STP791: Theoretical Fracture Resistance of Particle-Hardened Brittle Solids

    Gavigan, TH
    professor of engineering mechanics, The Pennsylvania State University, University Park, Pa.

    Queeney, RA
    professor of engineering mechanics, The Pennsylvania State University, University Park, Pa.

    Pages: 12    Published: Jan 1983


    Abstract

    The addition of dispersions of relatively stiff particulates to brittle materials is recognized to increase their fracture resistance as measured with conventional fracture mechanics parameters. Extant analytical models address the problem of particle hardening indirectly. One class of predictions is essentially a rule-of-mixtures approach and is of limited success in predicting particle strengthening. Another predictive model hypothesizes the existence of a line tension associated with the bowing of the crack front line as the crack front encounters particulates on the plane of crack extension; however, this approach fails to predict the measured effects of particle stiffness and particle size. The present analytical model deals directly with the extensibility of a crack on a plane containing particulates of an average size, spacing and stiffness. The elastic strain energy associated with the particulate field is calculated and compared to the energy of the non-particle-containing matrix. The strain energy release rate then is examined for unstable crack extension in the particle-hardened matrix, and the fracture resistance of the composite is compared to that of the plain matrix. The predictions are used to examine experimental data previously generated, and the model is found to be satisfactorily accurate in predicting changes in fracture resistance as particulate character is manipulated.

    Keywords:

    brittle fracture, composite fracture, ceramic inclusions, particulate composites, multiphase material strength, particle hardening, process zones, fracture mechanics


    Paper ID: STP37098S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37098S


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