Chirp generated acoustic wavefield images

Thomas E. Michaels; Jennifer E. Michaels; Sang Jun Lee; Xin Chen

doi:10.1117/12.880968

31 March 2011 Chirp generated acoustic wavefield images

Thomas E. Michaels, Jennifer E. Michaels, Sang Jun Lee, Xin Chen

Proceedings Volume 7984, Health Monitoring of Structural and Biological Systems 2011; 79840J (2011) https://doi.org/10.1117/12.880968
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2011, San Diego, California, United States

Abstract

Guided waves are being considered for structural health monitoring (SHM) applications, and they can also be used to reduce subsequent inspection times once defects are detected. One proposed SHM method is to use an array of permanently attached piezoelectric transducers to generate and receive guided waves between the various transducer pairs. The interrogation can be done on a continuous or periodic basis to assess the health of the structure. Once defects are suspected in the structure, the traditional approach is to disassemble components for conventional nondestructive evaluation (NDE); however, this is an expensive and time consuming process. A less expensive alternative to conventional NDE is to record acoustic wavefield images of guided waves generated from the attached transducers. These images clearly show details of guided waves as they propagate outward from the source, reflect from structural discontinuities and specimen boundaries, and scatter from any damage sites within the structure. However, the recorded waves are typically narrowband to enable effective visualization of echoes that are relatively compact in time. In this paper, we consider wavefield images that are recorded from a chirp excitation, which offers the advantage of high quality broadband data from a single excitation. However, responses are not directly useful because the received echoes are too extended in time. Signals are post-processed to obtain multiple narrowband and broadband responses containing echoes that are more compact in time to enable visualization of guided waves interacting with structural features. This technique is demonstrated on an aluminum plate that contains attached stiffeners and glued-on piezoelectric disc transducers. Wavefield data are recorded using an air-coupled transducer scanned over the plate surface while one of the attached transducers acts as a guided wave source. Waves interacting with the stiffener and the inactive discs are analyzed via broadband and narrowband processing at multiple frequencies.

Citation Download Citation

Thomas E. Michaels, Jennifer E. Michaels, Sang Jun Lee, and Xin Chen "Chirp generated acoustic wavefield images", Proc. SPIE 7984, Health Monitoring of Structural and Biological Systems 2011, 79840J (31 March 2011); https://doi.org/10.1117/12.880968

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available