具缺陷週期結構之波傳主動控制分析

Control of Wave Propagation in Periodic Structures Having Defects

本文研究具缺陷週期結構之波傳特性，利用有限元素法與轉移矩陣法，相互配合分析，對於週期性含缺陷結構進行波傳特性分析。首先比較完美的週期結構，與含缺陷的週期結構，兩者之間頻溝變化，接下來改變缺陷之幾何參數、材料參數，觀察系統之頻溝的改變。由於週期結構裡的形狀記憶合金會隨著溫度的改變而改變它的材料參數，所以本文也針對形狀記憶合金的特性，改變溫度去探討觀察頻溝的變化。希望藉由本文的分析，控制缺陷的幾何、材料參數、溫度，可發展出比單純週期結構還要更優越的濾波能力。 In this study, the influence on wave propagation of periodic structures having defects is investigated. Defects are used in periodic structures to study the unique characteristics of wave propagation in a periodic system. A structural rod model is developed to study the problems of one-dimensional periodic structures with defects. A finite element model and a transfer matrix method are developed to study these problems to predict the performance of the system; moreover, a shape memory alloy (SMA) is used to control the characteristics of the system. The behaviors of the periodic structure are evaluated at different length ratios and material properties of the defects. The effects of the SMA when applied at various temperatures are also discussed. The location and width of stop bands can be changed with different configurations of the additional defects.