At present, the detection of tire tread wear mainly relies on manual and mechanical measurement, which has low efficiency and poor accuracy, and it is difficult to meet the requirements. Compared with traditional technology, machine vision technology is favored by scholars due to its high efficiency, high precision, and noncontact advantages. Combined with recent progresses of researches at home and abroad, the tire tread wear detection technology is introduced and its future development trend is predicted, which provides reference for future research.

Residual stress will inevitably be introduced during the manufacture of mechanical components and products. Residual stress has an important impact on component performance and service life. There are many methods for testing residual stress. As a nondestructive testing method, X-ray testing technology has been widely used in engineering due to its mature theory and simple method. The characterization of residual stress is analyzed, and several confusing concepts in the definition and characterization of residual stress are further explained from the perspective of elastic mechanics; the conditions of linear fitting and ellipse fitting are analyzed.

The concrete is one of the most important materials of modern civil engineering, properties and construction quality of concrete structure are directly related to the safety of concrete structure and construction works. Therefore, strengthening the quality of concrete testing and control, is the essential part to ensure the quality of the building(structure).Based on the strength and defect detection of concrete, firstly the basic principles, and applicable scope of nondestructive testing methods for concrete were expounded. And then the application of various methods was analyzed briefly. At last,the development trend and emerging application of nondestructive testing methods for concrete in the future were prospected.

Lithium batteries are widely used in the field of new energy vehicles because of their high energy density, low self discharge rate and long cycle life. Due to the imperfection of lithium battery materials, production processes and other problems, it is easy to have potential safety hazards. This paper summarizes the factors that affect the safety performance of lithium batteries, expounds the defects of lithium batteries into three parts: surface defects, electrode defects and internal defects, introduces the types of defects and appropriate detection methods, and makes a summary comment on the integrated detection of the safety performance of lithium batteries.

Metal additive manufacturing (AM) technology is widely used in aerospace and other advanced industrial fields due to the unique advantage in the rapid forming of complex metal components. However, the defects induced damage behaviors of the AM parts under different service loads and environments are different. Traditional non-destructive testing technology can not dynamically characterize the evolutions of the internal microstructure of materials in real time, while synchrotron radiation X-ray tomography (SR-CT) has many advantages in it, such as strong penetration, high spatial and three-dimensional visualization, etc. Based on the analysis of the principle and characteristics of SR-CT and taking the AM titanium alloy as an example, some typical applications of SR-CT are briefly introduced, such as the quantitative analysis of the size, morphology and distribution characteristics of defects in AM parts, the in-situ observation of defects induced fatigue damage, and the finite element simulation analysis based on three-dimensional imaging data. The broad application prospects of SR-CT based on High Energy Photo Source (HEPS) in the field of AM metal materials are prospected.

In this paper, the common industrial pipes with outer diameters of 219 mm and 273 mm were researched. A variable diameter internal inspection robot was developed for horizontal pipe section, vertical pipe section, elbows, and reducing joints. Three independent track drive modules supported by connecting rods was used to adapt to different pipe diameters and crawling in different postures. A flexible sliding mechanism was used to adapt to small changes of pipe diameter and improve obstacle crossing ability. The pressure between the track and the pipe wall was obtained by several membrane pressure sensors, which was used to control the robot's posture in a closed loop. The experimental results showed that the robot has good adaptability to the environment of industrial pipeline inspection. It could pass horizontal, vertical, elbow and variable diameter pipe sections smoothly, and could carry various inspection modules to inspect industrial pipelines.

With the combination of radiographic evaluation system and artificial intelligence technique based on big data, the intelligent filter of invalid films and duplicate films and the intelligent identification and evaluation of weld defects were realized. It not only effectively improves the deficiency of the method of traditional inspection, but also enhances the quality of inspection and management. In this paper, the gordian methods of image segmentation model in the field of deep learning and classification and identification of weld defects and extraction of comprehensive information of weld and the modules of core algorithm were described. And the feasibility and stability of the radiographic evaluation system were verified by practical engineering projects, which could be a reference for the subsequent large-scale application.

