基于Shannon复数小波和时间反转聚焦的复合材料结构多源冲击成像定位方法

Multiple Impact Source Imaging and Localization on Composite Structure Based on Shannon Complex Wavelet and Time Reversal Focusing

在飞机结构上,复合材料结构大量应用。该种材料结构容易受到外界冲击而产生内部脱层等损伤,所以对复合材料结构的冲击事件进行在线结构健康监测是十分必要的。为了克服信号在复合材料结构中传播存在的频散、多种模式及模式转换的现象给冲击定位带来的困难,研究了一种基于Shannon复数小波和时间反转聚焦的复合材料结构多源冲击成像定位方法。分析了信号的时间反转聚焦原理,在此基础上,提出了冲击响应信号时反合成成像方法。针对宽带的冲击响应信号,利用Shannon复数小波变换提取冲击响应信号中特定尺度下的信号成分参与到成像过程中。整套方法在碳纤维复合材料层合板上得到了验证。验证结果表明该方法能够正确地对冲击监测区域中的多个冲击源进行成像和定位,冲击定位误差不超过2cm。

Composite materials widely used in aircraft structures are subject to inner delaminations because of outer impacts.Therefore,it is necessary to perform on-line structural health monitoring of impact events for composite structrures.Taking into consideration such issues as frequency dispersion,multi-mode and mode conversion of signal propagation on composite structures,this article proposes a Shannon complex wavelet and time reversal fouscing-based multiple impact source imaging and localization method of composite structures.First,the principle of time reversal focusing of signals is analyzed,based on which a time reversal synthesis and imaging method of impact response signals is proposed.To deal with broadband impact response signals,signal components extracted from impact response signals at a specific scale are used to participate in the imaging process.This method is validated on a carbon fiber reinforced polymer.The validation results show that this method could generate images and locate multiple impact sources correctly in the monitoring area with impact localization errors not more than 2 cm.