Nondestructive Detection Of Cracks Research Articles

Effect of the void and crack quantity and location on ultrasound: resin experiments and carbon brick validation

ABSTRACT In industrial applications, there is a lack of methods applicable to large-scale, rapid and non-destructive detection of voids and cracks inside carbon bricks. This paper used the ultrasonic testing (UT) A-scan method to investigate the influence of quantity (void fraction:1.4%-4.6%; number of artificial cracks:1–7) and location (five layers) of voids and cracks inside the resin on ultrasonic waves. Both fast Fourier transform (FFT) and synchrosqueezed wavelet transform (SWT) are employed to analyse the amplitude, main frequency and normalised peak time of ultrasonic waves. The results indicate that increased void fraction and number of cracks lead to greater amplitude attenuation, promoting the transition from the fundamental wave to harmonics. Void and crack location symmetrically affect ultrasound amplitude, main frequency, and normalised peak time around the sample centre. Meanwhile, fitting equations are established for the main frequency of the fundamental wave (f 1) in relation to defect quantity. A high-precision quantitative defects detection standard is also developed based on normalised peak time. The validation based on carbon bricks indicates that the derived empirical relations between these parameters and defects can lay the foundation for large-scale and rapid non-destructive detection in carbon bricks.

Application of AIE luminogen-loaded core–shell fibers in self-warning and self-healing polymer coatings with enhanced corrosion resistance

Aggregation-induced emission (AIE) materials have been used for non-destructive visual detection of cracks and damages to prevent the final structural failure and increase the service life of coatings. In this study, a self-warning and self-healing core–shell fiber is synthesized for developing AIE composite coatings. In these core–shell fibers, a mixture of hmethylene diisocyanate (HDI) and tetraphenylethylene (TPE) is used as core constituent, and polyacrylonitrile (PAN) is used for preparing the shell, which are continuously wrapped with a high loading rate through coaxial electrospinning technology. The parameters of electrospinning process are optimized to achieve core–shell fibers with smooth surface and average diameter of 100 ± 50 nm. The composite coating reveals effective fluorescence in case of cracks in a corrosive environment. The maximum self-healing efficiency of the fiber coating is 94.8 % after soaking for 120 h. The introduced composite coating paves the way for improving the safety and reliability of critical engineering components.

Non-destructive methodology for crack detection using machine learning-assisted resonant sensor

Condition monitoring of structures built using metallic supports is a significant issue in structural engineering. Through this work, design, fabrication, and optimization of a dual-scale resonance-based microwave sensor is discussed for monitoring cracks developed over metallic surfaces. These sensors were initially simulated and later fabricated in micro-wave (4.59 GHz) and radio-wave region (418 MHz) for which the power attenuation and frequency shifts were observed. With the structure having crack depth of 2 mm, microwave sensor showed the power shift ∼24 %, while the radio-wave range sensors showed ∼9 %. The corresponding frequency shifts were 2.4 % and 0.85 %, respectively. The microwave sensor (power shift data) showed ∼280 % more sensitivity than the radio-wave sensor. By using dual scale, comprising of both frequency and power shifts, the microwave sensor classification was further improved to 99.72 %, as compared to their individual counterparts. A non-destructive crack detection system in microwave regime is hence demonstrated, which can be further explored for range of crack studies in metallic structures.

Photoacoustic speckle pattern interferometry for detecting cracks of different sizes.

A system and method for non-destructive detection of cracks of different width and depths based on digital speckle interferometry coupled with pulsed laser excitation is introduced and tested. Based on photoacoustic effect, acoustic waves are induced onto the rear of the samples by pumping a pulsed laser beam on it. The generated mechanical wave propagates from the rear surface of the sample to the front while front surface is monitored by speckle interferometry. In order to acquire information about surface deformation, the front surface is illuminated by continuous wave laser and interference are imaged onto the camera as speckle images. After processing the produced fringe patterns, it indicates the presence and location of the cracks in qualitative way. In this study, the system and method mentioned above are validated by detecting medium density fiberboard with simulated cracks. The fringe patterns from areas with or without defects are compared and discussed. Besides, the system and method to distinguish and predict cracks sizes is proposed and validated.

