A technique for acoustic-emission testing of the wheel pairs of a freight-car carriage

A testing technique developed for determining the acceptance levels of different inspected zones of a wheel pair is considered. It has been shown that the acceptance levels are individual for different inspected zones and are set on the basis of the statistical data obtained during the tests of wheel pairs containing flaws detected beforehand. A test record sheet containing coordinates of flaws and comments on their hazard is issued during automated acoustic-emission testing of the wheel pairs of a freight-car carriage.     

Detection of discontinuities of a metal and a protective coating on pipelines

A technique of diagnostic nondestructive testing is proposed that ensures reliable detection of flaws in the interface of the protective coating on pipelines based on discrimination between discontinuities in the coating and the tube metal.     

Processing of active thermal nondestructive testing results by the method of wavelet analysis

Wavelet transforms can be used for active thermal nondestructive testing for the identification of flaws that are located at different depths and produce Gaussian-like signals characterized by a time shift on a heated surface. The results of the application of scalar and complex wavelet analysis for increasing the signal/noise ratio in the active thermal inspection of flaws in composite materials and thermal-barrier coatings, as well as also for revealing the corrosion in metals, are described. Parent Morlét, Paul, and Mexican-hat wavelets were used.     

Structural features of crack formation during corrosion cracking

Stress corrosion cracking (SCC) causes damage to main gas pipelines due to formation and development of cracks on the outer surface of a tube. Prevention of SCC crack development and fracture of a gas pipeline is an important problem of diagnostics that can be solved in various ways. The most effective approach involves systematic use of in-tube nondestructive testing and local testing in shafts, owing to which the position of a flaw and its linear size are determined. The hazard of the flaw (residual life of a tube with cracks) is found and a decision is made about the necessity and methods of flaw repair, such as cutting out the tube, grinding the flaw, and reinsulating the tube surface, and the date of repeated nondestructive testing is set. These measures ensure timely discovery of potentially hazardous flaws and make it possible to take the necessary steps for preventing development of SCC.     

Testing the technical state of gas-transferring unit compressor cases and their repair under the conditions of compressor stations

Problems related to the use of nondestructive testing methods during engineering diagnostics of the cast cases of compressors that are used in gas-transfer units that operate in gas-main pipelines are considered. Features of the renewal of cases with especially large flaws under the conditions of compressor stations are considered. Typical flaws that are detected during diagnostics of natural-gas compressors are systematized.     

In-tube nondestructive testing of main gas pipelines

A complex of auxiliary equipment for in-tube nondestructive testing of main gas pipelines (MGPs) via magnetic flaw detectors is described. A list and schedule of procedures for in-tube inspection of MGPs are presented. Typical flaws in the tube metal of MGPs are studied and classified by the degree of hazard.     

On the quality of examination questions on penetrant testing

The most substantial flaws in examination questions that are used during exams in various educational centers during training and certification of specialists in penetrant testing are considered.     

Improving the sensitivity of the penetrant-dye testing with the help of thermal preprocessing

A method of improving the sensitivity of the penetrant-dye testing through preheat of tested components prior to applying a penetrant liquid is described. The appropriate characteristics have been obtained, and experiments have been conducted on fabricated flaws.     

Recommendations on selection of anode voltages in X-ray testing of steel specimens

The processes of the formation of radiation images of steel objects during X-ray testing are investigated. Linear differential coefficients of X-ray radiation attenuation are calculated using their approximation by a polynomial from the third to the fifth degree. Anode voltages during X-ray testing of steel specimens during the formation of radiation images providing for detection of flaws with sizes of 1 and 2% of the X-rayed thickness are determined.     

Studying sources of acoustic emission during the cooling of a weld seam with the use of cluster analysis

Acoustic-emission (AE) signals localized during cooling of a weld seam were analyzed. The hazard degree of flaws (faulty fusions, cracks in the root of a weld seam, etc.) was studied using cluster analysis in the parameters of AE signals. Flaws were simulated via introduction of titanium and duralumin inserts into a weld seam. The results of metallographic investigations of specimens with artificial and actual flaws were analyzed. Localization of AE signals was performed for the specimens studied, and a time distribution taking into account the clustering of the total count and energy of AE signals was constructed.     

金属材料超声探伤缺陷分类辅助系统的研究

针对在目前工业生产的超声检测中缺陷难以定性的问题,在现有缺陷信号处理和人工神经网络分类研究工作的基础上,基于虚拟仪器的设计思想及功能模块化的设计方法,采用PC机和数据采集卡作为硬件系统,在L abV IEW平台上建立了能对缺陷进行智能识别的系统——金属材料超声探伤缺陷分类辅助系统。系统具有采集金属材料中缺陷回波数据、降噪、特征提取和智能识别缺陷等主要功能。实验结果表明,该系统基本上能自动识别出各类缺陷。     

Classification of flaws in ultrasonic and X-ray testing

Classification of flaws in welded joints during X-ray and ultrasonic nondestructive testing are considered. The consideration is focused on the parameters of flaws that affect the reliability of the tested item. Recommendations are made to improve identification of a flaw’s shape and type via relationships between test signatures and to assess parameters involved in calculations of the strength and service life of a tested item.     

