TY - GEN
T1 - Improved synthetic aperture focusing technique results of thick concrete specimens through frequency banding
AU - Clayton, Dwight
AU - Barker, Alan
AU - Albright, Austin
AU - Santos-Villalobos, Hector
N1 - Publisher Copyright:
© 2016 AIP Publishing LLC.
PY - 2016/2/10
Y1 - 2016/2/10
N2 - A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on ultrasonic data collected from thick, complex concrete structures such as in NPPs. Towards these goals, we apply 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. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To minimize artifacts caused by boundary effects, the dimensions of the specimens should not be too compact. In this paper, we apply this enhanced SAFT technique to a 2.134 m × 2.134 m × 1.016 m concrete test specimen with twenty deliberately embedded defects.1
AB - A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. This use has made its long-term performance crucial for the safe operation of commercial nuclear power plants (NPPs). Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on ultrasonic data collected from thick, complex concrete structures such as in NPPs. Towards these goals, we apply 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. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular NDE technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To minimize artifacts caused by boundary effects, the dimensions of the specimens should not be too compact. In this paper, we apply this enhanced SAFT technique to a 2.134 m × 2.134 m × 1.016 m concrete test specimen with twenty deliberately embedded defects.1
UR - http://www.scopus.com/inward/record.url?scp=84984588977&partnerID=8YFLogxK
U2 - 10.1063/1.4940458
DO - 10.1063/1.4940458
M3 - Conference contribution
AN - SCOPUS:84984588977
T3 - AIP Conference Proceedings
BT - 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation
A2 - Bond, Leonard J.
A2 - Chimenti, Dale E.
PB - American Institute of Physics Inc.
T2 - 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2015, Incorporating the 6th European-American Workshop on Reliability of NDE
Y2 - 26 July 2015 through 31 July 2015
ER -