Automatic quantitative recognition method for vertical concealed cracks in asphalt pavement based on feature pixel points and 3D reconstructions

Non-destructive detection and characterisation of concealed cracks in asphalt pavements is a key aspect of ground-penetrating radar (GPR) road maintenance. This paper proposes a method based on feature pixel points to quantify and calculate the vertical height of cracks. Firstly, the team used gprMax to conduct numerical simulations to study the GPR image characteristics of concealed cracks in asphalt pavement with varying lengths and widths. Subsequently, the relationship between the pixel value of the crack area and the two-way travel time was established to obtain the relationship between the vertical height of the crack and the pixel. This study combined with the deep learning model (YOLOv5) allows for the calculation of the vertical height of a crack while simultaneously recognizing it, with the minimum error being only 1.3 %. Finally, concealed cracks were visualized in three-dimensional(3D) by slicing the results of vertical crack simulations of asphalt pavement and observing cloud images, and the principle of computed tomography(CT) was employed to reconstruct 3D models of cracked asphalt pavement and estimate the vertical height of the cracks. This method achieved a minimum error of only 2.9 %. The research presents a theoretical framework for recognizing and more intuitive characterizing concealed cracks in asphalt pavement accurately, enabling it to be used in practical engineering applications.

Non-Destructive Detection of Pipe Line Cracks Using Ultra Wide Band Antenna with Machine Learning Algorithm

In this article, an Ultra-Wide Band (UWB) antenna for the pipeline crack detection process is proposed. A UWB antenna has been designed with the dimension of 32 x 32 mm2 and it resonates from 3 GHz to 10.8 GHz. The designed antenna produces a peak gain of 4.36 dB. A pair of UWB antennas are employed in various pipeline scenarios and the received pulse from antenna 1 to antenna 2 is used for further processing and detection of pipeline cracks. Through the suitable machine learning data classifier algorithm the dimension of the crack has been detected. The various features such as mean, standard deviation (σ), mean average deviation (mad), skewness, and kurtosis have been extracted from the received pulse. Then the three different machine learning algorithms namely Support Vector Machine (SVM), k-Nearest Neighbor (kNN), and Naïve Bayse (NB) were trained and tested using extracted features, and the dimension of the void has been identified. Out of these three machine learning algorithms, kNN provides better accuracy and precision. It predicts the small cracks with 100% accuracy having a dimension as small as 1 mm width.

Fatigue crack detection in edges of thin-walled structures with corners using the fundamental mode of edge waves

Non-destructive detection and evaluation of fatigue cracks is critical to maintain safety and effective operation of high-value assets working under cyclic loading. However, this can be difficult in the case of the corners of the structural elements, especially at inaccessible locations. In this article, the propagation of the fundamental symmetric mode of edge wave (ES0) along structural features such as sharp and rounded corners are investigated using experimental and numerical methods. The ultimate aim of this study is to demonstrate that the ES0 is a promising for defect detection in geometries with corners. The outcomes of this study show that ES0 wave is able to propagate through sharp and rounded corners and provides a way to inspect difficult-to-reach locations. Further, the numerical simulations indicate that the radius-to-wavelength ratio above 3 has no significant impact on the wave amplitude when the ES0 propagates through the rounded corner. The results also demonstrate that the presence of fatigue crack leads to generation of the second harmonic of the ES0 wave mode, and this phenomenon can be utilised in the development of fatigue crack detection and characterization procedures.

Development of a Robotic System for Non-Destructive Crack Detection on Railway Tracks

Development of a Robotic System for Non-Destructive Crack Detection on Railway Tracks

