The effect of surface-stress on the concentration of stress at nanoscale surface flaws

A simple analytical expression for the stress-field around a surface groove of varying sharpness due to the presence an intrinsic surface-stress is derived. It is shown that this stress becomes very significant for surface grooves of high curvature, particularly at the nanoscale. Anisotropic surface-stresses are also considered. It is found that the anisotropy can make a very significant contribution to the mechanical tractions on the surface. In regions of high curvature the anisotropic part induces stresses of greater magnitude (but opposite sign) to those induced by the isotropic component. As a consequence of this, the stress concentration factor at the base of surface grooves can be enhanced, nullified or reversed, depending on the sign of the applied load and the functional form of the surface-stress. This has implications for the ability of nanoscale surface flaws to act as initiation sites for the nucleation of defects. (C) 2007 Elsevier Ltd. All rights reserved.