Exploratory Development for a High Reliability Flaw Characterization Module.
Final rept. 31 Aug 81-31 Jan 85,
SOUTHWEST RESEARCH INST SAN ANTONIO TX
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Two sets of ultrasonic characterization procedures were applied under blind test conditions to 42 manufacturing flaws inclusions and voids embedded in titanium and IN100 alloy specimens. The Born inversion procedures BIP resulted in size estimates that were independent of not only flaw composition, but also shape, size, and orientation. Instead, the Born diameters were determined to be directly related to the period of the incident wave. For this reason, the BIP results could not be reproduced with different transducers. The Born inversion algorithm correctly treats the first half-cycle of the impulse response of a volumetric flaw as the front-surface echo, but mistakes its third half-cycle for a back-surface internal satellite pulse or a creeping-wave return external satellite pulse. The characterization procedures based on the satellite-pulse observation technique SPOT proved to be insensitive to the period of the employed high-frequency transducers and, as expected, the practically constant separation between the front-surface echo and the satellite pulse was found to be directly related to flaw size. Semiautomated satellite analysis procedures SSAP that waive the requirement for a highly trained ultrasonic examiner were developed and qualified on 32 test flaws. Keywords include Nondestructive evaluation, Quantitative flaw characterization, Ultrasonic scattering, Born inversion, Internal bulk flaws, Satellite pulses.
- Test Facilities, Equipment and Methods