基于时间反转的Lamb波无基准结构健康监测方法研究

发布时间：2019-03-11 08:57

【摘要】：主动Lamb波结构健康监测方法由于对结构中的裂纹、复合材料脱层等小损伤敏感，，是目前被认为最有效的板结构损伤监测方法之一。但是现有的主动Lamb波损伤监测方法大都采用基于参考信号的处理方法来获取损伤散射信号，即取健康状态响应信号为参考信号，对比损伤状态下的结构响应信号来获取损伤散射信号的方法。该方法对原理和实验研究具有很大的帮助，但由于基于参考信号的处理方法在真实应用环境下容易受到结构和外部条件变化的影响，因此在实用性方面受到一定的影响。本文针对无基准结构监测问题，着重研究了基于Lamb波的时间反转方法，在首先明晰Lamb波的传播特性之后，结合Lamb波自身传播特点，着重分析了Lamb波在时间反转过程中的传播情况，并根据结构损伤可破坏Lamb波在结构中的波形重构的现象，进行了基于时间反转的Lamb波无基准结构健康监测方法的实验研究及验证，内容包括实验相关条件的分析，存在损伤情况下方法可行性验证等。并且针对时间反转过程中的直达波提取问题，提出了时间窗函数的解决办法。最后，本文借鉴了数理统计的相关知识，提出了通过极值理论的进行实验数据处理的方法，进一步的实现了数据判别过程中的无基准对比。
[Abstract]:Active Lamb wave structural health monitoring method is considered to be one of the most effective methods for structural damage monitoring because it is sensitive to small damage such as crack delamination of composite materials and so on. However, most of the existing active Lamb wave damage monitoring methods use the reference signal processing method to obtain the damage scattering signal, that is to say, the health state response signal is taken as the reference signal. The method of obtaining the damage scattering signal by comparing the structural response signal under the damage state. This method is of great help to the research of principle and experiment, but because the processing method based on reference signal is easy to be affected by the change of structure and external conditions in the real application environment, the practicability of the method is affected to a certain extent. In this paper, the time reversal method based on Lamb wave is studied. After clarifying the propagation characteristics of Lamb wave, combining with the propagation characteristics of Lamb wave itself, this paper focuses on the problem of monitoring without reference structure. The propagation of Lamb wave in the process of time reversal is analyzed emphatically, and according to the phenomenon that the damage of the structure can destroy the waveform reconstruction of Lamb wave in the structure, An experimental study and verification of the health monitoring method of Lamb wave without reference structure based on time reversal is carried out. The contents include the analysis of the relevant experimental conditions and the feasibility verification of the method in the presence of damage and so on. Aiming at the problem of direct wave extraction in the process of time reversal, the solution of time window function is proposed. Finally, using the knowledge of mathematical statistics for reference, this paper puts forward an experimental data processing method based on extreme value theory, and further realizes the non-benchmark comparison in the process of data discrimination.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH165.3

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