Ultrasonic Measurement System for Detecting Penetration of Boulders by Autocorrelation Analysis

Abstract

An elastic impact wave method is used as a typical nondestructive test method to investigate the depth of boulder penetration. However, in the elastic impact wave method using, for example, a hammer, the discrimination of the reflection wave produced by minute cracks is difficult. Theoretically, if it becomes possible to input the vibration of an ultrasonic domain into artificial structures, such as a concrete and a boulder, with a strong amplitude, deeper investigation depth compared to the conventional way with a high precision will be attained. In this study, a concrete block, with a known size, which was, unlike boulders, not buried under ground, was used as a test piece in a basic experiment. As analysis methods, a wavelet analysis for checking the reflection wave and an autocorrelation analysis for identifying the time lag of the reflection wave were used. As a result, the reflection wave was detected in a down chirp signal from 50 kHz to 40 kHz.

High Precision Detection Method for Delamination Defects in Carbon Fiber Composite Laminates Based on Ultrasonic Technique and Signal Correlation Algorithm

“…As a classical signal processing method, signal correlation processing has been also applied to the processing of ultrasonic signals [ 35 , 36 , 37 ]. In the work by Kawamura et al [ 38 ], in order to investigate the depth of boulder penetration, autocorrelation was used to identify the time tag of the reflection wave in acoustic emission (AE). In the work by Liang et al [ 39 ], a maximum fractional cross-correlation spectrum (FCCS) parameter estimation method was proposed to estimate the time of arrival (TOA) of the ultrasonic echoes.…”

A Method for Estimating the Location of the Drill-Bit During Horizontal Directional Drilling Using a Giant-Magnetostrictive Vibrator

“…The vibrator can generate an arbitrary waveform. [16][17][18][19][20] The vibrator was thrust into a steel pile hammered into the ground during this initial experiment. The main body of the vibrator used for this experiment is 197 mm long and 42 mm in diameter.…”

“…14,15) An experiment to examine the suitability of the measuring method using a giant-magnetostrictive vibrator was conducted as part of this study. [16][17][18][19][20] The drill-head contains a space where the equipment used to generate the electromagnetic wave can be installed, and the fact that the vibrator is powered by batteries means that it can easily be installed in this space. In the subsequent experiment, this vibrator was used to generate an elastic wave.…”

Underground Imaging Method Using Magnified Cross-Correlation Analysis

“…11) The response of this element is faster than that of a piezoelectric element, and the maximum displacement of the giantmagnetostriction element is larger than that of the piezoelectric element. 12) This vibrator can generate an arbitrary waveform. For reference, the amplitude spectrum of the vibrator is shown in Fig.…”