臺灣博碩士論文加值系統

本文主要研究長形高功率揚聲器之加勁方式對聲音傳遞的影響。以相同面積下考量下，長形的揚聲器比圓形的揚聲器要來的容易利用空間。但對長形揚聲器而言，在中音域會產生一聲壓落差，影響聲傳表現，因此本文透過適當的加勁方式增加揚聲板的剛性，以改善揚聲器聲壓落差問題。本文可為二部分，第一部分，以”Rayleigh-Ritz Method”與”有限元素分析軟體ANSYS”互相驗證揚聲器之自然頻率與聲壓曲線，再以實驗驗證ANSYS模型，建立一套完整的分析方法。第二部分，利用”有限元素分析軟體ANSYS”，分析揚聲器較適當的加勁方式及分析較理想的揚聲板以及碳纖材料的常數，以達到延後中音谷頻率與提升揚聲板剛性。

This paper is focused on the sound radiation behavior of stiffened sound radiation panels for flat-panel loudspeaker. If the sound radiation panel is not properly design, it is easy for a flat-panel speaker to have a significant sound pressure drop in the mid-frequency range, which may affect the sound quality of the speaker. To suppress or even eliminate the sound pressure drop, this thesis attempts to enhance the rigidity of the plate by using an appropriate stiffening method. There are two parts in this thesis. In the first part, a Rayleigh-Ritz Method is constructed to analyze the sound radiation behavior of stiffened sound radiation panels. The results obtained using the proposed Rayleigh-Ritz Method are compared with those obtained from the finite element software ANSYS. It has been shown that the natural frequencies and the sound pressure level (SPL) curves produced by the proposed method are in good agreement with those produced by ANSYS or experiments. In the second part, ANSYS is used to find the appropriate stiffening pattern for designing the sound radiation panel and the ideal material constants of the panel so that the major sound pressure drop in the mid-frequency range can be suppressed.

目錄
中文摘要 I
英文摘要 II
誌謝 III
目錄 IV
表目錄 VII
圖目錄 IX
第一章 緒論 1
1-1 前言 1
1-2 文獻回顧 2
第二章 具彈性支承複合材料加勁平板推導方法 4
2-1複合材料加勁板數學模型 5
2-2應用理論基本假設 5
2-2-1古典平板基本假設 5
2-2-2 簡易梁理論其基本假設 5
2-3 基層振動板 6
2-3-1 平板的位移場與應變 6
2-3-2 平板的應力與應變關係 7
2-3-3 平板的應變能與動能 9
2-4 附加於平板上之音圈 10
2-4-1 音圈位移場與應變 11
2-4-2 音圈應力與應變關係 11
2-4-3 音圈的應變能與動能 12
2-5 附加於平板上下之碳纖 16
2-5-1 碳纖位移場與應變 16
2-5-2 碳纖應力與應變關係 17
2-5-3 碳纖的應變能與動能 17
2-6 平板邊界彈性支撐的應變能 21
2-7 瑞雷－里茲法(RAYLEIGH-RIZE METHOD) 22
2-8 特徵值與特徵向量 24
2-9 揚聲器結構之KM矩陣 25
2-10 受外力的振動系統 27
第三章 有限元素分析與聲壓計算 29
3-1 ANSYS有限元素模型之建立 29
3-1-1 懸邊之模型建立 29
3-1-2音圈、碳纖之模型建立 30
3-2 ANSYS模擬分析中各參數的取得 30
3-2-1 材料常數的給定 30
3-2-2 質點元素的參數 31
3-2-3 彈簧元素的參數 31
3-2-4 激振力的給定 31
3-2-5 阻尼比的給定 32
3-3 ANSYS模型建立步驟 33
3-4 聲壓的計算及應用 35
第四章 製作及實驗程序 37
4-1 平面揚聲器之各項組件製作 37
4-1-1 複材振動板之製作 37
4-1-2懸邊之製作 37
4-1-3音圈、激振器、框架及治具 38
4-2 揚聲器之組裝流程 38
4-3 揚聲器各項實驗程序 38
4-3-1 阻尼量測實驗 38
4-3-2 聲壓量測實驗 39
4-3-3 阻抗量測實驗 40
4-3-4 單體參數量測實驗 40
第五章 結果與討論 42
5-1 理論分析與實驗結果 42
5-1-1 音圈簡化模型之自然頻率驗證 42
5-1-2 Rayleigh-Rize method與ANSYS分析之自然頻率驗證 42
5-1-3 Rayleigh-Rize method與ANSYS分析之聲壓驗證 43
5-1-4 ANSYS分析與實驗之聲壓結果 43
5-2 ANSYS分析設計揚聲器加勁方式 44
5-2-1 聲壓落差的原因 44
5-2-2 常用的加勁方式 45
5-2-3 不同的加勁方式比較 45
5-2-4 改變「加勁組號3」之尺寸對聲壓的影響 46
5-2-5 選出較適當的加勁方式 47
5-3 ANSYS設計分析揚聲板、碳纖材料常數 48
第六章 結論與未來研究方向 50
6-1 結論 50
6-2 未來研究方向 51
參考文獻 52

