Omnidirectional Guided Wave PWAS Phased Array for Thin-wall Structure Damage Detection

摘要

Widely used 1-D guided wave phased arrays can only scan within 0°～180° range due to the intrinsic structural limitation. To overcome this limitation, multiple installations are unavoidable. However, by using 2-D configuration phased arrays, large structural interrogation can be conducted from a single location with a single scanning covering the entire 0°～360° range through omnidirectional beamforming. Based on the developed generic PWAS Lamb wave phased array beamforming formula, this paper aims to bring up the practical implementation of an 8×8 PWAS array and present analytical and experimental results concerning the omnidirectional damage detection ability. The theoretical beamforming of 2-D rectangular PWAS configuration will be presented at first based on the generic PWAS phased array beamforming formulation. Then, an 8×8 rectangular PWAS array is installed on the target aluminum specimen. Laboratory experiment is set up next and conducted various crack damage detection. Specimens include: (1) a single crack positioned at 90°; (2) a single crack positioned at 270°; (3) a single hole positioned at 180°; 4) a crack at 90 ° and a hole at 180 °, respectively. The experiments will demonstrate the 360° damage finding ability of the 2-D PWAS array and the multiple damage detection ability as well. We finally end up with discussions on the practical application and come up with plans for future work on various 2-D array developments.