simulation of wave motion. The wave propagation in a 3-D finite element model is studied by utilizing the formal solution in the paper, and the corresponding dispersion relations are derived. Then the main properties of wave motion in 3-D grids such as dispersion, cut-off frequency and polarization drift are discussed. Characteristics different from those of wave motion in 2-D grids are revealed.

关键词： finite elements discrete grids 3-dimensional wave motion

ON SEVERAL NEW METHODS TO POLAR DECOMPOSITION COMPUTATION

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Acta mechanica Solida Sinica 1998年第4期11卷 329-340页

作者： Huang, MJ Li, M Fu, MF Nanchang Univ Inst Engn Mech Nanchang 330029 Peoples R China

In this paper, the polar decomposition of a deformation gradient tensor is analyzed in detail. The four new methods for polar decompositioncomputation are given: (1) the iterated method, (2) the principal invariant's method, (3) the principal rotation axis' s method, (4) the coordinate transformation's method. The iterated method makes it possible to establish the nonlinear finite element method based on polar decomposition. Furthermore, the material time derivatives of the stretch tensor and the rotation tensor are obtained by explicit and simple expressions.

关键词： polar decomposition deformation gradient stretch tensor rotation tensor large deformation and large rotation

Modeling and Simulation of Iron-Carbon Phase Transformation During Tempering of Steel

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稀有金属材料与工程 2012年第S1期41卷 6-12页

作者： Dong-ying Ju1,Xiao-hu Deng 2 1Department of mechanical Engineering,Saitama institute of Technology,Saitama,Japan 2 Advanced Science Research Laboratory,Saitama institute of Technology,Saitama,Japan Saitama inst Technol Dept Mech Engn Saitama Japan Saitama inst Technol Adv Sci Res Lab Saitama Japan

Tempering is final process used in heat treatment of steel *** is important to improve the toughness and ductility of the quenched steel without a great loss of the hardness and ***,the traditional tempering process is hard to satisfy requirements of combination mechanical properties with low cost.A quantitative model is developed to simulate the micro-structural evolution during tempering process of carbon steel by modifying the previous Ju and Inoue's *** model takes into account tempering parameters,carbon content and morphology for iron-carbon *** of carbon atoms,precipitation of transition carbides(ε-carbide),decomposition of retained austenite and precipitation of cementite can be predicted *** precipitation of carbides is modeled by considering the competitive precipitations ofε-carbide and *** kinetics of decomposition of retained austenite into ferrite and cementite is depicted by the modified Avrami *** validate the model,it is applied to simulate the tempering process of the as-quenched plain carbon *** volume fractions of iron-carbon phase are calculated at different tempering temperature and *** is indicated that tempering time has greater effect on the volume fraction of carbides at high temperature *** calculated results are reasonable consistent with the theoretical descriptions.

关键词： tempering phase transformation kinetics transition carbide cementite

EFFECTS OF MICROSTRUCTURE ON THE MACROSCOPIC ELASTO-PLASTIC PROPERTIES OF METAL MATRIX COMPOSITES

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Acta mechanica Solida Sinica 1996年第1期9卷 52-58页

作者： Chen, HR Su, XF Tang, LM DALIAN UNIV TECHNOL RES INST ENGN MECHDALIAN 116023PEOPLES R CHINA

The generalized self-consistent finite-element iterative averaging method was adopted to analyze the elasto-plastic tensile properties of SiC whiskers reinforced aluminum matrix composites. The effects of varying fiber's aspect ratio and volume fraction on the macroscopic elasto-plastic deformation of the composites were studied. By the analysis of microscopic stress fields, the relation between the propagation of the elasto-plastic region in the matrix and the macroscopic elasto-plastic deformation of composites was discussed. It was found that the propagation of the plastic region in the matrix between the fiber's ends would affect prominently the elasto-plastic tensile behaviour of the composites. It was shown that the characterization of the stress-strain response in terms of the 0.2% offset yield strength is incomplete.

