Dynamic load on composite laminates in the presence of water

An experimental activity, in order to assess the impact behavior at room and low temperature, of carbon fiber in vinylester resin laminates used in the shipbuilding industry, was conducted. The conditions, which simulate the impact of a tool that drop on the panel mounted on a boat hull in contact with water, were reproduced. This is a condition named water backing, in the middle between the pure impact (air backing) and the hull slamming, and not already tested before. An innovative equipment was designed and realized at University of Naples 'Federico II,' to reproduce the real dynamic material behavior in the presence of water, at the aim to investigate the influence of the water backed on the response of laminates under impact conditions. The results were obtained impacting the laminates placed between the cylindrical steel impactor and a bag containing water. A falling weight machine, equipped with a thermal chamber, was adopted for the experimental tests. The simulated test condition is completely new since no similar research is possible to find in literature. The impact behavior in hostile environments was compared to the room conditions, and the data obtained by the water backed loading tests were compared with the results by the pure impact tests. In the latter case, a completely different behavior was observed between the two different loading conditions, in terms of both load-displacement curve and the internal damage. The effect of the impact load on the laminates has been analyzed through the delamination and the indentation.
INTRODUCTION Low temperature represents an environmental condition critical for structures made of composite material, in particular under dynamic loads. This problem is really important in the Artie Ocean navigation since [...]