Life Strength Prediction of GFRP Pressure Vessels Using Acoustic Emission Technique

Abstract

Acoustic Emission (AE) has the unique potential for the real time integrity evaluation of pressurized systems. The technique has found greater importance in its application towards fibre reinforced plastic (FRP) pressure vessels in aerospace use. There is no method till date spelt out in open literature for burst pressure prediction of composite pressure vessels. This paper brings out a methodology for the burst pressure prediction of Glass Fibre Reinforced Plastic (GFRP) pressure vessels using a lucid empirical relation. Acoustic Emission monitoring was carried out during hydrostatic loading of five identical GFRP pressure vessels, about 6- litre capacity. An empirical relation was generated on the basis of the governing AE parameters viz., count rate, duration rate, amplitude rate and felicity ratio exhibited when the h/w was subjected to cyclic proof pressure cum burst test. AE data is acquired up to 50% of the theoretical burst pressure, and then the vessels were pressurized upto failure. The authors have framed an empirical relation to predict the burst performance, solving the typical equations with MAT LAB program for the four identical GFRP vessels. An attempt is made on the fifth hardware to predict its burst pressure. This innovative methodology illustrates the behaviour of GFRP pressure vessels in terms of AE parameters and its derivatives. This can possibly predict in real time the burst pressure of similar hardware if extended to other material systems. The failure is significant even at 50 to 60% of Maximum Expected Operating Pressure (MEOP) with an acceptable error margin.