Nondestructive Testing Research Research Articles

Non-destructive testing research on the surface damage faced by the Shanhaiguan Great Wall based on machine learning

The Shanhaiguan Great Wall is a section of the Great Wall of the Ming Dynasty, which is a UNESCO World Heritage Site. Both sides of its basic structure are composed of rammed earth and gray bricks. The surface gray bricks sustain damage from environmental factors, resulting in a decline in their structural quality and even a threat to their safety. Traditional surface damage detection methods rely primarily on manual identification or manual identification following unmanned aerial vehicle (UAV) aerial photography, which is labor-intensive. This paper applies the YOLOv4 machine learning model to the gray surface bricks of the Plain Great Wall of Shanhaiguan as an illustration. By slicing and labeling the photos, creating a training set, and then training the model, the proposed approach automatically detects four types of damage (chalking, plants, ubiquinol, and cracking) on the surface of the Great Wall. This eliminates the need to expend costly human resources for manual identification following aerial photography, thereby accelerating the work. Through research, it is found that 1) compared with manual detection, this method can quickly and efficiently monitor a large number of wall samples in a short period of time and improve the efficiency of brick wall detection in ancient buildings. 2) Compared with previous approaches, the accuracy of the current method is improved. The identifiable types are increased to include chalking and ubiquinol, and the accuracy rate increases by 0.17% (from 85.70% before to 85.87% now). 3) This method can quickly identify the damaged parts of the wall without damaging the appearance of the historical building structure, enabling timely repair measures.

Research on photoacoustic microscopy imaging based on photoacoustic transmission matrix with a digital micromirror device

Due to the high penetrability of ultrasonic signals in scattering media, photoacoustic imaging based on photoacoustic effect is of great significance in the research of non-destructive testing and imaging of biological tissues. However, multiple light scattering will occur after the laser is incident on the scattering medium, resulting in poor imaging quality or inability to image. In this paper, we propose a novel method for wavefront shaping and photoacoustic imaging based on a photoacoustic transmission matrix. We use the photoacoustic transmission matrix method as the algorithm for wavefront shaping, and combine the superpixel method with a digital micromirror device (DMD) to modulate the amplitude and phase of the incident light, resulting in an enhancement factor of 10.75 for the photoacoustic signal. Then, we realize photoacoustic scanning imaging by moving the two-dimensional translation stage to drive the absorber above. Compared with the inability to image the initial photoacoustic signal before shaping, the shaped photoacoustic signal can obtain a clear photoacoustic image with a contrast ratio of 16.85. The wavefront shaping and photoacoustic imaging of photoacoustic signals based on photoacoustic transmission matrix method have a good prospect in the imaging of weaker photoacoustic signals.

Method of improve the level of product quality

Abstract Meeting customers’ requirements and achieved the right level of product quality is key action of enterprises. It is being done by controlling the product, using for example non-destructive testing (NDT). But the NDT not indicating what is the root of incompatibility. Additionally, previous research does not include the decision methods, which would be related the identify the causes of the problem as part of improving the product quality. Therefore, the aim is supporting the process of improving the product quality level in the context of precisely identify the incompatibility and the root of their occurrence with including the solve decision problem. In this aim, it was assumed that using after the NDT research in connection way: brainstorming, cause and effect diagram, AHP method (Fuzzy Analytic Hierarchy Process) and the 5Why method, will be allowed on effective identify the root of the problem. The method test was carried out for the porosity on a welded mechanical seal made of steel 410, which was identified by the fluorescence method (FPI) in Podkarpacie enterprise. The analysis has shown the effectiveness of using after NDT the combined methods as part of identifying the incompatibility and precisely identifying the root of its occurrence in context of solving the decision problem. The proposed method can be used to improving the quality of other products, for example from the aviation and automotive industry, as part of meeting customer requirements. Originality is the combined NDT research with quality management techniques and supported the process of improving the quality level of the product by implementing in this sequence the fuzzy multicriteria decision method.