In the field of NDT, with the advantages of real-time, non-contact, high detection accuracy and easy to achieve automation and many others, machine vision is gradually replacing the traditional visual detection for cracks, surface scratches, pits, broken nails and other structural surface damage detection and quantitative characterization. Based on the review of the development of machine vision technology, this paper mainly introduces the research achievements and application progress of machine vision in aircraft structural damage detection in recent years. Combined with the requirements of aircraft structural damage in-situ detection engineering, the development trend of machine vision technology is discussed and prospected.

Single crystal PMN-PT can effectively improve the sensitivity and bandwidth of ultrasonic transducer. This paper introduces a medical ultrasonic phased array transducer based on PMN-PT single crystal material. The transducer is made of PMN-32%(001) single crystal material and designed with two matching layer structure. On this basis, a single crystal transducer was fabricated, and the echo signal test analysis was performed on it. The results show that the center frequency of the developed ultrasonic transducer is about 2.6 MHz, and the -6 dB relative bandwidth is more than 80%. It has good sensitivity and bandwidth.

Aiming at the problem of nondestructive in-situ identification of double clad metal tube in oil industry, a method based on pulsed eddy current for composite metal layer materials identification is proposed. The method takes advantages of pulsed eddy current, such as its wide frequency band and large detection depth, to realize the detection and identification of cladding metal layer by eliminating its shielding effect. In the experiment, pulse eddy current signals of three specimens of copper, iron, and aluminum cladded by stainless steel were acquisited and four characteristics of peak amplitude, peak area, zero-crossing time and decay time were extracted. The result shows that the four characteristics can effectively distinguish magnetic materials (iron) from non-ferromagnetic materials (copper, aluminum), and zero-crossing time can further realize the distinction between copper and aluminum. This research demonstrates that pulsed eddy current is effective for the material identification of composite metal layers, it provides reference for the in-situ identification of double clad metal tube.

As a new inspection method, infrared non-destructive testing (IRT) technology can detect the internal defects of materials and components, evaluate the stress state of materials and achieve rapid prediction of fatigue life, and monitor the operating status and diagnose faults of equipment. This article briefly describes the basic principles of IRT technology, and elaborates the research and application status of IRT technology at home and abroad from the aspects of defect detection, stress detection, fatigue analysis, image processing, and testing and monitoring application. The relevant testing equipment and testing standards, applications of the testing technology at home and abroad were introduced and its development trend was also pointed out.

This paper introduces the component, working principle and application scope of stacked beam imaging system and ROV. Results of the application in the underwater structure inspection of sluice and dam show that they have the technical superiority of wide applicability, high efficiency, clear and intuitive image, thus providing a feasible and convenient method for hazard identification of underwater structure.

The development of ultrasonic phased array technology at home and abroad is reviewed. The achievements of ultrasonic phased array key technology in recent years are mainly summarized. Combined with engineering examples, the applications of ultrasonic phased array in nondestructive testing of nuclear engineering are introduced. Besides, the future development trend and new opportunities of ultrasonic phased array are pointed out.

The basic principle, components and the key performance of industrial computed tomography (CT) imaging technology are introduced in this work. The presentation also includes mechanism of internal defect in parts remanufactured by laser cladding technology and the practical application of industrial computed tomography in the detection of defects such as crack, voids and inclusions. In allusion to interface defect in parts remanufactured by laser cladding technology, research difficulty and prospect for application of industrial CT technique in detecting the defects in remanufacturing interface are discussed.

