无基准Lamb波时间反转损伤概率成像监测方法

Baseline free Lamb wave damage probability imaging monitoring method based on time reversal theory

根据损伤散射信息进行结构损伤特征参数提取与损伤监测,是Lamb波结构健康监测研究中的最为有效的方法之一,而目前常用的有基准差信号提取损伤散射信号技术在应用中存在实用性差的问题。采用Lamb波时间反转聚焦原理,结合损伤概率思想,提出了无基准损伤概率成像监测方法。利用信号时间反转处理对波源的自适应聚焦机理,消除Lamb波的频散效应;并根据单模式Lamb波响应信号的各波包在时反聚焦信号中的相对时刻,提取损伤散射信号的传播时间,以此计算出结构中各点出现的损伤概率,从而实现对损伤的成像、定位和监测。在金属铝板结构上的实验表明,该方法可在无需基准信号的情况下,较为清晰地分离出损伤散射信号和信息,得到结构各点的损伤概率图像,有助于结构健康监测的实用化。

Structure damage characteristic parameter extraction and damage monitoring based on damage scattering information is one of the most effective ways in Lamb wave based structural health monitoring （SHM） study. However, common damage scattering signal collection techniques based on baseline difference signal have poor practicality in applications. Adopting Lamb wave time reversal focalization theory and combining damage probability method, a new baseline free damage probability imaging monitoring approach is proposed. The adaptive focusing mechanism of signal time reversal processing to wave source is used to eliminate the dispersion effect of Lamb wave. The time of flying of the damage scattering signals could be obtained from the relative time of the wave packets of single mode Lamb wave response signals in time reversal focusing signals, and the damage probabilities in different points of the structure are calculated, so that the imaging, positioning and monitoring of the damage can be achieved. Experiments on aluminum plate were carried out;and the experiment results show that this proposed baseline free monitoring method could separate the damage scattering signals and its time of flying clearly from the response signals without requiring baseline signal and obtain the damage probability images of different points in the structure, which is helpful for the practicality of the SHM.