Design and Analysis of a Compact Tension (ct) Specimen for Intralaminar Fracture Toughness Characterisation of Woven Composite Laminates

Final failure of laminated composite structures is preceded by different damage mechanisms involving fracture initiation and propagation. Fracture in a composite laminate can appear either between two plies or within a lamina. In the first case, interlaminar fracture or delamination, the crack causes separation of two adjacent plies and will mainly involve matrix failure or matrix-to-fibre debonding although some failure of fibres bridging the delamination may also occur. In the second case, intralaminar or translaminar fracture, the crack is located within the lamina, either parallel to the fibres (matrix crack) or at an angle (with fibre failure). When an intralaminar crack propagates at a certain angle to the reinforcing fibres, the fibres bridge both surfaces of the crack, arresting or reducing further crack opening until the bridging fibres are broken. Although the energy consumed in fibre fracture is usually much larger than in matrix cracking or fibre-matrix debonding [1], experimental determination of the fibre fracture toughness is important for accurate numerical modelling of composite component failures.