Characterization of Lamina and Interlaminar Damage in Graphite/Epoxy Composites by the Deply Technique

A unique technique is described for separating a cured graphite/epoxy composite into its individual laminae while maintaining the integrity of each lamina. The use of this technique provides information heretofore unavailable for fracture and failure analysis. Examples of damage characterization using this technique are presented for pin-loaded holes and impact areas. In the case of the pin-loaded holes the extent of fiber bundle fractures in the internal laminae are shown to be a function of increasing loads. For impact-damaged areas the delaminations between the various laminae were marked with a unique process prior to the deplying process. After the laminae were deplied, the indicated areas of delamination and the incidents of fiber fracture were measured using a digital image analyzer. Photographs of typical damage are included.