Fracture of Ceramics

Dänzer, Robert; Supancic, Peter; Damani, R. J.

doi:10.1002/9783527631735.ch12

Cited by 38 publications

(75 citation statements)

References 85 publications

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“…Therefore, probabilistic failure mechanics are essential for proper designing with this brittlelike material [37,38]. According to Weibull distribution standards [39], the range of failure probabilities covered by the experimental assessment of the Weibull curve increases with the dimension of the sample (i.e.…”

Section: Microstructural Effects On Failure Probabilitymentioning

confidence: 99%

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Tarragó

Coureaux

Torres

et al. 2018

International Journal of Refractory Metals and Hard Materials

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Strength and reliability of WC-Co cemented carbides (hardmetals) are dependent on effective fracture toughness as well as on nature, size and distribution of processing flaws. Regarding toughness, they exhibit a crack growth resistance (R-curve) behavior, derived from the development of a multiligament bridging zone at the crack wake. Accordingly, successful implementation of fracture mechanics requires consideration of tangency criterion, between applied stress intensity factor and R-curve, in addition to fractographic inspection. It is the aim of this study to evaluate the strength behavior of a series of experimental WC-Co grades on the basis of R-curve failure criteria. Results indicate that microstructural effects on the strength of hardmetals may be satisfactorily rationalized following the referred criterion.The analysis includes consideration of nature and distribution of fracture origins, found to be more diverse and wider respectively for the harder fine-grained grades. This experimental evidence, together with the fact that these hardmetals exhibit steeper rising R-curves than tougher coarse-grained ones, leads to lower reliability for the former. This investigation documents and validates the great relevance of R-curve behavior for optimizing the mechanical performance of WC-Co cemented carbides on the basis of microstructural design.

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Section: Microstructural Effects On Failure Probabilitymentioning

confidence: 99%

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Tarragó

Coureaux

Torres

et al. 2018

International Journal of Refractory Metals and Hard Materials

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“…Therefore, a proper account of the spatial variation in the stress triaxiality (e.g. effect of shear stresses) must be taken by using a multiaxial failure criterion 5,24,25 .…”

Section: Methodsmentioning

confidence: 99%

“…Since PIA criterion does not exist in STAU, the first principle stress criterion (FPS) will be used instead according to the fact that as Danzer et al 5 stated, for a material with a Weibull modulus of m = 20, there is only 4% deviation between PIA and FPS and this difference between the equivalent stresses is often hidden by the scatter of data. In the following, the considered multiaxial failure criteria in this article will be introduced.…”

mentioning

confidence: 99%

“…effect of shear stresses), is known, the failure probability of ceramic components under multiaxial stress state can be predicted by using the results of uniaxial tests 4 . Under multiaxial stress state, cracks are subjected to Mode-I (crack opening caused by normal stress perpendicular to the crack plane) as well as Mode-II (crack opening by shear stress acting in the crack plane and perpendicular to its leading edge) and Mode-III (crack opening by shear stress acting in the crack plane and parallel with its front) loading, depending on the position and orientation of the crack plane relative to the principal stresses 5 . Therefore the loading of a given flaw has to be expressed in terms of a suitably defined equivalent stress which depends on the orientation of the crack plane in the local stress field.…”

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confidence: 99%

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Determination of the multiaxial failure criteria for alumina ceramics under tension–torsion test

Nohut¹,

Usbeck²,

Özcoban³

et al. 2010

Journal of the European Ceramic Society

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Failure probability of ceramic components in multiaxial stress state can be predicted using the uniaxial test results (e.g. Tension Test, 4-Point-Bending Test) when a suitable multiaxial criterion, which introduces the triaxiality of stress state, is known. In this article, tension-torsion tests were performed with alumina (Alsint 99.7) specimens from a standard manufacturer under two different load cases. Next experimental results were compared with the numerically calculated effective volume and effective surface values according to different multiaxial failure criteria. It was concluded that the specimens failed due to surface flaws and the normal stress criterion is the most appropriate criterion for the strength prediction of alumina ceramics under multiaxial stress state. Furthermore, it was shown that the Weibull modulus does not play a big role for the prediction of strength of alumina ceramics.

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“…Ceramic materials have been widely used in thermostructural engineering due to their excellent high temperature performance [1,2]. However, their inherent brittleness and poor resistance to thermal shock have slowed their use.…”

Section: Introductionmentioning

confidence: 99%

Crack patterns corresponding to the residual strength plateau of ceramics subjected to thermal shock

Hou

Peng

et al. 2012

Acta Mech Sin

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The formation mechanism of the residual strength plateau of ceramics subjected to thermal shock is addressed.A set of thermal shock experiments of 99Al 2 O 3 are conducted, where the thin specimens of 1 mm × 10 mm × 50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of thermal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.

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Fracture of Ceramics

Cited by 38 publications

References 85 publications

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Strength and reliability of WC-Co cemented carbides: Understanding microstructural effects on the basis of R-curve behavior and fractography

Determination of the multiaxial failure criteria for alumina ceramics under tension–torsion test

Crack patterns corresponding to the residual strength plateau of ceramics subjected to thermal shock

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