Assessment of strains along fiber surface features in graphite/epoxy composites loaded in compression

Kink-band formation in graphite/epoxy composites is not well understood. In this study we have monitored fiber failure before and during kink-band for mation. It was found that several surface features and types of breaks deve lop during the damage progression before kink-bands form. The strain around these surface features was measured by means of micro-Raman spectroscopy ( MRS). In order to determine the validity of using the strain profiles to ca lculate the interfacial shear stress (ISS) values, it was also determined w hether the various features represented fiber breaks. The reliability of MR S to obtain strain maps in these composites using the fiber as an internal strain gage as well as the validity of obtaining ISS values from the strain profiles is discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.