Journal ArticleDOI
High‐Temperature Failure of an Alumina‐Silicon Carbide Composite under Cyclic loads: Mechanisms of Fatigue Crack‐Tip Damage
Lily X. Han,Subra Suresh +1 more
TLDR
In this article, the authors investigated the mechanisms of tensile cyclic fatigue crack growth in an A1203-33-vol%-SiC-whisker composite at 1400°C.Abstract:
Experimental results are presented on the mechanisms of tensile cyclic fatigue crack growth in an A1203-33-vol%-SiC-whisker composite at 1400°C. The ceramic composite exhibits subcritical fatigue crack propagation at stress-intensity-fator values far below the fracture toughness. The fatigue characterized by the stressintensity-factor range, ΔK, and crack propagation rates are found to be strongly sensitive to the mean stress (load ratio) and the frequency of the fatigue cycle. Detailed transmission electron microscopy of the fatigue crack-tip region, in conjunction with optical microscopy, reveals that the principal mechanism of permanent damage ahead of the advancing crack is the nucleation and growth of interfacial flaws. The oxidation of Sic whiskers in the crack-tip region leads to the formation of a silica-glass phase in the 1400°C air environment. The viscous flow of glass causes debonding of the whisker-matrix interface; the nucleation, growth, and coalescence of interfacial cavities aids in developing a diffuse microcrack zone at the fatigue crack tip. The shielding effect and periodic crack branching promoted by the microcracks result in an apparently benefcial fatigue crack-growth resistance in the A1203—SiC composite, as compared with the unreinforced alumina with a comparable grain size. A comparison of static and cyclic load crack velocities is provided to gain insight into the mechanisms of elevated temperature fatigue in ceramic composites.read more
Citations
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Book ChapterDOI
Elastic Solids with Many Cracks and Related Problems
TL;DR: In this article, the impact of interactions on individual cracks, particularly on the stress intensity factors (SIFs), and the effective elastic properties of solids with many cracks are discussed.
Journal ArticleDOI
A review of crack closure, fatigue crack threshold and related phenomena
TL;DR: In this article, a new model was proposed to rationalize the observed variations in the fatigue crack threshold with load ratio, which is based on a requirement for two critical stress intensity parameters, namely ΔK th ∗ and K max ∗, that must be satisfied simultaneously as the crack tip driving forces for fatigue crack growth.
Journal ArticleDOI
Cyclic Fatigue-Crack Propagation in Magnesia-Partially-Stabilized Zirconia Ceramics
TL;DR: In this article, the subcritical growth of fatigue cracks under tension-tension cyclic loading was demonstrated for ceramic materials, based on experiments using compact C(T) specimens of a MgO-partially-stabilized zirconia (PSZ), heat-treated to vary the fracture toughness Kc from ∼3 to 16 MPa·m1/2 and tested in inert and moist environments.
Journal ArticleDOI
Cyclic Fatigue-Crack Growth in a SiC-Whisker-Reinforced Alumina Ceramic Composite: Long- and Small-Crack Behavior
TL;DR: In this article, the authors investigated the cyclic-fatigue loading in a SiC-whisker-reinforced alumina (Al2O3-SiCw) composite (fracture toughness, Kc∼ 4.5 MPa · m1/2).
Journal ArticleDOI
Crack tip driving forces and crack growth representation under fatigue
K. Sadananda,A.K. Vasudevan +1 more
TL;DR: In this article, a unified approach was developed to consider interplay of these two governing forces, Δ K and K max, as fundamental to fatigue, since K max is the governing parameter for these effects.
References
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Journal ArticleDOI
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Journal ArticleDOI
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Journal ArticleDOI
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L. Ewart,Subra Suresh +1 more
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Journal ArticleDOI
Some effects of microcracks on the mechanical properties of brittle solids—II. Microcrack toughening
Anthony G. Evans,Y. Fu +1 more
TL;DR: In this article, the stress-strain characteristics of a microcracking material are used as the basis for computations of the fracture toughness, by applying a line integral formulation, pertinent to frontal and steady-state microcrack process zones.
Journal ArticleDOI
Static and Cyclic Fatigue Behavior of a Sintered Silicon Nitride at Room Temperature
TL;DR: In this article, the static and cyclic fatigue behavior of sintered silicon nitride was investigated at room temperature, and it was shown that the minimum time to failure was almost the same, in spite of differences in loading mode or frequency.