Stress Analysis for Nano-Scaled Elastic Materials. (Elastic Contact Problems Considering Surface Stresses).

Abstract

It is known that intrinsic mechanical stresses exist in a general free surface or interface, because of surface atomic structure changes relative to the bulk. This paper presents an analysis using the interrelationships between surface stresses, free surface and volume stress deduced in the previous paper. The surface stresses have a close relationship with surface energy and surface geometry (mean curvature) of materials. In the present paper, an elastic contact problem which pressed an axisymmetric elastic body into an elastic half region coated with a thin elastic film is analyzed by using the three-dimensional theory of elasticity. In this analysis, the relevant dimensionless parameter, called the elastic capillary number, which is a function of surface energy, elastic modulus and the film thickness, is introduced. It is shown that the modulus for the thin film apparently increases and the bulk stress also increases by taking into account the surface stresses.