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Advanced Nondestructive Evaluation and Characterization of Surface

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A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (20 July 2021) | Viewed by 38999

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Prof. Dr. Youn ho Cho

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Guest Editor

School of Mechancial Engineering, Pusan National University, Busan 609-735, Korea
Interests: ultrasonic guided wave; nondestructive evaluation; nonlinear ultrasonic NDT
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Weibin Li

E-Mail Website
Guest Editor

School of Aerospace Engineering, Xiamen University, Xiamen 361005, China
Interests: nonlinear acoustics; guided wave; material characterization

Special Issue Information

Dear Colleagues,

Nondestructive evaluation (NDE) is an interdisciplinary field, which has been developed rapidly over recent decades as an important tool for damage detection, quality assessement and material characterization. Initiation and progression of degradation or cracks generally occurs on the surface of industrial components. This Special issue of Coatings is poised to collect original scientific or technical research articles and review papers relaed to advanced nondestructive evaluation and characterization of surfaces in solid structures. Especially, novel theoretical and experimental appraochs, with improved sensitivity, characterization capability, and efficiency of measurement, are of interest.

In particular, the topics of interest include, but are not limited to:

Surface waves based nondestructive evaluation
Surface cracks detection
Characterization of surface properties
Online monitoring of structural surface

Prof. Dr. Youn ho Cho
Prof. Dr. Weibin Li
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (11 papers)

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Research

12 pages, 4466 KiB

Open AccessArticle

Detection of Superficial Defects in the Insulation Layers of Aviation Cables by Infrared Thermographic Technique

by Fang Wen and Jie Jin

Coatings 2022, 12(6), 745; https://doi.org/10.3390/coatings12060745 - 29 May 2022

Viewed by 1568

Abstract

Superficial defects in the insulation layers of aviation cables can cause serious failures of and disasters for aircraft. Considering the critical importance of safety for aircraft, there is a need to develop a nondestructive technique to detect these kinds of defects in aviation cables. The objective of this paper is to investigate defect detection in aviation cable insulation by an infrared technique. The temperature distribution in the tested cable insulation surface under different thermal excitations and its time variation law are firstly analyzed by numerical simulation. Experimental testing is simultaneously conducted to study the influence of insulation wear defects on the temperature distribution of the cable surface. Complex background temperature distributions are eliminated in infrared images to improve the recognition of defects and extract the difference of the cable surface to draw a curve. The obtained results clearly indicate that the temperature variation interval in the curve can successfully reflect the sizes and locations of insulation defects. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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11 pages, 5589 KiB

Open AccessArticle

Non-Destructive Evaluation of Coating Thickness Using Water Immersion Ultrasonic Testing

by Jiannan Zhang, Younho Cho, Jeongnam Kim, Azamatjon Kakhramon ugli Malikov, Young H. Kim, Jin-Hak Yi and Weibin Li

Coatings 2021, 11(11), 1421; https://doi.org/10.3390/coatings11111421 - 20 Nov 2021

Cited by 21 | Viewed by 3779

Abstract

The coating is applied to prevent corrosion on the surface of ships or marine structures, and the thickness of the coating affects its anti-corrosion effect. As a result, non-destructive testing (NDT) is required to measure coating thickness, and ultrasonic NDT is a convenient and quick way to measure the thickness of underwater coatings. However, the offshore coating’s energy attenuation and absorption rates are high, the ultrasonic pulse echo test is difficult, and the testing environment is harsh. Because of the coating’s high attenuation, the distance of the optimal water delay line designed based on the reflection coefficient of the vertically incident wave is used. To accurately measure the thickness of the coating material, TOF of the reflected echo on the time-domain waveform was evaluated. The experimental results show that, when compared to caliper measurements, the coating thickness measured by the proposed method has a lower error and can be used for accurate measurement. The use of ultrasonic water immersion measurement is almost limitless in terms of size, location, and material of the object to be measured, and it is expected to be used to measure the thickness of the surface coating of ships or marine structures in the water. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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18 pages, 46552 KiB

Open AccessFeature PaperArticle

Ultrasonic Assessment of Thickness and Bonding Quality of Coating Layer Based on Short-Time Fourier Transform and Convolutional Neural Networks

by Azamatjon Kakhramon ugli Malikov, Younho Cho, Young H. Kim, Jeongnam Kim, Junpil Park and Jin-Hak Yi

