Acoustography as a means of monitoring damage in composites during static or fatigue loading

The integration of an acoustography ultrasonic imaging system with a mechan ical testing machine is described. The apparatus is designed for real-time ultrasonic imaging of impact damage growth in composite material samples su bjected tu either static or fatigue loading. Experimental results are prese nted of the damage growth to failure of an aerospace standard carbon-fibre composite sample subjected to compressive cyclic loading. Experimental resu lts: fur static loading show a reversible increase and decrease in damage a rea, indicating an opening and closing of delamination defects, which point s to the possibility of an under-estimation of defect size by the conventio nal ultrasonic testing of unloaded components.