【作者】 蒋济同；

【导师】 李华军；

【作者基本信息】 中国海洋大学 ， 港口、海岸及近海工程， 2003， 博士

【摘要】 本文发展了一套有应用价值的海洋平台损伤诊断方法。对现有的结构模态参数识别和损伤诊断研究成果进行了分类总结，对结构健康监测的若干概念进行了讨论，对现有的海洋平台损伤诊断成果进行了评述。以单自由度结构体系为对象，研究了结构参数估计和损伤识别的较有共性的特性。损伤发生在系统位移不为零时，加速度信号中会有突变，可以作为损伤时间的标志。损伤发生后，分解后的相应于激励频率的加速度信号的幅值会发生变化。对加速度信号进行分解，分别应用短时Fourier变换、小波变换和经验模式分解方法等信号处理方法实现了结构损伤时间确定。指出通过结构频率的变化可以计算结构的损伤程度并给出了相应的公式。将上述方法应用于一个简化的海洋平台试验模型，证实了方法的可靠性。研究了输入未知条件下的海洋平台模态参数识别方法。实现了基于互谱的频域方法和时域的ITD方法，方法应用于实验实测数据，二种方法结果吻合的较好，可以互相印证。指出短时Fourier变换和经验模式分解方法可以用来发现海洋平台的损伤时刻，发展了参数识别和损伤诊断的消去质量法可以用于损伤定位。同时还发展了损伤定位的二步法，通过振型的垂直和水平变化的特征分析也可以实现损伤定位。更多还原

【Abstract】 A set of algorithm is developed for damage detection for offshore platforms in this paper. The development of structure health monitoring technique so far is summarized first then the methods of damage detection for offshore platforms are concluded. Some general characteristics of structure parameter identification and damage detection are discussed in case of SDOF. A sudden change in acceleration can be found as the index of damage time if the system has a non-zero displacement when damage happen while the amplitude corresponding with the frequency of excitation may change after damage happen. The short-time Fourier Transform, the Wavelet Analysis and the Empirical Mode Decomposition method are applied to decompose the acceleration signal for damage time identification successfully. Two algorithms (one cross-spectrum based in frequency domain and the other one is ITD method in time domain) for mode parameter identification are realized and adjacent result from experiment data of a scaled model obtained respectively. The mass elimination algorithm are developed for damage detection in vertical direction while the damage location with in horizontal plan can be find from some characteristics of mode shape changes.更多还原