| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 98 === This thesis discusses the measurement results using a laboratory-made P(VDF-TrFE) analysis ultrasonic transducer and the analysis data predicted by angular spectrum theory. Traditional focusing ultrasound transducer gives only one voltage signal by integrating all received wave signals on the surface of a piezoelectric material. This integration process destroys some important information in the ultrasound field. In this thesis, a PZT/PVDF hybrid ultrasound focusing transducer is proposed, fabricated, and experimentally tested. This new type ultrasound transducer contains a number of independent PVDF hydrophone elements on the concave spherical surface of the transducer. Each PVDF element can recording the back-scattered wave signal reflected and scattered by a sample, and therefore can be used to analyze the back-scattered ultrasound field and derive useful information about the sample. For understanding the performance of this new transducer, angular spectrum theory is used to calculate the reflection signal which is reflected from a sample. The theoretical or predicted signal waveforms on each PVDF element are then compared with their experimental counterparts. Good agreement is observed. By observing the reflected signal waveforms, it is possible to recognize the angular refection coefficients of a sample and identify the material properties of the sample. It demonstrates the potential in non-destructive evaluation of this new analytical transducer.
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