Effect of Specimen Thickness and Stress Intensity Factor Range on Plasticity-Induced Fatigue Crack Closure in A7075-T6 Alloy

Fatigue crack growth experiments are performed using A7075-T6 compact tension (CT) specimens with various thicknesses (1-21 mm). The stress intensity factor at the crack opening level K is measured, and the effects of and the stress intensity factor range ΔK on K are investigated. In addition, the c...

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Bibliographic Details
Published in:Materials 2021-01, Vol.14 (3), p.664
Main Authors: Masuda, Kenichi, Ishihara, Sotomi, Oguma, Noriyasu
Format: Article
Language:English
Subjects:
Aluminum alloys
Aluminum base alloys
Behavior
Carbon steel
Compact tension
Crack closure
Crack propagation
Crack tips
Elastoplasticity
Experiments
Fatigue failure
Finite element method
Fracture mechanics
Metal fatigue
Radius of curvature
Research methodology
Stress intensity factors
Thickness
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Summary:Fatigue crack growth experiments are performed using A7075-T6 compact tension (CT) specimens with various thicknesses (1-21 mm). The stress intensity factor at the crack opening level K is measured, and the effects of and the stress intensity factor range ΔK on K are investigated. In addition, the change in K value due to specimen surface removal is investigated. Furthermore, we clarify that the radius of curvature of the leading edge of the fatigue crack decreases as becomes thinner. Using the three-dimensional elastoplastic finite element method, the amount of plastic lateral contraction (depression depth ) at the crack tip after fatigue loading is calculated quantitatively. The following main experimental results are obtained: In the region where ΔK is 5 MPam or higher, the rate of fatigue crack growth da/dN at a constant ΔK value increases as increases from 1 to 11 mm. The da/dN between = 11 and 21 mm is the same. Meanwhile, in the region where ΔK is less than 5 MPam , the effect of on da/dN is not observed. The effects of and ΔK on the da/dN-ΔK relationship are considered physically and quantitatively based on .
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14030664