Role of fibre fragmentation on pseudo-ductility of thin-ply [±277/0]s carbon fibre laminates with high modulus 0° plies under compressive and flexural loading

Abstract Pseudo-ductile tensile, compressive and flexural behaviour was achieved in a thin-ply carbon fibre [±277/0]s laminate with different fibre types in the angle plies and 0° plies. The laminate with the present layup was tested in both tension and compression, the latter through an unconventional indirect compressive test method using a sandwich beam configuration and the compressive stress was derived by considering the change in position of the neutral axis. The tests demonstrated for the first time that pseudo-ductility and progressive failure can be obtained under compressive loading on thin-ply [±θm/0n]s laminates using a combination of intermediate modulus and high modulus fibre prepregs. Delamination was suppressed throughout the testing and only occurred at the final fracture of the angle plies. Multiple fibre fractures of the 0° plies were obtained within the laminate with the support of the surrounding angle plies in both loading cases. When the laminate was subjected to monolithic flexure, a gradual failure and significant amount of non-linearity occurred. This was primarily due to 0° ply fragmentation on both the compressive and tensile sides of the beam; the fragmentation on both sides resulted in shifts of the neutral axis, retarding the strain increase on the compressive side, delaying the final failure and achieving a higher failure strain in flexure than in compression.