Neural-Network-Based Ultrasonic Inspection of Offshore Coated Concrete Specimens

Abstract

A thin layer of protective coating material is applied on the surface of offshore concrete structures to prevent its degradation, thereby extending the useful life of the structures. The main reasons for the reduction in the protective capability of coating layers are loss of adhesion to concrete and flattening of the coating layer wall. Usually, the state of the coating layer is monitored in the setting of water immersion using ultrasonic inspection methods, and the method of inspection still needs improvement in terms of speed and accuracy. In this study, the ultrasonic pulse echo method was used in a water immersion test of the coated specimens, and continuous wavelet transform (CWT) with complex Morlet wavelets was implemented to define the received waveforms’ time of flight and instantaneous center frequency. These allow one to evaluate the thickness of the coating layer during water immersion. Furthermore, phases of reflected echoes at CWT local peaks were computed using a combination of Hilbert transforms (HT) and wave parameters derived from CWT. In addition, three relative wave parameters of echoes were also used to train deep neural networks (DNN), including instantaneous center frequency ratio, CWT magnitude ratio, and phase difference. With the use of three relative waveform parameters of the DNN, the debonded layer detection accuracy of our method was 100%.

Interfacial Bond Properties of Underwater Concrete Coated with Bisphenol A Epoxy Resins

“…This expectation was confirmed under constant laboratory conditions, and the effect of the coating method on changes in coating thickness over the exposure period was relatively minimal. The decreasing trend in thickness observed only in the RS conditions can be attributed to surface abrasion issues; nonetheless, further investigation remains necessary, and nondestructive methods could be useful for determining the reason for this reduction [43][44][45][46]. However, it should be noted that the thickness did not exhibit a significant relationship with the strength within the range of this study.…”

Optimization of tunnel grouting detection technology based on ultrasonic phased array

“…On the other hand, all kinds of noise may appear in the process of ultrasonic detection [8][9][10], so suitable noise reduction algorithms [11] are needed. Doha et al [12] compared the ability of two stochastic approaches of blind source separation, namely, independent component analysis and canonical correlation analysis, and of two deterministic approaches, namely, empirical mode decomposition (EMD) and wavelet transform, to remove muscle artifacts from electroencephalographic signals.…”

A novel ultrasonic inspection method of the heat exchangers based on circumferential waves and deep neural networks

“…Proper signal processing techniques can be used to separate CW modes and select the most sensitive wave modes. Several methods have successfully been used to filter Lamb waves using Hilbert transform, 17 , 18 bandpass filters, 19 Fourier transforms, 20 wave decomposition, 21 continuous wavelet transform (CWT) and inverse CWT (iCWT) methods. 22 CWT and iCWT have the advantage of extracting certain frequencies from waveforms without impacting others.…”