Enhancing Fatigue Resistance in Aerospace Materials Through Shot Peening-Induced Compressive Residual Stresses

Fatigue failure remains a critical concern in aerospace structural components. The combined effects of thermal treatment and mechanical processing in engineering components often result in the formation of residual stress fields. While tensile residual stresses can exacerbate existing flaws and reduce component lifespan, compressive residual stresses are beneficial as they inhibit crack propagation and enhance fatigue life. Shot peening serves as an established mechanical treatment method designed to impart favourable compressive stresses within the near-surface region. This study investigates the effectiveness of shot peening in enhancing fatigue resistance by introducing compressive residual stresses in aerospace-grade 7449 aluminium alloys. Specimens were subjected to shot peening at three intensity levels, followed by residual stress measurements using X-ray diffraction. The experimental results were compared with numerical simulations conducted through Finite Element Analysis (FEA), showing strong correlation. The study demonstrates that optimized shot peening parameters can significantly retard fatigue crack initiation and propagation, thereby offering an effective strategy for fatigue life extension in critical aerospace components.