CHARACTERIZATION OF COMPOSITE-MATERIALS BY ULTRASONIC METHODS - MODELIZATION AND APPLICATION TO IMPACT DAMAGE

This paper presents some ultrasonic methods to detect and to character ize defects, possibly obtained after damage caused in composite materi als. Firstly, a two-dimensional ultrasonic cartography, performed sect ion by section, at different positions from the impact point, allows t he participation of the delamination mechanisms which took part throug h the thickness of a pultruded glass fiber-reinforced plastic composit e beam, to be analyzed. A very good agreement has been found with dest ructive testings. Furthermore, some examples are given on the use of a n ultrasonic propagation model which has been developed. This model pe rmits optimum experimental configurations to be determined, by the use of transmission and reflection coefficients or of Lamb waves. In addi tion, experimental and modelized time signals have been compared. (C) 1998 Elsevier Science Limited. All rights reserved.