Coatings 2021, 11(8), 909; https://doi.org/10.3390/coatings11080909 - 29 Jul 2021

Cited by 13 | Viewed by 3088

Abstract

Ultrasonic non-destructive analysis is a promising and effective method for the inspection of protective coating materials. Offshore coating exhibits a high attenuation rate of ultrasonic energy due to the absorption and ultrasonic pulse echo testing becomes difficult due to the small amplitude of the second echo from the back wall of the coating layer. In order to address these problems, an advanced ultrasonic signal analysis has been proposed. An ultrasonic delay line was applied due to the high attenuation of the coating layer. A short-time Fourier transform (STFT) of the waveform was implemented to measure the thickness and state of bonding of coating materials. The thickness of the coating material was estimated by the projection of the STFT into the time-domain. The bonding and debonding of the coating layers were distinguished using the ratio of the STFT magnitude peaks of the two subsequent wave echoes. In addition, the advantage of the STFT-based approach is that it can accurately and quickly estimate the time of flight (TOF) of a signal even at low signal-to-noise ratios. Finally, a convolutional neural network (CNN) was applied to automatically determine the bonding state of the coatings. The time–frequency representation of the waveform was used as the input to the CNN. The experimental results demonstrated that the proposed method automatically determines the bonding state of the coatings with high accuracy. The present approach is more efficient compared to the method of estimating bonding state using attenuation. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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18 pages, 5973 KiB

Open AccessArticle

Denoising of LCR Wave Signal of Residual Stress for Rail Surface Based on Lifting Scheme Wavelet Packet Transform

by Peilu Li, Chunguang Xu, Qinxue Pan, Yuren Lu and Shuangyi Li

Coatings 2021, 11(5), 496; https://doi.org/10.3390/coatings11050496 - 23 Apr 2021

Cited by 3 | Viewed by 1859

Abstract

According to the acousto elastic effect, the residual stress on the surface of the rail can be evaluated by measuring the change in the propagation velocity of ultrasonic waves, such as longitudinal critically refracted (LCR) waves on the surface of the rail. The LCR wave signal is often polluted by a variety of noise sources, coupled with the influence of the poor surface condition of the inspected component, which greatly reduces the detectability and online measurement ability of the LCR wave signal. This paper proposes the application of the lifting scheme wavelet packet transform (LSWPT) denoising method to solve the noise suppression problem of LCR wave signal. The traditional wavelet transform (WT), wavelet packet transform (WPT), as well as the lifting scheme wavelet transform (LSWT) and lifting scheme wavelet packet transform are compared and analyzed in the soft thresholding and hard thresholding processing of denoising ability and efficiency of the noisy LCR wave signal. The experimental results show that the LSWPT method has the characteristics of fast calculation speed and a good denoising effect, and it is an efficient method of denoising signals for on-line ultrasonic measurement of residual stress on the rail surface. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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21 pages, 10325 KiB

Open AccessArticle

Meso-Simulation and Experimental Research on the Mechanical Behavior of an Energetic Explosive

by Qinxue Pan, Shuangyang Li, Yang Liu, Xiaoyu Xu, Meile Chang and Yunmiao Zhang

Coatings 2021, 11(1), 64; https://doi.org/10.3390/coatings11010064 - 07 Jan 2021

Cited by 5 | Viewed by 1896

Abstract

This study establishes a model for polymer-bonded explosives (PBX) using Digimat-FE. The model identifies the relationship between the material’s effective elastic modulus and the explosive particle volume fraction, shape and gradation, and porosity, as well as other factors. Further, finite element analysis of the stress distribution of the PBX composite material is performed, and the mathematical models between the ultrasonic attenuation coefficient, particle volume fraction, and ultrasonic frequency are established. Finally, an efficient ultrasonic nondestructive testing system is designed to determine the stress distribution and fine crack groups in the material. Experimental results indicate that the relative error of stress detection is within 15%, which meets the requirements of engineering applications. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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9 pages, 3227 KiB

