Introduction

Abstract

In classical continuum mechanics, materials are viewed as ideal, continuous, homogeneous media. The aim of continuum mechanics is to describe the response of homogeneous materials to external forces using approximate constitutive relations without microstructural considerations. In fact, all materials are inhomogeneous in the microscopic scale. Manufactured composites, natural soils and rocks as well as biological tissues are typical examples. The continuum is a model of materials in the macroscopic scale. Therefore, the homogeneity of materials depends on the scale of measurement. The magnitude of the micro-scale used differs for specific materials. In general, the approximate range of the micro-scale is 10⁻⁷ m to 10⁻⁴ m.