Damage development in thick composite tubes under impact loading and influence on implosion pressure: Experimental observations

This paper presents experimental results obtained from quasi-static and impact indentation tests on thick ±55° filament wound glass/epoxy tubes intended for underwater applications. Drop weight impact tests have been performed on 55 mm internal diameter 6 mm thick tubes at energies up to 45 J. Ultrasonic inspection was employed first to determine projected damage areas. A large number of samples were then sectioned and polished and the true damage area was revealed by a dye penetrant technique. This has enabled detailed descriptions of damage development to be made. The true damage area is roughly 10 times the projected area. The influence of impact damage on implosion pressure is described. Above a critical impact energy level a significant drop in implosion resistance is noted, which is related to the appearance of intralaminar cracks.