Linear stress relations for a metal matrix composite sandwich beam with any core material

Abstract

In this paper, it is shown that shear stresses are developed in the interface between the facing material and the core of a sandwich beam. The sandwich beam is composed of a core of any suitable material sandwiched between an upper unreinforced metal facing and a bottom facing made from metal matrix composite (MMC) material. The shear stress is shown to be a consequence of the differences in the core and facing elastic moduli. The magnitude of the shear stress increases as the core stiffness is made to diminish. The shear stress can exceed the bond strength between facing and core, resulting in delamination. Consequently, structural materials using this type of construction and particularly flexural experiments should contain a relatively stiff core. The magnitude of the facing stresses is shown to be relatively insensitive to the assumption or neglect of these shear stresses. In the worst case considered, neglecting the interfacial shear stresses results in an overestimation of the compressive and tensile stresses by less than 5%.