Acoustic Emission for periodic inspection of composite wrapped pressure vessels


To appear in the proceedings of Emerging Technologies in NDT, Held 26-28 May 2003, Thessaloniki, Greece

M.A., R.D.Finlayson, V.Godinez-Azcuaga, S.J.Vahaviolos, P. Cole, A. Anastassopoulos


Type 3 composite cylinders are used by the U.S. Navy to store compressed gases. The recertifi-cation procedure for these cylinders requires a hydrostatic test and an internal visual inspection every five years.Physical Acoustics Corporation has developed an AE based test method for the periodic inspection of thesecylinders. AE baseline tests were performed on over fifty “good” cylinders and damage and/or fatigue cyclingwas introduced in fourteen cylinders. After damage and cycling the cylinders were tested again, which resultedin a dramatic increase in AE activity compared to that prior to the damage. The most active cylinders were alsohydrostatically tested. No cylinders failed this test. However, a subsequent burst test showed a substantiallydecreased burst pressure for the AE active cylinders. A consistent correlation between burst pressure and AEactivity was observed. An accept/reject criterion was developed to differentiate those cylinders with acceptableburst strength from those with unacceptable burst strength.