Progress |
Spoolable composite
tubes were acquired from Hydril (courtesy of Thomas J. Walsh.)
Ultrasonic inspection
station has been assembled. Four-point bending test setup and a setup for
controlled impact of pipe were manufactured. A real-time data analysis
algorithm was developed to invert ultrasonic time domain signal to the
properties of the individual composite layers of the filament wound
Spoolable tube. A modification of Habibi-Ashrafi and Mendel suboptimal
maximum-likelihood parameter estimator was developed. It consists of two
filters connected in series: a matched filter to treat noise; and a
transversal equalizing filter to correct for wavelet overlapping effects. An
optimization of the transversal equalizing filter has been performed to
increase numerical stability of detection. For medium and high noise levels,
section methods remained stable, although a number of false boundaries were
found. Automatic defect classification algorithm was developed. The
algorithm automatically recognizes, identifies, and classifies defects of
different types using the pulse-echo technique, dramatically reducing
inspection time. The classification process extracts several features from
the time and frequency domain responses of the ultrasonic echo signals and
attribute position in feature space to the probability of different
practical defects (for instance voids, cracks, delaminations, etc.)
appearing in composite tubes during manufacturing and in service.
Non-contact acoustic emission monitoring during tubular spooling is under
development. The final detailed
results are not available from MMS |