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Numerical Solution of Heat Tranfer Problemwith Flow and Solidification in Round BilletContinuous Casting of Steel

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Communications in Nonlinear Science and Numerical Simulation 1999年第3期4卷 236-239页

作者： Jiahong GUO(Shanghai Institute of Applied Mathematics and mechanics, Shanghai university,Shanghai 200072, china)Xin HONG(college of Material Science, Shanghai university, Shanghai 200072, china) Shanghai Institute of Applied Mathematics and mechanics Shanghai University Shanghai 200072 China college of Material Science Shanghai University Shanghai 200072 China

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关键词： heat transfer flow and solidification round billet continuous casting

Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3 1 college of Automotive Engineering, South china university of Technology, Guangzhou 510640, china 2 Beijing Research Institute of Mechanical and Electrical Technology, Beijing 100083, china 3 Department of Engineering mechanics, Tsinghua university, Beijing 100084, china college of Automotive Engineering South China University of Technology Guangzhou China Beijing Research Institute of Mechanical and Electrical Technology Beijing China Department of Engineering mechanics Tsinghua University Beijing China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

Encapsulation of inorganic particles by dispersion polymerization through ultrasonic irradiation

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Science china Chemistry 2005年第6期48卷 545-552页

作者： ZHANG Kai1,2, FU Qiang1, HUANG Yuhong2 & ZHOU Dehui2 1. college of Polymer Science and Engineering, Sichuan university, Chengdu 610065, china 2. Institute of Structure mechanics, china Academy of Engineering Physics, Mianyang 621900, china college of Polymer Science and Engineering Sichuan University Chengdu China Institute of Structure mechanics China Academy of Engineering Physics Mianyang China

The nano-silica/polystyrene composite particles were prepared and characterized according to the following steps. First, the nano-silica particles were pretreated with surfactants under ultrasonic field. Second, the dispersion polymerization of styrene in a water/ethanol (1/6, weight ratio) medium, with poly(N-vinyl pyrrolidone) (PVP) as stabilizer and 2,2’-azobisizobu- tyronitrile (AIBN) as initiator in the presence of nano-silica particles was initiated with N2 purging through ultrasonic irradiation by taking its advantages of multieffect, i.e. dispersion, crushing, activation, and initiation. Finally, the polymerization kinetics characteristics were studied, and the encapsulation of composite particles was investigated with optical microscope, SEM, TEM, FTIR, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

关键词： composite particle, dispersion polymerization, ultrasonic irradiation.

A SEMI-ANALYTICAL AND SEMI-NUMERICAL METHOD FOR SOLVING 2-D SOUND-STRUCTURE INTERACTION PROBLEMS

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Acta Mechanica Solida Sinica 2003年第2期16卷 116-126页

作者： Xiang Yu Huang Yuying (college of Civil Engineering and mechanics,Huazhong university of Science and Technology,Wuhan 430074,china) Coll. of Civ. Eng. and mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

Based on the transfer matrix method and the virtual source simulation technique, this paper proposes a novel semi-analytical and semi-numerical method for solving 2-D sound- structure interaction problems under a harmonic *** any integration segment, as long as its length is small enough,along the circumferential curvilinear coordinate,the non- homogeneous matrix differential equation of an elastic ring of complex geometrical shape can be rewritten in terms of the homogeneous one by the method of extended homogeneous capacity proposed in this *** the exterior fluid domain,the multi-circular virtual source simulation technique is *** source density distributed on each virtual circular curve may be ex- panded as the Fourier's *** with the inverse fast Fourier transformation,a higher accuracy and efficiency method for solving 2-D exterior Helmholtz's problems is presented in this *** the aspect of solution to the coupling equations,the state vectors of elastic ring induced by the given harmonic excitation and generalized forces of coefficients of the Fourier series can be obtained respectively by using a high precision integration scheme combined with the method of extended homogeneous capacity put forward in this *** to the superposition princi- ple and compatibility conditions at the interface between the elastic ring and fluid,the algebraic equation of system can be directly constructed by using the least square *** of acoustic radiation from two typical fluid-loaded elastic rings under a harmonic concentrated force are *** results show that the method proposed is more efficient than the mixed FE-BE method in common use.

关键词： sound-structure interaction acoustic radiatlon multi-circular virtual source simulation technique transfer matrix method inverse fast Fourier transformation semi-analytical and semi-numerical method

A theoretical model of collision between soft-spheres with Hertz elastic loading and nonlinear plastic unloading

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Theoretical & Applied mechanics Letters 2011年第4期1卷 34-39页

作者： Youhe Zhou 1,2,a) 1) Key Laboratory of mechanics on Disaster and Environment in Western china,the Ministry of Education of china 2)Department of mechanics and Engineering Science,college of Civil Engineering and mechanics,Lanzhou university,Lanzhou 730000,china Key Laboratory of mechanics on Disaster and Environment in Western china the Ministry of Education of China China Department of mechanics and Engineering Science College of Civil Engineering and Mechanics Lanzhou University Lanzhou 730000 China

This paper presents a theoretical model on the normal(head-on) collision between soft-spheres on the basis of elastic loading of the Hertz contact for compression process and a nonlinear plastic unloading for restitution one,in which the parameters all are determined in terms of the material and geometric ones of the spheres,and the behaviors of perfect elastic,inelastic,and perfect plastic collisions appeared in the classical mechanics are fully described once a value of coefficient of restitution is specified in the region of 0 ≤ ε ≤ *** an empirical formula of the coefficient of restitution dependent on the impact velocity is suggested to fit the existing experimental measurements by means of the least square method,the predictions of the dependency and the collision duration are in well quantitative agreement with their experimental *** is found that the measurable quantities are dependent on both the impact velocity and the parameters of *** this model,finally,an approach to determine the spring coefficient in the linear viscoelastic model of the collision is also *** results obtained here will be significantly beneficial for the applications where a collision model is requested in the simulations of relevant grain flows and impact dynamics etc..

