scholarly journals Large plastic zones and extensive influence of notch under near-threshold mode II and mode III loading of fatigue cracks

2018 ◽  
Vol 13 ◽  
pp. 1123-1128 ◽  
Author(s):  
M. Hrstka ◽  
S. Žák ◽  
T. Vojtek
Keyword(s):  
Fatigue Cracks ◽  
Mode Ii ◽  
Mode Iii ◽  
Plastic Zones ◽  
Near Threshold

Near-threshold propagation of mode II and mode III fatigue cracks in ferrite and austenite

2013 ◽  
Vol 61 (12) ◽  
pp. 4625-4635 ◽  
Author(s):  
T. Vojtek ◽  
R. Pippan ◽  
A. Hohenwarter ◽  
L. Holáň ◽  
J. Pokluda
Keyword(s):  
Fatigue Cracks ◽  
Mode Ii ◽  
Mode Iii ◽  
Near Threshold

scholarly journals Fatigue. Propagation Behavior of Mode II and Mode III Fatigue Cracks in SS400 Carbon Steel.

2001 ◽  
Vol 50 (10) ◽  
pp. 1102-1107
Author(s):  
Shigetomo NUNOMURA ◽  
Yasuhiro YAMAZAKI ◽  
Hideharu OOTAKI
Keyword(s):  
Carbon Steel ◽  
Fatigue Cracks ◽  
Mode Ii ◽  
Mode Iii ◽  
Propagation Behavior

Description of Fatigue Crack Propagation under Mixed-Mode II+III in Terms of J-Integral

2014 ◽  
Vol 627 ◽  
pp. 145-148 ◽  
Author(s):  
Jana Horníková ◽  
Pavel Šandera ◽  
Tomáš Vojtek ◽  
Jaroslav Pokluda
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Mixed Mode ◽  
Armco Iron ◽  
Fatigue Cracks ◽  
Mode Ii ◽  
J Integral ◽  
Mode Iii ◽  
Equivalent Factor ◽  
The Difference

The paper is dedicated to experiments on near-threshold fatigue cracks under mixed-mode II+III in the ARMCO iron. The mixed mode crack growth was described using an equivalent factor ΔJeff,eq=(1-α)ΔJeff,eqII+αΔJeff,eqIII. The most appropriate description was found for α = 0.67 indicating that the mode III component should be more efficient than that of the mode II which is in contradiction of a ΔKeq–based analysis. This result shows that, unlike in the austenitic steel, the difference in the efficiency of modes II and III in the ARMCO iron is very small.

Intrinsic Behaviour of Mode II and Mode III Long Fatigue Cracks in Zirconium and the Ti-6Al-4V Alloy

2016 ◽  
Vol 258 ◽  
pp. 265-268 ◽  
Author(s):  
Tomáš Vojtek ◽  
Jaroslav Pokluda ◽  
Anton Hohenwarter ◽  
Richard Pippan
Keyword(s):  
Fatigue Cracks ◽  
Pure Titanium ◽  
Common Mechanism ◽  
Local Mode ◽  
Shear Mode ◽  
Mode Ii ◽  
Pure Mode ◽  
Special Device ◽  
Mode Iii ◽  
High Tendency

This work is focused on experimental study of micromechanisms of mode II and mode III fatigue cracks in metallic materials in the near-threshold regime. The resistance to fatigue crack growth can be divided to an intrinsic component (ahead of the crack tip) and an extrinsic component (shielding, closure), which is significantly higher than the intrinsic one. Fracture surfaces from the Ti6Al4V alloy and pure zirconium were observed in three dimensions. Experiments were conducted using a special device for simultaneous crack loading in modes II and III. Additionally, pure mode II and pure mode III experiments were done using CTS and torsion specimens, respectively. At the beginning of all experiments, crack closure was eliminated due to precracks generated under cyclic compressive loading. A common mechanism of local mode II advances was observed in both modes II and III. The results were similar to those of pure titanium. The hcp metals exhibit a transition behaviour between materials with coplanar shear-mode crack propagation and materials with a high tendency to deflect to the opening mode I.

Plastic Strain Distribution at the Tips of Propagating Fatigue Cracks

1976 ◽  
Vol 98 (1) ◽  
pp. 24-29 ◽  
Author(s):  
D. L. Davidson ◽  
J. Lankford
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Strain Distribution ◽  
Dimensionless Parameter ◽  
Fatigue Cracks ◽  
Crack Tip ◽  
Cyclic Plastic Zone ◽  
Plastic Zones

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.

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