Fatigue crack growth behaviour of a nickel base super alloy GTM720 under cold-TURBISTAN spectrum load sequence

Malipatil, SG and Majila, AN and Fernando, CD and Manjuprasad, M and Manjunatha, CM (2021) Fatigue crack growth behaviour of a nickel base super alloy GTM720 under cold-TURBISTAN spectrum load sequence. Theoretical and Applied Fracture Mechanics, 112. pp. 1-7. ISSN 0167-8442

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Abstract

Damage tolerance concept is widely used in aerospace industry for designing structural components against fatigue. In this study, an attempt is made to predict fatigue crack growth behavior in an aero-engine material under a standard spectrum load sequence using a closure independent crack driving force parameter, K* and compare with experimental results. Initially, constant amplitude (CA) fatigue crack growth rate (FCGR) behavior of GTM720, a nickel based super alloy was determined at stress ratios, R = σmin/σmax ranging from R = 0.1 to 0.7. Then, empirical fatigue crack growth law was derived from this CA-FCGR data in terms of two parameter crack driving force, K*. Further, the fatigue crack growth behavior was predicted through cycle-by cycle approach in a pre-cracked compact tension (CT) specimen of GTM720 alloy under standard cold-TURBISTAN spectrum load sequence using K* as the crack driving force. Also, experimental fatigue crack growth behavior under the same load sequence was determined in a CT specimen and compared with predicted results. A fairly good correlation was observed with predicted and experimental results. Predicted fatigue crack growth life was conservative and the fatigue crack growth life ratio, Npred/Nexpt was about 0.92.

Item Type:	Article
Uncontrolled Keywords:	Fatigue crack growth,Cold-TURBISTAN,Spectrum loading, GTM720
Subjects:	CHEMISTRY AND MATERIALS > Composite Materials CHEMISTRY AND MATERIALS > Nonmetallic Materials ENGINEERING > Mechanical Engineering
Depositing User:	Mrs SK Pratibha
Date Deposited:	25 Aug 2022 16:20
Last Modified:	25 Aug 2022 16:20
URI:	http://nal-ir.nal.res.in/id/eprint/13641

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