The effect of surface stress on the configurational equilibrium of voids and cracks

摘要

The title problem is studied for a linear surface energy density with two surface stress coefficients. In terms of a Young's modulus E and an applied traction T, the perturbation of a smooth (equilibrium or nonequilibrium) configuration affected by a surface stress εo. is proportional to εoT/E, which is small but depends on the sign of T. It is shown that, through the existence of an interaction energy between the applied traction and the surface stress, a Griffith crack can actually be strengthened (weakened) by a crack-parallel tension (compression) via surface stress, an intuitively reasonable conclusion that does not follow from linear elasticity. In general, surface stress can effectively reduce an uPPlied stress- intensity factor to a lower effective stress-intensity factor.