Title:
Experimental study on the nonlinear mixing of ultrasonic waves in concrete using array technique
Experimental study on the nonlinear mixing of ultrasonic waves in concrete using array technique
Author(s)
Weiss, Fiona Jacqueline
Advisor(s)
Jacobs, Laurence J.
Kim, Jin-Yeon
Kim, Jin-Yeon
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Abstract
This research develops a procedure that combines array technology with non-collinear ultrasonic wave mixing to detect and scan internal microscale damage in a concrete prism specimen. By mixing two wave fronts of incident shear waves generated by two ultrasonic transducer arrays, one can exploit the underlying mechanics of nonlinear wave mixing to create a longitudinal mixed wave and measure the magnitude of this nonlinear wave at a frequency that is the sum of the fundamental frequencies. The frequency of the incident waves is chosen such that it is low enough to propagate without being scattered by the in- herently inhomogeneous concrete microstructure, while the resulting nonlinear phenomena are still sensitive to damage much smaller than the wavelength of the incident waves. The arrays enable beam steering, making it possible to scan for damage along an arc. Overall, scanning and imaging at different locations in a large volume throughout the specimen’s thickness is accomplished by manually adjusting the placement of the two arrays to move the mixing zone any desired, internal depth, while beam steering is used to scan at different locations of the same depth close to each other.
The effectiveness of the proposed technique is demonstrated by characterizing different types of damage embedded at known locations in a concrete prism specimen. The results of this thesis are in accordance with previous research and show that beam steering along an arc to scan for damage in the concrete specimen is in fact possible.
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Date Issued
2023-08-21
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Thesis