Analysis of Crack Propagation Behavior in Alumina with Different Grain Sizes under Static and Cyclic Fatigue

2004 ◽  
Vol 264-268 ◽  
pp. 793-796
Author(s):  
Hassan El Attaoui ◽  
Malika Saâdaoui ◽  
Jérôme Chevalier ◽  
Gilbert Fantozzi
Keyword(s):  
Crack Propagation ◽  
Cyclic Fatigue ◽  
Grain Sizes ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

CYCLIC PARAMETERS GOVERNING CRACK PROPAGATION BEHAVIOR UNDER IN-PHASE AND OUT-OF-PHASE TENSILE-TORSIONAL LOADING

2008 ◽  
Vol 22 (11) ◽  
pp. 857-862
Author(s):  
YONG-HAK HUH ◽  
DONG-JIN KIM ◽  
HAE-MOO LEE ◽  
WAN-GUE LEE
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Growth Rates ◽  
Biaxial Loading ◽  
Crack Opening ◽  
Equivalent Stress ◽  
Cyclic Fatigue ◽  
Stress Intensity Factor Range ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

Cyclic fatigue parameters governing fatigue crack propagation behavior under out-of-phase biaxial fatigue loading has been investigated considering the crack propagation direction and the growth rates. The fatigue crack was propagated by employing out-of-phase cyclic tensile-torsional loads with various phase differences to the thin-walled tubular specimen. Using two crack gages mounted near a notch, the crack propagation was measured and crack opening behaviors were monitored by unloading compliance method. The directions and growth rates of the fatigue crack propagated under respective biaxial loading conditions were examined using several cyclic fatigue parameters, including equivalent stress intensity factor range, ΔKeq, crack tip opening displacement range, ΔCTD, minimum strain energy density factor range, Δ S min . It is found that the parameters, ΔCTD and Δσθθ, max , might be useful for prediction of the crack directions and the fatigue crack growth rates were relatively well correlated with ΔKeq and Δ S min . On the other hand, the crack opening levels under in-phase loading could be relatively clearly determined, while it was ambiguous to define those under out-of-phase loading.

Crack Propagation Behavior of Alumina with Different Grain Sizes under Static and Cyclic Fatigue

2006 ◽  
Vol 317-318 ◽  
pp. 449-452 ◽  
Author(s):  
Hassan El Attaoui ◽  
Malika Saâdaoui ◽  
Jérôme Chevalier ◽  
Gilbert Fantozzi
Keyword(s):  
Torsion Test ◽  
Cyclic Fatigue ◽  
Fatigue Threshold ◽  
Cyclic Loads ◽  
Grain Sizes ◽  
Propagation Behavior ◽  
Fine Grain ◽  
Grain Bridging ◽  
Crack Propagation Behavior ◽  
Double Torsion

A compliance function is used to quantify the shielding capacity of grain bridging, the degradation of which is the main cyclic fatigue mechanism in alumina. Materials with different grain sizes were processed and the fatigue experiments were performed using the double torsion test. Significant degradation is observed in the coarse grain material and a marked sensitivity to the loading level is outlined. At moderate loads, bridging degradation occurs prior to fatigue crack growth during an incubation period. At low cyclic loads, the shielding capacity can be entirely degraded, leading to a cyclic fatigue threshold equivalent to that of the fine grain material.

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