基于曲率模态和小波分析的桥梁损伤识别研究

发布时间：2018-07-09 12:13

本文选题：小波分析 + 曲率模态　；参考：《上海应用技术学院》2015年硕士论文

【摘要】：本文针对桥梁的局部损伤,从模态分析角度入手,以曲率模态为基础,以小波分析为手段,利用小波对突变信号敏感的优势,分析曲率模态信号,依据分析得到的小波系数来识别损伤。本文简单地介绍了曲率模态理论,利用ANSYS对一简支梁进行损伤模拟,发现曲率模态无法有效识别结构的微小损伤,若将曲率模态作为判别损伤的指标是不科学的；但是基于损伤区域刚度减小从而引起曲率发生变化的理论上可行,所以引入小波,利用小波“数学放大镜”的效用进一步挖掘曲率模态的特征信息。通过模型仿真验证基于曲率模态和小波分析的方法的识别效果,分析损伤前后的曲率模态作信号,对比损伤前后的小波系数图,发现未损伤单元表现平滑,损伤附近的突变明显。继续对简支梁进行仿真分析,对其损伤的曲率模态进行多尺度分析,拟合尺度-小波模极大值对数曲线求出Lipschitz指数,发现损伤程度与Lipschitz指数一一对应。提出延拓曲率模态信号的方法进行梁端损伤判别。最后对一实际的单箱单室的人行天桥进行损伤模拟,取得了满意的识别效果,进一步证明了该方法的理论与实用价值。
[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.
【学位授予单位】：上海应用技术学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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