Advanced peening processes for the fatigue life improvement of aerospace components

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Shot peening consists in impacting a metal part with high velocity shots. The impacts plastically stretch the surface and induce a layer of compressive residual stresses and cold working. Under the right conditions, the process delivers components that can withstand 20 times more fatigue cycles than untreated parts. Nearly every metallic part of an aircraft is shot peened. High Temperature Shot Peening (HTSP) consists in carrying out conventional shot peening at elevated temperature. Authors have demonstrated that HTSP can deliver even further fatigue life improvement than shot peening. Vibratory Peening (VP) is a modified finishing process that induces similar benefits as shot peening but for a much better surface finish. The applicability of these two processes within an industrial context have yet to be demonstrated. This research will thoroughly investigate the effects of HTSP and VP on the fatigue lives of aerospace materials, namely: steel, titanium and aluminum. The research will involve manufacturing research HTSP and VP setups and thoroughly investigate their effects in terms of surface characteristics, residual stresses, hardness, microstructural changes and fatigue life. The work will be carried out by 10 B.Eng, 1 MSc and 4 PhD students over 4 years. The work will be carried out in collaboration with Polytechnique Montréal, Centre Technologique en Aérospatiale and Safran S.A. (in Canada and in France). This project has the potential to trigger significant innovation for the Canadian aerospace industry. First, HTSP has the potential to yield better fatigue life improvement than shot peening, which will yield to lighter and more durable Canadian aircraft. VP has the potential to also yield better fatigue life improvement than shot peening and also to combine two manufacturing processes into one: peening and surface finishing. These processes have therefore the potential to increase the competitiveness of our aerospace industry by producing lighter and more durable parts, as well as yielding cheaper and faster post-manufacturing processes. Moreover, lighter and more durable parts reduce the environmental imprint of air travel, which is beneficial for the environment.