Influence of Fibre-Matrix Adhesion on Mechanical Properties of Graphite/Epoxy Composites: III. Impact and Dynamic Mechanical Properties

Abstract

An experimental investigation was carried out on the graphite/epoxy composites with two different fibre surface conditions to identify the effect of fibre-matrix adhesion on the impact and dynamic mechanical properties. The results obtained from Charpy and falling weight impact tests did not show a clear influence of fibre-matrix adhesion on the impact properties of the composites. This is attributed to the highly localised damage process of impact tests, in which the main damage mechanism is the fibre breakage and there are no extensive delamination and fibre pull-out mechanisms involved. The dynamic mechanical analysis (DMA) is a non-destructive method and it is different from the common methods for characterisation of fibre-matrix interfacial properties such as fibre pull-out and fibre fragmentation tests in which fibre-matrix interface debonding is produced. The results of DMA tests indicate the dynamic properties of the composites are not very sensitive to the change of fibre-matrix adhesion. During the DMA tests, there is no or little fibre-matrix debonding induced. Therefore, the DMA method may not be very applicable for evaluating the fibre-matrix interfacial adhesion in practical applications.