Real - time detection of fatigue cracks at multiple holes in 7075 aluminum using acoustic emission.

Download
Author
Flatley, Thomas.
Date
1992-09Advisor
Gorman, Michael R.
Second Reader
Lindsey, Gerald H.
Metadata
Show full item recordAbstract
In the E-2C Hawkeye's wing center section, stress fractures have been
identified in the main beam web section. The cracks occurred in several web section
attachment holes. Previous work, concerned with fatigue data, used a finite element
code to design a specimen which modeled the actual section of the beam at one
particular fastener hole near wing station 49. Acoustic emission testing was used to
determine if crack initiation could be identified. In this work, acoustic emission
techniques were applied to the monitoring of multiple cracks. The E-2C fatigue
spectrum was used to load the specimens but fatigue testing was not an objective.
Specimens were modified by drilling holes and attaching angles that represented the
structural shapes used to attach the section to the wing skin. The original one-hole
configuration and the new multiple hole specimen configuration were tested. The
cap angles were found to create a great deal of noise containing frequency
components below 400kHz. Special high pass filters were fabricated which
eliminated most of this noise. It was shown that linear location could be used to
discriminate between crack growth signals and the filtered noise signals.
Collections
Related items
Showing items related by title, author, creator and subject.
-
Acoustic emission from spectrum fatigue cracks in 7075 aluminum
Smith, Wallace Dean, Jr. (1990-12);The E-2C Hawkeye, a U.S. Navy aircraft, has experienced problems with fatigue cracks in its wings. This problem was studied in the laboratory using a representative specimen under simulated flight loading. Acoustic emission ... -
Investigation of strain distribution around fatigue cracks in aluminum sheets
Tucker, Edwin B. (Monterey, California: U.S. Naval Postgraduate School, 1965);A survey of developments in the field of crack propagation and an experimental investigation of the strain distribution around fatigue cracks in flat aluminum sheets was conducted by Lt. E. B. Tucker, USN, at the ... -
Quasi-static tearing tests of metal plating
Woertz, Jeffrey C. (Jeffrey Collin), 1969- (2002-09);Great effort is being focused on making the next generation of naval combatant ships more resistant to the effects of close-aboard explosions. The examination of the deformation modes in blast-loaded metal plating suggests ...