本文選題：小波分析 + 曲率模態(tài)　； 參考：《上海應(yīng)用技術(shù)學院》2015年碩士論文

【摘要】：本文針對橋梁的局部損傷,從模態(tài)分析角度入手,以曲率模態(tài)為基礎(chǔ),以小波分析為手段,利用小波對突變信號敏感的優(yōu)勢,分析曲率模態(tài)信號,依據(jù)分析得到的小波系數(shù)來識別損傷。本文簡單地介紹了曲率模態(tài)理論,利用ANSYS對一簡支梁進行損傷模擬,發(fā)現(xiàn)曲率模態(tài)無法有效識別結(jié)構(gòu)的微小損傷,若將曲率模態(tài)作為判別損傷的指標是不科學的；但是基于損傷區(qū)域剛度減小從而引起曲率發(fā)生變化的理論上可行,所以引入小波,利用小波“數(shù)學放大鏡”的效用進一步挖掘曲率模態(tài)的特征信息。通過模型仿真驗證基于曲率模態(tài)和小波分析的方法的識別效果,分析損傷前后的曲率模態(tài)作信號,對比損傷前后的小波系數(shù)圖,發(fā)現(xiàn)未損傷單元表現(xiàn)平滑,損傷附近的突變明顯。繼續(xù)對簡支梁進行仿真分析,對其損傷的曲率模態(tài)進行多尺度分析,擬合尺度-小波模極大值對數(shù)曲線求出Lipschitz指數(shù),發(fā)現(xiàn)損傷程度與Lipschitz指數(shù)一一對應(yīng)。提出延拓曲率模態(tài)信號的方法進行梁端損傷判別。最后對一實際的單箱單室的人行天橋進行損傷模擬,取得了滿意的識別效果,進一步證明了該方法的理論與實用價值。
[Abstract]:Aiming at the local damage of bridge, this paper starts with modal analysis, based on curvature mode and wavelet analysis, makes use of the advantage that wavelet is sensitive to sudden change signal, and analyzes curvature modal signal. The damage is identified according to the wavelet coefficients obtained from the analysis. In this paper, the curvature mode theory is briefly introduced, and the damage simulation of a simply supported beam by ANSYS is carried out. It is found that the curvature mode can not effectively identify the minor damage of the structure, and it is not scientific to use curvature mode as the index to judge the damage. However, it is feasible to reduce the stiffness of damaged region and cause curvature change, so wavelet is introduced and the characteristic information of curvature mode is further mined by using the utility of wavelet "mathematical magnifying glass". The recognition effect of the method based on curvature mode and wavelet analysis is verified by model simulation. The curvature mode before and after damage is analyzed as signal, and the wavelet coefficient figure before and after damage is compared, and it is found that the undamaged element is smooth. The mutation near the injury is obvious. The simple supported beam is simulated and the curvature mode of the damage is analyzed by multi-scale analysis. The Lipschitz exponent is obtained by fitting the logarithmic curve of the maximum wavelet modulus and the damage degree corresponds to the Lipschitz exponent one by one. An extended curvature mode signal method is proposed to judge the damage at the end of the beam. Finally, the damage simulation of a practical pedestrian bridge with single box and single room is carried out, and the result of identification is satisfactory, which further proves the theoretical and practical value of the method.
【學位授予單位】：上海應(yīng)用技術(shù)學院
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U446

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本文編號：2109327