The benefits of using time-frequency analysis with synthetic aperture focusing technique

Austin Albright, Dwight Clayton

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Scopus citations

Abstract

Improvements in detection and resolution are always desired and needed. There are various instruments available for the inspection of concrete structures that can be used with confidence for detecting different defects. However, more often than not that confidence is heavily dependent on the experience of the operator rather than the clear, objective discernibility of the output of the instrument. The challenge of objective discernment is amplified when the concrete structures contain multiple layers of reinforcement, are of significant thickness, or both, such as concrete structures in nuclear power plants. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on data collected from thick, complex concrete structures. A secondary goal is to improve existing SAFT results, with regards to repeatedly and objectively identifying defects and/or internal structure of concrete structures. Towards these goals, we are applying the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band's interaction with the contents of the concrete structure. We apply our technique to data sets collected using a commercial, ultrasonic linear array (MIRA) from two 1.5m × 2m × 25cm concrete test specimens. One specimen contains multiple layers of rebar. The other contains honeycomb, crack, and rebar bonding defect analogs. This approach opens up a multitude of possibilities for improved detection, readability, and overall improved objectivity. We will focus on improved defect/reinforcement isolation in thick and multilayered reinforcement environments. Additionally, the ability to empirically explore the possibility of a frequency-band-defect-type relationship or sensitivity becomes available.

Original languageEnglish
Title of host publication41st Annual Review of Progress in Quantitative Nondestructive Evaluation, Volume 34
EditorsDale E. Chimenti, Leonard J. Bond
PublisherAmerican Institute of Physics Inc.
Pages94-103
Number of pages10
ISBN (Electronic)9780735412927
DOIs
StatePublished - 2015
Event41st Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2014 - Boise, United States
Duration: Jul 20 2014Jul 25 2014

Publication series

NameAIP Conference Proceedings
Volume1650
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference41st Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2014
Country/TerritoryUnited States
CityBoise
Period07/20/1407/25/14

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