Transverse Horizontal Guided Wave Transducers Using Face Shear Piezoelectric Fiber Composites

• Main Authors: Chiang, Yu, 江宇
• Other Authors: Yin, Ching-Chung
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/pg6q73

碩士 === 國立交通大學 === 機械工程系所 === 105 === Piezoelectric fiber composites (PFC) are in the sandwiched configuration. The core material is made of parallel piezoelectric fibers embedded in epoxy resin; face shear deformation is of difficulty to induce therein. This thesis presents a novel face shear PFC device to generate transverse horizontal plate waves by applying an alternating electric field along the piezoelectric fibers which were transversely poled. Such piezoelectric fiber composites are abbreviated as TH-PFC. The sensing and actuating performances of TH-PFC were verified through numerical and experimental investigation. Dimensions of the PFC device measured by metallographic examination are used in the thereafter numerical analysis. An appropriate working condition for transverse poling is found by numerical study based on the strain monitoring data during axial poling along the fibers. The single ply TH-PFC transducers of 4.48 mm wavelengths are designed and manufactured in the laboratory, and can effectively excite and sense both TH0 and TH1 modes in one mm thick aluminum plates. The transverse horizontal plate wave signals are in high quality. The TH0 modes can be generated by the transducers at two separate resonant frequencies. Single-side excitation induces the TH1 mode with a stronger response than double-side excitation. For TH0 mode, larger responses are usually actuated by double-side excitation. The radiation field launched by a TH-PFC attached to the aluminum plate was examined numerically. It is found that the transducer can excite both TH waves and Lamb waves. High response TH0 modes are induced in front of the transducers; side lobes cannot be ignored. Smaller A0 and S0 modes can be yielded at the orientations of 10o、22o. Attenuation measurement has been conducted, and it reveals that the TH0 mode excited at 0.42 MHz has a low attenuation coefficient of 3.3 Np/m. The non-dispersive TH0 modes have been shown to have a good potential for long distance inspection.