Effects of external patch configuration on repaired composite laminates subjected to multi-impacts

This work intends to study the impact performance of repaired composites by the overlap patch technique and, for this purpose, experimental tests were carried out on single and double-patch specimens. In order to evaluate the impact fatigue strength, both configurations were submitted to multi-impacts, until the full perforation occurs. It was possible to conclude that the double-patch geometry supports higher maximum loads, lower displacements and promotes higher elastic energies. Relatively to the impact energy of 6 J, for example, the maximum load and the elastic energy is 97.1% and 51.2% higher, respectively, but the maximum displacement is about 50% lower than the values obtained with the single-patch geometry. Higher impact fatigue life was also observed, as consequence of its higher stiffness. The impact bending stiffness confirms the difference of stiffness between them, and shows to be a parameter able to monitor the damage progression