STP1059

    Fatigue Growth, Deflections, and Crack-Opening Displacements in Cracked Lap Shear Specimens

    Published: Jan 1990


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    Abstract

    Results are presented for a cracked lap shear AS4/3501-6 unidirectional laminate geometry, with a strap thickness of 2.19 mm and a lap thickness of 1.17 mm. There is some fiber bridging across the delamination crack surfaces, which can lead to lower than expected compliance values and crack arrest in fatigue. Analysis of the fatigue crack growth rates in terms of the energy release rate range yields an exponent of 6.02 in the power law, and no apparent mean load influence. However, analysis in terms of the applied load suggests a large mean load influence. Deflections and crack-opening displacements (COD) near the crack tip were measured successfully with adequate resolution. The crack remains closed up to a load of 5000 N, corresponding to a strain energy release rate of 29 J/m2 and a crack growth rate of 10-7 mm/cycle. In principle, COD results can be used to determine the Mode I energy release rate, but the results presented here were not of sufficient accuracy.

    Keywords:

    composite materials, fatigue, delamination, cracked lap shear, crack-opening displacement, strain energy release rate, fiber bridging


    Author Information:

    Poursartip, A
    The University of British Columbia, Vancouver, B.C.

    Chinatambi, N
    The University of British Columbia, Vancouver, B.C.


    Paper ID: STP24118S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP24118S


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