Studies on fatigue crack growth for airframe structural integrity applications
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In this paper, a review is made of efforts at the National Aerospace Laboratories in the development of fatigue crack growth prediction technology for airframe applications, focusing on extension of rainflow techniques for crack growth analysis and development of accelerated crack growth calculation methods for spectrum loading.Abstract:
A review is made of efforts at the National Aerospace Laboratories in the development of fatigue crack growth prediction technology for airframe applications. The research was focused on extension of rainflow techniques for crack growth analysis and development of accelerated crack growth calculation methods for spectrum loading. Fatigue crack closure forms a crucial element of modelling and fractographic techniques were developed for its study. These, combined with binary coded event registration enabled crack growth and closure mapping for part-through cracks in metallic materials. Experimental research on short cracks at notches led to discovery of the hysteretic nature of crack closure, which explains well-known history-sensitive local mean stress effects in notch root fatigue. Optical fractography of failures obtained under simulated service conditions revealed that short cracks do not exhibit any more scatter than long cracks at comparable growth rates. The nature of multi-site crack initiation and growth of small cracks at notches was investigated and the effort extended to lug joints that are widely used in airframe applications. Results from this work suggest the possibility of modelling crack growth from a size smaller than 50 microns through to failure, thereby accounting for a major fraction of total life.read more
Citations
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Journal ArticleDOI
A quantitative assessment of the impact of corrosion on fatigue life of aircraft components
TL;DR: In this paper , the effects of corrosion of Al-alloys on the fatigue life of aircraft structures are examined and quantified using standard crack models, and cycle-by-cycle fatigue crack growth analysis is carried out for an aircraft horizontal stabilizer under spectrum loading conditions.
Book ChapterDOI
Alloys and Fatigue Crack Propagation
TL;DR: In this article, the fatigue crack propagation behavior of typical Al alloys, including Al-Li alloys of interest because of their low weight and high strength, is reviewed, as well as other alloys such as Ti alloys and steel.
References
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Book ChapterDOI
Cumulative damage in fatigue
TL;DR: The aircraft designer today is faced with the necessity of estimating not only the strength of a structure, but also its life — a task with which he was not confronted before.
Book ChapterDOI
The Significance of Fatigue Crack Closure
TL;DR: Al alloy sheet fatigue crack closure under cyclic tensile loading, deriving expression for crack propagation rate in terms of effective stress amplitude as discussed by the authors, was derived for the first time in the literature.
Journal ArticleDOI
Theory of Stress Concentration for Shear-Strained Prismatical Bodies With Arbitrary Nonlinear Stress-Strain Law
Book ChapterDOI
A crack-closure model for predicting fatigue crack growth under aircraft spectrum loading
TL;DR: In this article, the development and application of an analytical model of cycle crack growth is presented that includes the effects of crack closure, and the model is used to correlate crack growth rates under constant amplitude loading and to predict crack growth under aircraft spectrum loading on 2219-T851 aluminum alloy sheet material.