Deconvolution of ultrasonic signals using a convolutional neural network

Successfully employing ultrasonic testing to distinguish a flaw in close proximity to another flaw or geometrical feature depends on the wavelength and the bandwidth of the ultrasonic transducer. This explains why the frequency is commonly increased in ultrasonic testing in order to improve the axial resolution. However, as the frequency increases, the penetration depth of the propagating ultrasonic waves is reduced due to an attendant increase in attenuation. The nondestructive testing research community is consequently very interested in finding methods that combine high penetration depth with high axial resolution. This work aims to improve the compromise between the penetration depth and the axial resolution by using a convolutional neural network to separate overlapping echoes in time traces in order to estimate the time-of-flight and amplitude. The originality of the proposed framework consists in its training of the neural network using data generated in simulations. The framework was validated experimentally to detect flat bottom holes in an aluminum block with a minimum depth corresponding to λ/4.

An intelligent algorithm based on evolutionary strategy and clustering algorithm for Lamb wave defect location

Imaging algorithms for visualization of defects play a significant role in Lamb wave–based research of nondestructive testing and structural health monitoring. In classical algorithms, the position or distribution of defects is located by mapping the amplitude or phase information of signals from the time domain to every discrete spatial grid of the structure. It is time-consuming. In this study, the diversity, statistical, and fuzzy characteristics of the elliptic imaging algorithm are analyzed first; then, an intelligent defect location algorithm is proposed based on the evolutionary strategy and the K-means algorithm. The position of defects can be identified by observing the distribution of individuals. There are six parts in the proposed algorithm, including the data structure design, adaptive population screening, adaptive population reproduction, diversity maintenance mechanism, and cutoff criterion. Considering the statistical and fuzzy characteristics in the detection, several specific input parameters are defined in our algorithm, such as the distance-dependent screening threshold, path-dependent residual vector, and path-independent residual. To maintain the diversity of individuals in the analysis, we have made two adjustments to the evolutionary strategy: one is to optimize the population screening and reproduction steps with the K-means algorithm, and the other is to add a diversity maintenance method into the evolutionary strategy. The effectiveness of the proposed intelligent defect location algorithm is verified by numerical simulations and experiments. Numerical studies indicate that the proposed algorithm has a reliable performance in the detection of defects with different shapes and sizes. In the experimental research, we demonstrate that the efficiency of the proposed algorithm is about 200 times faster than the elliptic imaging algorithm. And the optimum parameter setting of the algorithm is investigated by analyzing the influence of parameter setting on the detection.

On-line Monitoring by Acoustic Emission of Butt Joint Structure on the Composite Fuselage Frame

Acoustic emission (AE) technique is an online and dynamic non-destructive testing technology by diagnosing sounds, applicable to damage identification of all sorts of materials and structures. In order to fulfill the requirement of on-line monitoring for butt joint structure on the composite fuselage frame in static loading, Acoustic Emission (AE) is employed in this article. The experiment research is focused on examining the damage evolution process of the specimen subjected to mechanical tests by constantly monitoring the AE and strain responses. Combined with strain results, the recorded acoustic signals are analyzed using AE characteristic parameters such as AE amplitude and AE accumulative energy to identity five different damage stages and conclude the corresponding damage style during the entire test. The outcomes of this article can be available for supplementation and improvement of the current on-line non-destructive testing research for composite structures.

New insights on ground control in intelligent mining with Internet of Things

The conception of Smart city has been gaining momentum in recent years. Coal mines as a part of city should be characterized with smart or intelligent features. Production and safety are two major themes in coal mining. With the development of automation, Internet of Things (IoT), big data, artificial intelligence, and cloud computing in Fourth Industrial Revolution, Intelligence Mining has been put forward by Chinese Academy of Engineering to achieve the goal of unmanned workface production. However, safety is not highlighted in the novel idea. In this paper, ground control in intelligent mining with IoT is studied. An architecture of ground control with IoT is proposed. The previous research on theoretical modeling and on-site monitoring methods are reviewed. Then the IoT based ground control method is proposed. An on-going dynamic platform on ground control are proposed based on our research of nondestructive testing (NDT) on rock bolt anchorage quality assessment. The research progress is introduced with equipment introduction, principles, and an on-site experiment. Future developments on combination of NDT and IoT of ground control is discussed. The ideas, frameworks, and results in this paper can make efforts on safety control and spark new ideas in the much-anticipated Intelligence Mining.