參考文獻
1. J. N. Reddy, “Energy and Variational Methods in Applied Mechanics”, Applied Mathematical Modelling, 1984.
2. R. D. Mindlin, “Influence of Rotatory Inertia and Shear Deformation on Flexural Motion of Isotropic Elastic Plates”, J. Applied Mechanics, Vol. 18, pp.33-38, 1951.
3. J. N. Whitney, “Shear Correction Factor Laminates Under Static Load”, J. Applied Mechanics, Vol. 40, pp.302-304, 1973.
4. J. M. Whitney, “Stress Analysis of Thick Laminated Composite and Sandwich Plates”, J. Applied Mechanics, Vol. 40, pp.302-304, 1973.
5. E. Reissner, “Finite Deflection of Sandwich Plates”, J. Aeronaut. Sci., pp.435-440, 1948.
6. D. J. O’Connor, “A Finite Element Package for the Analysis of Sandwich Construction”, Compos. Struct., Vol. 8, pp.143-161, 1987.
7. H. H. Kanematsu, Y. Hirano and H. lyama, “Bending and Vibration of CFRP-Faced Rectangular Sandwich Plates”, Compos. Struct., Vol. 10, pp.145-163, 1988.
8. L. Dozio, H. M. Ricciardi, “Free vibration analysis of ribbed plates by a combined analytical-numerical method”, Journal of Sound and Vibration, Vol. 319, pp.681-697, 2009
9. K. Satoh, H. Takewa and M. Iwasa, “A High Fidelity Small-Size Loudspeaker”, IEEE Transactions on Consumer Electronics, Vol. 43, 1997.
10. P. M. Morse and K. U. Ingrad, “Theoretical Acoustics”, McGraw-Hill, NY, 1968, rpt. Princeton University Press, NJ, pp. 375-379, 1986.
11. T. Shindo, O. Yashima and H. Suzuki, “Effect of Voice-Coil and Surround on Vibration and Sound Pressure Response of Loudspeaker Cones”, Journal of the Audio Engineering Society, Vol. 28, pp.31-51, 1997.
12. S. Li and X. Li, “The effects of distributed masses on acoustic radiation behavior of plates”, Applied Acoustics, Vol. 69, pp.272-279, 2008.
13. 陳建儒, “具附加質量長形平面揚聲器之最佳化設計”, 國立交通 大學 , 機械工程研究所碩士論文 , 新竹市 , 2008.
14. S. L. Moyne , J. L. Tebec and I. Tawfiq , “Acoustical Influence Of Stiffeners on Acoustic Radiation of Plates”, Mechanical Systems and Signal Processing, Vol. 19, pp.195-212 , 2005.
15. Y. Qiao and Q. Huang , “The Effect of Boundary Conditions on Sound Loudness Radiated from Rectangular Plates”, Archive of applied Mechanics, Vol. 77, pp.21-34, 2007.
16. D. Robert , “formulas for natural frequency and mode shape” ,Van Nostrand Reinhold Company ,Inc.Reprinted by Arrangement ,New York ,1979.
17.Z. Ding ,J. Tianjian, “Free vibration of rectangular plate with continuously distributed spring-mass” ,International Journal of Solid and Structures, Vol. 43,pp.6052-6520,2006
18. C.R. Lee, T.Y. Kam, “Identification of mechanical properties of elastically restrained laminated composite plates using vibration data”, Journal of Sound and Vibration 295,999–1016, 2006
19. H. Reismann, P. S. Pawlik, “Elasticity theory and applicayions” ,A
Wiley-Intersience Publication, 1980