An experimental investigation of the impact response of composite laminates

In this study, the impact response of unidirectional glass/epoxy laminates has been investigated by considering energy profile diagrams and associated load–deflection curves. Damage modes and the damage process of laminates under varied impact energies are discussed. Two different stacking sequences, [0/90/0/90]s and [0/90/+45/−45]s, were chosen in tests for comparison. An alternative method, based on variation of the excessive energy (Ee) versus impact energy (Ei), is presented to determine penetration threshold (Pn). The penetration threshold for stacking sequence [0/90/+45/−45]s is found to be smaller than that of [0/90/0/90]s. The primary damage mode was found to be fiber fracture for higher impact energies; whereas, it was indentation resulting in delamination and matrix cracks for smaller impact energies. Contour plots of the overall damage areas are also depicted for several impact energies.