Low Velocity Impact Response of Composite Panels for Aeronautical Applications

The present experimental work analyses the impact behaviour of thermosetting composite materials for aeronautic applications. The main goal of the experimental activity was to identify the energy level in correspondence of which penetration occurs. The initial values of the impact energy were estimated according to analytical correlations found in literature. Tests were performed on three types of composite panels: carbon fibre laminated panels, fibreglass laminated panels and hybrid panels. The technology of lamina is that of prepeg fabric with twill sequence and fibres weaving at 0°-90° and ± 45°. The fixture used for tests is a Charpy impact test machine, which was conveniently equipped to evaluate the angular variation and the acceleration of the impacting mass. Preliminarily, non-destructive ultrasonic controls were performed to check that the specimens were not damaged before impacts tests. The interesting results of the tests were identification of the energy absorbed and the impact force for each specimen. Moreover, for each energy and force level, it was possible to associate a different fracture state. Comparisons among the results obtained for specimens made up of just one type of reinforcement (glass or carbon) and the results obtained with hybrid specimens were performed.