The effect of peening on the fatigue life of aluminium alloys

Abstract

Many changes in the design and manufacture of high-performance military aircraft  for example, the use of highly optimised design and the use of higher-strength material  have led to an increased sensitivity of airframe fatigue life to surface features such as corrosion or mechanical damage. The 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 thorough understanding of 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 of aluminium alloys, and summarises the improvements in peening which have arisen from this research. . The overall aim of 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 of measuring peening quality, to allow the full exploitation of peening to improve fatigue life. It also highlights areas where further research could be beneficial in relation to peening and the structural integrity of the F/A-18 aircraft. The report highlights the practical problems of introducing changes to fatigue critical surfaces, with particular reference to the RAAF and CF fleets. Approved for public release. Published by DSTO Aeronautical and Maritime Research Laboratory 506 Lorimer St Fishermans Bend Victoria 3207 Telephone: (03) 9626 8111 Fax: (03) 9626 8999 © Commonwealth of Australia 2001 AR No. 011-795 March 2001 Conditions of Release and Disposal This document is the property of the Australian Government; the information it contains is released for defence purposes only and must not be disseminated beyond the stated distribution without prior approval. The document and the information it contains must be handled in accordance with security regulations applying in the country of lodgement, downgrading instructions must be observed and delimitation is only with the specific approval of the Releasing Authority as given in the Secondary Distribution statement. This information may be subject to privately owned rights. The officer in possession of this document is responsible for its safe custody. When no longer required DSTO Reports should be returned to the DSTO Library, (Reports Section), Salisbury SA. The Effect of Peening on the Fatigue Life of 7050 Aluminium Alloy