An automatic arrival time picking algorithm of ultrasonic waves for concrete crack depth detection

Accurately and quickly picking up the arrival time of ultrasonic waves is crucial for detecting concrete cracks by using the ultrasonic pulse echo method. In order to determine the arrival time of ultrasonic waves in concrete components more accurately and quickly, a new algorithm was proposed based on the concept of shifting window and Akaike information criterion (AIC). The arrival time of ultrasonic waves was defined as the time of minimum AIC value, which was calculated from the proposed new characteristic equation. First, the validity and accuracy of the proposed method were verified by synthesized data with different signal-to-noise ratios. When the signal-to-noise ratio is 0 dB, the pickup error does not exceed 10 %, and when the signal-to-noise ratio is greater than 20 dB, the pickup error is less than 5 %. Then, the proposed method was compared to other six methods using 41 ultrasonic signals collected in four different concrete components. The results showed that the proposed method had a minimal deviation from the manual pickup. The average deviation from manual pickup is 1.78 mu s and the standard deviation of these deviations is 2.18 mu s . The experimental results demonstrated that the proposed method achieved higher accuracy compared to the rest of the methods when picking the arrival time of ultrasonic waves in concrete structures, regardless of whether the data was filtered.