Micromechanical model of cross-over fibre bridging - Prediction of mixed mode bridging laws

Bent F. Sørensen, E.K. Gamstedt, Rasmus Christian Østergaard, Stergios Goutianos

    Research output: Contribution to journalJournal articleResearchpeer-review


    The fracture resistance of fibre composites can be greatly enhanced by crack bridging. In situ observations of mixed mode crack growth in a unidirectional carbon-fibre/epoxy composite reveal crack bridging by single fibres and by beam-like ligaments consisting of several fibres. Based on the observed bridging mechanism, a micromechanical model is developed for the prediction of macroscopic mixed mode bridging laws (stress-opening laws). The model predicts a high normal stress for very small openings, decreasing rapidly with increasing normal and tangential crack opening displacements. In contrast, the shear stress increases rapidly, approaching a constant value with increasing normal and tangential openings. The solutions for the bridging laws and the resulting toughening due to the bridging stresses are obtained in closed analytical form.
    Original languageEnglish
    JournalMechanics of Materials
    Issue number4-5
    Pages (from-to)220-234
    Publication statusPublished - 2008


    • Fracture resistance
    • ESEM testing
    • Polymer–matrix composites
    • Potential function


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