Fatigue crack growth, physical understanding and practical application

The paper presents a discussion on two problems associated with fatigue crack growth in aluminium alloys. First, the application of the similarity approach to crack growth prediction in specimens and structures of aluminium alloys is discussed. The significance of similarity conditions is emphasized and the K-dominated zone is briefly addressed. Secondly, the significance of water vapour for fatigue crack growth in aluminium alloy is reported with a case history of subsurface crack initiation and crack growth in vacuum. Some comments are presented on physical understanding and practical applications.