Comparative Response in Repeated Impact Tests of Hand Lay-Up and Vacuum Infusion Glass Reinforced Composites

Vacuum infusion is now being considered as a viable alternative to more traditional hand lay-up. Main reason in favor of the more costly technique is the cleaner and friendlier work environment. However, vacuum infusion potentially offers another important benefit over hand lay-up in that prepreg levels of resin may be achieved, resulting in stronger and lighter laminates. The present paper compares the two manufacturing techniques on the basis of the response to repeated impact loading. The laminate is a non-symmetric glass fiber reinforced plastics intended for nautical application. Four impact velocities (1.5 m/s, 2.2 m/s, 3.1 m/s and 3.8 m/s) were considered, and a minimum of four specimens for any given velocity were subjected to forty repeated impacts or up to perforation. The impact response was evaluated in terms of damage progression by visual observation of the impacted specimens, evolution of the peak force and of the bending stiffness with the number of impacts and by calculating the damage degree (ratio between the absorbed energy and the impact energy). Results point out that for impact velocities for which no perforation occurs within test duration, the experimental data of the two series essentially overlap. On the contrary, for perforation tests, the number of impacts to perforation is smaller for vacuum infusion specimens.