High-resolution ultrasonic imaging technology for the damage of concrete structures based on total focusing method

摘要

Concrete has diverse internal acoustic interface, and the scattering of ultrasonic wave is serious and complicated. Based on total focusing method (TFM) imaging, this paper investigates the concrete inspection resolution optimization method. Firstly, the reinforced concrete model was simulated, using time reversal (TR) algorithm to process the signal, the defects and rebars signal amplitudes increased by 7.6 dB and 4.7 dB, respectively. Then in order to reduce the structural noise, the phase coherence imaging (PCI) algorithm was applied, resulting in a signal-to-noise ratio (SNR) improvement of about 22.2 dB on average. Finally, the imaging positions were cor-rected. In the experiment, to eliminate the influence of the probe ringing on the detection signal, digital filtering was introduced to restore the signal wave packet,and the image SNR was improved by 3.2 dB after TR processing and by 9.4 dB after PCI processing.

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