Abstract: The polymeric composite laminates show relatively high impact sensitivity. Even the low-energy impact on the laminates in service is easy to cause invisible damages and the degradation of the strength and stiffness and thus severely threaten the safety of the laminates. The bending stiffness degradations of glass fiber reinforced vinylester composite corners made of five lay-ups are respectively observed with the aid of four-point bending tests. The influence of various lay-ups and impact energy levels on the impact resistance of the composite corners is evaluated. The results conclude that the increase in the impact energy leads to more impact damage and lower residual bending stiffness; the impact damage areas of the five specimens exhibit basically identical tendency with their stiffness degradation. The closer fiber angles of two adjacent layers result in the higher bending stiffness and the lower after-impact stiffness degradation of the composite corners. It is further indicated that the [45°/0°/-45°/90°] lay-up produces the lowest after-impact stiffness degradation of the composite corners and the cross-ply specimens have the lowest impact resistance.

Key words: composite materials, corner, impact damage, bending stiffness