Some aspects of variability in fatigue crack initiation and propagation in thick aluminium alloy sections

Mann, Jonathan; Pell, R.A.; Machin, A. S.

doi:10.1016/0142-1123(86)90054-x

Cited by 3 publications

(2 citation statements)

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“…[1][2][3][4] To counter these issues, the application of engineered residual stresses through cold expansion of fastener holes, as either a repair or preventative modification, is one of the most enduring and effective techniques for improving the fatigue life of such holes. [5][6][7] Briefly explained, the cold expansion process draws a tapered mandrel through a split sleeve installed into the fastener hole, plastically deforming the surrounding material, which results in a beneficial residual compressive stress field around the hole, and a balancing tensile zone of residual stresses away from the hole. Any subsequent fatigue crack growth (FCG) emanating from the hole must first grow through this zone of residual compressive stress, and, if imparted correctly, FCG is slowed.…”

Section: Introductionmentioning

confidence: 99%

“…These include, for example, production hole quality, corrosion during service, and/or stressing errors during design 1–4 . To counter these issues, the application of engineered residual stresses through cold expansion of fastener holes, as either a repair or preventative modification, is one of the most enduring and effective techniques for improving the fatigue life of such holes 5–7 . Briefly explained, the cold expansion process draws a tapered mandrel through a split sleeve installed into the fastener hole, plastically deforming the surrounding material, which results in a beneficial residual compressive stress field around the hole, and a balancing tensile zone of residual stresses away from the hole.…”

Section: Introductionmentioning

confidence: 99%

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A fractographic study of fatigue crack growth from a cold expanded fastener hole at an engineering “crack initiation” scale

Main,

Russell,

Barter

2024

Fatigue Fract Eng Mat Struct

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The effects of cold expansion on fatigue crack growth from fastener holes in aircraft structure are a well‐studied problem, with many contributions focusing on both residual stresses and “long crack” experimental data. In this study, the authors have used quantitative fractography techniques to measure fatigue crack growth from naturally occurring discontinuities on an engineering “crack initiation” scale. Fatigue crack growth rates were measured through the full range of crack depths, allowing the effects of beneficial residual stresses to be directly observed. The almost identical early crack growth rates in cold expanded and non‐cold expanded specimens were demonstrated up to crack depths of approximately 0.1–0.2 mm. Beyond this depth, fatigue crack growth in cold expanded specimens was markedly slowed to the point at which failure ultimately arose from cracks away from, or growing into, the fastener hole. The available life improvement factor for cold expansion is therefore maximized through a crack growth‐based lifing approach.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A fractographic study of fatigue crack growth from a cold expanded fastener hole at an engineering “crack initiation” scale

Main,

Russell,

Barter

2024

Fatigue Fract Eng Mat Struct

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Fatigue characteristics of joints with holes cold-expanded in a multi-layer stack

Mann

Sparrow

Beaver

1989

International Journal of Fatigue

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Analysis and Interpretation of Aircraft Component Defects Using Quantitative Fractography

Goldsmith

Clark

1990

Quantitative Methods in Fractography

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Quantitative fractography techniques have been in use at the Aeronautical Research Laboratory (ARL), Melbourne, Australia, for more than 15 years, and they have been developed into a specialized facility for deriving crack growth histories from fracture surfaces. This capability has played a fundamental role in a number of pioneering life extension programs which have permitted the continued operation of several aircraft types in current service with the Royal Australian Air Force (RAAF). The increasing RAAF demand for advanced fractography has required the development over a number of years of computer-based semiautomated data acquisition and data processing facilities for fractographic analysis; these developments have permitted a significant improvement in the speed with which fracture surfaces may be analyzed and are now used routinely in ARL's quantitative fractography. This paper describes current ARL activities in the use and further development of quantitative fractographic techniques and the specialized facilities employed to derive and process data from fracture surfaces observed by both scanning electron microscopy and optical microscopy. The results able to be obtained are illustrated by reference to case histories of defects in components from service aircraft, from full-scale component tests, and from laboratory test samples. Procedures for minimizing or overcoming some of the difficulties associated with interpretation of fracture surface markings are discussed. The paper also describes the way in which fracture mechanics concepts need to be used in conjunction with fracture surface analysis to achieve a correct understanding of the crack growth history. In particular, some empirically based approaches developed for interpolation and extrapolation of incomplete crack growth histories may now be understood by reference to fracture mechanics concepts. Finally, current and future developments in fracture surface analysis are discussed, with particular reference to the benefits to be gained by the introduction of modern image processing and image enhancement techniques.

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Some aspects of variability in fatigue crack initiation and propagation in thick aluminium alloy sections

Cited by 3 publications

References 1 publication

A fractographic study of fatigue crack growth from a cold expanded fastener hole at an engineering “crack initiation” scale

A fractographic study of fatigue crack growth from a cold expanded fastener hole at an engineering “crack initiation” scale

Fatigue characteristics of joints with holes cold-expanded in a multi-layer stack

Analysis and Interpretation of Aircraft Component Defects Using Quantitative Fractography

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