RESIDUAL STRENGTH OF DAMAGED GLASS/EPOXY TUBULAR STRUCTURES

摘要

Composite materials with organic matrix resins are increasingly being used for marine and underwater applications. There are many advantages of composites in the marine field: low weight, corrosion resistance, and stiffness. This paper presents results from static indentation and impact tests on thick filament wound glass/epoxy tubes. Drop weight impact tests have been performed on 55-mm internal diameter, 6.5-mm thick tubes at energies up to 50 Joules. The first part involves the identification of damage initiation and its development. 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 second part of the paper is concerned with the evaluation of the influence of this damage on residual strength under hydrostatic pressure loading. The improved understanding of these phenomena and the development of predictive tools is part of an ongoing effort to improve the long-term integrity of composite structures for underwater applications. Above a critical impact energy level a significant drop in implosion resistance is noted, which is related to the appearance of intra-laminar cracks.