An ultrasonic wave‐based framework for imaging internal cracks in concrete

Nondestructive detection and sizing of internal cracks initiated in reinforced concrete have been critical problems. Geometric characterization of internal cracks and delaminations contributes to predicting their propagation path and failure pattern followed by structural prognostics. There have been limited studies on quantitative detection and characterization of vertical cracks in concrete using wave-based NDE techniques. This study focuses on solving the problem of imaging deep internal crack planes in the concrete medium by leveraging the ultrasonic shear horizontal (SH) waves from a transducer array. Post-processing the array full matrix capture (FMC) data with both total focusing method (TFM) and plane wave imaging (PWI) reveals their efficiency in mapping planar defects inclined between 0° and 60°. However, their performance on vertical/near-vertical defects is found to be inferior with imaging limited to the tip of the defect planes. Further, half-skip modes of wave dispersion have been adopted in addition to the directly scattered pulses for imaging the vertical and near-vertical cracks. We propose an imaging framework based on the outcomes of our investigation on the best suitable methodology to detect and map planar defects like cracks inclined in the range of 0–90°. Statistical quantification of defect inclinations from the reconstructed images is compared to the ground-truth orientations, and they are found to be 94%–99% accurate. Besides accuracy, the computational efficiency of the proposed techniques makes them desirable and reliable for quick on-site inspections on built infrastructure.

Nondestructive diagnostics and detection of subsurface cracks in non-rigid pavements with GPR

Nondestructive diagnostics and detection of subsurface cracks in non-rigid pavements with GPR

Natural Crack Diagnosis System Based on Novel L-Shaped Electromagnetic Sensing Thermography

Nondestructive detection of small fatigue cracks is a critical and challenging task in evaluating the properties of material. This article proposes a novel L-shaped ferrite magnetic open sensing structure of the eddy current pulsed thermography system for fatigue crack inspection on metallic materials with anomalistic geometry. The theoretical derivation model of the proposed structure is developed to generate a guided distribution of electromagnetic field for enhancing the weak thermal signal detection. The proposed detection model provides a region of interest that has relatively uniform magnetic field. This significantly enhances the detectability and thermal contrast of omnidirectional microfatigue cracks. In addition, the detection is completely in the open view of the infrared camera, and the configuration has advantages of dramatically increasing portability and efficiency for detecting complex workpiece. Experiments on natural cracks in several samples have been conducted to validate the reliability and efficiency of the proposed system.

A New Grating Thermography for Nondestructive Detection of Cracks in Coatings: Fundamental Principle

It is important to detect the surface and/or subsurface cracks in coatings because the cracks usually indicate the failure of the system. Conventional detection techniques face two main challenges. One is the locating of the shallow cracks or defects in thin coatings. The other is the detection of the vertical cracks. Conventional infrared thermography can efficiently detect the horizontal cracks or defects. However, when locating the shallow cracks, it requires a high sampling frequency which is unrealistic for most of the infrared cameras. In terms of the vertical cracks, it is invalid since the propagation of its detecting signal is parallel to the cracks and does not interact with them. We introduce a new grating thermography method to overcome the two difficulties. In this paper we mainly illustrate its fundamental principle, which is validated by numerical simulations and a simple experiment. Overall, the principle analysis shows that grating thermography is highly effective in detecting cracks in coatings.

Nonlinearity from stress corrosion cracking as a function of chloride exposure time using the time reversed elastic nonlinearity diagnostic.

The Time Reversed Elastic Nonlinearity Diagnostic (TREND) has a long history of successful nondestructive detection of cracks in solids using nonlinear indicators. Recent research implemented TREND to find stress corrosion cracking (SCC) in the heat-affected zone adjacent to welds in stainless steel. SCC development around welds is likely to occur due to the temperature and chemical exposure of steel canisters housing spent nuclear fuel. The ideal SCC detection technique would quantify the size and extent of the SCC, rather than just locating it, as TREND has been used for in the past. The current paper explores TREND's ability to detect an assumed increase in SCC over time using 13 samples exposed to a magnesium chloride (MgCl2) bath for different lengths of time. The samples are then scanned with TREND and nonlinearity is quantified for each scan point and each sample. The results suggest that TREND can be used to not only locate SCC in the heat-affected zone, but also track an increase in nonlinearity, and thereby an increase in damage, in samples exposed to the MgCl2 solution for a longer duration.

Non-destructive crack detection of preserved eggs using a machine vision and multivariate analysis

Pidan or century egg, also known as preserved egg, is one of the most traditional and popular egg products in China. The crack detection of preserved eggshell is very important to guarantee its quality. In this study, we develop an image algorithm for preserved eggshell’s crack detection by using natural light and polarized image. Four features including crack length, crack state coefficient, maximum projection and angular point are extracted from the natural light image by morphology calculus algorithms. The support vector machines (SVM) model with radial basis kernel function is established using the four features with an accuracy of about 92%. The detection accuracy is improved to 94% by using a new characteristic parameter of crack length on polarization image. The Multi-information fusion analysis indicates the potential for cracks detection by a real-time synthesis imaging system.

