STP937: Rate Effects on Delamination Fracture Toughness of a Toughened Graphite/Epoxy

    Daniel, IM
    Professor, Northwestern University, Evanston, IL

    Shareef, I
    Assistant professor, Bradley University, Peoria, IL

    Aliyu, AA
    Graduate student, Ahmadu Bello University, Zaria,

    Pages: 15    Published: Jan 1987


    Abstract

    The objective of this study was to determine the effects of loading rate on interlaminar fracture toughness of T300/F-185 graphite/epoxy composite, having an elastomer-modified epoxy resin matrix. Mode I interlaminar fracture was investigated by means of uniform width and width-tapered double cantilever beam (DCB) specimens. Hinged tabs were used to insure unrestrained rotation at the free ends. Specimens were loaded at quasi-static deflection rates of up to 8.5 mm/s (20 in./min) corresponding to crack extension rates of up to 21 mm/s (49.6 in./min). Crack extension was monitored by means of strain gages mounted on the surface of the specimen. Continuous records were obtained of load, deflection, and crack extension for determination of the strain energy release rate. The latter was calculated by means of the area method and beam analysis method, and expressed as a power law of the crack extension velocity. Results indicate that the strain energy release rate decreases with crack velocity by over 20% over three decades of crack velocity.

    Keywords:

    graphite/epoxy, toughened composites, fracture toughness, rate effects, strain energy release rate, double cantilever beam, crack propagation, test methods


    Paper ID: STP24382S

    Committee/Subcommittee: D30.06

    DOI: 10.1520/STP24382S


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