Material Research Centre, Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, United Kingdom.
J Acoust Soc Am. 2011 Jul;130(1):168-75. doi: 10.1121/1.3598458.
This paper presents an imaging method for the localization of the impact point in complex anisotropic structures with diffuse field conditions, using only one passive transducer. The proposed technique is based on the reciprocal time reversal approach (inverse filtering) applied to a number of waveforms stored into a database containing the experimental Green's function of the structure. Unlike most acoustic emission monitoring systems, the present method exploits the benefits of multiple scattering, mode conversion, and boundaries reflections to achieve the focusing of the source with high resolution. Compared to a standard time reversal approach, the optimal refocusing of the back propagated wave field at the impact point is accomplished through a "virtual" imaging process. The robustness of the inverse filtering technique is experimentally demonstrated on a dissipative stiffened composite panel and the source position can be retrieved with a high level of accuracy in any position of the structure. Its very simple configuration and minimal processing requirements make this method a valid alternative to the conventional imaging Structural Health Monitoring systems for the acoustic emission source localization.
本文提出了一种仅使用一个被动换能器对具有漫射场条件的复杂各向异性结构中的撞击点进行定位的成像方法。所提出的技术基于互易时间反转方法（逆滤波）应用于存储在包含结构实验格林函数的数据库中的多个波形。与大多数声发射监测系统不同，本方法利用多次散射、模式转换和边界反射的优势来实现高分辨率的源聚焦。与标准的时间反转方法相比，通过“虚拟”成像过程完成反向传播波场在撞击点的最佳重聚焦。逆滤波技术的稳健性在耗散加筋复合材料板上进行了实验验证，并且可以在结构的任何位置以高精度检索源位置。其非常简单的配置和最小的处理要求使得该方法成为传统成像结构健康监测系统用于声发射源定位的有效替代方案。
