On the homogenization analysis of composite materials based on discretized fluctuations on the micro-structure

Abstract

The paper investigates a numerical procedure for the computation of the overall macroscopic elasticity moduli of linear composite materials with periodic micro-structure. We consider a homogenized macro-continuum with locally attached representative micro-structure which characterizes a representative cell of a composite. The deformation of the micro-structure is assumed to be coupled with the local deformation at a typical point of the macro-continuum by three alternative constraints of the microscopic fluctuation field. The underlying key approach is a finite element discretization of the boundary value problem for the fluctuation field on the micro-structure of the composite. This results into a distinct closed-form representation of the overall elasticity moduli in terms of a Taylor-type upper bound term and a characteristic softening term which depends on global fluctuation stiffness matrices of the discretized micro-structure. With this representation in hand, overall moduli of periodic composites can be computed in a straightforward manner for a given finite element discretization of the micro-structure. We demonstrate the concept for three types of periodic composites and compare the results with well-known analytical estimates.