Technology for residual stress measurement by X-ray is a non-destructive testing method, which has been widely used in engineering because of the features of theoretical maturity, elegant simplicity, and high reliability. X-ray residual stress measurement is based on the elastic mechanics theory on combining the changes of crystal lattice with the elastic mechanics to calculate the residual stress. At the same time, the development of testing equipment and software has simplified the testing process, which has further aggravated the ignorance of testing principles by relevant personnel and increased the risk of the entire testing process. Based on the elastic mechanics such as Cauchy stress, Cauchy strain and Hooke's law, this paper deduces the testing formula of residual stress completely, and analyzes the calculation of the stress tensor under the plane stress and three-dimensional stress with least square method, the examples of “±ψ strain addition and subtraction method” and ellipse fitting method are given. Explained some misunderstood conceptual symbols, pointed out the problems that need to be paid attention to during the test.

During the service of the engine, the compressor blades are damaged by foreign objects, resulting in cracks, falling blocks and other defects, this paper uses the failure analysis method based on fracture analysis technology and energy spectrum analysis technology to find out the mechanism and root cause of compressor blade damage, and puts forward the integrated endoscopic detection and eddy current detection in one monitoring strategy. The typical characteristics of blade damage image and damage detection signal are analyzed through inspection test, and the corresponding relationship between eddy current signal display of defect and actual size is found out, which provides a reference for accurate and reliable quantitative judgment.

Magnetic flux leakage (MFL) testing method has been successfully applied in the inspection of various ferromagnetic materials. However, the development of modern manufacturing technology and new application areas brought new challenges in the testing speed of MFL testing. The distortion of MFL signals in high speed testing limits the testing speed. Therefore, many researchers studied the mechanism of signal distortion and found that the time-lag in magnetization was the main reason to affect the MFL signal. When the steel pipe passing through the magnetizing coil at a high speed, the eddy current will influence the magnetization of pipe wall and further influence the MFL signal. Based on the mechanism study, methods such as increasing coil length and using multi-stage magnetization have been proposed to reduce the distortion of MFL signals at high speed. Velocity induced eddy current testing method and velocity induced eddy current thermography have also been proposed and achieved good results in high speed testing.

A brief analysis is made on the current laboratory accreditation situation for the competence of PAUT in China. A detailed comparison is made of the requirements for personnel in relevant standards for phased array ultrasonic testing at home and abroad. Based on the understanding of special aspects of PAUT and the situation of its application in China,some special requirements on personnel, equipment and control of technique for the laboratory accreditation of PAUT competence are suggested.

Through analysis on the influence of high temperature on the performance of ultrasonic transducers, measures to optimize the selection of wedge and piezoelectric material, as well as the assembly process are proposed to improve the high temperature performance of ultrasonic transducers. The wedge material with slow change of sound Velocity-Temperature and the parameter design according to the velocity of operating temperature are selected to reduce the influence of temperature on transducers angle and position. The piezoelectric material with Curie temperature greater than operating temperature and epoxy with higher glass transition temperature are selected as composite piezoelectric fillers. In order to improve the sensitivity and stability of the transducers in high temperature environment, the probe assembly uses high temperature bonding glue and gradient temperature curing process to improve its service life in high temperature environment. A batch of high-temperature probe performance tests was performed to verify the above analysis results.

The correlation between wave velocity and temperature is the premise and foundation of ultrasonic solid temperature measurement. Due to the complex waveform in solid medium, the wave propagation characteristics are also very complex, and the theoretical formula of wave velocity and temperature when temperature changes has not been given, which greatly limits the accuracy and application range of ultrasonic solid temperature measurement. Therefore, the temperature sensitivity of ultrasonic solid temperature measurement is theoretically analyzed, and a theoretical experimental platform of ultrasonic solid temperature measurement based on acoustic time measurement is built. On this basis, the experimental study on the correlation between wave velocity and temperature is carried out, and the relationship between shear wave velocity and temperature and its influence law are obtained.It provides a basis for ultrasonic solid temperature measurement at high temperature.

