基于模态信息的结构模糊损伤识别

发布时间：2018-06-22 02:34

本文选题：模糊参数 + 应变模态　；参考：《兰州理工大学》2010年硕士论文

【摘要】： 基于结构动力特性的损伤识别技术是近20年来发展起来的一门新技术,国内外很多学者在这方面做了大量的研究工作,取得了一系列研究成果,并有部分研究成果已成功应用于实际工程。但对于大型的土木工程来讲,由于结构构件制作或者结构施工误差,往往使得结构的参数具有一定的不确定性,这些不确定性可能是随机的也可能是模糊的,甚至可能是模糊随机的。而在大多数结构设计与分析中,都是将结构参数看成是一个确定性的量,进行计算与分析,这样分析的结果不仅不能反映结构的实际情况,而且再加上结构使用荷载的不确定性,这必将影响基于结构动力特性损伤识别结果的准确性。因此在工程设计与分析过程中,考虑结构参数的不确定性是很有必要的。本文首先介绍了结构损伤识别研究的国内外现状以及损伤识别的基本理论。其次选取桁架结构的应变模态改变值作为结构损伤识别指标,对桁架结构不同杆件发生不同程度的损伤进行识别。结果表明,利用应变模态改变值作为损伤指标可以识别结构的损伤。然后采用结构的应变模态改变值建立标准模式库,利用模糊贴近度的方法,对结构的损伤程度进行识别。通过考虑材料强度特性、结构尺寸以及负载的模糊特性,建立桁架的刚度矩阵和质量矩阵,并通过Rayleigh商法得到结构的自振特性。通过一桁架模型,分析了由于考虑结构材料强度、结构尺寸以及负载的模糊特性对结构动力特性的影响。以上分析都是结构振动分析的正问题,本文还对结构振动的反问题做了研究,通过利用特征值反问题识别结构的刚度,算例表明,该方法可以很好的识别结构的刚度。最后将其应用于一实际加固工程,验证其在实际工程应用中的可行性与可靠性。
[Abstract]:The damage identification technology based on the dynamic characteristics of structures is a new technology developed in the past 20 years. Many scholars at home and abroad have done a lot of research work in this area and made a series of research results. Some of the research results have been successfully applied to practical projects. However, for large-scale civil engineering, the structural parameters are often uncertain due to the structural component fabrication or structural construction errors, which may be random or fuzzy. It may even be fuzzy and random. In most structural design and analysis, the structural parameters are regarded as a deterministic quantity to be calculated and analyzed, so the results of the analysis can not only reflect the actual situation of the structure. In addition, the uncertainty of the structural load will affect the accuracy of damage identification based on the dynamic characteristics of the structure. Therefore, it is necessary to consider the uncertainty of structural parameters in the process of engineering design and analysis. In this paper, the present situation of structural damage identification and the basic theory of damage identification are introduced. Secondly, the strain mode change value of truss structure is selected as the damage identification index to identify the damage of truss structure with different degree of damage. The results show that the damage of the structure can be identified by using the strain mode change value as the damage index. Then, the standard mode library is established by using the strain mode change value of the structure, and the damage degree of the structure is identified by the method of fuzzy closeness degree. The stiffness matrix and mass matrix of the truss are established by considering the strength characteristics of the material, the size of the structure and the fuzzy characteristics of the load, and the natural vibration characteristics of the structure are obtained by Rayleigh quotient method. By means of a truss model, the influence of fuzzy characteristics of structural material strength, structural size and load on the dynamic characteristics of the structure is analyzed. The above analysis is the positive problem of structural vibration analysis. The inverse problem of structural vibration is also studied in this paper. By using eigenvalue inverse problem to identify the stiffness of the structure, the example shows that the method can identify the stiffness of the structure very well. Finally, it is applied to a practical reinforcement project to verify its feasibility and reliability in practical engineering application.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TU312.3

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