SYMPOSIA PAPER Published: 01 January 1981
STP28821S

Evaluation of Crack Growth Gages for Service Life Tracking

Source

An analysis and test program was performed to evaluate the ability of a crack growth gage to monitor crack growth damage in fatigue-critical areas of F-4C/D aircraft structure. Crack growth gages were designed and manufactured for use on the F-4 lower wing skin. The crack growth behavior of the gage and relationship of gage crack growth to potential crack growth in the wing skin were determined through analysis and test. Eight gages were bonded on the Air Force F-4C/D full-scale fatigue test article at Wright-Patterson Air Force Base. Assessments were made of (1) the capability to predict crack growth behavior of the gages mounted on the fatigue test article, (2) the ability of crack growth gage to monitor potential crack growth damage at specified control points, and (3) the impact of manufacturing, installation, and data collection procedures on the utility of the gage as a damage monitoring device. Sheet thickness was found to have a profound effect on crack growth retardation under spectrum loading in 7075-T6 aluminum.

Author Information

Saff, CR
McDonnell Aircraft Co., McDonnell Douglas Corp., St. Louis, Mo.
Holloway, DR
Air Force Flight Dynamics Laboratory, Wright-Patterson AFB, Ohio
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Details
Developed by Committee: E08
Pages: 623–639
DOI: 10.1520/STP28821S
ISBN-EB: 978-0-8031-4809-3
ISBN-13: 978-0-8031-0732-8