Critical notch-root radius effect in SENB-S fracture toughness testing

Damani, R. J.; Gstrein, R.; Dänzer, Robert

doi:10.1016/0955-2219(95)00197-2

Cited by 199 publications

(131 citation statements)

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“…There is a wide variety of specimen and load geometries where the stress intensity factor is known for a crack of a given shape and size (77)(78)(79)(80)(81)(82). Due to the difficulties involved in machining ceramic parts with special shapes as well as to the tendency of brittle materials to fail under shear stresses originated by deficient clamping and/or alignment, the most widely used geometry for mechanical testing of ceramics is that of parallelepipedic bars subjected to bending, due to the ease mechanization and the simplicity of the test apparatus required.…”

Section: Determination Of Fracture Parametersmentioning

confidence: 99%

“…According to the reviews conducted by different authors (79)(80)(81)(82), the experiments with beams in bending with straight notches (SENB: Single Edge Notch Beam, Fig. 8a) lead to critical stress intensity factor values which are highly reproducible when results between different laboratories are compared.…”

Section: Determination Of Fracture Parametersmentioning

confidence: 99%

“…In addition, they are easy to produce, as compared to the complexity of preparing other notch geometries such as Chevron, and the analysis of the results obtained is simple, in comparison with the results from other configurations, such as double torsion (9). The main drawback of the SENB tests is the dependence of the results on the radius of the notch, since its behaviour becomes more remote from the behaviour of a crack as its radius increases (79).…”

Section: Determination Of Fracture Parametersmentioning

confidence: 99%

“…However, it has been observed that the actual value of the radius below which constant values are reached depends on the microstructure and type of material (79). In alumina materials, constant toughness values are obtained for radii smaller than approximately three times the grain size or the size of the characteristic flaws (pores, microcracks, machining damage, etc.)…”

Section: Determination Of Fracture Parametersmentioning

confidence: 99%

“…In alumina materials, constant toughness values are obtained for radii smaller than approximately three times the grain size or the size of the characteristic flaws (pores, microcracks, machining damage, etc.) (79). For these reasons, SENB method is not considered for European (CEN) and ISO standards.…”

Section: Determination Of Fracture Parametersmentioning

confidence: 99%

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Comportamiento mecánico de materiales cerámicos estructurales

Bueno¹,

Baudı́n²

2007

Bol. Soc. Esp. Ceram. Vidr.

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The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, K IC , and critical energy release rate, G IC ) are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γ WOF ), critical J-integral value (J IC ) and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.Keywords: Microstructure, Strength, Weibull modulus, Fracture toughness, Toughening mechanisms. Comportamiento mecánico de materiales cerámicos estructuralesEl uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su caracterización. En primer lugar, se revisan los parámetros de fractura utilizados para caracterizar materiales frágiles y los criterios de control estadístico que permiten determinar la probabilidad de que se sobrepasen los factores de seguridad exigidos en cada aplicación. A continuación, se discuten los mecanismos de refuerzo que se pueden desarrollar en los materiales cerámicos a través del diseño microestructural. En los materiales cerámicos en los que la actuación de mecanismos de refuerzo conduce a un comportamiento significativamente distinto del puramente frágil, los parámetros derivados del tratamiento lineal elástico (factor crítico de intensidad de tensiones, K IC , y tasa crítica de liberación de energía, G IC ), determinados experimentalmente, dejan de ser propiedades intrínsecas del material, independientes del tamaño de grieta y el sistema de carga. El presente trabajo revisa los parámetros mecánicos propuestos para...

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Section: Determination Of Fracture Parametersmentioning

confidence: 99%