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研究生:洪慶良
研究生(外文):Ching-liang Hung
論文名稱:隨機振動在樑結構破壞偵測之應用
論文名稱(外文):THE APPLICATION OF RANDOM VIBRATION IN BEAM STRUCTURAL DESTRUCTION INSPECTION
指導教授:曾世雄曾世雄引用關係
指導教授(外文):Shin-Shong Tseng
學位類別:碩士
校院名稱:國立高雄應用科技大學
系所名稱:土木工程與防災科技研究所
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:2003
畢業學年度:91
語文別:中文
論文頁數:79
中文關鍵詞:隨機振動共振頻率模態分析
外文關鍵詞:random vibrationresonancefrequencymodel analysis
相關次數:
  • 被引用被引用:1
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在土木工程中各種結構物都有其自然頻率,當外界激振頻率接近結構物之自然頻率時,即發生共振(resonance)且當結構體老化,損傷時其自然頻率、加速度等皆有不同之變化,在各種載重及地震力的破壞模式下,常有樑破壞的情況發生,如何迅速有效的偵測結構使用的現況和評估安全性將是我們急需開發及研究的課題。
本文主要以傳統模態分析方法從事結構非破壞檢測,探討結構有缺陷產生時,結構在自然頻率及模態振型上之變化特性,並嘗試由各點量測訊號的響應值去預測缺陷發生之位置。
吾先以有限元素分析軟體分別求出中空鋁樑與RC樑的自然頻率與模態振型的近似解,然後再進行模態實驗。
本文使用鋁樑及RC樑分析量測其缺陷前後之響應,並嘗試去求得缺陷位置
以有限元素分析部份,在樑有缺陷發生時隨著缺陷的加深,自然頻率有隨著下降的趨勢,且在缺陷發生位置其樑振型曲線出現不連續之現象。
樑振型而言,其缺陷前後模態振型自然頻率變化最大的模態數,由各量測點之響應值與未缺陷之量測值比較差異百分比,再由各差異百分比去比較相鄰兩點間之差異則相鄰兩點間之變化最大處為缺陷可能位置,但經由各測點頻率響應值差異百分比顯示,若使用此法去發現缺陷位置,似乎乃有疑慮,且可能造成誤判。
就各模態振形而言可將各振型逐一放大其振幅,可直接由模態振型的不連續看出缺陷可能之位置。
In civil engineering different structural bodies have their own natural frequencies. As the excitation frequency outside is close to the natural frequency of a structural body, resonance happens. And with the aging and damaging of the structural body, its natural frequency and acceleration, etc. will vary accordingly. Under the destruction model of various loads and earthquake forces, destruction of beam happens all the time. How to detect the current situation of structural use speedily and effectively and how to evaluate the safety are the issues we urgently need to develop and study.
The research paper primarily adopts traditional model analysis to engage in structural non-destruction inspection, and then investigates the variation characteristics of the natural frequency and mode shape of structure as there is a defect happened in the structure, and attempts to use the response values of the measured signals of various points to forecast the position where defect happens.
First of all, the researcher uses finite element to analyze the software, and thus finds out the approximate solutions of the natural frequencies and mode shapes of hollowed aluminum beam and RC beam, and then carries out mode experiment.
The research paper uses aluminum beam and RC beam to analyze and measure the responses before and after the defect, and tries to find out the position of defect. As for the part of analysis by finite element, when a defect is found on beam, and as the defect is deepening, the natural frequency tends to fall. And at the position the defect happens, its beam shape curve appears to be non-continuous.
When speaking of the beam shape, the greatest alteration of natural frequency of the mode shape before and after the defect is the model value. Compare the difference percentage between the response values of various measure points and measure values before the defect. Then compare the difference between the two adjacent points by using various difference percentages, then the place with the greatest variation between two adjacent points is the possible position of the defect. However, as shown from the difference percentages of the frequency response values of various measure points, if this method is adopted to find out the position of defect, it seems that there are doubts existed, and misjudgment might be caused.
When speaking of various mode shapes, the amplitude of each of the shapes can be magnified one by one. Then the possible position of the defect can be seen directly from the non-continuous mode shape.
