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1.
Igor V. Andrianov Vladyslav V. Danishevs’kyy Dieter Weichert 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(5):889-903
Improved bounds for effective transport properties of a random non-percolated composite with cylindrical fibres are developed
by means of the security-spheres approach. The key point of the method is to obtain a solution for a regular composite that
can be valid for all values of the volume fractions and properties of the components. For this aim we use the asymptotic homogenization
method; a cell problem is solved by a modified version of the boundary shape perturbation technique.
相似文献
2.
A. A. Pan'kov 《Mechanics of Composite Materials》1997,33(2):112-118
A new method is developed for the statistical mechanics of composite materials — the generalized selfadjustment method — which makes it possible to reduce the problem of predicting effective elastic properties of composites with random structures to the solution of two simpler “averaged” problems of an inclusion with transitional layers in a medium with the desired effective elastic properties. The inhomogeneous elastic properties and dimensions of the transitional layers take into account both the “approximate” order of mutual positioning, and also the variation in the dimensions and elastics properties of inclusions through appropriate special averaged indicator functions of the random structure of the composite. A numerical calculation of averaged indicator functions and effective elastic characteristics is performed by the generalized self-adjustment method for a unidirectional fiberglass on the basis of various models of actual random structures in the plane of isotropy. 相似文献
3.
《Communications in Nonlinear Science & Numerical Simulation》2011,16(3):1186-1194
This paper presents a computational technique for the solution of the nonlinear mixed Volterra–Fredholm–Hammerstein integral equations. The method is based on the composite collocation method. The properties of hybrid of block-pulse functions and Lagrange polynomials are discussed and utilized to define the composite interpolation operator. The estimates for the errors are given. The composite interpolation operator together with the Gaussian integration formula are then used to transform the nonlinear mixed Volterra–Fredholm–Hammerstein integral equations into a system of nonlinear equations. The efficiency and accuracy of the proposed method is illustrated by four numerical examples. 相似文献
4.
A. Yousfia S. Fréour F. Jacquemin M. Rahmani H. Osmani R. Guillén 《Mechanics of Composite Materials》2010,46(1):101-112
The mechanical behavior of carbon-fiber-reinforced polymer matrix composites having undergone a thermo-oxidation process is
studied. The purpose is to perform a multiscale analysis of the consequences of oxidation on the intrinsic mechanical properties
of the external composite ply and on the internal mechanical states experienced by the structure under mechanical loads. The
effective mechanical properties of oxidized composite plies are determined according to the Eshelby–Kr?ner self-consistent
homogenization procedure, depending on evolution of the oxidation process. The results obtained are compared with estimates
found by the finite-element method. The macroscopic mechanical states are calculated for a unidirectional composite and laminates.
The macroscopic stresses in each ply of the structure are determined by the classical lamination theory and the finite-element
method, whereas the local stresses in the carbon fiber and epoxy matrix are calculated by using an analytical stress concentration
relation. 相似文献
5.
Armours are usually manufactured from polymer matrix composites and used for both military and non-military purposes in different
seasons, climates, and regions. The mechanical properties of the composites depend on temperature, which also affects their
ballistic characteristics. The armour is used to absorb the kinetic energy of a projectile without any major injury to a person.
Therefore, besides a high strength and lightness, a high damping capacity is required to absorb the impact energy transferred
by the projectile. The ballistic properties of a Kevlar 29/polyvinyl butyral composite are investigated under varied temperatures
in this study. The elastic modulus of the composite is determined from the natural frequency of composite specimens at different
temperatures by using a damping monitoring method. Then, the backside deformation of composite plates is analysed experimentally
and numerically employing the finite-element program Abaqus. The experimental and numeric results obtained are in good agreement. 相似文献
6.
In order to perform uncertainty quantification of elastic mechanical properties for composite laminates with multi-dimensional parameters, this paper is to develop a novel quantification approach based on grey mathematical theory. Here, uncertain parameters are modeled as correlated interval variables by virtue of some limited experimental points. The developed method not only can eliminate big errors in experimental points, but also can estimate uncertain information including nominal values, uncertain intervals, auto and mutual uncertainties of elastic properties. Besides, it can give out feasible domains of mechanical properties when considering mutual uncertainties for uncertainty propagation analysis. The numerical examples are implemented to demonstrate the feasibility and availability of the developed method. The results show that the developed method can become an important and powerful tool for uncertainty quantification of composite laminates with mutual uncertainties. 相似文献
7.