关键词： metal-matrix composites microstructure macroscopic elasto-plastic behaviour microscopic plastic region generalized self-consistent finite-element iterative averaging method

SCATTERING OF ELASTIC WAVES IN AN ELASTIC MATRIX CONTAINING AN INCLUSION WITH INTERFACES

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Acta mechanica Solida Sinica 2002年第3期15卷 270-276页

作者： Li Fengming Hu Chao Huang Wenhu Harbin inst Technol Dept Aerosp Engn & Mech Harbin 150001 Peoples R China

Based on the theory of elastic dynamics, the scattering of elasticwaves and dynamic stress concentration of fiber-reinforced compositewith interfaces are studied. Analytical expressions of elastic wavesin different medium areas are presented and an analytic method ofsolving this problem is established. The mode coefficients aredetermined by means of the continuous conditions of displacement andstress on the boundary of the interfaces. The influence of materialproperties and structural size on the dynamic stress con- centrationfactors near the interfaces is analyzed.

关键词： fibre-reinforced composite interfaces scattering of elastic waves dynamicstress concen- tration

QUASI-PERIODIC AND CHAOTIC BEHAVIOUR OF A TWO-DEGREE-OF-FREEDOM IMPACT SYSTEM IN A STRONG RESONANCE CASE

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Acta mechanica Solida Sinica 1999年第3期12卷 279-282页

作者： Luo Guanwei Xie Jianhua Sun Xunfang Lanzhou Railway inst Dept Mech Engn Lanzhou 730070 Peoples R China SW Jiaotong Univ Dept Mech Engn Chengdu 610031 Peoples R China

A two-degree-of-freedom system contacting a single stop isconsidered. Quasi-periodic and chaotic behavior of the system in astrong resonance case is investigated by theoretical analysis andnumerical simulation.

关键词： vibro-impact strong resonance bifurcation

mechanical Properties of Coating and Part by Laser Engineered Net Shaping by Nanoindentation Testing

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稀有金属材料与工程 2011年第S4期40卷 261-265页

作者： Xue Chunfang1,Tian Xinli2,Lin Keling11Department of mechanical Engineering,Armored Force Engineering institute,Beijing 100072,China2National Key Laboratory for Equipment Remanufacturing,Armored Force Engineering institute,Beijing 100072,China Armored Force engn inst Dept Mech Engn Beijing 100072 Peoples R China Armored Force engn inst Natl Key Lab Equipment Remfg Beijing 100072 Peoples R China

The mechanical properties,such as hardness and modulus of elasticity of coatings and the part of thin walls of Ni-based and Co-based alloy prepared by LENS were measured by nanoindentation testing,scanning electron microscopy and energy dispersive spectroscopy were used to analyze their microstructure,the affect of parameters on structure and mechanical properties were *** results showed that the mechanical properties were basically identical with the whole coating;the hardness and modulus of elasticity of nanoindentation were evenly distributed in the defect *** average hardness and modulus of elasticity of coating of Ni-based alloy are 8.29GPa and *** average hardness and modulus of elasticity of coating of Co-based alloy are 7.08GPa and *** modulus of elasticity of part of thin walls has relationship with the grain orientation.

关键词： nanoindentation laser engineered net shaping (LENS) solidify speediness mechanical property.

Effects of lanthanum on structures and grain sizes of Ti 44Al alloy

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中国有色金属学会会刊：英文版 1999年第3期9卷 599-604页

作者： Liu Changming(刘昌明) Li Huaji(李华基) He Naijun(何乃军) Chongqing Univ Sch Mech Engn State Key Lab Mech Transmiss Chongqing 400044 Peoples R China

By vacuum arc melting, lanthanum (La) was added in the range from 0.05% to 0.3% (mole fraction) to binary Ti 44%Al alloy to refine its fully lamellar (FL) colonies for high ductility. Effects of La on structures and grain sizes of the alloy were determined. It was observed that La greatly promoted growth of columnar grains in as cast structures of the ingots and reduced their diameters. The ingots were subsequently heat treated to obtain well defined fully lamellar structures. The material without La displayed large average size of equiaxed lamellar colonies over 1 400 μm (resulted from five measurement positions in a sample), and the material with 0.1% addition of La consisted of the finest average lamellar colonies as 381 μm, the finest grain size was 337 μm at top position. When La addition was over 0.1%, La stabilized the columnar structure and it was difficult to refine the columnar grains in heat treatment, therefore, grains were coarser.

关键词： titanium alumiruium alloy lanthanum addition structures