STP1012

    Fatigue Damage Development in Notched (02/±45)s Laminates

    Published: Jan 1989


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    Abstract

    This study investigates delamination growth from holes in carbon fibre reinforced epoxy (CFRE) AS/3501-6 (02/±45)s laminates under tensile static and fatigue loading. Delaminations grow in a direction parallel to the loading at the 0/45 and 45/−45 interfaces. Attempts to control the location of the delamination by using inserts were unsuccessful. The delamination growth rates were fitted by a power function of the stress amplitude and mean stress. The stress amplitude is the dominant parameter. Tests were performed on dry and saturated specimens at room temperature, and there was no measurable difference in growth rates. However, block loading tests, where an overload was applied at regular intervals, resulted in growth rates five times higher than a linear sum of the individual growth rates. Compliance changes were measured and correlated with the extent of delamination. The associated matrix cracking contributes substantially to the compliance changes. The amount of matrix cracking for a given delamination length is a function of the type and level of loading. The results are interpreted in terms of the total strain energy release rate, G. Once the presence of matrix cracking is allowed for, there is reasonable agreement with results in the literature.

    Keywords:

    fatigue, delamination, matrix cracking, graphite fiber, strain energy release, rate, overload, stiffness, moisture


    Author Information:

    Poursartip, A
    Assistant professor and senior research technician, The University of British Columbia, Vancouver, B.C.

    Chinatambi, N
    Assistant professor and senior research technician, The University of British Columbia, Vancouver, B.C.


    Paper ID: STP10408S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP10408S


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