Title: A viewpoint on environmental contributions to fatigue crack growth

Authors: A.K. Vasudevan, K. Sadananda

Addresses: Office of Naval Research, Code-332, Materials Science Division, 875 North Randolph Street, Arlington, VA, USA. ' Technical Data Analysis, Inc., 7600 Leesburg Pike, Falls Church, VA, USA

Abstract: Fatigue crack growth behaviour is examined using the Unified Damage Approach developed by the authors since 1994. The approach is based on the understanding that a fatigue damage requires two loading parameters; a requirement manifesting in terms of two fracture mechanics parameters: maximum stress intensity factor Kmax and a stress amplitude ΔK. Kmax governs the breakage of crack tip bonds allowing for crack extension and ΔK controls the extent of cycle damage needed ahead of the crack tip. The overall changes in crack growth depend on several factors like microstructure, deformation mode and its properties and environment. The Unified Damage Approach describes these closely related changes in the damage mechanisms due to synergistic effects of mechanical and environmental driving forces. Crack growth trajectory maps developed using the Unified Damage Approach summarises these changes in mechanisms that occur with increasing crack growth rate or stress intensity.

Keywords: deltaK; Kmax; unified damage approach; UNIGROW model; environmental effects; steels; Ti-alloys; fatigue design; fatigue crack growth; stress intensity factors; stress amplitude; microstructure; deformation mode; crack initiation; growth kinetics.

DOI: 10.1504/IJMPT.2007.013105

International Journal of Materials and Product Technology, 2007 Vol.30 No.1/2/3, pp.3 - 16

Published online: 09 Apr 2007 *

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