Computational Modelling of the Residual Strength of Repaired Composite Laminates Using a Cohesive Damage Model

This work reports on a three-dimensional numerical analysis to assess the residual strength of single and double-strap repaired CFRP composite laminates, under tensile, compressive and bending loads. Interface finite elements including a triangular cohesive mixed-mode damage model are used in order to simulate damage onset and growth. The influences of several geometric changes on damage onset as well as growth and on the repair residual strength are addressed. The geometric changes include chamfering the outer and inner patch faces, filling the drilled hole with adhesive ( plug filling), use of fillets of different shapes and dimensions at the outer edge of the overlap, chamfering the outer and inner parent laminate faces and combinations thereof. This work showed that with the correct repair geometry, a significant strength improvement could be achieved for all the loads considered and for both single and double-strap geometries. (C) Koninklijke Brill NV, Leiden, 2008