An application of a new ultrasonic technique to jute composite laminates subjected to low-velocity impact

A new ultrasonic technique, in the form of reflection, was used to determine the internal damage status of very low-cost composite laminates, subjected to transversal impact loads at low-velocity. The natural base materials consist of jute fibres woven rovings embedded with a vinylester resin. The common moulding by vacuum bag polymerisation technique was applied to this very cheap material. 100×100×8mm square specimens were subjected to impact loads at different energies and the internal damage status, in form of delaminations, was determined by means of a new ultrasonic technique, pointed out by the authors themselves. Ultrasonic maps were obtained before and after the impact loads; the formers are necessary to evaluate the parameters of the ultrasonic system and to obtain the initial reference image. The experimental technique is described in the paper and some ultrasonic maps are presented and discussed. The damage is correlated to the impact loads.