Patent ID: 7131310

Claim:
A method for working a bounding portion of material in a structure, said bounding portion adjacent a pre-selected location for an opening through said structure, in order to provide residual compressive stresses in said bounding portion for improving the fatigue life of said structure, said method comprising: providing a first compound indenter, said first compound indenter comprising a first indenter surface portion, said first indenter surface portion adapted to impact said structure at pre-selected surface locations adjacent said pre-selected location for said opening through said structure, and a second indenter surface portion, said second indenter surface portion adapted to impact said structure at pre-selected surface locations adjacent said pre-selected location for said opening through said structure; said first indenter surface portion spaced apart from said second indenter surface portion; and indenting said pre-selected surface location of said structure with said first compound indenter to provide said residual compressive stresses in bounding portion of material.