The chirp-Z transform applied to adhesively bonded structures |
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Authors: | Nair V.K. Ludwig R. Anastasi R.F. |
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Affiliation: | Dept. of Electr. Eng., Worcester Polytech. Inst., MA; |
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Abstract: | A signal-processing technique based on the chirp-Z transform is presented to evaluate the echo signals of longitudinal ultrasonic transducers in contact with bonded materials. Both a simulated glass-glass interface of variable thickness and a realistic double lap bonded aluminum sample were tested. The observed frequency dips and peaks in the transducer spectrum from pulse-echo and through-transmission modes were recorded and related to the condition of zero reflection coefficient at the interfacial layer. Resulting thickness predictions for different transducer center frequencies ranging from 5-20 MHz are in excellent agreement with experimental measurements |
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