Active health monitoring of an aircraft wing with an embedded….pdfVIP

IOP PUBLISHING SMART MATERIALS AND STRUCTURES Smart Mater. Struct. 16 (2007) 1218–1225 doi:10.1088/0964-1726/16/4/033 Active health monitoring of an aircraft wing with an embedded piezoelectric sensor/actuator network: II. Wireless approaches 1,3 1 1 1 Xiaoliang Zhao , Tao Qian , Gang Mei , Chiman Kwan , Regan Zane2 2 2 2 , Christi Walsh , Thurein Paing and Zoya Popovic 1 Intelligent Automation Inc., 15400 Calhoun Drive, Rockville, MD 20855, USA 2 Department of Electrical and Computer Engineering, University of Colorado at Boulder, Boulder, CO 80309, USA E-mail: xzhao@ Received 24 October 2006, in final form 11 June 2007 Published 29 June 2007 Online at /SMS/16/1218 Abstract The objective of this study is to develop a wireless ultrasonic structural health monitoring (SHM) system for aircraft wing inspection. In part I of the study (Zhao et al 2007 Smart Mater. Struct. 16 1208–17), small, low cost and light weight piezoelectric (PZT) disc transducers were bonded to various parts of an aircraft wing for detection, localization and growth monitoring of defects. In this part, two approaches for wirelessly interrogating the sensor/actuator network were developed and tested. The first one utilizes a pair of reactive coupling monopoles to deliver 350 kHz RF tone-burst interrogation pulses directly to the PZT transducers for generating ultrasonic guided waves and to receive the response signals from the PZTs. It couples enough energy to and from the PZT transducers for the wing panel inspection, but the signal is quite noisy and the monopoles need to be in close proximity to each other for efficient coupling. In the second