EFFECTS OF THE INTERFACE ON THE MECHANICAL RESPONSE OF CF EP MICROCOMPOSITES AND MACROCOMPOSITES

The aim of this study was to investigate the effects of the interfacia l bond quality on the mechanical response of composite laminates, for example an epoxy matrix reinforced by continuous carbon fibres of vary ing surface coating. The fibre/matrix adhesion was characterized by de termining the interfacial shear strength tau(i) in single-fibre fragme ntation and microdroplet pull-off tests. The failure mechanisms were d educed from the stress birefringent patterns (fragmentation test) and from fractographic analysis in a scanning electron microscope (microdr oplet pull-off test). Selected interface-relevant properties were eval uated in mechanical tests on laminates. The present paper highlights t he problems related to the micromechanical characterization and the in terface relevance of data resulting from transverse tensile, transvers e flexure and interlaminar shear tests. Furthermore, the effects of th e interface on the impact performance of unidirectional and cross-ply laminates were studied. Attempts were made to correlate the macroscopi c mechanical response with the interface-related characteristics (tau( i) and failure mechanisms).