Abstract
This paper presents the influence of impact energy level and the composite thickness on the impact characteristics. The composite is made of stratified quadriaxial glass fiber prepreg layers (0°/+45°/90°/-45°), from Castro Composites (Spain), and an epoxy resin as matrix (SikaBiresin® CR82 with the hardener CH80-2), from Sika Group (Austria). This research study has as input parameters: the number of quadriaxial prepreg layers (6, 8 and 10, respectively), impact energy of 45 J, 100 J and 150 J, respectively. The constant parameters were the impact velocity (approx. 4 m/s) and the diameter of the hemispherical hard steel impactor of 16 mm. Tests were carried out on Instron CEAST 9340 machine and at least three tests with close results are presented. There was discussed the influence of impact energy and composite thickness on the maximum force (Fmax) during impact, time to Fmax and duration of impact, tf. The value of impact energy was decisive in determining the extent of damage. At low energy level (45 J), the response of composites was predominantly elastic, with limited delamination or matrix cracking, while at 150 J severe damage was observed, including yarn fracture and total penetration for the thinner composite. The intermediate level of 100 J revealed the transition zone, where matrix–fiber decohesion and delamination became more pronounced.