Performance of composite materials under high-speed impact in extreme environments

Abstract

High-speed impact performance of composites of naval relevance is an important issue for analysing the reliability of components of battle ships produced with composite materials that may be subjected to impulsive loads in extreme conditions of temperature and aggressive environments. This paper presents preliminary results of a wide experimental research programme aiming to determine the response and failure of fibre-reinforced polymer composites of naval relevance under high-speed impact in extreme environments. Six different materials have been produced, namely S-2 glass, carbon, mate glass and hybrid glass/carbon woven fabric-reinforced vinyl ester matrix composites. The production method is by infusion of the resin into a vacuum mould. Impact tests have been carried out by shooting steel balls at speeds in the range of 200–600 m/s, approximately, by means of a compressed-gas gun. Impact velocities and residual velocities were measured by a high-speed camera and the corresponding software. Impact tests have been performed at room temperature 25 °C, as well as at low temperature − 50 °C, and high temperature + 50 °C. The whole experimental programme has been repeated by testing specimens previously conditioned by immersion in seawater up to saturation, aiming to analyse the influence of the aggressive environment on the performance of composites under high-speed impact. The experimental results, residual-velocity vs. impact-velocity curves and ballistic limits (impact velocity for 50% probability of target perforation), show no significant differences in the performance of all materials tested, although the best behaviour is observed in non-mixed hybrid glass/carbon reinforcement. On the other hand, saturated specimens show a slightly better behaviour except for low temperatures. Experimental results are compared with predictions of a new analytical model, previously developed by the authors. A good concordance is observed, showing that the analytical model may be a useful tool for predicting the response and failure of fibre-reinforced polymer composites under impact of different threats (fragments, bullets, etc.).