Equations In Composite Materials Research Articles

A Multiscale Method for Coupled Steady-State Heat Conduction and Radiative Transfer Equations in Composite Materials

Abstract Predictions of coupled conduction-radiation heat transfer processes in periodic composite materials are important for applications of the materials in high-temperature environments. The homogenization method is widely used for the heat conduction equation, but the coupled radiative transfer equation is seldom studied. In this work, the homogenization method is extended to the coupled conduction-radiation heat transfer in composite materials with periodic microscopic structures, in which both the heat conduction equation and the radiative transfer equation are analyzed. Homogenized equations are obtained for the macroscopic heat transfer. Unit cell problems are also derived, which provide the effective coefficients for the homogenized equations and the local temperature and radiation corrections. A second-order asymptotic expansion of the temperature field and a first-order asymptotic expansion of the radiative intensity field are established. A multiscale numerical algorithm is proposed to simulate the coupled conduction-radiation heat transfer in composite materials. According to the numerical examples in this work, compared with the fully resolved simulations, the relative errors of the multiscale model are less than 13% for the temperature and less than 8% for the radiation. The computational time can be reduced from more than 300 h to less than 30 min. Therefore, the proposed multiscale method maintains the accuracy of the simulation and significantly improves the computational efficiency. It can provide both the average temperature and radiation fields for engineering applications and the local information in microstructures of composite materials.

A Multiscale Approach and a Hybrid FE-FDTD Algorithm for 3D Time-Dependent Maxwell's Equations in Composite Materials

This paper discusses the multiscale analysis of the initial-boundary value problem for three-dimensional (3D) time-dependent Maxwell's equations in composite materials. The new contributions in this paper are the determination of higher-order correctors and an explicit convergence rate for the approximate solution. Consequently, a multiscale hybrid finite element finite-difference time-domain (FE-FDTD) method is presented. The numerical results demonstrate that this multiscale method has potential applications in engineering electromagnetics.

Multiscale Computation and Convergence for Coupled Thermoelastic System in Composite Materials

This paper discusses the multiscale computation for linear time-dependent thermoelastic equations in composite materials with a periodic microstructure. The new contributions presented in this study are the formulation of the correction terms and the strong convergence result with an explicit rate for the second-order multiscale solutions. By application of the Laplace transform, the multiscale method is developed for the static coupled thermoelastic system instead of the original time-dependent equations. Numerical results are reported to demonstrate that the proposed method has a competitive advantage for solving the dynamic thermoelastic system in three-dimensional composite materials. Moreover, the method is highly suitable for parallel computation.

FE Design Tool for Laminated Composite Plates

Considering the non-linearity, complexity and anisotropy of constitutive equations in composite materials, numerical methods are essential to evaluate the behaviour of this material. The finite element method (FEM) is a powerful computational technique for the solution of differential and integral equations that arise in various fields of engineering and applied science such as composite materials. Here, an FEM tool is designed to analyse non-linearity in the behaviour of composites caused by the effect of transverse shear and twist in laminated composite plates. The tool is established by using FEM for composites in ABAQUS combined with programming in Python to run the tests for all possible fibre orientations in laminated composite plates. It is shown that the tool has the ability to design laminated composite plates by considering the effect of transverse shear and the tool’s output provides results for all different fibre orientations. It is demonstrated that there is good agreement between numerical results obtained from this tool and experimental results. The advantages of the tool give designers the opportunity to use this tool for wide range of products.

The method of fundamental solutions for Helmholtz-type equations in composite materials

In this paper, we introduce and develop the method of fundamental solutions (MFS) for solving Helmholtz-type elliptic partial differential equations in composite materials. This study builds upon the previous developments and applications of the MFS to linear and nonlinear heat conduction, elasticity, and functionally graded composite layered materials. Numerical results are presented and discussed for four examples involving both the modified Helmholtz and the Helmholtz equations in two-dimensional or three-dimensional, bounded or unbounded, smooth or non-smooth composite domains. It was found that the method produces numerical results which are in good agreement with the analytical solutions, where available.

Multiscale Asymptotic Method for Maxwell's Equations in Composite Materials

In this paper we discuss the multiscale analysis of Maxwell's equations in composite materials with a periodic microstructure. The new contributions in this paper are the determination of higher-order correctors and the explicit convergence rate for the approximate solutions (see Theorem 2.3). Consequently, we present the multiscale finite element method and derive the convergence result (see Theorem 4.1). The numerical results demonstrate that higher-order correctors are essential for solving Maxwell's equations in composite materials.

Multiscale Computations for 3D Time-Dependent Maxwell's Equations in Composite Materials

We discuss multiscale computations of the initial-boundary value problem for three-dimensional time-dependent Maxwell's equations in composite materials. A multiscale algorithm is developed, and the convergence results are presented. Numerical simulations are carried out to validate the theoretical results reported in the present paper.

Multiscale finite element algorithm of the eigenvalue problems for the elastic equations in composite materials

In this paper, we discuss the multiscale computation of the eigenvalue problems for the elastic equations in composite materials. The multiscale finite element method for solving these problems is presented. Numerous numerical results validate the proposed method of this paper.

Multiscale asymptotic method of optimal control on the boundary for heat equations of composite materials

In this paper, we study the optimal control on the boundary for parabolic equations with rapidly oscillating coefficients arising from the heat transfer problems and the optimal control on the boundary of composite materials or porous media. The multiscale asymptotic expansion of the solution for the problem in the case without any constraints is presented. We derive the proofs of all convergence results.

A discontinuous Galerkin method on refined meshes for the two-dimensional time-harmonic Maxwell equations in composite materials

In this paper, a discontinuous Galerkin method for the two-dimensional time-harmonic Maxwell equations in composite materials is presented. The divergence constraint is taken into account by a regularized variational formulation and the tangential and normal jumps of the discrete solution at the element interfaces are penalized. Due to an appropriate mesh refinement near exterior and interior corners, the singular behaviour of the electromagnetic field is taken into account. Optimal error estimates in a discrete energy norm and in the L 2 -norm are proved in the case where the exact solution is singular.