In international and domestic standards of phased array ultrasonic testing for welded joints, Time-corrected gain (TCG) calibration are usually required or recommended to be used to compensate the sensitivity of reflectors at different depths, so as to ensure the accuracy of detection result. At the same time, in the corresponding phased array ultrasonic acceptance standard, the acceptance method based on the amplitude and length is mostly adopted, so the accuracy of TCG calibration is the basis of phased array ultrasonic detection application, its importance is self-evident. In this paper, the influence of near field on phased array ultrasonic TCG calibration is analyzed through calculation and comparative test. The research results can provide reference for the selection of probe and wedge and the setting of parameters in phased array ultrasonic testing.

This paper introduces AWS D1.1 and the application process for PAUT of welds. The specific requirements for PAUT of welds in AWS D1.1 are interpreted and its strong operability is revealed. The paper can provide reference for phased array inspection personnel establishment rules and field operation.

Based on the brief analysis of the principle of cold cathode X-ray tube and digital X-ray imaging detection, this paper further introduces the detection of cold cathode X-ray tube in power industry. Through the test of small tube, water-wall tube, buried cable and other components, the feasibility of the application of this technology in the power industry is verified, and the future application of the cold cathode X-ray digital imaging system is also prospected.

Glass Fiber Reinforced Polymer (GFRP) composites are widely used in aerospace and other fields due to their excellent material properties. However, defects generated during the production and usage phases can greatly affect the stability and safety of the GFRP composites. Traditional non-destructive testing methods have certain limitations when they are applied to the internal defect detection of GFRP composites with anisotropic and layered structures. To address the material inspection challenges of GFRP, we have developed a laser ultrasonic inspection system based on a low-frequency air-coupled ultrasonic probe that can retain the high resolution of the laser ultrasonic inspection system with low-cost and high robustness of the air-coupled ultrasonic probe. In this paper, using a hybrid system combining the advantages of laser ultrasound and air-coupled ultrasound inspection, different types of minor defects in glass fiber reinforced composites were non-contact detected using a low-frequency air-coupled ultrasonic probe at 450 kHz, and the results were compared with those of contact ultrasound phased array inspection. The results show that the use of the hybrid system can effectively achieve low-cost, non-contact, high signal-to-noise ratio and high accuracy detection of the shape, size and location of defects in GRFP composites.

Based on acoustic emission (AE) waveform, this paper proposes a method of AE signal classification based on deep neural network and cluster analysis. In order to avoid the difficulty of making AE signal label manually, a large number of measured AE waveforms are used for deep one-dimensional convolutional autoencoder training in an unsupervised learning method to realize the automatic extraction of AE signal characteristics, and then the k-means clustering algorithm is combined to accurately distinguish different types of AE signals. The AE experiments of sudden fracture and friction of lead core on composite plates show that the proposed method can automatically identify different types of AE signals, and the identification accuracy is higher than the clustering method based on the artificial characteristics of AE signals.

Internal inspection data are currently the source of basic data for the integrity management of long distance oil and gas pipelines at home and abroad. The comparison of internal inspection data is the main direction for deep mining and comprehensive utilization of internal inspection data. The development status of internal inspection data comparison at home and abroad was investigated and summarized, and then the main contents of internal inspection data comparison were introduced in detail: comparison of basic information such as girth weld, deformation, metal loss and weld defect comparison, pipeline coordinates. Suggestions on the comparison of internal inspection data were put forward, which has important practical significance for the improvement of theoretical technology.

The crimping quality of strain clamp is directly related to the safety of electric transmission lines. By designing corresponding testing tools and improving testing equipment, this paper successfully adopted the DR technology and tested the crimping quality of the strain clamp, which not only met the relevant standard requirements, but also improved the detection efficiency, thus providing a guarantee for the safety of electric transmission lines.

The graphs of GB standard context and application status are analyzed. What described in the paper should be a beneficial reference for NDT inspectors to use GB/T 37910.2-2019 correctly.