In this paper, we present two composite Milstein methods for the strong solution of Stratonovich stochastic differential equations driven by d-dimensional Wiener processes. The composite Milstein methods are a combination of semi-implicit and implicit Milstein methods. The criterion for choosing either the implicit or the semi-implicit method at each step of the numerical solution is given. The stability and convergence properties of the proposed methods are analyzed for the linear test equation. It is shown that the proposed methods converge to the exact solution in Stratonovich sense. In addition, the stability properties of our methods are found to be superior to those of the Milstein and the composite Euler methods. The convergence properties for the nonlinear case are shown numerically to be the same as the linear case. Hence, the proposed methods are a good candidate for the solution of stiff SDEs. 相似文献
8.
A. A. Pan'kov 《Mechanics of Composite Materials》1999,35(6):513-520
The generalized self-consistent method is extended to the problems of statistical mechanics of composites with random elastic properties of inclusions. This approach makes it possible to reduce the problem of predicting the effective elastic properties of composites with random structures to a sequence of simpler homogenized boundary-value problems for solitary inclusions with inhomogeneous elastic transition layers in a homogeneous effective elastic medium and with the corresponding boundary conditions. The elastic properties of a solitary inclusion for the gth homogenized problem are found from the solutions of the gth and (g+1)th homogenized problems. The elastic properties and sizes of the transition layers account for the random distribution, random sizes, and random elastic properties of inclusions in the composite. A test problem of predicting the effective elastic properties of a transversely isotropic layer composite with random elastic properties of some layers is solved by using the method proposed. The solution obtained coincides with the known exact solution [1].Perm State Technical University, Perm, Russia. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 6, pp. 785–796, November–December, 1999. 相似文献
9.
Composite quantile regression model with measurement error is considered. The SIMEX estimators of the unknown regression coefficients are proposed based on the composite quantile regression. The proposed estimators not only eliminate the bias caused by measurement error, but also retain the advantages of the composite quantile regression estimation. The asymptotic properties of the SIMEX estimation are proved under some regular conditions. The finite sample
properties of the proposed method are studied by a simulation study, and a real example is analyzed. 相似文献
10.
??Composite quantile regression model with measurement error is considered. The SIMEX estimators of the unknown regression coefficients are proposed based on the composite quantile regression. The proposed estimators not only eliminate the bias caused by measurement error, but also retain the advantages of the composite quantile regression estimation. The asymptotic properties of the SIMEX estimation are proved under some regular conditions. The finite sample
properties of the proposed method are studied by a simulation study, and a real example is analyzed. 相似文献
11.
The effects of orientation and shape of filler particles on the elastic properties of composites have been analyzed. The elastic
constants of a composite with irregularly oriented filler particles were calculated by using the method of orientational averaging
of the properties of a representative structural element. The elastic constants of the structural element were found according
to a known generalized Eshelby solution for a finite concentration of ellipsoidal inclusions. The diagrams of elasticity anisotropy
for a transversely isotropic structural element and an orthotropic composite with irregularly oriented inclusions are presented.
A quantitative estimate for the degree of anisotropy of elastic properties of composites is suggested. Data on the influence
of shape anisometry of inclusions on the anisotropy coefficient of filled composites are also reported. 相似文献
12.
R. Minero M.J.H. Anthonissen R.M.M. Mattheij 《Numerical Methods for Partial Differential Equations》2006,22(5):1149-1172
We present a method for solving partial differential equations characterized by highly localized properties in which the local defect correction (LDC) algorithm for time‐dependent problems is combined with a finite volume discretization. At each time step, LDC computes a numerical solution on a composite grid, a union of a global uniform coarse grid and a local uniform fine grid. The main feature of the method is that the discrete conservation property, typical of the finite volume approach is preserved on the composite grid. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 相似文献
13.
V. A. Kochetkov 《Mechanics of Composite Materials》1996,31(4):337-345
A theoretical investigation was carried out to examine the possibilities of a structural approach to prediction of elastic constants, creep functions, and thermal properties of multiphase polymer composite materials filled with composite or hollow spherical Inclusions of several types. The problem of determining effective properties of the composite was solved by generalizing the effective medium method, a variant of the self-consistent method, for the case of a four-phase kernel-shell-matrix-equivalent homogeneous medium model. Exact analytical expressions for the bulk modulus thermal expansion coefficient, thermal conductivity coefficient, and specific heat were obtained. The solution for the shear modulus is given in the form of a nonlinear equation whose coefficients are the solution of a system of 12 linear equations.To be presented at the Ninth International Conference on the Mechanics of Composite Materials, Riga, October 1995.Published in Mekhanika Kompozitnykh Materialov, Vol. 31, No. 4, pp. 462–472, July–August, 1995. 相似文献
14.
