Effect of distance between impact point and hole position on the impact fatigue strength of composite laminates

An impact fatigue study was performed to evaluate the effect of the distance between the impact point and the hole on the fatigue life of glass fibre/epoxy laminates. For this purpose, experimental tests were carried out in square plates and for the distances of 0, 5, 10 and 20 mm, from the impact point. The results were compared with the ones obtained in plates without hole. It was possible to conclude that the fatigue life decreased, comparatively to the control samples, about 10.9%, 40%, 63.6% and 69.1% for the distances of 20 mm, 10 mm, 5 mm and 0 mm, respectively. Higher distances promote higher maximum loads and elastic restitution, but an opposite trend in terms of maximum displacement. For example, it was found for 20 mm a maximum load around 5.54 kN, a displacement of about 4.4 mm and an elastic energy of 59.2%, while for 0 mm these values were about 4.59 kN, 5.7 mm and 40.4%, respectively. In terms of multi-impacts, the damage severity is also very influenced by the distance. For small distances the damage progresses quickly, while three stages can be found for the control samples and for the distance of 20 mm.