Fibre reinforced plastic (FRP) composites consist of two or more components combined to give a synergistic effect for a better performance in service. One of the phases comprises layers of fibrous material while the other phase comprises of a polymer matrix. In this project, carbon fibre pre-preg material was used. All materials contain imperfections. Materials constituents and manufacturing anomalies are the main causes of faults in FRP composites. The presence of voids in FRP composites is the most common defect. The aim of this project was to determine the influence of voids on the static and dynamic compressive properties of carbon fibre reinforced plastic (CFRP) composites. The influence of voids on fatigue life and failure behaviour were also investigated.

Carbon fibre-reinforced plastics (CFRP) are widely used in aerospace, automobile and other structural applications due to their superior mechanical and physical properties. CFRP outperform conventional metals in high strength-to-weight ratio. Usually, CFRP parts are manufactured near to net-shape;however,machining is unavoidable when it comes to assembly. Drilling the holes are essential to facilitate riveting and bolting of the components. However, conventional drilling (CD) induces different types of damages such as cracking, fibre pull-out, sprintling and delamination due to the abrasive nature, inhomogeneity and anisotropy of CFRP. A novel technique, ultrasonically-assisted drilling (UAD) is hybrid machining technique in which highfrequency (typically above 20 kHz) vibration are superimposed on a standard twist drill bit in axial direction using ultrasonic transducer. UAD has shown several advantages such as thrust force reduction, improving surface quality and lower bur-formation in drilling of conventional metals. UAD has also effectively been used for drilling brittle materials.