Open AccessArticle

Measuring the Wall Thickness of a Trailing Arm Using Ultrasonic Measurement Model

by Feng Chen, Siqi Chen, Rongfan Zhang, Yongsheng Shi and Liangyao Gu

Coatings 2020, 10(8), 773; https://doi.org/10.3390/coatings10080773 - 08 Aug 2020

Viewed by 2246

Abstract

Trailing arms are widely used in the automobiles’ suspension system, and effective detection of their wall thickness is essential to ensure their mechanical properties and to evaluate the casting process. In this work, an ultrasonic measurement model (UMM) is firstly established with consideration of the curvature and thickness of the trailing arm, then the UMM is introduced to predict the theoretical ultrasonic waveforms with different hypothetical thicknesses of the trailing arm. Next, the experimental ultrasonic waveforms are collected and matched with the predicted theoretical waveforms by using the correlation matching algorithm. The hypothetical thickness with the best match is regarded as the wall thickness of the trailing arm. Finally, an automatic ultrasonic experiment was conducted on a trailing arm with a 5-degrees of freedom (DOF) manipulator, in which the ultrasonic beam can radiate into a trailing arm at normal incidence. The results are compared with those determined by the micrometer and microscope, showing that their relative errors are controlled within 0.08 mm, which reveals the effectiveness of the present method. The method can also work for wall thickness measurements of curved components with CAD models. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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14 pages, 3727 KiB

Open AccessArticle

Experimental Study on the Local Drag of Completion String with Packers in Horizontal Wells

by Qimin Liang, Bairu Xia, Baolin Liu, Zhen Nie and Baokui Gao

Coatings 2020, 10(7), 657; https://doi.org/10.3390/coatings10070657 - 08 Jul 2020

Cited by 3 | Viewed by 2549

Abstract

The multistage stimulation technology of horizontal wells has brought huge benefits to the development of oil and gas fields. However, the completion string with packers often encounters stuck due to the large drag in the horizontal section, causing huge economic losses. The local drag of the completion string with packers in the horizontal section is very complicated, and it has not been fully understood by theoretical calculations. A local drag experiment is designed to simulate the influence of microsteps and cuttings on the local drag of the completion string with packers in the inclined and horizontal sections. An obvious increase of the local drag of the packer is found at microsteps of the horizontal section, and the local drag is greatly affected by the amount of sand. In addition, the string with packers will vibrate during the tripping process in the deviated section, and the local drag is different when different amounts of sand are in the hole, but the change law is similar. The experimental results show that the friction coefficients of the packers with different materials in the horizontal section vary greatly, resulting in different local drags. It indicates that the local drag of the completion string not only depends on the microsteps and sand quantity in the wellbore, but also on the material difference of the packers. Only if microsteps and cuttings are removed can the completion string be tripped into horizontal wells smoothly. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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17 pages, 1925 KiB

Open AccessArticle

Analysis of Linear Non-Destructive Testing and Evaluation Methods for Thin-Walled Structure Inspection Using Ultrasonic Array

by Yang Li, Zhenggan Zhou and Jun Wang

Coatings 2019, 9(2), 146; https://doi.org/10.3390/coatings9020146 - 22 Feb 2019

Cited by 1 | Viewed by 3554

Abstract

The ultrasonic array used for thin-walled structure non-destructive inspection usually has a high central frequency so that the thickness-to-acoustic wavelength ratio is greater than 10. When the ratio is much smaller than 10, the reliability of the conventional ultrasonic array method will dramatically decrease due to the influence of the acoustic near-field. This situation is unavoidable since the available central frequency of the array transducer cannot be an arbitrarily large value. To optimize the inspection performance in this case, the testing of an ultrasonic array and the evaluation of a structure whose thickness is smaller than five-times the longitudinal wavelength are analyzed in this paper. Linear ultrasonic array methods using different combinations of wave patterns, reflection times, and coupling conditions are uniformly expressed as full matrix algorithms. Simulated and experimental full matrices of 6 mm-thick aluminum plates using a 5-MHz array transducer are captured to analyze their imaging performances and sizing abilities with respect to various defects. Analyses show that the inspection results of the wedge coupling method have a much higher signal-to-noise ratio (SNR) than the results of conventional direct contact methods. Circular defects and rectangular defects can be distinguished by comparing the imaging results of different modes. For the simulated circular defect, the diameter can be measured according to the maximum image amplitude of the defect. To simulate a rectangular defect located in the lower half of the region, the nominal length can be measured using a linear function whose input is a −6 dB drop in length of the SS-S mode image. For a real sample, the material anisotropy and complex self-reflections will decrease the SNR by about 10 dB. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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10 pages, 2160 KiB

