板状结构中基于Lamb波单模态的缺陷成像试验研究

Lamb波技术非常适于板类结构的各种缺陷检测。为了得到模态较为单一的Lamb波,使得接收信号更具有解释性,缺陷更容易识别,该文中在板上下表面的相同位置分别布置压电传感器阵列,采用同一位置上下表面的双压电片同相或反相激励,激励出单一S₀或A₀模态。运用这种单模态的Lamb波激励方式对板中缺陷进行检测,结合椭圆成像算法与数据融合方法对压电传感器阵列接收到的多组信号进行缺陷成像。该方法有效的实现了板中缺陷的二维成像定位,检测出人工缺陷,并提高了缺陷的可识别能力和定位精度。

EXPERIMENTAL STUDY ON DEFECT IMAGING BASED ON SINGLE LAMB WAVE MODE IN PLATE-LIKE STRUCTURES

Lamb wave technology is used for defect detection in plate-like structures. It is easier to interpret received signals and to identify defects if single mode Lamb waves are applied. In this study, piezoelectric transducers are attached, in a form of arrays, on the top and bottom sides of plate. When two piezoelectric transducers at the same locations on each side of the plate are excited by voltage signal simultaneously in phase or out phase, single S₀ mode or A₀ mode is generated, respectively. In combination with the elliptic imaging algorithm and the data fusion method, single Lamb wave mode can be used for defect imaging for multiple signals received by piezoelectric transducer arrays. The method proposed in this study is effective to obtain two-dimensional images of defects and detect artificial defects in plate-like structures, with improved recognition ability and accuracy.