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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2010, Vol. 31 ›› Issue (3): 519-525.

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Small Crack Behavior and Fatigue Life Prediction for Shot Peening Aluminum Alloy 7475-T7351

Chen Bo, Gao Yukui, Wu Xueren, Ma Shaojun   

  1. Beijing Institute of Aeronautical Materials
  • Received:2009-01-04 Revised:2009-03-28 Online:2010-03-25 Published:2010-03-25
  • Contact: Chen Bo

Abstract:

Experimental study of small crack behavior is made on shot peening and un-shot peening single-edge-notch tension (SENT) specimens for aluminum alloy 7475-T7351. The weight function method (WFM) is used to calculate the stress intensity factors (SIF) for 3D small surface cracks under the combined action of external uniform load and residual stresses. The calculated SIF results are added to the small crack growth calculation program, FASTRAN3.9. This program is used to predict the fatigue life of naturally occurring small crack growth a-N data of shot peening and un-shot peening SENT specimens under an external load of σmax=160 MPa and R=0.06. It is found that the reduction of small crack growth rate by shot peening residual stresses is the main cause for prolonging the fatigue life of the specimens, and the fatigue life prediction method based on small crack theory and crack closure concept can be well used to quantitatively predict the effect of prolonging fatigue life by shot peening.

Key words: shot peening, single-edge-notch tension specimen, residual stresses, stress intensity factors, fatigue life prediction

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