Preprint Article Version 1 This version is not peer-reviewed

Effects of Shot-Peening and Stress Ratio on the Fatigue Crack Propagation of AL 7475-T7351 Specimens

Version 1 : Received: 23 January 2018 / Approved: 24 January 2018 / Online: 24 January 2018 (03:51:56 CET)

A peer-reviewed article of this Preprint also exists.

Ferreira, N.; Antunes, P.V.; Ferreira, J.A.M.; D. M. Costa, J.; Capela, C. Effects of Shot-Peening and Stress Ratio on the Fatigue Crack Propagation of AL 7475-T7351 Specimens. Appl. Sci. 2018, 8, 375. Ferreira, N.; Antunes, P.V.; Ferreira, J.A.M.; D. M. Costa, J.; Capela, C. Effects of Shot-Peening and Stress Ratio on the Fatigue Crack Propagation of AL 7475-T7351 Specimens. Appl. Sci. 2018, 8, 375.

Journal reference: Appl. Sci. 2018, 8, 375
DOI: 10.3390/app8030375

Abstract

Shot peening is an attractive technique for fatigue enhanced performance of metallic components, because it promotes crack initiation retardation and later crack growth. Engineering design based on fatigue crack propagation predictions applying the principles of fracture mechanics is commonly used in aluminum structures for aerospace engineering. The main purpose of present work was to analyze the effect of shot peening on the fatigue crack propagation of the 7475 aluminum alloy, under both constant amplitude loading and periodical overload blocks. The tests were performed on 4 and 8 mm thickness specimen's with stress ratios of 0.05 and 0.4. The analysis of the shot-peened surface showed a small increase of the micro-hardness values, due to the plastic deformations imposed by shot peening. The beneficial effect of surface peening on fatigue crack growth rates is quite limited to an increasing near the threshold. The specimens’ thickness has only marginal influence on the crack propagation, in opposite to the stress ratio. Periodic overload blocks of 300 cycles promotes a reduction of the fatigue crack growth rate for both intervals of 7,500 and 15,000 cycles.

Subject Areas

aeronautical aluminum alloys; fatigue crack propagation; overloads; shot peening; Paris law

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