复杂结构损伤检测的分段小波变换法

SUBSECTION WAVELET TRANSFORMATION METHOD FOR DAMAGE DETECTIONS IN COMPLEX STRUCTURES

小波变换由于具有表征信号局部特征的能力,很适合探测信号中的反常成分,因此已越来越广泛的应用于简单结构的损伤检测。但对于工程中常见的复杂结构,转折点的存在却限制了小波变换的应用,尤其是难以检测到转折点处的损伤。该文采用将复杂结构分段化的方法来模拟海上自升式平台的两种损伤工况,经合理地选取模态类型,成功地检测到了此种复杂结构的多损伤情况。为了避免采用分段方法后因边界效应而引起的伪破坏,该文引入了模态扩展方法。对结构的模态进行扩展处理后,可准确地检测到结构端部或转折处发生的破损。

Wavelet transformation could be used to identify abnormal information in particular locations. Therefore, it has more and more applications in damage detection for simple structures. However, the existence of turning points limits its application in complex structures. In this paper, the wavelet transformation method is used to identify damages in an offshore platform. The subsection technique is used for complex structures, which will introduce more end points and turning points. To combine the wavelet transformation method with the subsection technique, the modal expansion method is introduced in this paper. Numerical results demonstrate that the proposed method can generate good results if appropriate form of modal is used. Introduction of subsection method could guarantee the accurate damage detection for even end points and turning points, so that false detection will be avoided and real damage will not be missed.