REAL-TIME ULTRASONIC AND ACOUSTIC-EMISSION MONITORING OF DAMAGE IN GRAPHITE EPOXY LAMINATES/

Progressive failure of a crossply composite laminate under uniaxial te nsion was characterized by correlating ultrasonic and acoustic emissio n measurements with damage in real time. Both ultrasonic backscattered energy and acoustic emission gave consistent results and proved to be sensitive indicators of matrix cracking and other failure mechanisms. The acoustic emission signals were analyzed by investigating the ampl itude and count frequency and the corresponding applied strain. Loadin g/unloading tests showed that no additional damage occurs upon reloadi ng up to the previous peak load.