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Proceedings Paper

Localization of structural flaws from vibrational analysis
Author(s): Allen M. Flusberg; T. Luongo; A. de Mesquita
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Paper Abstract

A new method to detect and localize structural flaws, mode signature analysis, has been developed and demonstrated on a large realistic model bridge. The presence and location of flaws are detected by analyzing the vibrational response of the structure at a single, fixed point to an impulse excitation at a different fixed point. The localization method has successfully pinpointed a defect with a resolution of approximately 4 cm when both the impulse- excitation source and the point at which the vibration is monitored are located several tens of cm away from the defect. The detection method has been demonstrated by 1) contact measurements made by an accelerometer mounted on the structure and 2) remotely, from the time-dependent Doppler shift of a laser beam reflected from the structure. After the accelerometer signal, proportional to acceleration, is integrated to produce a signal proportional to velocity, it is found to be essentially identical to the remotely observed laser-vibrometer signal. Data analysis illustrates the tradeoff between maximizing the probability that an existing flaw is detected and minimizing the probability that a structure that is in good condition is misdiagnosed as faulty.

Paper Details

Date Published: 13 November 1996
PDF: 19 pages
Proc. SPIE 2946, Nondestructive Evaluation of Bridges and Highways, (13 November 1996); doi: 10.1117/12.259144
Show Author Affiliations
Allen M. Flusberg, Science Research Lab., Inc. (United States)
T. Luongo, Science Research Lab., Inc. (United States)
A. de Mesquita, Science Research Lab., Inc. (United States)


Published in SPIE Proceedings Vol. 2946:
Nondestructive Evaluation of Bridges and Highways
Steven B. Chase, Editor(s)

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