The Effect of Peening on the Fatigue Life of 7050 Aluminium Alloy

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DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION
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2. TITLE
<strong>The</strong> <strong>Effect</strong> <strong>of</strong> <strong>Peening</strong> on the Fatigue Life <strong>of</strong> 7050 Aluminium Alloy
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Document
Title
Abstract
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4. AUTHOR(S)
P.K. Sharp and G. Clark
5. CORPORATE AUTHOR
Aeronautical and Maritime Research Laboratory
506 Lorimer St
Fishermans Bend Vic 3207
6a. DSTO NUMBER
DSTO-RR-0208
6b. AR NUMBER
AR-011-795
6c. TYPE OF REPORT
Research Report
7. DOCUMENT DATE
March 2001
8. FILE NUMBER
M1/9/328
13. URL on the World Wide Web
9. TASK NUMBER
AIR 98/217
10. TASK SPONSOR
DGTA ASI Section
11. NO. OF PAGES
53
14. RELEASE AUTHORITY
12. NO. OF
REFERENCES
51
http://www.dsto.defence.gov.au/corporate/reports/DSTO-RR-0208.pdf
Chief, Airframes and Engines Division
15. SECONDARY RELEASE STATEMENT OF THIS DOCUMENT
Approved for public release
OVERSEAS ENQUIRIES OUTSIDE STATED LIMITATIONS SHOULD BE REFERRED THROUGH DOCUMENT EXCHANGE, PO BOX 1500, SALISBURY, SA 5108
16. DELIBERATE ANNOUNCEMENT
No Limitations
17. CASUAL ANNOUNCEMENT Yes
18. DEFTEST DESCRIPTORS
Crack propagation, Aluminium alloy, Fatigue, Crack growth, Finishing, <strong>Peening</strong>, Metal finishing
19. ABSTRACT
Many changes in the design and manufacture <strong>of</strong> high-performance military aircraft ⎯ for example, the use <strong>of</strong> highly
optimised design and the use <strong>of</strong> higher-strength material ⎯ have led to an increased sensitivity <strong>of</strong> airframe fatigue life to
surface features such as corrosion or mechanical damage. <strong>The</strong> peening applied to the F/A-18 represents a significant
departure from traditional manufacture, and it is therefore important that the RAAF and AMRL have a through
understanding <strong>of</strong> the peening process, the surface conditions produced, and their effect on structural integrity. This
report discusses the fatigue crack growth research at AMRL, and elsewhere, relating to peening <strong>of</strong> aluminium alloys, and
summarises the improvements in peening which have arisen from this research. . <strong>The</strong> overall aim <strong>of</strong> the peening research
and development discussed was to establish a Life-Improvement-Factor (LIF) for the peening used on the F/A-18, as well
as any future peening required by modifications. It also attempted to provide a means <strong>of</strong> measuring peening quality, to
allow the full exploitation <strong>of</strong> peening to improve fatigue life. It also highlights areas where further research could be
beneficial in relation to peening and the structural integrity <strong>of</strong> the F/A-18 aircraft. <strong>The</strong> report highlights the practical
problems <strong>of</strong> introducing changes to fatigue critical surfaces, with particular reference to the RAAF and CF fleets.
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