Acoustic emission from spectrum fatigue cracks in 7075 aluminum
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Authors
Smith, Wallace Dean, Jr.
Subjects
aircraft fatigue
aging aircraft
crack growth
7075 alumiunum
spectrum loading
acoustic emission
plate waves
aging aircraft
crack growth
7075 alumiunum
spectrum loading
acoustic emission
plate waves
Advisors
Gorman, Michael R.
Date of Issue
1990-12
Date
December 1990
Publisher
Language
Abstract
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 monitoring was used to detect the stress pulses emitted during cracking. A new wave analysis technique was applied in order to distinguish extraneous noise from crack growth. This technique distinguishes between the extensional and flexural waves in thin aluminum plates. Extensional waves were found to correlate experimentally with waves from crack growth, while noise sources show different waveforms with lower frequencies. It was shown that acoustic emission provided early (crack length less than 0.01 inch) detection of fatigue cracking. This show promise for use in monitoring aircraft fatigue life.
Type
Thesis
Description
Series/Report No
Department
Department of Aeronautics and Astronautics
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
iv, 72 p. p. ill.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.