基于EMD-HHT的海洋平台结构损伤检测技术研究

发布时间：2018-05-15 05:38

本文选题：损伤检测 + 希尔伯特黄变换　；参考：《中国海洋大学》2014年硕士论文

【摘要】：对结构完整性进行监测已经成为许多工程研究领域的焦点。结构的健康监测离不开传感器技术以及相应的信号处理技术，信号处理技术是传感器信号和结构完整性检测之间的纽带。如何快速有效地从传感器采集到的结构振动响应信号中提取出重要的特征信息，并判断结构的健康状况，具有很大的应用价值。基于希尔伯特黄变换的损伤检测方法是一种全局性的检测方法，与传统的损伤检测方法相比，其具有自适应性、高时频分辨率等优点，具有非常广阔的应用前景。本文系统的总结了目前主要的时频分析方法，对其研究现状、研究成果及存在的问题做了较全面的论述。阐述了希尔伯特黄变换的基本原理、发展历程及其应用于时频分析的优越性。结合之前有关希尔伯特黄变换的研究成果，对希尔伯特黄变换应用于损伤检测领域进行了进一步的研究。考虑到经验模式分解的精度容易受噪声干扰的缺点，利用小波变换的消噪功能结合希尔伯特黄变换进行损伤检测，并依据HHT方法识别出的低阶瞬时频率变化定义了一个损伤指标。对一个三层剪切模型进行了数值模拟研究，并利用此指标研究了模型在不同损伤程度、不同噪声背景下的损伤检测情况，证明了该方法的有效性，为结构状况的在线监测提供了一定的参考依据。结构的动力特性参数会受到环境因素和操作条件的影响，，而且环境因素和操作条件的改变所引起的结构动力特性参数的变化，可能会掩盖结构由于损伤所引起的比较微小的变化。针对这一现状，本文提出了希尔伯特黄变换结合主成分分析的损伤检测方法。采用一个悬臂梁模型进行了数值模拟，用主成分分析排除温度对由希尔伯特黄变换方法得到的模态频率的影响，然后应用异常检测技术对主成分分析得到的预测误差矩阵进行处理判断损伤是否发生。数值研究结果表明这种方法可以有效排除温度对模态频率的影响，并可以准确地检测到损伤的发生。导管架平台是浅海中比较常用的平台形式，因此研究这类平台的损伤检测技术具有很重要的现实意义。本文分别建立了单立柱式和导管架式井口平台的有限元模型，利用HHT方法分析研究了模型在不同损伤程度、不同外界激励下的损伤检测，并应用添加噪声的方式模拟外界环境的影响，得到了一些有用的结论。
[Abstract]:Structural integrity monitoring has become the focus of many engineering research fields. Structural health monitoring can not be separated from the sensor technology and the corresponding signal processing technology, signal processing technology is the link between sensor signal and structural integrity detection. How to extract the important characteristic information from the structural vibration response signal collected by the sensor quickly and effectively, and to judge the health condition of the structure, has great application value. The damage detection method based on Hilbert-Huang transform is a kind of global detection method. Compared with the traditional damage detection method, it has the advantages of self-adaptability, high time-frequency resolution and so on, so it has a very broad application prospect. In this paper, the main methods of time-frequency analysis are systematically summarized, and the research status, research results and existing problems are discussed comprehensively. The basic principle and development of Hilbert-Huang transform and its advantages in time-frequency analysis are described. The application of Hilbert-Huang transform to damage detection is further studied. Considering the disadvantage that the precision of empirical mode decomposition is easily disturbed by noise, the wavelet transform is used to remove noise and Hilbert-Huang transform is used to detect the damage. A damage index is defined according to the low order instantaneous frequency change identified by HHT method. The numerical simulation of a three-layer shear model is carried out, and the effectiveness of the method is proved by using this index to study the damage detection of the model in different damage degree and different noise background. It provides a certain reference for the on-line monitoring of the structure condition. The dynamic characteristic parameters of the structure will be affected by the environmental factors and the operating conditions, and the change of the structural dynamic characteristic parameters caused by the change of the environmental factors and the operating conditions. It may cover up minor structural changes caused by damage. In this paper, a damage detection method based on Hilbert-Huang transform and principal component analysis (PCA) is proposed. A cantilever beam model is used for numerical simulation. The influence of temperature on the modal frequency obtained by Hilbert-Huang transform is excluded by principal component analysis. Then the prediction error matrix obtained by principal component analysis is processed by anomaly detection technique to judge whether damage occurs or not. The numerical results show that this method can effectively eliminate the influence of temperature on modal frequency and can accurately detect the damage. Jacket platform is a commonly used platform in shallow water, so it is of great practical significance to study the damage detection technology of this kind of platform. In this paper, the finite element models of single column and conduit type wellhead platform are established, and the damage detection of the model under different damage degree and different external excitation is analyzed by using HHT method. Some useful conclusions are obtained by using the method of adding noise to simulate the influence of external environment.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P751

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