STP1253

    A Methodology to Predict Damage Initiation, Damage Growth, and Residual Strength in Titanium Matrix Composites

    Published: Jan 1996


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    Abstract

    In this research, a methodology to predict damage initiation, damage growth, fatigue life, and residual strength in titanium matrix composites (TMC) is outlined. Emphasis was placed on micromechanics-based engineering approaches. Damage initiation was predicted using a local effective strain approach. A finite element analysis verified the prevailing assumptions made in the formulation of this model. Damage growth, namely, fiber-bridged matrix crack growth, was evaluated using a fiber bridging (FB) model that accounts for thermal residual stresses. This model combines continuum fracture mechanics and micromechanics analyses yielding stress-intensity factor solutions for fiber-bridged matrix cracks. In the FB model, fibers in the wake of the matrix crack are idealized as a closure pressure, and an unknown constant frictional shear stress is assumed to act along the debond length of the bridging fibers. This frictional shear stress was used as a curve-fitting parameter to the available experimental data. Figure life and post-fatigue residual strength were predicted based on the axial stress in the first intact 0° fiber calculated using the FB model and a three-dimensional finite element analysis.

    Keywords:

    fracture mechanics, fiber bridging model, matrix cracking, fiber breakage, thermal residual stresses, micromechanics


    Author Information:

    Bakuckas, JG
    Senior research engineer, Galaxy Scientific Corporation, Egg Harbor Twp., NJ

    Johnson, WS
    Professor, School of Material Science and Engineering, Georgia Institute of Technology, Atlanta, GA


    Paper ID: STP18238S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP18238S


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