應用先進光學量測技術探討板結構及避震系統的即時動態實驗結果和其工業應用

Abstract

本篇論文研究目的，主要應用實驗室所開發精密量測技術，包括電子斑點干涉數(ESPI)、光纖光柵感測器(FBG)以及數位影像相關法(DIC)，針對學術研究板結構系統的動態特性，與工業應用所研究懸吊系統避震器的動態特性及Micro LED瑕疵檢測進行深入研究探討，突顯本論文所應用量測技術與傳統量測方法，具有優異且精確的量測結果。 理論分析上，對於厚度呈現階梯變化之固定邊界圓板，運用模態展開法數學方式，將自由振動理論分析所得到的模態形狀，視為圓板暫態位移的基底函數，採用模態形狀正交特性，可分析圓板承載動態外力下所生成暫態的波傳行為。藉由全域光學系統電子斑點干涉術(AF-ESPI) 量測實驗方法，來量測圓板共振模態與頻率，並比較有限元素數值計算、實驗的量測與理論上解析等結果。另一實驗上，也利用壓電薄膜感測器PVDF來量測鋼珠落擊圓板的波源歷時，探討動態外負載與在不同觀察點位置，對於圓板暫態行為之影響，並將波源歷時代入理論的解析解和進行有限元素模擬，並比較實驗的量測結果。 在量測壓電方板實驗研究上，主要參照吳亦莊(107)博士論文依據Mindlin理論推導，應用於分析全自由邊界壓電長方板，分別在彎曲振動與伸展振動主導動態特性的共振頻率及模態分析結果，藉由全域光學系統電子斑點干涉術(AF-ESPI) 實驗來量測共振模態與頻率，並進行有限元素軟體分析壓電板振動時產生的位移場、應力場與電場等模擬結果，進一步探討彼此間關聯性，作為激振壓電板有效方法之參考依據，成功驗證理論分析與實際工程應用具有高度相關性。 本文在實驗部分也著重應用於工業上相關問題的探討，將光纖光柵感測器黏貼於避震器表面進行多點量測，並利用MATLAB軟體所開發的即時訊號分析系統，透過分析計算即時將溫升與熱應變進行解耦合，直接獲得避震器試驗過程中溫升及熱變形歷程，同時與熱電偶與熱像儀進行比較，進而分析得到避震器表面材料的熱膨脹係數，藉由量測避震器各區段熱變形後，可得到避震器作動時整體伸長量，並經由頻譜分析得到避震器作動頻率。本文也將光纖光柵感測器黏貼在彈簧表面量測壓縮彈簧變形量，也藉由MATLAB程式語言開發即時量測系統，針對彈簧系統在各種不同頻率作動下動態行為進行精密且多點變形量測，並以交互相關的方式解析彈簧壓縮過程產生交變應力訊號差異性，可預先診測彈簧系統是否達到損壞或疲勞情況。 本文應用精密量測方法係數位影像相關法(DIC)，應用於量測跨領域與跨尺度工程問題，藉由這個量測技術所量到的結果，與MTS萬能試驗機輸出負載及位移計算彈簧係數進行分析與驗證彈簧係數正確性。也利用數位影像相關法(DIC)進行Micro LED良品與瑕疵品影像辨視檢測與分類，驗證實驗中所開發量測系統可靠性與量測優勢。

The research purpose of this thesis is mainly to apply the experimental measurement technology developed in the laboratory, including electronic speckle pattern interferometry (ESPI)、fiber grating sensor (FBG) and digital image correlation (DIC) for subjects investigated in this study. The dynamic characteristics of the plate system in academic research, the dynamic characteristics of the suspension system shock absorbers of the industrial application research and the defect detection in Micro LED will be analyzed and discussed. The experimental result measurement by the proposed technology is compared with the traditional method and excellent performance is shown in this thesis. This theoretical analysis combined theoretical methods and experimental measurements to investigate the transient behavior of a fixed-boundary circular plate with varying thickness subjected to impact loading. The dynamic displacement, defined as a product of time and spatial functions (mode shapes), formed the basis of the theoretical derivation. The superposition method determined the mode shapes and resonant frequencies of free vibrations, while the orthogonality of the mode functions solved the time function. In the experimental phase, Amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) measured resonant frequencies and precise mode shapes of the circular plate. Comparisons between the theoretical analysis, the finite element method, and experimental measurements validated the accuracy of the theoretical analysis. Experimental PVDF sensors recorded the time history of the external force, which was incorporated into the theoretical analysis to determine transient responses, including displacement and strain. The experimental research of the piezoelectric plate in this thesis is mainly based on the theoretical derivation of Wu Yi-Chuang(107) doctoral dissertation based on Mindlin theory. This technique is applied to analyze the resonance frequency and mode shape of the full-free piezoelectric rectangular plate in the dynamic characteristics of flexural and extensional dominated vibration. Theoretical analysis results, the electronic speckle interferometry (AF-ESPI) experimental measurement of to measure the resonance frequency and modal shape, and the finite element software analysis were presented when the piezoelectric plate vibrates in resourance. To further explore the correlation between each other, as a reference basis for effective methods of exciting piezoelectric plates, this research verify that theoretical analysis is highly correlated with practical engineering applications. This thesis also applies digital image correlation method to the precision measurement of multi-scale and multi-field engineering problems. The measurement results of the digital image correlation and the output load and displacement datas from MTS are used to calculation spring coefficient. According to the DIC measurement results , the correctness of the spring constant is verified. Digital image correlation (DIC) are also used to identify and classify the defect Micro LED.