Approximate Conditions and Passage to the Limit in Sobolev Spaces over Thin and Composite Structures
S. E. Pastukhova 《Journal of Mathematical Sciences》2006,133(1):931-948
Approximate properties of variable measures compose a base of the two-scale convergence method with respect to a variable
measure, which is used in averaging on periodic thin and composite structures. The paper gives a survey of methods for verifying
approximate properties. The main focus is on studying composite measures, which have been little studied.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 16, Partial
Differential Equations, 2004. 相似文献
15.
Mehdi Dehghan Mehdi Ramezani 《Numerical Methods for Partial Differential Equations》2008,24(3):950-959
Many physical subjects are modeled by nonclassical parabolic boundary value problems with nonlocal boundary conditions replacing the classic boundary conditions. In this article, we introduce a new numerical method for solving the one‐dimensional parabolic equation with nonlocal boundary conditions. The approximate proposed method is based upon the composite spectral functions. The properties of composite spectral functions consisting of terms of orthogonal functions are presented and are utilized to reduce the problem to some algebraic equations. The method is easy to implement and yields very accurate result. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008 相似文献
16.
F. Qi N. Phan-Thien X. J. Fan 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2001,26(4):1-17
To efficiently calculate the effective properties of a composite, which consists of rigid spherical inclusions not necessarily of the same sizes in a homogeneous isotropic elastic matrix, a method based on the lubrication forces between neighbouring particles has been developed. The method is used to evaluate the effective Lamé moduli and the Poisson's ratio of the composite, for the particles in random configurations and in cubic lattices. A good agreement with experimental results given by Smith (1975) for particles in random configurations is observed, and also the numerical results on the effective moduli agree well with the results given by Nunan & Keller (1984) for particles in cubic lattices. 相似文献
17.
针对组合预测比单项预测具有更高的预测精度,本提出了一种基于模糊神经网络的上市公司被ST的非线性组合建模与预测新方法,并给出了相应的混合学习算法。通过与多元线性回归模型、Fisher模型和Logistc回归模型的预测结果对比表明,该方法具有预测精度高,学习与泛化能力强,适应性广的优点。 相似文献
18.
A. A. Pan'kov 《Mechanics of Composite Materials》1997,33(3):201-208
The feasibility of using a generalized self-consistent method for predicting the effective elastic properties of composites with random hybrid structures has been examined. Using this method, the problem is reduced to solution of simpler special averaged problems for composites with single inclusions and corresponding transition layers in the medium examined. The dimensions of the transition layers are defined by correlation radii of the composite random structure of the composite, while the heterogeneous elastic properties of the transition layers take account of the probabilities for variation of the size and configuration of the inclusions using averaged special indicator functions. Results are given for a numerical calculation of the averaged indicator functions and analysis of the effect of the micropores in the matrix-fiber interface region on the effective elastic properties of unidirectional fiberglass—epoxy using the generalized self-consistent method and compared with experimental data and reported solutions.Perm State Technical University. Translated from Mekhanika Kompozitmykh Materialov, Vol. 33, No. 3, pp. 289–299, May–June, 1997. 相似文献
19.
T. A. Yakubenko 《Computational Mathematics and Mathematical Physics》2006,46(6):1073-1080
Effective properties of composite and porous materials are determined by using an approach based on two-scale asymptotic expansions. Explicit approximate formulas are derived for the effective moduli of composite and porous materials of elongated structures. A numerical method is proposed for finding solutions to cell problems, which are used to determine “exact” effective moduli. Examples are computed for a two-dimensional porous medium with variously shaped pores and various degrees of “elongation.” The effective moduli produced by the explicit approximate formulas prove to be similar to those found by numerically solving cell problems. 相似文献
20.
企业财务危机预警Rough-Fuzzy-ANN模型的建立及应用 总被引:2,自引:0,他引:2
本文提出了一种基于粗糙一模糊神经网络(Rough-Fuzzy-ANN)的企业财务危机建模和预测新方法,并给出了相应的算法,在通过以我国上市公司财务数据为基础进行的实证分析之后,结果表明,Fuzzy-Rough-ANN模型具有预测精度高。学习和泛化能力强,适应性广的优点;同时有效、可行,为企业财务危机的动态预警提供了一条新的途径。 相似文献