Fatigue of Yttria‐Stabilized Zirconia: II, Crack Propagation, Fatigue Striations, and Short‐Crack Behavior

Abstract

Fatigue crack propagation in 3Y-TZP was investigated using controlled surface flaws. A unique growth law strongly dependent on the maximum stress intensity factor and quadratically dependent on the amplitude of the range of stress intensity factor was established. This growth law was found to apply for both surface flaws and internal flaws and could be used to predict fatigue lifetime. The presence of residual stress altered the growth mechanics so that an inverse growth rate dependence on the applied stress, reminiscent of the so-called "short-crack behavioe was manifested. Fatigue striations resulting from alternate overload fracture and fatigue fracture during stress cycling were observed. The appearance of striations varied with the R ratio and was very sensitive to the loading condition and crack geometry.[

In vitro lifetime of dental ceramics under cyclic loading in water

“…In the case of polycrystalline ceramics such as 3Y-TZP, the crack velocity under cyclic loading exhibits a stronger dependence on the maximum stress intensity factor K I,max than on the stress amplitude DK I [8,21,22]. Other empirical equations that explicitly address this issue have thus been proposed to describe the fatigue behavior of polycrystalline ceramics [8,22].…”

“…Other empirical equations that explicitly address this issue have thus been proposed to describe the fatigue behavior of polycrystalline ceramics [8,22]. Since these equations have not yet been generalized to other polycrystalline materials, we described the fatigue behavior of the dental ceramics evaluated here in terms of the simple relation v ¼ A Ã K n I;max .…”

“…In this case, the samples were tested in air and the crack velocity was normalized for comparison with fatigue results obtained for the same material using other measuring techniques. Based on the fatigue empirical equation suggested by previous authors [8,22,25], we used the ratio v/(1ÀR) 2 as normalized velocity for comparison of data measured at different DK I and R values.…”

Fatigue of Cemented Carbides

“…However, the description of FCG kinetics in terms of a modified Paris-Erdogan growth relationship of type da/dN ¼ CK max m DK n , as it had been shown to apply for other brittle-like materials such as structural ceramics (Liu & Chen, 1991b;Steffen et al, 1991) or intermetallics (Badrinarayanan, McKelvey, Venkateswara Rao, & Ritchie, 1996), allowed them to discern a decreasing prevalence of K max over DK (m/n ratio) as the controlling fracture mechanics parameter with rising mean binder free path ( Figure 5). Such a behavior was associated with the changes in relative predominance of static over cyclic modes of fracture during stable FCG.…”

“…The static mode option was introduced for assessing possible environmental-assisted (even in air) failure, as it had been reported in glass, porcelain and alumina. On the other hand, there were strong interests in evaluating and analyzing the fatigue behavior of cemented carbides on the basis that microstructural developments leading to an increase of toughness for new ceramic materials and ceramic-containing composites were also found to induce a decreased resistance against cyclic loads (Dauskardt, James, Porter, & Ritchie, 1992;Grathwohl, 1988;Liu & Chen, 1991a;Liu & Chen, 1991b;Ritchie, 1988;Steffen, Dauskardt, & Ritchie, 1991;Suresh, 1991).…”