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In situ characterization of fatigue damage evolution in a cast Al alloy via nonlinear ultrasonic measurements / Anish Kumar in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2143–2154 Titre : In situ characterization of fatigue damage evolution in a cast Al alloy via nonlinear ultrasonic measurements Type de document : texte imprimé Auteurs : Anish Kumar, Auteur ; Christopher J. Torbet, Auteur ; Tresa M. Pollock, Auteur Année de publication : 2011 Article en page(s) : pp. 2143–2154 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nonlinear  ultrasonics  Fatigue  crack  initiation  Fatigue  crack  growth  Casting  pores  Cast  Al  alloy Résumé : A new methodology is described for in situ characterization of fatigue damage accumulation using nonlinear ultrasonic measurements via analysis of the feedback signal of a closed-loop ultrasonic fatigue system. In the very high-cycle fatigue regime, ultrasonic nonlinearity increases with initiation and growth of a dominant, life-limiting fatigue crack. Based on the increase in the ultrasonic nonlinearity with fatigue cycling, crack initiation, small fatigue crack growth and fast crack growth regimes have been distinguished during cycling in specimens with different pore sizes tested at various stress amplitudes. The fraction of fatigue life spent in initiation of a life-limiting fatigue crack decreases with increasing stress amplitude. For a constant stress amplitude, the initiation life also decreases with increasing pore size. The present study also demonstrates the applicability of the methodology for fatigue crack growth studies from natural defects located internally or at the surface in smooth specimens. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008349 [article] In situ characterization of fatigue damage evolution in a cast Al alloy via nonlinear ultrasonic measurements [texte imprimé] / Anish Kumar, Auteur ; Christopher J. Torbet, Auteur ; Tresa M. Pollock, Auteur . - 2011 . - pp. 2143–2154. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 2143–2154 Mots-clés : Nonlinear  ultrasonics  Fatigue  crack  initiation  Fatigue  crack  growth  Casting  pores  Cast  Al  alloy Résumé : A new methodology is described for in situ characterization of fatigue damage accumulation using nonlinear ultrasonic measurements via analysis of the feedback signal of a closed-loop ultrasonic fatigue system. In the very high-cycle fatigue regime, ultrasonic nonlinearity increases with initiation and growth of a dominant, life-limiting fatigue crack. Based on the increase in the ultrasonic nonlinearity with fatigue cycling, crack initiation, small fatigue crack growth and fast crack growth regimes have been distinguished during cycling in specimens with different pore sizes tested at various stress amplitudes. The fraction of fatigue life spent in initiation of a life-limiting fatigue crack decreases with increasing stress amplitude. For a constant stress amplitude, the initiation life also decreases with increasing pore size. The present study also demonstrates the applicability of the methodology for fatigue crack growth studies from natural defects located internally or at the surface in smooth specimens. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008349