The Optimization of Band Gap in Phononic Crystal and Acoustic Rectification Design using Genetic Algorithm

• Main Authors: Chi-WeiLiu, 劉紀緯
• Other Authors: I-Ling Chang
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/fg4cb8

碩士 === 國立成功大學 === 機械工程學系 === 107 === In this study, genetic algorithm is adopted to carry out the topology optimization of phononic crystal (PnC) plate with the maximized relative band gap between two prescribed consecutive dispersion branches. This method is to design the periodic structures with broadband and low frequency band gaps, and then comparing the results with round hole-type PnC’s. Finally, we preliminarily designed for the acoustic diode by using the partial band gaps of the round hole-type one. In three-dimensional model, it is more difficult to find the complete or even the partial band gap than the two-dimensional one, so some strategies are used to analyze the band structure. For round hole-type, we classify the dispersion band by the characteristics of the displacement field of different Lamb wave propagation modes. For band gap optimization, it is useful to filter out the non-Lamb wave modes by simplifying the simulation model into plane stress. At the same time, it also reduces a large amount of computing resource, which is beneficial for the optimization of genetic algorithm. In experimental measurement, we utilize the PZT transducer to measure the SS304 plate with PnC structures. The decrease of transmittance on band gaps can be found in measurement results, which is consistent with simulation results. Based on this research, we can build a set of procedures and analysis methods for the optimization of PnCs, which can be treat as a basis for the design of PnC plate components in the future.