- 學位論文
夾持效應模擬與基座激振懸臂樑之振動分析
Simulation of Clamped Effect and Vibration Analysis of Base Excitation Cantilever Beam
摘要
本研究旨在結合實驗模態分析與有限元素分析進行模型驗證確認固定邊界基座激振懸臂樑等效分析模型，並以此等效分析模型之響應預測與實驗結果進行振動特性比較。首先振動分析理論回顧以簡單回顧介紹了振動名詞、振動量測設備以及振動特性。於基座激振懸臂樑結構分析，主要以堆疊概念由自由邊界單一零組件進而到組合結構進行模型驗證與夾持效應模擬驗證，其第一個構成的組件為有、無加速規自由樑有限元素分析模型，並進行驗證確認加速度規、自由樑有限元素分析模型之幾何、材料參數等效性，接著以簡化固定邊界懸臂樑有限元素分析模型進行探討夾持邊界模擬的可行性，最後以懸臂樑與基座所構成之完整組合結構進行模擬實際的固定邊界；結果顯示基座激振懸臂樑之等效分析模型進行了多個響應預測，且響應預測結果具有相當可信度；其中，於實驗觀察與響應預測模擬結果顯示出一些振動特性，如共振現象、多重簡諧激振、掃描頻率之簡諧激振以及質塊對自然頻率影響之振動特性。本文進行了振動分析於響應預測與實驗觀察，兩者可搭配進行振動教學示範，並可以本文的振動教案回饋學界與業界，使學習者能快速、有效的學習振動基礎理念。
並列摘要
This work aims to integrate experimental modal analysis (EMA) and finite element analysis (FEA) to validate the finite element model for the cantilever beam structure subject to base excitation as well as the clamped boundary. The validated analytical model can then be used to predict the structural response compared with the experimental observation for vibration characteristics. First, theoretical vibration analysis is briefly reviewed by introducing some terminologies, vibration characteristics and equipments in vibration measurement. The base excitation cantilever beam structure is then analyzed by accumulating the components from free boundary to assembly structure. The finite element model can be performed model verification to validate the simulation of clamped boundary effect. The finite element model for the free-free beam is first constructed including with or without the mass effect of accelerometer and verified for calibrating the geometry and material parameters. A simple fixed boundary condition for the clamped beam is also studied for its quick solution in simulating the clamped boundary. Finally, the complete assembly structure including the beam and base structure is built to simulate the practical clamped end boundary. Results show the equivalent model for the base excitation cantilever beam can be well validated and applied to other response prediction case studies. In comparison to experimental observation, the simulation results are shown to demonstrate some vibration characteristics, such as resonant phenomenon, multiple harmonic excitations, swept sine excitation and the mass effect on structure. This work carries out the vibration analysis for theoretical response prediction as well as experimental observation that can be integrated for vibration demonstration. This work shows the efficient and effective vibration instruction kits that will be beneficial to the academic and industrial applications, in particular for the learning of vibration.