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Micromechanics of fiber-reinforced brittle-matrix composite materials

Thesis/Dissertation ·
OSTI ID:5331377

The theory of micromechanics is used to investigate fracture mechanisms in fiber-reinforced brittle-matrix composite materials. Mori-Tanaka theory and Eshelby's method were applied to obtain a more accurate evaluation of average elastic and elasto-plastic relationships of composite materials with spherical, prolate spheroidal, and elliptic cylindrical inhomogeneities. Using the inclusion method, toughening of composites by mixing strong continuous fibers into a brittle material was examined. The fibers suppress the extension of a crack through bridging, interfacial debonding, and sliding effects. The energy release rate of a fiber-bridged crack and the resistance to crack extension by energy dissipation were evaluated separately to account for these effects. Tests on cement-based composite specimens with steel wires as fibers and under uniaxial tension conditions were performed with different fiber diameters and fiber-volume ratios. Theoretical considerations show that depending on the values of fiber volume ratio, fiber diameter, matrix and interfacial properties, a composite which is under tensile loading may or may not contain debonding at BOP (bend-over-point).

Research Organization:
Northwestern Univ., Evanston, IL (United States)
OSTI ID:
5331377
Country of Publication:
United States
Language:
English