Fast Characterization of the Width of Vertical Cracks Using Pulsed Laser Spot Infrared Thermography

In-service non-destructive detection of cracks is a challenging task for industries to prevent failures. In the last decades several methods based on infrared thermography have been proposed to detect vertical cracks. In a recent paper, the authors used a lock-in thermography setup with focused laser excitation to characterize the width of infinite vertical cracks accurately. As this method is very time consuming, we propose in this work to measure the width of an infinite vertical crack using pulsed laser spot infrared thermography. A semi-analytical solution for the surface temperature of a sample containing such a crack when the surface is illuminated by a pulsed Gaussian laser spot close to the crack is obtained. Measurements of the surface temperature on samples containing calibrated cracks have been performed using an infrared camera. A least square fit of the surface temperature is used to retrieve the thickness of the crack. Very good agreement between the nominal and retrieved thickness of fissure is found, even for widths down to 1 $$\upmu $$ m, confirming the validity of the model.

Implementation of Nondestructive Crack Detection System for Automotive Press Panel

The first nondestructive crack detection system using acoustic emission (AE) parameter in the AE method for automotive press panels is presented. The cost damage caused by all inspections is worse, recently in the automotive industry. In this paper, a real-time crack detection system with the AE method that is especially produced for the automotive industry is demonstrated. The main purpose of this system is to correctly detect a crack during an ongoing process that operated seven times a minute. The system consisted of two parts: 1) the hardware and 2) digital signal processing part. The software part consisted of the AE parameter analyzer, which used the LabVIEW program. The AE was continuously monitored during the test using a sensor with a sampling rate of 300 kHz. A dome height test was employed for a laboratory measurement. The crack occurrence tendency was measured using a data acquisition system with a sampling rate of 300 kHz and a 20-dB preamplification. As a result, the maximum received frequency is 150 kHz with 120 W of power consumption according to the field test. The operating temperature ranges from −40 °C to +85 °C, considering the severe press factory environment for automotive with 1 s for analyzing the data. This research found a promising technique for improving a crack detection system based on experimental results, which showed that the duration of the AE parameters had a high probability of success.

Scanning Acoustic Microscopy Beyond Conventional Applications

The ultimate aim in the development of concepts, methods and architectures in microelectronic technologies is the continuous reduction of lateral dimensions by increasing integration density, functionality and processing performance of electronic and microelectronic components. Recent trends therefore employ all three spatial dimensions for further increasing integration density and functionality. Novel challenges and additional requirements on the physical and electrical behavior arising from these integration concepts result in the need for specifically adapted compositions and materials. Also existing testing methods are likely compromised due to challenges of either their resolution capabilities or the underlying contrast mechanisms. As novel architectural concepts require the development of appropriate processing technologies the robustness, reliability and performance of the individual processing steps are of superior importance with respect to their global applicability and thus require comprehensive evaluation prior to introduction into industrial manufacturing. In process development, quality assessment, failure analysis and others inspection methods operating non-destructively are of major importance. The application of multiple tests employing a variety of contrast mechanisms is extremely valuable for assessment, defect localization and evaluation. Scanning acoustic microscopy (SAM) employ elastic waves that interact with a specimens mechanical properties. With the elastic waves capability of penetrating optically opaque materials acoustic microscopy enables the assessment of internal structures and features and allows the depth specific assignment. The contrast mechanism is based on the wave interaction with gradients in either elastic properties or mass density and can be evaluated both quantitatively and qualitatively. The properties of the elastic waves employed by the acoustic microscope can be adjusted and specifically adapted to the requirements of the inspection task. This provides a high degree of freedom for acoustically based analyses and makes SAM a valuable and powerful tool for non-destructive evaluation and assessment. Limitations and challenges of current conventional acoustic microscopy for the inspection of novel 3D-integration concepts mainly have their origin in the lateral resolution required for imaging feature sizes in the low micrometer range. However, in some cases phenomena are required that cannot be exploited easily and may require an adapted set-up for acoustic insonation. In a broad range of applications additional and specifically adapted signal analysis can be of high values for the detection and identification of defects and deviations. The current paper focusses on scanning acoustic microscopy and its applications and challenges as non- and semi-destructive testing method for 3D integration but also for microelectronic and wafer bonding technologies. The development and modification of an acoustic GHz-microscope and its application for inspection of 3D-relevant technologies is described. With lateral imaging resolutions of 1 µm and below TSVs of 10 µm diameter have been inspected for filling-voids and rim-delaminations. Due to the large numerical apertures employed in the GHz-SAM wave modes like Rayleigh- or shear modes can be excited in addition to the pure compressional wave component potentially providing access to new contrast phenomena. For assisting result interpretation however, modelling and numerical simulation of the complex wave propagation became necessary and will be described. The high sensitivity to surface and near-surface structures is illustrated by the detection and localization of sub-surface µ-cracks describing the value of acoustic GHz-microscopy for non-destructive crack detection in near-surface regions of highly integrated microelectronic components. In additionally to GHz-SAM conventional scanning acoustic microscopy supplemented by signal analysis approaches operating in time- and spectral domain and their value for defect localization and evaluation will be presented.

