Characteristics of delamination in graphite/epoxy laminates under static and impact loads

In the present research, the characteristics of delamination in graphite/epoxy laminates subjected to static and impact load are discussed by the method of fractography experimentally. At first, delaminations were developed by double cantilever beam (DCB) test and end-notch flexure (ENF) test for some kinds of laminates. Their fracture surfaces were observed by scanning electron microscope. The propagated orientation of the delamination could be specified from the patterns of fracture surface. Next, each static and impact load was applied to square laminates to generate ripwise delaminations known as the typical pattern of low velocity impact damage. Based on the pattern specified by DCB and ENF tests, the propagation of delaminations for both loads were identified. Then it is obtained that the delamination in static and impact can be explained by the propagation from the transverse crack and the sequential delamination mechanism respectively.