PREDICTING BURST PRESSURES IN FILAMENT-WOUND COMPOSITE PRESSURE-VESSELS BY USING ACOUSTIC-EMISSION DATA

Multivariate statistical analysis was used to generate equations for predicting burst pressures in 14.6 cm (5.75 in.) dia. fiberglass-epoxy and 45.7 cm (18 in.) dia. graphite-epoxy pressure vessels from acoustic emission (AE) data taken during hydroproof. Using the AE energy and amplitude measurements as the primary independent variables, the less accurate of the two linear equations was able to predict burst pressures to within +/- 0.841 MPa (+/- 122 psig) of the value given by the 95 percent prediction interval. Moreover, this equation included the effects of two bottles that contained simulated manufacturing defects. Because the AE data used to generate the burst-pressure equations were both taken at or below 25 percent of the expected burst pressures, it is anticipated that by using this approach, it would be possible to lower proof pressures in larger filament-wound composite pressure vessels such as rocket motor cases. This would minimize hydroproof damage to the composite structure and the accompanying potential for premature failure in service.