Imaging Enhancement for Deep Concrete Blocks by
Wave-packet Decomposition and Amplitude
Publication: Publication Date: 1 May 2016Testing Method:
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
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