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Proceedings Paper

Wide-area imaging of ultrasonic Lamb wave fields by electronic speckle pattern interferometry
Author(s): Grant A. Gordon; Truman Douglas Mast
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Paper Abstract

Ultrasonic elastic waves have traditionally been examined using single point measurement techniques. In this paper, we present a technique capable of recording out-of-plane ultrasonic displacement data over wide areas. The method employs 2D surface vibration data collected via electronic speckle pattern interferometry used in combination with laser modulation and optical phase stepping. Using this rapid, wide-area measurement method, images of ultrasonic Lamb waves on ideal and flawed plate structures are presented. For a single ultrasonic excitation frequency, multiple data records are collected as an externally excited traveling plate wave moves through the sample. When an optical phase shift is introduced between the data records, the data can be processed to yield quantitative displacement fields. The resulting processed images demonstrate evidence of Lamb wave reflection, transmission and scattering. Following the full field data collection, a novel inverse scattering algorithm was applied to reconstruct images of the scattering sources responsible for the measured displacement field data. The results of these investigations will be presented and discussed in the context of detecting hidden flaws in aging aircraft.

Paper Details

Date Published: 28 January 1999
PDF: 13 pages
Proc. SPIE 3586, Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware III, (28 January 1999); doi: 10.1117/12.339899
Show Author Affiliations
Grant A. Gordon, The Pennsylvania State Univ. (United States)
Truman Douglas Mast, The Pennsylvania State Univ. (United States)


Published in SPIE Proceedings Vol. 3586:
Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace Hardware III
Ajit K. Mal, Editor(s)

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