| Summary: | 碩士 === 國立成功大學 === 奈米科技暨微系統工程研究所 === 96 === The thesis investigates the generation of Lamb waves on PVC (Polyvinyl chloride) substrates using current-induced Lorentz force. Standard LIGA (Lithographie GaVanoformung Abformung) process was used to fabricate single and double side meander line structures which have line width around 0.6~1 mm on PVC substrates. The meander line structure was placed under a transverse permanent magnetic field and was excited by an alternative current which has a specific frequency. Then the longitudinal Lorentz force was generated to excite symmetric and anti-symmetric modes of Lamb waves.
Through Lamb wave theorem, a meander line structure with a specific line width was designed to excite a specific frequency of Lamb wave. In anti-symmetric mode, the resonate frequency of meander line structure with a line width of 0.6 mm, 0.8 mm and 1 mm was 82, 125 and 225 kHz, respectively. In symmetric mode the resonate frequency was 520 kHz at line width of 1 mm. Conical transducer which had the advantage of a point sensing area was use to measure the vibration signal of Lamb wave on different point of the PVC substrates. The Spectrum Analysis Surface Wave (SASW) method was used to analyze the received data to verify the wave velocity of anti-symmetric and symmetric modes. Through the comparison between experimental and theoretical wave velocity, the thesis prove the Lamb wave could be excited by Lorentz force induced by an electrical current in meander line structures.
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