NON DESTRUCTIVE EVALUATION OF COMPOSITE MATERIALS USING ULTRASONIC SPECTROSCOPY M. OURAK, B. NONGAILLARD, J.M. ROUVAEN and N. IMOULOUDENE J. Phys. Colloques, 51 C2 (1990) C2-1261-C2-1264 DOI: 10.1051/jphyscol:19902296