Geometry-independent attenuation and randomness of ultrasound wave propagation in concrete measured by embedded PZT transducers

Ultrasound is widely used in nondestructive testing (NDT). It is the basis of many NDT techniques, such as acoustic emission, phased array and synthetic aperture focusing technique. The attenuation of ultrasound is a key factor that ensures the feasibility of these techniques. Conventional studies of attenuation are mostly conducted in specimens that have dimensions smaller than ultrasound wavelengths. In this type of study, reflections from media boundaries interfere with the wave, resulting in a geometry-dependent attenuation that cannot be applied in another specimen with a different geometry, even if the material is identical. Another factor that impacts on the viability of ultrasound NDT techniques is the spatial uniformity of waves in the concrete sample. To serve as a reference in testing defects, the degree of randomness caused by the material’s heterogeneity should be estimated in conditions free of defects. In this study, a large concrete specimen was fabricated to suppress boundary reflections of the wave, creating an environment less dependent on geometry. Twenty-two PZT (lead zirconate-titanate ceramics) transducers were arranged in a three-by-seven array to transmit and receive ultrasound waves. This experiment sought to measure attenuation over distance and by frequency, as well as analyzing attenuation factors such as geometrical spreading and material absorption. A quadratic trend with good consistency between attenuation and frequency was found, indicating minimal local attenuation. The degree of randomness in the wave was measured by three indices: amplitude, group velocity and the frequency spectrum cross-correlation factor. Frequency dispersion was also described using group velocity. The findings of this study can serve as a reference for other NDT research, disclosing geometry-independent attenuation and the variability of wave characteristics in concrete.

Comparing the Efficiency of Ultrasonic Infrared Thermography under High-Power and Resonant Stimulation of Impact Damage in a CFRP Composite

The quality control of composite materials remains an important topic of research in nondestructive testing (NDT) of modern materials, in particular, the ones intended for aerospace industry. Over the last decade, there has been a noticeable increase in interest to the ultrasonic stimulation of tested materials and analysis of dynamic temperature distributions. This method is commonly implemented with two techniques, viz. high-power stimulation at a fixed acoustic-signal frequency and low-power resonant ultrasonic stimulation. Results are provided on comparing the above ultrasonic NDT methods using the example of an impact damage in a graphite epoxy-filled composite. The comparison is made based on the criteria of temperature signals, revealed flawed zone, and productivity of testing.

Integrated optical Mach-Zehnder interferometer-based defect detection using a laser-generated ultrasonic guided wave.

The laser-based transmitter used in this Letter is composed of an integrated optical Mach-Zehnder interferometer, which was first used in fault diagnosis. With the help of the effective signal processing method and laser-based integrated optical Mach-Zehnder (IOMZ) system, the location of the defect in an aluminum plate can be successfully determined. Moreover, a comparison study is conducted to investigate the effectiveness of both the conventional laser spot source and the IOMZ interferometer-based laser source. The results indicate that the IOMZ interferometer-based method can be very useful to the nondestructive testing research field. The potential for industrial applications is also significant, especially for the health monitoring and integrity inspection of metal plates.

The effect of the diameter of the detector collimator on saturation thickness in gamma scattering measurement

The effect of the diameter of the detector collimator on the saturation thickness in gamma-scattering measurements is studied using the spectrum of singly scattering. Geometric arrangement of gamma-scattering measurement includes: a gamma-ray collimated beam with the energy of 662 keV emitted from 137Cs source is irradiated on a rectangular aluminium target with incident angle of 90o, and detector NaI(Tl) 5.1cmx5.1cm with collimator is used to record the scatterd gamma rays at scattered angle of 120°. The experimental measurements are carried out to obtain scattered spectra with various target thickness and diameter of detector collimator. The profile of the singly scattering and multiply scattering in the scattered spectra are determined by a spectrum processing technique based on the least squares fitting. The experimental results showed that the saturation thickness of the counts of singly scattering increases with increasing the window diameter of the detector collimator. These results will support for the non-destructive testing research of application of gamma-scattering method to determine the thickness or the defect of the sample.

