Dynamic mode Ⅱ delamination fracture of unidirectional graphite/epoxy composites

摘要

Dynamic fracture and delamination of unidirectional graphite/epoxy composites are investigated for end-notched flexure (ENF) and center-notched flexure (CNF) pure mode Ⅱ loading configurations using a modified split Hopkinson pressure bar. Results show that delamination and energy absorbed in fracture increase with impact energy with CNF > ENF. A power law analytical model reasonably describes the variation of energy release rate with delamination and energy absorbed. A crack embedded deeper in a specimen (as in CNF) contributes more to dynamic fragmentation than cracks at the surface or near the edge (as in ENF). Hackle features on mode Ⅱ fracture surfaces decrease with impact energy.