圓錐殼結構振動分析

Abstract

本文目的在討論圓錐殼結構之振動，尤其探討同心圓頻率，其特點為環狀波數為1。若於等向性圓錐殼下緣施予力量1Nt、1k~10k Hz之寬頻雜訊，所產生頻率域反應的尖峰值皆由同心圓頻率所主導。故本文在改變圓錐角、斷面形狀、邊界條件、材料係數的情況下，討論其頻率值與振動模態的變化。 圓錐殼力學理論將考慮厚度方向的剪力，使分析能適用於較厚的圓錐殼結構；有限元素部份，將利用套裝軟體MSC NASTRAN來分析。實驗結果顯示理論預測的正確性；材料性質對圓錐殼結構的影響亦被討論之。複合材料圓錐殼結構能達成許多等向性材料所無法達成之性能，本文將對複合材料圓錐殼與等向性圓錐殼之數值解與實驗做比較。

In this thesis, vibration characteristics of the conical shell structures are studied, especially the characteristics of concentric modes with circumferential wave numbers equaling to one. For given edge loads, modal characteristics and responses in frequency range from 1k Hz to 10k Hz are determined for different shell structures. The changes of the modal frequencies and mode shapes are presented with different conical angles, profiles, boundary conditions, and material constants. In analyzing thicker conical shells, shear along the thickness direction is considered based on the first-order shear deformation. The finite element analysis of the shell structures is achieved using the commercial code MSC NASTRAN. Experiments have been performed to verify the accuracy of the theoretical predictions. The effects of material properties on the behaviors of the shell structures have also been studied. It has been found composite conical shells have different behaviors from the isotropic ones. Both theoretical and experimental results on isotropic and composite conical shells are given for comparison.