Open AccessEditor’s ChoiceArticle

Application of Industrial XRF Coating Thickness Analyzer for Phosphate Coating Thickness on Steel

by Aleksandr Sokolov, Jelena Hasikova, Aleksej Pecerskis, Vladimir Gostilo, Ki Yong Lee, Hoobok Jung and Jung Hyun Lim

Coatings 2018, 8(4), 126; https://doi.org/10.3390/coatings8040126 - 30 Mar 2018

Cited by 3 | Viewed by 7184

Abstract

The results of industrial application of an online X-ray fluorescence coating thickness analyzer for measuring the thickness of phosphate coatings on moving steel strips are considered in the article. The target range of coating thickness to be measured is from tens to hundreds of mg/m² in a measurement time of 10 s. The measurement accuracy observed during long-duration factory acceptance test was 10–15%. The coating thickness analyzer consists of two XRF gauges, mounted above and below the steel strip and capable of moving across the moving strip system for their suspension and relocation and electronic control unit. Fully automated software was developed to automatically and continuously (24/7) control both gauges, scanning both sides of the steel strip, and develop and test methods for measuring new coatings. It allows performing offline storage and retrieval of the measurement results, remotely controlling the analyzer components and measurement modes from a control room. The developed XRF coating thickness analyzer can also be used for real-time measurement of other types of coatings, both metallic and non-metallic. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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9 pages, 17814 KiB

Open AccessEditor’s ChoiceArticle

New Method to Identify Field Joint Coating Failures Based on MFL In-Line Inspection Signals

by Lianshuang Dai, Ting Wang, Caiyan Deng, Qingshan Feng and Dongpo Wang

Coatings 2018, 8(3), 86; https://doi.org/10.3390/coatings8030086 - 27 Feb 2018

Cited by 3 | Viewed by 6144

Abstract

Above ground indirect detections and random excavations that have applied the past years for buried long distance oil and gas pipelines can only identify some damaged coating locations. Hence, large number of field joint coating (FJC) failures happen unconsciously until they lead to failures of the pipelines. Based on the analysis of magnetic flux leakage (MFL) in-line inspection (ILI) signals, combined with the statistical results of 414 excavations from two different pipeline sections, a new method to identify the failed FJC is established. Though it can only identify FJC failures when there are signs of corrosion on pipe body, it is much more efficient and cost-saving. The concluded identification rule still needs more validations and improvements to be more applicable and accuracy. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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8 pages, 1672 KiB

Open AccessArticle

Effects of the Oxide Coating Thickness on the Small Flaw Sizing Using an Ultrasonic Test Technique

by Xiujuan Miao, Xiongbing Li, Hongwei Hu, Guangjun Gao and Shuzeng Zhang

Coatings 2018, 8(2), 69; https://doi.org/10.3390/coatings8020069 - 09 Feb 2018

Cited by 4 | Viewed by 3997

Abstract

When magnesium alloys are tested using ultrasonic techniques, their oxide coating will affect the transmitted ultrasonic energy and the accuracy of the flaw sizing. In this work, the effects of the coating thickness on the flaw sizing are investigated. An ultrasonic measurement model is employed to predict the flaw response signal, and the reflected and transmitted ultrasonic energy in the coated surface are corrected by modifying the reflection and transmission coefficients related to the effects of the coating thickness. The effectiveness of these coefficients and the ultrasonic measurement model are verified through experiments. With the correction of the coating thickness effects, the flaw-sizing curves predicted using the ultrasonic measurement model are provided. The flaws in magnesium alloy specimens with different coating thicknesses are tested, and the determined flaw sizes from these curves agree well with the actual sizes, which reveals the effectiveness of the proposed work. This work provides an effective tool to improve the flaw sizing performance using ultrasonic techniques in practical applications. Full article

(This article belongs to the Special Issue Advanced Nondestructive Evaluation and Characterization of Surface)

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