A coated inclusion in an elastic medium

Abstract

Many inhomogeneous systems of practical interest are made up of an inclusion, or several inclusions, of one elastic phase bonded to a surrounding matrix of another phase, and the behaviour of such systems has been studied extensively. A thin layer of some other elastic phase intervenes between an inclusion and the matrix in some important applications, for instance, where coated nuclear fuel particles are bonded in a matrix, or where duplex cylindrical fibres are employed in fibre-reinforcement, or wherever chemical action induces a protective finish either intentionally or inevitably as when an oxide coating covers a metallic surface. Our objective is to show how to take account of the pronounced influence that even a thin coating may exert upon, for instance, the stress concentrations just outside an inclusion or cavity, or upon the overall elastic moduli of a suspension of inclusions (though discussion of this latter topic is omitted here in order that it may be explored more fully elsewhere).