Increasing the reliability of the detection of flaws in complex structures by integrating the information of multiparametric nondestructive testing

The basic principles and methods for integrating information from multiparametric nondestructive testing for the purpose of detecting anomalies, flaws, and damage in different objects and structures are considered. Some experimental data and the results of the development of algorithms for the integration of nondestructive testing techniques that are aimed at solving formulated problems on the basis of telescoping-effect estimation methods and the construction of the multidimensional analogues of inverse probability methods are cited.     

聚乙烯管道电熔焊接接头的超声检测

聚乙烯管连接中大量使用电熔接头,其质量的好坏直接影响管道系统的安全。分析了超声聚焦检测技术对聚乙烯管电熔接头各类缺陷的检出能力。在此基础上,运用相控阵超声技术及B扫描实时成像超声方法检测大量含缺陷接头,对比超声成像图与接头实剖图,发现该方法有较高的检测灵敏度和检出精度,可以应用于工程实践。     

Use of the Harmonic Analysis of an Induction Probe's Signal for Increasing the Information Content of Test Results

The harmonic content of a probe's electromotive force when magnetic testing is conducted with the use of alternating fields is significantly affected by the possible presence of a flaw in the specimen. Magnetic biasing of the specimen with a static field enables identification of internal flaws in addition to surface flaws. The electromotive force's harmonic content depends on the flaw's dimensions and depth. This circumstance can be used to determine these parameters in a separate way. The effect of a gap between the surface of a tested specimen and the probe is significantly weaker on the topography and amplitude of higher harmonics than on the corresponding parameters of the first harmonic. This observation, which holds for both internal and surface flaws, enables testing of larger gaps.     

基于神经网络的压力容器焊缝磁性无损检测的研究

研究了压力容器焊缝磁性无损检测系统。结合压力容器检测的具体要求，设计了检测装置，探讨神经网络的方法在压力容器焊缝缺陷的特征识别应用。应用表明基于神经网络的压力容器焊缝磁性无损检测技术具有重要的应用前景。     

基于神经网络的压力容器焊缝磁性无损检测的研究

研究了压力容器焊缝磁性无损检测系统。结合压力容器检测的具体要求,设计了检测装置,探讨神经网络的方法在压力容器焊缝缺陷的特征识别应用。应用表明基于神经网络的压力容器焊缝磁性无损检测技术具有重要的应用前景。     

STRUCTURAL HEALTH MONITORING OF AN AIRCRAFT JOINT

A major concern with ageing aircraft is the deterioration of structural components in the form of fatigue cracks at fastener holes, loose rivets and debonding of joints. These faults in conjunction with corrosion can lead to multiple-site damage and pose a hazard to flight. Developing a simple vibration-based method of damage detection for monitoring ageing structures is considered in this paper. The method is intended to detect damage during operation of the vehicle before the damage can propagate and cause catastrophic failure of aircraft components. It is typical that only a limited number of sensors could be used on the structure and damage can occur anywhere on the surface or inside the structure. The research performed was to investigate use of the chirp vibration responses of an aircraft wing tip to detect, locate and approximately quantify damage. The technique uses four piezoelectric patches alternatively as actuators and sensors to send and receive vibration diagnostic signals.Loosening of selected screws simulated damage to the wing tip. The results obtained from the testing led to the concept of a sensor tape to detect damage at joints in an aircraft structure.     

Estimating the depth of surface flaws by penetrant testing

Experimental dependences are provided for the time growth of the areas of the indications of surface dead-end and through flaws with openings of 1–15 μm and depths of up to 12 mm during development under penetrant testing of stainless steel samples. A technique is proposed for estimating the depth of the surface flaws using the first derivative of the dependences 100 s after the beginning of development.     

Experience in the ultrasonic testing of fastening studs in the covers of hydraulic units at hydroelectric power plants

The criteria for evaluation of the admissibility of discontinuity flaws under the threads of studs during their inspection from the end face without unscrewing them from their seat in a hydraulic unit frame are experimentally substantiated. A transducer with the optimal parameters that allows one to reveal cracks of minimal depths is selected. Ultrasonic inspection of studs with a hexahedron at the end face is used as an example and the results of the ultrasonic testing of studs with detected cracks are presented.