Multi-Reflected-Wave-Model Based Non-Destructive Inspection System Using Ultrasonic Taking Into Account of the Attenuation Coefficient

Detection and Identification of an Inclined Crack in Concrete Structures Using an Ultrasonic Sensor

“…Therefore, a band-pass filter was used to suppress the reflected wave along the concrete surface. The cut-off frequencies of the filter were 40kHz and 100kHz and were obtained as the desirable ones in the previous paper [7]. Since we used a reflected wave model to measure the propagation time to the crack and back, therefore, our adopted model had no high frequency components.…”

“…Since the surface wave is generally too large to detect the reflected wave signal from the crack, we first suppress the surface wave using an adequate band-pass filter [7]. We denote the band-pass filtered output asr s (t) and it can be modeled as…”