目錄
中文摘要------------------------------------------------------------------------------------------Ⅰ
英文摘要------------------------------------------------------------------------------------------------Ⅱ
誌謝------------------------------------------------------------------------------------------------------Ⅳ
目錄 -----------------------------------------------------------------------------------------------Ⅵ
表目錄----------------------------------------------------------------------------------------------Ⅶ
圖目錄----------------------------------------------------------------------------------------------Ⅷ
第一章 緒論-----------------------------------------------------------------------------------------1
1-1 前言---------------------------------------------------------------------------------------1
1-2 文獻回顧---------------------------------------------------------------------------------1
1-3 本文目的---------------------------------------------------------------------------------5
第二章 研究內容與方法--------------------------------------------------------------------------6
2-1 研究方法---------------------------------------------------------------------------------6
2-1-1 ANSYS分析簡介---------------------------------------------------------------------6
2-1-2 ANSYS基本架構---------------------------------------------------------------------6
2-1-3 模態分析-------------------------------------------------------------------------------7
2-2 研究內容----------------------------------------------------------------------------------8
第三章 相關理論-----------------------------------------------------------------------------------9
3-1 樑動力分析理論-------------------------------------------------------------------------9
3-2 模態分析理論---------------------------------------------------------------------------13
3-3 隨機振動---------------------------------------------------------------------------------------17
3-4時域採樣定理及疊混現象(Aliasing)-------------------------------------------------------20
3-5泄漏與加窗-------------------------------------------------------------------------------------20
3-6頻率嚮應函數的估計-------------------------------------------------------------------------21
第四章 實驗部份----------------------------------------------------------------------------------23
4-1 實驗儀器----------------------------------------------------------------------------------23
4-2 試體制作及架設-------------------------------------------------------------------------24
4-3 儀器設定----------------------------------------------------------------------------------25
4-4 實驗步驟----------------------------------------------------------------------------------27
4-5 量測中注意事項-------------------------------------------------------------------------28
4-6 量測值比較-------------------------------------------------------------------------------29
第五章 結論與建議------------------------------------------------------------------------------31
參考文獻----------------------------------------------------------------------------------------33
附錄:樑振動模態圖-----------------------------------------------------------------------------72
表目錄
表1訊號量測儀器-------------------------------------------------------------------------------35
表2實驗組別-------------------------------------------------------35
表3簡支中空鋁樑材料性質-----------------------------------------35
表4 RC簡支樑材料性質----------------------------------------------36
表5使用儀器型號覽表-----------------------------------------------36
表6鋁樑量測值與理論值(未切)-----------------------------------------------------------37
表7鋁樑量測值與理論值(切1cm寬,0.2cm深)------------------------------------------37
表8鋁樑量測值與理論值(切1cm寬,2.55cm深)----------------------------------------37
表9 RC樑量測值與理論值(未切)---------------------------------------------------------38
表10 RC樑量測值與理論值(切1cm寬,1cm深) -----------------------------------------38
表11 RC樑量測值與理論值(切1cm寬,3cm深) -----------------------------------------38
表12鋁樑不同切割深度阻尼比(應變計量測值)-------------------------38
表13鋁樑不同切割深度阻尼比(加速規量測值)-------------------------39
表14 RC樑不同切割深度阻尼比(應變計量測值)------------------------39
表15 RC樑不同切割深度阻尼比(加速規量測值)------------------------39
表16簡支鋁樑理論值與實驗值加速規值(未切割)--------------------------39
表17簡支鋁樑理論值與實驗值應變計值(未切割)-----------------------39
表18加速規量測值(切割0.2cm 深1cm寬)----------------------------40
表19應變計量測值(切割0.2cm深1cm寬)-----------------------------40
表20加速規量測值(切割2.55cm深1cm寬)----------------------------40
表21應變計量測值(切割2.55cm深1cm寬)----------------------------40
表22 RC簡支樑理論值與實驗值(加速規)----------------------------40
表23加速規量測值(切割1cm深1cm寬)----------------------------41
