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Characteristics of dry friction backward whirl—A self-excited oscillation in rotor-to-stator contact systems

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Science china(Technological Sciences) 2010年第3期53卷 674-683页

作者： JIANG Jun,SHANG ZhiYong & HONG Ling moe key Laboratory of {2. and vibration,xi’an jiaotong university,xi’an 710049,china moe key Laboratory of {2. and vibration Xi’an Jiaotong University Xi’an China

In this paper,the response characteristics of dry friction backward whirl of a general rotor/stator model,which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces,are *** existence boundaries and the whirl frequencies of the dry friction backward whirl are determined *** is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions,either standing completely separately,or overlapping each other partly,or one containing the other completely,depending upon the system *** whirl frequencies in the two existence regions are quite different and may jump between the lower and the higher values with the variation of the rotating *** results have been found to have good correspondence in the related rotor/stator rubbing experiments.

关键词： a general rotor/stator model dry friction backward whirl existence boundaries backward whirl frequencies

Ultralight X-type lattice sandwich structure (Ⅱ):Micromechanics modeling and finite element analysis

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Science china(Technological Sciences) 2009年第9期52卷 2670-2680页

作者： ZHANG QianCheng1,CHEN AiPing 2.CHEN ChangQing2.3 & LU TianJian2.1 State key Laboratory for Mechanical Behavior of Materials,school of Material Science and Engineering,{2.,xi’an 710049,china 2.moe key Laboratory for strength and vibration,school of aerospace,{2.,xi’an 710049,china 3 Department of Engineering Mechanics,AML,Tsinghua university,Beijing 100084,china State key Laboratory for Mechanical Behavior of Materials School of Material Science and Engineering Xi’an Jiaotong University Xi’an China moe key Laboratory for {2. and vibration School of Aerospace Xi’an Jiaotong University Xi’an China Department of Engineering Mechanics AML Tsinghua University Beijing China

The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.

关键词： sandwich panel lattice structure equivalent homogenization finite element model

Ductility of copper films on sandblasting polyimide substrates

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Science china(Technological Sciences) 2010年第8期53卷 2215-2221页

作者： YANG JinShui,XU Wei,WANG Fei&LU TianJian moe key Laboratory for {2. and vibration,xi’an jiaotong university,xi’an 710049 moe key Laboratory for {2. and vibration Xi’an Jiaotong University Xi’an China

Different surface morphologies of polyimide(PI)foils widely applied in flexible electronics were obtained using the technique of ***(Cu)films were subsequently deposited on the treated surface of PI *** tensile loading, the critical strain,crack density and count of cracks were measured to examine the ductility of Cu films on PI *** results show that after sandblasting treatment,the critical strain of Cu film decreases from 8.0%to 6.9%and,in comparison with the case without sandblasting,its surface crack density decreases remarkably,with no saturation of the crack *** reduced crack density is attributed to the increase of contact area and interfacial adhesion after sandblasting,and whether the crack density is saturated or not is dependent upon the morphology of the cracks formed as a function of tensile strain.

关键词： flexible electronics sandblasting surface roughness copper films ductility

Fundamental formulation for frictional contact with graded materials

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Journal of Pharmaceutical Analysis 2009年第1期21卷 1-10页

作者： Bing Yan, Jing Zhao moe key Laboratory for {2. and vibration, Department of Engineering Mechanics, school of aerospace, xi’an jiaotong university, xi’an 710049, china. moe key Laboratory of {2. and vibration Department of Engineering Mechanics Xi'an Jiaotong University Xi'an 710049 China

In the paper, we develop the fundamental solutions for a graded half-plane subjected to concentrated forces acting perpendicularly and parallel to the surface. In the solutions, Young’s modulus is assumed to vary in the form of E(y)=E0eαy and Poisson’s ratio is assumed to be constant. On the basis of the fundamental solutions, the singular integral equations are formulated for the unknown traction distributions with Green’s function method. From the fundamental integral equations, a series of integral equations for special cases may be deduced corresponding to practical contact situations. The validity of the fundamental solutions and the integral equations is demonstrated with the degenerate solutions and two typical numerical examples.

关键词： graded half-plane contact problem fundamental solutions singular integral equations

A two scaled numerical method for global analysis of high dimensional nonlinear systems

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Theoretical & Applied Mechanics Letters 2011年第6期1卷 45-50页

作者： Jun Jiang) moe key Laboratory of {2. and vibration, xi’an jiaotong university, xi’an 710079, china moe key Laboratory of {2. and vibration Xi'an Jiaotong University Xi'an 710079 China

This paper first analyzes the features of two classes of numerical methods for global analysis of nonlinear dynamical systems, which regard state space respectively as continuous and discrete ones. On basis of this understanding it then points out that the previously proposed method of point mapping under cell reference (PMUCR), has laid a frame work for the development of a two scaled numerical method suitable for the global analysis of high dimensional nonlinear systems, which may take the advantages of both classes of single scaled methods but will release the difficulties induced by the disadvantages of them. The basic ideas and main steps of implementation of the two scaled method, namely extended PMUCR, are elaborated. Finally, two examples are presented to demonstrate the capabilities of the proposed method.

