Dispersion Behaviors of Wedge Wave Propagating in Wedges with Coatings

• Main Authors: Sheng-Wei Tang, 湯盛瑋
• Other Authors: Che-Hua Yang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/67751853556009070145

碩士 === 長庚大學 === 機械工程研究所 === 93 === When microcantilever (MC ) is used as a probe in an atomic force microscope (AFM), it is strongly influenced by the environments. As s result MC was further developed for the applications of physical, chemical and biological sensors. For the past years, various problems regarding to the propagation behaviors of antisymmetric modes (ASF) propagating along wedges has been studied by the author. Further investigation on ASF modes is expected leading towards the development for ASF modes in sensor application. ASF modes are guided waves propagating along the tip of sharp wedges, with energy tightly confined near wedge tips. Wedge waves propagating along isotropic wedges have been studied regarding to the effects of material properties, apex angles, truncations, and curvature of wedge tips. It has been shown that ASF modes propagating along a truncation free wedge is dispersion-free, and has an increasing slope in the dispersion curve while the truncation increases. However, ASF modes propagating in wedges with thin film coatings have not been studied before and have its importance in sensor applications. Regarding to the above-mentioned research, this project proposes a combined numerical and experimental investigations. The investigated parameter include the material properties and geometrical features of wedge, mechanical properties, thickness, and distribution of the film. The numerical part of this research will employ dynamic three dimensional finite element analyses to simulate the dispersion behaviors of ASF modes. On the other hand, a laser ultrasonic technique, including a pulse laser for the generation of acoustic wave, and a laser-based optical acoustic wave detector, is used to provide non-contact, point-wise generation and detection of ASF modes. Finally, results of the finite element simulation will be compared with the experiments as a verification procedure. After that, a parameter study will be conducted to find the influence of all the parameters influence the dispersion behavior of ASF modes. Results of the current study will provide a basics for further the development of ASF-based sensors.