Volume 10, Issue 1, 2001

Fatigue Damage Mechanisms in Carbon-Epoxy Multi-Fibre Model Composites

S. Goutianos^1,3 and T. Peijs^1,2

¹ Materials Department, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.

² Dutch Polymer Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

³ Institute of Chemical Engineering & High Temperature Chemical Processes, Foundation of Research & Technology - Hellas, Stadiou Street, Platani, P.O.Box 1414, GR-265 00, Patras, Greece.

(Received 11/00; accepted 1/01)

ABSTRACT

Polarised-light microscopy was used to investigate the influence of stress level and fibre/matrix adhesion on the fatigue failure process in carbon-epoxy multi-fibre model composites. It was shown that the fatigue stress has a strong influence on the damage accumulation process in such model composites. Increasing levels of tension-tension fatigue stress resulted in an increase in total number of fibre breaks, stronger fibre-fibre interaction, i.e. fibre failure due to stress concentrations caused by a fractured adjacent fibre, and more interfacial damage. An increase in fibre-matrix adhesion was also found to result in more fibre-fibre interactions, whereas in the case of poor fibre/matrix adhesion extensive debonding takes place. Finally, the experimental observations were interpreted using a 3-D finite element analysis of the model composites.