Retirement criteria for many structural components and particularly landing gear structural parts, are generally based on
analytical fatigue methods because the current means of detecting actual component damage cannot detect sufficiently
small levels of damage such that safe operation for a useful interval can be confidently determined; limiting the
capability to apply damage tolerance methods. The testing completed in these projects demonstrated that Induced
Positron Analysis (IPA) technologies are sensitive to the tensile plastic strain damage induced in aerospace material
specimens and components. The IPA process has shown that IPA methods can reliably detect and quantify plastic strain
and plastic deformation under simulated and operational conditions. A preliminary functional relationship between total
strain and the normalized IPA S parameter has been developed for several aerospace materials. The fatigue testing has
demonstrated the IPA technologies have potential to detect fatigue damage induced in specimens and operational
components when the loads are large enough to cause plastic deformation.
The ability to detect and quantify beneficial surface and subsurface residual stresses, and operational damage in
aerospace materials/structures in a reliable and efficient manner presents significant challenges to existing
nondestructive inspection technologies. Induced Positron Analysis (IPA) has demonstrated the ability to
nondestructively quantify shot peening/surface treatments and relaxation effects in single crystal superalloys, steels,
titanium and aluminum with a single measurement as part of a National Science Foundation SBIR program and in
projects with commercial companies. IPA measurement of surface treatment effects provides a demonstrated ability to
quantitatively measure initial treatment effectiveness along with the effect of operationally induced changes over the life
of the treated component. Use of IPA to nondestructively quantify surface and subsurface residual stresses in turbine
engine materials and components has the potential to significantly improve the understanding at the microscale level the
effects of surface coatings and treatments on the durability and fatigue life of critical components.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.