AN ANALYSIS OF CRACK TIP SHIELDING IN ALUMINUM ALLOY 2124: A COMPARISON OF LARGE, SMALL, THROUGH-THICKNESS AND SURFACE FATIGUE CRACKS

Author(s):  
R. O. Ritchie ◽  
W. Yu ◽  
A. F. Blom ◽  
D. K. Holm
1976 ◽  
Vol 98 (1) ◽  
pp. 24-29 ◽  
Author(s):  
D. L. Davidson ◽  
J. Lankford

The techniques of selected area electron channeling and positive replica examination have been used to study the plastic zones attending fatigue crack propagation in 304 SS, 6061-T6 aluminum alloy, and Fe-3Si steel. These observations allowed the strain distribution at the crack tip to be determined. The results indicate that the concepts of a monotonic and a cyclic plastic zone are essentially correct, with the strains at demarcation between these two zones being 3 to 6 percent. Strain distribution varies as r−1/2 in the cyclic zone and as ln r in the monotonic plastic zone. The strain distributions for all materials studied may be made approximately coincident by using a dimensionless parameter related to distance from the crack tip.


1988 ◽  
Vol 120 ◽  
Author(s):  
Jian Ku Shang ◽  
R. O. Ritchie

AbstractAs part of an investigation into the micro-mechanisms of crack-tip shielding associated with the growth of fatigue cracks in metal-matrix composites, simple models are developed for the role of crack bridging in high-strength aluminum alloys reinforced with SiC particulate (AI/SiCp). Based on experimental observations of crack growth, crack-tip shielding and crack-path morphology in these alloys, the bridges are found to be associated with uncracked ligaments in the wake of the crack tip, and are modelled in terms of approaches based on a critical crack-opening displacement or critical tensile strain in the ligament.


2007 ◽  
Vol 345-346 ◽  
pp. 255-258 ◽  
Author(s):  
Yasuo Ochi ◽  
Kiyotaka Masaki ◽  
Takashi Matsumura ◽  
Yuji Sano ◽  
Koichi Akita ◽  
...  

In order to investigate effects of low energy laser peening (LP) without protective coating on surface fatigue crack growth behavior, rotating bending fatigue tests were carried out on cast Al-Si-Mg aluminum alloy with a pre-cracked round bar type specimens. As the results, the fatigue crack growth was restrained by the compressive residual stress induced by laser peening treatment. And also, the three dimensional (3D) image of surface fatigue cracks was reconstructed by using a micro computed tomography (μCT) with phase contrast technique. It was also shown that the surface crack growth was restrained for the laser peened materials.


2017 ◽  
Vol 2017 (4) ◽  
pp. 322-329 ◽  
Author(s):  
L. R. Botvina ◽  
G. I. Nesterenko ◽  
A. P. Soldatenkov ◽  
Yu. A. Demina ◽  
A. A. Sviridov

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