Delamination Growth and Thresholds in a Carbon/Epoxy Composite Under Fatigue Loading

    Volume 23, Issue 2 (April 2001)

    ISSN: 0884-6804

    CODEN: CTROAD

    Page Count: 14


    Sjögren, A
    SICOMP (Swedish Institute of Composites), Mölndal,

    Greenhalgh, ES
    Mechanical Sciences Sector, DERA, Farnborough,

    Asp, LE
    SICOMP (Swedish Institute of Composites), Mölndal,

    (Received 8 September 1999; accepted 19 September 2000)

    Abstract

    This paper presents a study on delamination growth in Mode I, Mode II and mixed mode under fatigue loading in an HTA/6376C composite. The computed slopes of the modified Paris plots were high. Therefore, threshold values of the strain energy release rate for delamination growth were determined. Low fatigue threshold values revealed a significant effect of fatigue loading. The largest effect was found for the ENF test (Mode II) for which the fatigue threshold value was only 10% of the critical strain energy release rate in static tests. Threshold values for MMB (mixed mode) and DCB (Mode I) tests were 15% and 23% of the static values, respectively.

    Fractographic evaluation revealed identical initial failure mechanisms in fatigue and static loading conditions for the ENF specimen. The ENF specimen failed by formation and coalescence of microcracks. The low fatigue threshold for the ENF specimen was explained by microscopical observations on the specimen edge. It was also shown that the fracture surfaces generated in static and fatigue DCB and MMB tests were similar.


    Paper ID: CTR10914J

    DOI: 10.1520/CTR10914J

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    Author
    Title Delamination Growth and Thresholds in a Carbon/Epoxy Composite Under Fatigue Loading
    Symposium , 0000-00-00
    Committee D30