Residual stress will inevitably be introduced during the manufacture of mechanical components and products. Residual stress has an important impact on component performance and service life. There are many methods for testing residual stress. As a non-destructive testing method, X-ray testing technology has been widely used in engineering due to its mature theory and simple method. The qualitative analysis and judgment of possible important influencing factors on the residual stress test results was discussed and the characterization of the error and uncertainty in the residual stress test process was briefly analyzed. The case study to calculate the uncertainty in a single laboratory by using the simplified “two-step method” was given. Finally suggestions on the application of residual stress measurement in failure analysis are also given.

The important load-bearing components in the Integrated Head Package (IHP) system are mainly the lifting tripods. According to the requirement of design document, each component of lifting tripod should be tested by magnetic particle after machining and loading test. Because there are many special-shaped parts, it is necessary to analyze each part to work out reasonable magnetic particle testing technology and select related testing equipment. In this paper, according to the standard test requirements, through parameter calculation and related test, the test process specifications in line with the test standards are worked out. The process code has been applied to the construction practice to provide quality assurance for the localization of the third generation nuclear power.

This paper presents a new method for detecting the stress of ferromagnetic materials. The magnetostrictive properties of ferromagnetic materials are related to the microstructure of the material, which itself changes with its own stress state. According to the hysteresis phenomenon of ferromagnetic materials, stress is applied to the specimen, and the curve of ultrasonic signal amplitude-static excitation current corresponding to the hysteresis loop is obtained by the EMAT platform based on magnetostriction. The characteristic parameters in the curve can be extracted and the characteristic parameter-stress value curve can hence be drawn. Experimental results show that this new method can qualitatively detect the stress state of ferromagnetic materials.

There inevitably exist defects such as pores, microcracks and delamination in C/SiC composites during CVI deposition, resulting in material anisotropy, great acoustic attenuation, and extremely non-uniform microstructure. Therefore, there is hardly any secondary bottom wave appearing during the ultrasound echo test for this material, and the sound velocity cannot be measured by the conventional multiple bottom wave method. This paper proposes a method to measure the sound velocity by using the correlation principle in signal processing, and simulates it with MATLAB to verify the feasibility of the method. The experimental results show that the sound velocity of the six materials is measured by the correlation method, and the error is within 2.5%. Therefore, it is feasible to measure the sound velocity of a C/SiC composite by this method. It has great practical significance for the determination of sound velocity of C/SiC composites.

In order to solve the problem that the location and degree of defects of oil storage equipment such as oil pipeline with cladding layer are not easy to be determined due to corrosion, a set of defect detection system of ferromagnetic materials based on pulse eddy current is developed and designed according to the advantages of wide spectrum and strong signal penetration ability of pulse eddy current detection. Through the design of a new type of detection sensor, the precise measurement of the defect position is realized. Through the quantitative relationship between the time-domain and frequency-domain eigenvalues of the detection voltage signal and the changes of ferromagnetic materials with different thickness, the defect degree of the test piece is determined. The experimental results show that the system can accurately detect the thickness and defect degree of ferromagnetic materials under 20 mm coating layer, which has a certain application value.

This article outlines the advantages of the full matrix capture (FMC) and total focus method (TFM) technology compared to conventional PAUT(phased array ultrasonic testing), explores alternative data acquisition and imaging techniques, and discusses the calibration of key parameters. Some typical application cases were analyzed, which were expected to provide a useful reference for the standardization of the general use of the FMC and TFM technology.

Based on a review of different nondestructive testing methods, we focused on three ultrasonic testing methods for composite insulator defects and analyzed their respective advantages and disadvantages. We also discussed the ultrasonic defect identification method based on the machine learning principle, summarized the advantages of deep learning in ultrasonic defect recognition and prediction, and discussed the three major problems in the ultrasonic testing of composite insulators based on deep learning. Finally, a feasible solution strategy is given, which can provide a technical reference for further research in this field.