ACOUSTIC
EMISSION & NDT SCIENTIFIC PUBLICATIONS
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.