Fast Detection Method of Rice Storage Quality Based on Machine Olfaction

A fast detection method of rice storage quality was studied in this paper. The smell quality detection of stored rice was as a research object, and the odor data was collected by the gas sensor array. The method of principal component analysis was used for feature dimension reduction. Finally the BP network and stochastic resonance algorithm were used for classification respectively. The test results showed that the correct recognition rate was 93.33% by using the classification method of stochastic resonance. The machine olfaction system proposed in this paper can achieve the purpose of testing the rice storage quality non-destructively, rapidly and accurately, which provides a new way for food quality nondestructive testing research.

Infrared thermography for detection and evaluation of bone density variations by non-stationary thermal wave imaging

Osteoporosis has been characterized as a skeletal disorder of reduced bone strength that leads to an increased risk of fracture. As the age of the person grows, early diagnosis of the disease is necessary to maintain good bone strength and to avoid unbearable fractures. While the disease cannot be reversed, it can be effectively managed by detecting bone density variations. Recently introduced non-stationary thermal wave imaging techniques have gained wide acceptance in the thermal non-destructive testing research community due to their merits over the conventional methods. This paper attempts to test the capabilities of one of the widely used non-stationary thermal imaging techniques to characterize the severity of osteoporosis in the modeled human bone. A 3D finite element analysis has been carried out to model a multilayered bone having different density variations, with tissue, skin and muscle over layers. Obtained results from frequency domain analysis scheme has been studied in order to detect the density variations with improved test sensitivity.

Evaluation of the lift-off robustness of eddy current imaging techniques

The development of lift-off invariant strategies is one of the main goals in Eddy Current Non-Destructive Testing research. In the present work, from the analysis of amplitude and phase signals of magnetic field sensors under Multi-Frequency Eddy Current excitation, two imaging procedures are analyzed and compared with respect to their ability to retrieve reliable results even in presence of huge changes of lift-off. A figure of merit based on the Signal to Noise Ratio evaluated on the 2D reconstructed images allows the comparison of the different strategies in terms of the quality of the image to show the defect. The numerical and the experimental tests realized show that the imaging procedure relying on the analysis of the phase-lag is quite insensitive to changes in the lift-off with respect to that based on the amplitude analysis. In detail the former guarantees good results even when the probe lift-off is randomly changed during the test with variations up to 3mm, while the latter is able to tolerate only lift-off fluctuation lower than 1mm.

Investigation of synthetic aperture methods in ultrasound surface imaging using elementary surface types

Synthetic aperture imaging methods have been employed widely in recent research in non-destructive testing (NDT), but uptake has been more limited in medical ultrasound imaging. Typically offering superior focussing power over more traditional phased array methods, these techniques have been employed in NDT applications to locate and characterise small defects within large samples, but have rarely been used to image surfaces. A desire to ultimately employ ultrasonic surface imaging for bone surface geometry measurement prior to surgical intervention motivates this research, and results are presented for initial laboratory trials of a surface reconstruction technique based on global thresholding of ultrasonic 3D point cloud data. In this study, representative geometry artefacts were imaged in the laboratory using two synthetic aperture techniques; the Total Focusing Method (TFM) and the Synthetic Aperture Focusing Technique (SAFT) employing full and narrow synthetic apertures, respectively.Three high precision metallic samples of known geometries (cuboid, sphere and cylinder) which featured a range of elementary surface primitives were imaged using a 5MHz, 128 element 1D phased array employing both SAFT and TFM approaches. The array was manipulated around the samples using a precision robotic positioning system, allowing for repeatable ultrasound derived 3D surface point clouds to be created. A global thresholding technique was then developed that allowed the extraction of the surface profiles, and these were compared with the known geometry samples to provide a quantitative measure of error of 3D surface reconstruction. The mean errors achieved with optimised SAFT imaging for the cuboidal, spherical and cylindrical samples were 1.3mm, 2.9mm and 2.0mm respectively, while those for TFM imaging were 3.7mm, 3.0mm and 3.1mm, respectively. These results were contrary to expectations given the higher information content associated with the TFM images. However, it was established that the reduced error associated with the SAFT technique was associated with significant reductions in side lobe levels of approximately 24dB in comparison to TFM imaging, although this came at the expense of reduced resolution and coverage.

