Plastic CTOD as fatigue crack growth characterising parameter in 2024‐T3 and 7050‐T6 aluminium alloys using DIC

The plastic range of crack tip opening displacement (CTOD) has been used for the experimental characterisation of fatigue crack growth for 2024‐T3 and 7050‐T6 aluminium alloys using digital image correlation (DIC). Analysis of a complete loading cycle allowed resolving the CTOD into elastic and plas...

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Bibliographic Details
Published in:Fatigue & fracture of engineering materials & structures 2020-08, Vol.43 (8), p.1719-1730
Main Authors: Vasco‐Olmo, José Manuel, Díaz Garrido, Francisco Alberto, Antunes, Fernando Ventura, James, M.N.
Format: Article
Language:English
Subjects:
2024‐T3 and 7050‐T6 aluminium alloys
Alloy development
Aluminum base alloys
Compact tension
Correlation analysis
Crack opening displacement
Crack propagation
Crack sensitivity
Crack tips
CTOD
DIC
Digital imaging
fatigue crack growth
Fatigue failure
Fatigue tests
Fracture mechanics
Parameters
Position measurement
Sensitivity analysis
Stress intensity factors
Stress propagation
Stress ratio
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Summary:The plastic range of crack tip opening displacement (CTOD) has been used for the experimental characterisation of fatigue crack growth for 2024‐T3 and 7050‐T6 aluminium alloys using digital image correlation (DIC). Analysis of a complete loading cycle allowed resolving the CTOD into elastic and plastic components. Fatigue tests were conducted on compact tension specimens with a thickness of 1 mm and a width of 20 mm at stress ratios of 0.1, 0.3 and 0.5. The range of plastic CTOD could be related linearly to da/dN independent of stress ratio for both alloys. To facilitate accurate measurements of CTOD, a method was developed for correctly locating the crack tip and a sensitivity analysis was performed to explore the effect of measurement position behind the crack tip on the CTOD. The plastic range of CTOD was demonstrated to be a suitable alternate parameter to the stress intensity factor range for characterising fatigue crack propagation. A particularly innovative aspect of the work is that the paper describes a DIC‐based technique that the authors believe gives a reliable way to determine the appropriate position to measure CTOD.
ISSN:8756-758X
1460-2695
DOI:10.1111/ffe.13210