表24加速規量測值(切割3cm深1cm寬)-----------------------------41
表25應變計量測值(未切割)---------------------------------------41
表26應變計量測值(切割1cm深1cm寬)-----------------------------41
表27應變計量測值(切割3cm深1cm寬)-----------------------------41
圖目錄
圖1 結構振動分析步驟流程-----------------------------------------------------------------42
圖2 模態測試分析流程圖--------------------------------------------43
圖3 實頻圖與虛頻圖------------------------------------------------------------------------44
圖4 簡支樑量測點位放樣圖-------------------------------------------44
圖5 RC樑斷面圖-------------------------------------------------------45
圖 6 BEAM3有限元素模型分割--------------------------------------------45
圖7 試體樑採用加速規量測架設示意圖---------------------------------46
圖8 試體樑採用應變計量測架設示意圖--------------------------------47
圖9 RC梁模態量測實體圖----------------------------------------------47
圖10 輸入之時域訊號---------------------------------------------------------------------------48
圖11 為輸出所接收到之時域訊號,下為輸出之自功率頻譜-----------------------------48
圖12 頻率反應函數圖,因果函數圖-----------------------------------------------------------49
圖13 量測點頻率反應函數圖------------------------------------------------------------------49
圖14 頻率反應函數圖曲線崁和------------------------------------------50
圖15 試體樑激振位置--------------------------------------------------50
圖16 SIGLAB 訊號分析儀-----------------------------------------------51
圖17 RC樑切口缺陷處---------------------------------------------51
圖18 量測訊號圖----------------------------------------------------------------------------------52
圖19 加速規: 未切vs切0.2cm(粗線切)-------------------------------------------------52
圖20 加速規: 未切vs切2.55cm(粗線切)---------------------------------------------52
圖21 應變計: 未切vs切2.55cm(粗線切)----------------------------------------------53
圖22應變計:未切VS切2.55cm(粗線表示切割後) ---------------------------------------53
圖23 加速規:RC樑未切vs切1cm(粗線切)------------------------------------------53
圖24 加速規:RC樑未切vs切2.55cm(粗線切)--------------------------------------54
圖25 應變計:RC樑未切vs切1cm(粗線切)---------------------------------------------- -54
圖26應變計:RC樑未切vs切2.55cm(粗線切)--------------------------------------54
圖27鋁樑mode1量測點響應相鄰差異百分比(加速規)-----------------------55
圖28鋁樑mode1量測點響應相鄰差異百分比(加速規)-----------------------55
圖29 鋁樑mode1量測點響應相鄰差異百分比(應變計值)-------------------------------56
圖30 鋁樑mode1量測點響應相鄰差異百分比(應變計值)-------------------------------56
圖31 鋁樑缺陷前後旋轉角差異百分比(mode1)--------------------------------------------57
圖32 鋁樑缺陷前後旋轉角差異百分比(mode2)--------------------------------------------57
圖33 RC樑mode1量測點響應相鄰差異百分比(加速規值)-------------------58
圖34 RC樑mode1量測點響應相鄰差異百分比(加速規值)-------------------58
圖35 RC樑mode1量測點響應相鄰差異百分比(應變計值)-------------------59
圖36 RC樑mode1量測點響應相鄰差異百分比(應變計值)-------------------59
圖37 FEM值(鋁樑切0.2cm,mode1)-------------------------------------------------60
圖38 FEM值(鋁樑切0.2cm,mode2)-------------------------------------------------60
圖39 FEM值(鋁樑切0.2cm,mode3)--------------------------------------------------61
圖40 FEM值(鋁樑切2.55cm,mode1)------------------------------------------------61
圖41 FEM值(鋁樑切2.55cm,mode2)-------------------------------------------------62
圖42 FEM值(鋁樑切2.55cm,mode3)------------------------------------------------62
圖 43 FEM 值(RC樑切1m,mode1)---------------------------------------------------------63
圖44 FEM值(RC樑切3cm,mode1)--------------------------------------------------63
圖 45 RC樑未切旋轉角FEM值--------------------------------------------------------------64
圖46 RC樑切1CM旋轉角FEM值----------------------------------------------------------64
圖47RC樑切3CM旋轉角FEM值-----------------------------------------------------------65
圖48鋁樑未切旋轉角MODE1FEM值------------------------------------------------------65
圖49鋁樑未切旋轉角MODE2 FEM值-----------------------------------------------------66
圖50鋁樑未切旋轉角MODE3 FEM值---------------------------------------------------66
圖51鋁樑切0.2CM旋轉角MODE1 FEM值--------------------------------------------67
圖52鋁樑切0.2CM旋轉角MODE2 FEM值--------------------------------------------67
圖53鋁樑切0.2CM旋轉角MODE3 FEM值--------------------------------------------68
圖54鋁樑切2.55CM旋轉角MODE1 FEM值------------------------------------------68
圖55鋁樑切2.55CM旋轉角MODE2 FEM值------------------------------------------69
圖56鋁樑切2.55CM旋轉角MODE3 FEM值------------------------------------------69
圖57 鋁樑加速規量測值(mode1)------------------------------------------------------------70
圖58 鋁樑加速規量測值(mode2)------------------------------------------------------------70
圖59 RC樑加速規量測值(mode1)---------------------------------------------------------71
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