Application of Weakest-Link Fracture Statistics to Fiber-Reinforced Ceramic-Matrix Composites

Autor: J. C. McNulty, Frank W. Zok
Rok vydání: 2005
Předmět:
Zdroj: Journal of the American Ceramic Society. 80:1535-1543
ISSN: 1551-2916
0002-7820
Popis: The strength and reliability of fiber-reinforced ceramic-matrix composites (CMCs) are dependent on whether conditions of local or global load sharing prevail. Global load sharing is promoted by a low interfacial sliding stress and is manifested in a zero-tangent modulus at the point of tensile failure along with random fiber failures and extensive fiber pullout. In this paper, it is demonstrated that conditions of global load sharing are not present in two commonly studied CMCs, despite the fibrous appearance of their fracture surfaces. This behavior is manifested in a volume-dependent strength, as evidenced by strength differences measured in tension and flexure (accounting for the nonlinear stress distribution in flexure). Methods of weakest-link statistics are used to relate the strengths measured in the two test configurations. Estimates for the Weibull moduli of the two systems are obtained from the experiments and compared with values obtained through Monte Carlo simulations based on a three-dimensional-lattice Greens function method. The implications of these results on the strength of large components and of small regions of high stress concentration are discussed briefly.
Databáze: OpenAIRE
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