Development States and Existing Problems Research of Nondestructive Testing of Bolt

As the primary technique to offer safety and productivity improvement s for under- ground project s , rock bolt s have been widely used in t he construction of t raffic and hydro- power stations. The quality of the rock bolt s is of great importance and has been paid a lot of at tention to. This paper reviewed the history of some techniques used for the inspection of rock bolt s and analyzed their t heory and application. It point sout that the t heoretic p roblem is t he primary problem existed in t hese techniques.Nondestructive testing of bolt develops quickly with plenteous accomplishments and experiences.And we state these accomplishments mainly and look into the future.

누설자속센서를 탑재시킨 이동로봇을 이용한 사장교 케이블 비파괴검사 시스템의 현장 적용

In this study, an automated cable non-destructive testing(NDT) system was developed to monitor the steel cables that are a core component of cable-stayed bridges. The magnetic flux leakage(MFL) method, which is suitable for ferromagnetic continuum structures and has been verified in previous studies, was applied to the cable inspection. A multi-channel MFL sensor head was fabricated using hall sensors and permanent magnets. A wheelbased cable climbing robot was fabricated to improve the accessibility to the cables, and operating software was developed to monitor the MFL-based NDT research and control the climbing robot. Remote data transmission and robot control were realized by applying wireless LAN communication. Finally, the developed element techniques were integrated into an MFL-based cable NDT system, and the field applicability of this system was verified through a field test at Seohae Bridge, which is a typical cable-stayed bridge currently in operation.

The Research of Nondestructive Testing of Apple Acidity Based on Near Infrared Spectroscopy

the detection of the apple internal acidity using near infrared reflection spectroscopy is researched in this paper. This paper also elaborates the principle of partial least squares (PLS), and models spectral data by using the partial least squares method. Focuses on the comparison of the single points measurement and multiple points measurement in the Apple’s maximum diameter measurements, gets the following conclusions: a single point spectral scans can not accurately predict the internal acidity of the apple, the experimental precision of the multi-points measurement is higher then the single points measurement. The authors suggest that the measurement of average spectral values by multi-fiber optic probe should be used for the detection of the apple acidity.

A Nondestructive Testing Research Based on Metal Bumper Bar System Inspired by Guided-wave

During the nondestructive testing for metal bumper bar system, it is a critical problem that it cannot identify the reflected wave. Based on the guided-wave inspiration and through studying lots of simulations, this paper systematically analyses the states of quality test for metal bumper bar system in the following four aspects respectively: area inspired by guided-wave, time inspired by guided-wave, head-wave width inspired by guided-wave and rate inspired by guided-wave. The paper also resolves completely the critical problem and completes the subject of quality test. DOI: http://dx.doi.org/10.11591/telkomnika.v10i4.866

Research of Non-Destructive Testing of Wire Rope Using Magnetic Flux Leakage

Based on the magnetic theory, the paper reviewed the factors of affecting the distribution of magnetic flux leakage (MFL) on the ferromagnetic material and analyzed the wire rope defects characters from MFL signal. A non-destructive testing (NDT) instrument of steel wire rope using magnetic flux leakage was presented in this paper. By using permanent magnets to magnetize wire rope and using Hall element arrays to test MFL, Intelligent signal processing was applied for effective discrimination of wire rope’s flaws. The experiment results show the degree and the width of defects, the annular distribution of localized flaws such as concentrated or dispersive broken wires can be well distinguished. The instrument can be used conveniently with good resolution and repeatability and can meet the requirement of real time.