Method and Apparatus for Producing Beneficial Stresses Around Apertures by use of Focused Stress Waves

Author:  Eric T. Easterbrook
Source:  US Patent 6,389,865
Doc ID:  2002141
Year of Publication:  2002
Abstract:  
Tooling and a method of employing tooling to produce beneficial stress waves in a substrate to provide high fatigue life structures. Stress waves are provided to work a substrate, causing dimples in the workpiece, along a uniform pressure profile in the workpiece. By use of the method, uniform beneficial residual stress is provided at surface and midplane apertures in a workpiece, so as to improve overall fatigue life. An improved tool shape is described, having a smooth curve, rather than a flat punch. Also, the use of a consumable wafer provides additional uniform stress profile benefits.