Development of the antipodal Vivaldi antenna for detection of cracks inside concrete members

ABSTRACTUltrawide band (UWB) nondestructive testing and evaluation techniques can provide the detection of defects and damages in construction materials and members. The development of UWB antennas with proper dimensions and high performance for these systems is one of the major challenges. In this letter, an antipodal Vivaldi antenna (AVA) has been developed to be used in UWB techniques for nondestructive detection of cracks in concrete members. To obtain a desirable antenna performance including the wider impedance bandwidth, the higher directivity, and higher front‐to‐back ratio rectangular‐shaped slits (RSS) and a half‐circular‐shaped lens (HCSL) have been added in the design of a conventional tapered slot AVA. A parametric study on the dimensions of the slits is provided to optimize performance and size of the proposed antenna. The optimum size of the proposed antenna is 40 × 80 × 0.508 mm3, and it operates over the frequency range from 3.4–40 GHz. It is shown that the RSS increase impedance bandwidth especially at the lower frequencies. Directivity of the proposed antenna at higher frequencies has been increased by the HCSL. The feasibility of the proposed antenna for nondestructive evaluation of concrete members is demonstrated by investigation into its performance with concrete specimens possessing an air‐gap inside a concrete specimen. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1573–1578, 2015

Nondestructive detection of cracks near the surface of wooden boards by dynamic heat dissipation

A method to detect cracks near the surface of wooden boards has been developed where the change in surface temperature of the wood sample is monitored using an infrared camera following momentary heating by a flash. Cylindrical holes simulating cracks were drilled into the wood samples, and blackbody paint was painted onto the surface of the samples to assist flash absorption. This method uses the dynamic heat transport process from the blackbody paint to the surface of the wood sample to the cracks over a short timescale. The theoretical foundations of the observation method were outlined, and the technique was verified in experiments with samples of Cercidiphyllum japonicum, Western red cedar, Japanese cedar, Balsa, and medium-density fiberboard. The developed technique is able to detect the presence of holes located near the surface of some samples. However, this method could not detect the presence of holes in Balsa nor holes located deeper than 1 mm from the surface of the sample. A theoretical analysis of these phenomena was provided to help interpreting them.

Research on NDT System of Steel Bar Crack

With the rapid development of society, the demand for steel production is increasing, and the demand of the bar’s quality is getting higher and higher. However, what is constraining the production efficiency of the Bar industry is that the development of NDT of surface crack on the bar is unpleasant. This paper presents a new NDT method which is machine vision-based and fully automatic, and designs an application system which is more viable and practical. The bar non-destructive crack detection system use the Industrial Control Computer as Master Parts. Combine with the CCD image acquisition and the PLC control of the pipeline as a whole. This system utilizes Testing Technology of Fluorescent Magnetic particle, realize machine recognition through the Digital Image Processing Technology. What’s more, this system use the set method of adaptive threshold based on probability of detection and false alarm probability in machine recognition. It has a significant and Practical significance for reducing the computation of the system, improving the processing speed of this system, and meeting the needs of the entire system in real-time requirements.