Shot Peening Plays A Vital Roll In Rejuvenation Of Aging Aircraft
Author: Eckersley, John S.
Source: Shot Peening Theory and Appl., IITT Intl., 1991
Doc ID: 1991052
Year of Publication: 1991
Abstract:
Aircraft Components design engineers are very well aware of the benefits of surface residual compressive stresses on new parts as a means of retarding or even preventing catastrophic failures from fatigue, fretting fatigue, corrosion fatigue and stress corrosion cracking. Each of these failure modes depends on the presence of surface tensile stresses either residual or applied but, in service, usually both. It has been common practice, on parts for jet engines, propellers and landing gear, to reintroduce surface compressive stresses at overhaul intervals. Thousands of such parts are shot peened every day for rejuvenation purposes. Airframe parts present a different problem since they are not normally dismantled at overhaul and it is precisely these parts that come to mind when we consider "aging aircraft". Airframe components, whether they are steel, aluminum or titanium, can be rejuvenated by the introduction or restoration of surface residual compressive stresses, in most cases without requiring dismantling from the aircraft. This paper also reviews practical methods of shot peening aircraft structures "in situ", using inert media, under fully controlled conditions of Almen intensity, coverage, angle of impingement, media recovery, etc. Examples of actual applications on commercial and military aircraft are covered in detail, including offsetting the debiting effects of exfoliation corrosion. Peen forming of wing skins on aircraft is also addressed.
Descriptors: Metal failures; Fatigue; Fretting fatigue; Corrosion fatigue; Stress corrosion cracking; Exfoliation; Aging aircraft; Shot peening; Peen forming
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