关键词： nonlinear systems global analysis multi-scaled numerical methods point mapping cell mapping point mapping under cell reference

An analytical solution for the elastic fields near spheroidal nano-inclusions

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Acta Mechanica Sinica 2009年第6期25卷 821-830页

作者： Z. Y. Ou G. F. Wang T. J. Wang Department of Engineering Mechanics,moe key Laboratory for {2. and vibration,xi’an jiaotong university, xi’an 710049, china Department of Engineering Mechanics MOE Key Laboratory for Strength and Vibration Xi’an Jiaotong University Xi’an China

When the size of an inclusion shrinks to nanometers, interface energy plays an important role in the deformation around it. In the present paper, we consider the effect of interface energy on the elastic fields near a spheroidal nanoinclusion embedded in an elastic medium on the basis of surface elasticity theory. Using Boussinesq-Sadowsky potential function method, we obtain the deformation field near the inclusion subjected to a uniformly uniaxial loading at infinity. The results show that the elastic fields near the nano-inclusion depend strongly on the interface properties, the size and shape of inclusion. These new characteristics may be helpful to understand various relevant mechanical performances of nanosized inhomogeneities.

关键词： Interface energy .Elastic fields .Inhomogeneity - Nanometer

Some notes on betting commitment distance in evidence theory

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Science china(Information Sciences) 2012年第3期55卷 558-565页

作者： HAN DeQiang1 , DENG Yong2. HAN ChongZhao1 & YANG Yi3 1moe KLINNS Lab, SKLMSE Lab, Institute of Integrated Automation, school of Electronics and Information Engineering, {2., xi’an 710049, china 2.1} of Electronics and Information Technology, Shanghai jiaotong university, Shanghai 2.02.0, china 3school of aerospace, {2., xi’an 710049, china moe KLINNS Lab SKLMSE Lab Institute of Integrated Automation School of Electronics and Information Engineering Xi’an Jiaotong University Xi’an China school of Electronics and Information Technology Shanghai Jiaotong University Shanghai China school of aerospace Xi’an Jiaotong University Xi’an China

The distance of evidence, which represents the degree of dissimilarity between bodies of evidence, has attracted more and more interest and has found extensive uses in many realms. In this paper some notes on a widely used distance of evidence, i.e., betting commitment distance, are provided, including the arguments on the rationality of its definition, some misuses and some counter-intuitive behaviors of betting commitment distance. Several numerical examples are also provided to support and verify our arguments.

关键词： pignistic probability evidence theory betting commitment distance distance of evidence

Thermoelastic properties of sandwich materials with pin-reinforced foam cores

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Science china(Technological Sciences) 2008年第12期51卷 2059-2074页

作者： LU TianJian1,LIU Tao2.3 & DENG ZiChen2.4 1 moe key Laboratory of {2. and vibration,school of aerospace,xi’an jiaotong university,xi’an 710049,china 2.Department of Engineering Mechanics,Northwestern Polytechnical university,xi’an 710072.china 3 Department of Engineering,university of Cambridge,Cambridge CB2.1PZ,UK 4 State key Laboratory of Structural Analysis of Industrial Equipment,Dalian university of Technology,Dalian 11602.,china moe key Laboratory of {2. and vibration School of Aerospace Xi’an Jiaotong University Xi’an China Department of Engineering Mechanics Northwestern Polytechnical University Xi’an China Department of Engineering University of Cambridge Cambridge UK State key Laboratory of Structural Analysis of Industrial Equipment Dalian University of Technology Dalian China

Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins(trusses) into a foam matrix to create a truss-like network reinforced foam *** loading,the pins deform predominantly by local stretching whilst the deformation of foam is governed by local *** paper presents a theoretical study on the thermoelasticity of pin-reinforced foam sandwich *** calculate the effective thermoelastic properties of pin-reinforced foam cores,the energy-based homogenization approach is employed to develop a micromechanics-based model,calibrated by the existing experimental *** is found that the stiffness of the sandwich core is mainly governed by pin reinforcements:the foam matrix contributes little to sandwich *** with traditional foam cores without pin reinforcements,the changes in inplane thermal expansion coefficients are not vigorous as a result of pin reinforcements,while the through-thickness thermal expansion coefficient changes *** is also demonstrated that it is possible to design materials with zero or negative thermal expansion coefficients under such a context.

关键词： sandwich panel pin reinforcement analytical solutions homogenization thermoelasticity thermal expansion

vibration CONTROL IN A KAGOME BASED HIGH AUTHORITY SHAPE MORPHING STRUCTURE

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VIBRATION CONTROL IN A KAGOME BASED HIGH AUTHORITY SHAPE MOR...