請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51998
標題: | 吉他面板之建構與模擬 Constructions and simulations of acoustic guitar soundboard |
作者: | Che-Hung Lee 李哲宏 |
指導教授: | 王昭男(Chao-Nan Wang) |
關鍵字: | 吉他面板,力木切削,有限元素法,模態分析,結構設計分析, guitar soundboard,brace scalloping,finite element simulations,model analysis,structural design analysis, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 本研究針對吉他面板設計三階段的實驗量測模擬,以了解吉他面板之振動與聲學特性。首先,本文以脈衝激振量測法結合有限元素法計算材料楊氏係數與剪力模數,俾利後續吉他建構模擬等相關使用。接著,本研究以有限元素法建構吉他面板模型,利用模態分析、預應力分析與簡諧響應分析等模擬方式,探討吉他力木結構、腔體大小等面板結構改變對吉他振動與聲學性質之影響。最後,本研究設計實驗量測吉他面板模型之頻率響應,並與前模擬結果趨勢進行比較及討論。 面板為吉他之主要發聲部位,故其之於吉他聲學特性影響顯著。然而吉他面板因其多變之材料性質、面板形狀與力木分布型態,增加面板振動特性之複雜與困難度。此特殊結構設計使有限元素模擬分析成為適合預測面板特性之方法,得以輔助吉他面板結構設計提升效率,亦減少實體測試之時間及成本。 本研究分析發現,不同吉他面板結構改變將對面板振動特性造成不同方式與程度之變化。力木X-brace切削將使低階模態下降,增進吉他之低頻響應;而Tone-brace切削之影響則集中於吉他較高頻率範圍。力木過量的切削,具有大幅減少面板結構強度之趨勢,然而亦有特殊切削組合將減少應力集中進而增進面板結構穩定性之情況,值得深入探討。最後,將面板組裝於吉他後腔體後,腔體耦合空氣將使吉他產生共振增進低頻,不同腔體大小亦對其共振與吉他低階特徵模態頻率造成不同程度影響。結合上述不同現象表徵,本文將提供吉他製琴時較明確之方向,達到輔助吉他調音過程之效果。 The study design three different simulations and experiments to understand the vibrational and acoustical properties of a guitar soundboard. First, the study presents a method using IMT (Impulse Excitation Technique) and FEM (Finite Element Method) to estimate Young's modulus and Shear modulus of wooden material for the guitar soundboard, and the results would employ in further analytical investigations for guitar construction. Next, the study shows a numerical method utilizing FEM to predict acoustic guitar characteristics through model analysis, structural analysis, and frequency response. By modifies the structure design of guitar bracing and body's volume, the study understands how will different soundboard structures influence the guitar soundboard acoustical characteristic. Last, the study designs an experiment to measure the frequency response of a real guitar soundboard model and compares the measurements with previous simulation results. As the primary sounding section of a guitar, soundboard considerably influences guitars acoustic feature. However, the variation among its materials, shapes, and bracing patterns increases the complexity to have a clear understanding of the instrument. The complex designed structure makes FEM be a perfect way to predict the behavior of the soundboard, which will help the soundboard designing process more efficient and reduce the time and cost for experiments. The research discovered that different kinds of structural modifications affect the soundboard vibrational behavior in various ways. X-brace scalloping decreases the frequencies of lower modes, which benefits the lower frequency range response, and tone-brace scalloping is quite the opposite that mainly influences the higher frequency response range. However, overly scallops the guitar bracing may reduce the structural durability of the soundboard, though the study still found some particular cases which will increase the structural stability by spreading the stress more evenly, which is worth the efforts for further studies. Last, joining the side and back to the soundboard of the guitar will not only produce new air resonance to improve low-frequency response but also affect the lower mode frequencies in different degrees depends on its size. This study expects to provide a clearer designing dereliction for guitar making and tuning by employing these discoveries. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51998 |
DOI: | 10.6342/NTU202002655 |
全文授權: | 有償授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
U0001-0708202016584600.pdf 目前未授權公開取用 | 9.22 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。