关键词： normal collision of soft-spheres theoretical model residual displacement restitution coefficient collision duration

Boundary conditions for the bending of a piezoelectric beam

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Science china(Physics,mechanics & Astronomy) 2008年第7期51卷 847-856页

作者： GAO Yang1, XU SiPeng2 & ZHAO BaoSheng3 1 college of Science, china Agricultural university, Beijing 100083, china 2.college of Engineering, Ocean university of china, Qingdao 266071, china 3 School of Mechanical Engineering, university of Science and Technology Liaoning, Anshan 114044, china college of Science China Agricultural University Beijing China college of Engineering Ocean University of China Qingdao China School of Mechanical Engineering University of Science and Technology Liaoning Anshan China

For beam bending in transversely isotropic piezoelectric media, the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all orders for the beam of general edge geometry and loadings. By generalizing the method developed by Gregory and Wan, a set of necessary conditions on the edge-data for the existence of a rapidly decaying solution is established. The prescribed edge-data of the beam must satisfy these conditions in order that they could generate a decaying state within the beam. When stress and mixed conditions are imposed on the beam edge, these decaying state conditions for the case of bending deformation of piezoelectric beam are derived explicitly. They are then used for the correct formulation of boundary conditions for the beam theory solution (or the interior solution). Besides, an analytical solution of elastic beam is formulated to verify validity of our boundary conditions. For the stress data, our boundary conditions coincide with those obtained in conventional forms of beam theories. More importantly, the appropriate boundary conditions with two sets of mixed edge-data are obtained for the first time.

关键词： boundary conditions beam bending piezoelectric media decaying states regular states

Mixed boundary conditions for piezoelectric plates

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Science china(Physics,mechanics & Astronomy) 2009年第5期52卷 755-761页

作者： GAO Yang 1 ,XU SiPeng 2 &ZHAO BaoSheng 3 1college of Science,china Agricultural university,Beijing 100083,china 2college of Engineering,Ocean university of china,Qingdao 266071,china 3 School of Mechanical Engineering,university of Science and Technology of Liaoning,Anshan 114044,china college of Science China Agricultural University Beijing China college of Engineering Ocean University of China Qingdao China School of Mechanical Engineering University of Science and Technology of Liaoning Anshan China

For plate bending and stretching problems in piezoelectric materials,the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate mixed boundary conditions accurate to all order.A decay analysis technique is used to establish necessary conditions that the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the *** the case of axisymmetric bending and stretching of a circular plate,these decaying state conditions are obtained explicitly for the first time when the mixed conditions are imposed on the plate *** are then used for the correct formulation of boundary conditions for the interior solution.

关键词： boundary conditions piezoelectric plates mixed data bending problems stretching problems

Microwave peak absorption frequency of liquid

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Science china(Physics,mechanics & Astronomy) 2008年第9期51卷 1254-1263页

作者： HAN GuangZe1 & CHEN MingDong2 1 Department of Physics,South china university of Technology,Guangzhou 510640,china 2 Guangzhou Auto college,South china university of Technology,Guangzhou 510800,china Department of Physics South China University of Technology Guangzhou China Guangzhou Auto college South China University of Technology Guangzhou China

Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

关键词： microwave-assisted extraction microwave heating relaxation time liquid viscosity peak absorption fre-quency

A GENERALIZED MODELING FOR CEMENT-BASED materials UNDER LARGE RANGE OF COMPRESSION STATE

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Acta Mechanica Solida Sinica 2011年第S1期24卷 22-33页

作者： Yan Zhang 1 ,2 Jianfu Shao 2 Shouyi Xie 2 ( 1 college of mechanics and materials, hohai university, nanjing 2.0098, china) ( 2 Laboratory of mechanics of Lille, UMR 8107 CNRS, Polytech’Lille, Villeneuve d’Ascq 59655, France)

The aim of this study is to describe the main behavior of cement-based materials under large compression state based on the recent experimental research. In this paper, the strainstress relations are firstly analyzed and confining pressure state is regarded as low/medium/high state. A generalized cup modeling is introduced by a coupled deviatoric shearing, pore collapse and damage mechanism within thermodynamic framework. A series of numerical simulations are performed for the considered cement paste and concrete. Comparisons between numerical predictions and experimental results show that the proposed model is able to describe the main features of mechanical behavior under large range of compression state.

关键词： cement-based materials cup modeling deviatoric shearing pore collapse damage criterion large range of compression state