Article Article
Imaging Enhancement for Deep Concrete Blocks by Wave-packet Decomposition and Amplitude Compensation

Nondestructive testing plays an important role in the detection of discontinuities and degradation in concrete structures. The synthesized aperture focusing technique (SAFT) improves imaging quality by superimposing the received signals from adjacent transducers. However, in testing of deep concrete blocks, the reflected ultrasonic signals from targets usually combine with scattering, and the amplitude of the useful signal decreases rapidly with its propagation distance. It is hard for traditional SAFT to give a clear display of the target near the bottom. This paper proposes an amplitude compensation technique to enhance the reflected signals from deep targets, and a wavepacket decomposition approach is used to identify these reflections. The relative attenuation coefficient of ultrasonic waves propagating in concrete is obtained by measuring the decay in amplitude of the first and second peaks of the processed envelope signal. Experimental results in an artificial concrete specimen (70 cm length × 60 cm width × 60 cm height) show that the proposed technique has higher imaging resolution than SAFT and the traditional wave-packet decomposition technique.

References
  • Bigelow, T.A., “Estimating the Total Ultrasound Attenuation along the Propagation Path by Applying Multiple Filters to Backscattered Echoes from a Single Spherically Focused Source,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 57, No. 4, 2010, pp. 900–907.
  • Fink, M., F. Hottier, and J. Cardoso, “Ultrasonic Signal Processing for In Vivo Attenuation Measurement: Short Time Fourier Analysis,” Ultrasonic Imaging, Vol. 5, No. 2, 1983, pp. 117–135.
  • Ganguli, A., C.M. Rappaport, D. Abramo, and S. Wadia-Fascetti, “Synthetic Aperture Imaging for Flaw Detection in a Concrete Medium,” NDT&E International, Vol. 45, No. 1, 2012, pp. 79–90.
  • Kim, B.-C., and J.-Y. Kim, “Characterization of Ultrasonic Properties of Concrete,” Mechanics Research Communications, Vol. 36, No. 2, 2009, pp. 207–214.
  • Mayer, K., R. Marklein, K. Langenberg, and T. Kreutter, “Three-dimensional Imaging System Based on Fourier Transform Synthetic Aperture Focusing Technique,” Ultrasonics, Vol. 28, No. 4, 1990, pp. 241–255.
  • McCann, D., and M. Forde, “Review of NDT Methods in the Assessment of Concrete and Masonry Structures,” NDT&E International, Vol. 34, No. 2, 2001, pp. 71–84.
  • Ophir, J., R. McWhirt, N. Maklad, and P. Jaeger, “A Narrowband Pulseecho Technique for In Vivo Ultrasonic Attenuation Estimation,” IEEE Transactions on Biomedical Engineering, Vol. 32, No. 3, 1985, pp. 205–212.
  • Philippidis, T.P., and D.G. Aggelis, “Experimental Study of Wave Dispersion and Attenuation in Concrete,” Ultrasonics, Vol. 43, No. 7, 2005, pp. 584–595.
  • Schickert, M., “Automated Ultrasonic Scanning System for Three-dimensional SAFT Imaging of Concrete Elements using an Electronically Switched Transducer Array,” 2012 IEEE International Ultrasonics Symposium, Dresden, Germany, 7–10 October 2012, pp. 40–43.
  • Schickert, M., “Progress in Ultrasonic Imaging of Concrete,” Materials and Structures, Vol. 38, November 2005, pp. 807–815.
  • Schmitz, V., S. Chakhlov, and W. Müller, “Experiences with Synthetic Aperture Focusing Technique in the Field,” Ultrasonics, Vol. 38, Nos. 1–8, 2000, pp. 731–738.
  • Shao, Z., L. Shi, J. Cai, “Wavelet Modeling of Signals for Non-destructive Testing of Concretes,” Measurement Science and Technology, Vol. 22, March 2011.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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