Method for Measuring and Extending the Service Life of Fatigue-Limited Metal Components

Author:  Stanley G. Berkley
Source:  US Patent 5,490,195
Doc ID:  1996191
Year of Publication:  1996
Abstract:  
Improved methods for managing a population of metal components subject to fatigue failure are provided. The residual compressive stress in the critical surfaces of such components, especially in areas of high stress concentration, are measured non-destructively using x-ray diffraction techniques. The measured residual compressive stress is used as a management criteria. A component having a residual compressive stress greater than a predetermined value can be returned to service. However, once the measured residual compressive stress of a component galls below the predetermined value, it can either be removed permanently from service, or it can be reworked to increase its residual compressive stress and then returned to service. Additionally, by measuring the residual compressive stress of an individual component, the remaining service life of that individual can be estimated. These methods for management of populations of such metal components allow for increasing the service life of the components in a safe and effective manner.